WO2015178458A1

WO2015178458A1 - Adsorption material for adsorbing membrane-fouling-causing substance, water treatment method using same, and method for regenerating adsorption material

Info

Publication number: WO2015178458A1
Application number: PCT/JP2015/064635
Authority: WO
Inventors: 祐貴立花; 圭介森川; 寛山村; 義公渡辺
Original assignee: 株式会社クラレ; 学校法人中央大学
Priority date: 2014-05-23
Filing date: 2015-05-21
Publication date: 2015-11-26

Abstract

　Provided are: an adsorption material for adsorbing membrane-fouling-causing substances, the adsorption material efficiently adsorbing membrane-fouling-causing substances for membrane filtration, particularly biopolymers such as polysaccharides and proteins; a water treatment method in which the adsorption material is used; and a method for regenerating the adsorption material. The adsorption material includes a first polymer which contains a cationic group, wherein the adsorption material is used for adsorbing membrane-fouling-causing substances, has a region in which the cationic group density is 10-30 mmol/g, and has adsorptive capacity with regards to membrane-fouling-causing substances. The water treatment method is provided with at least an adsorption step for bringing water to be treated, which contains a membrane-fouling-causing substance, into contact with an adsorption material and causing the membrane-fouling-causing substance contained in the water to be treated to be adsorbed by the adsorption material. In the method for regenerating an adsorption material, an adsorption material to which a membrane-fouling-causing substance is adsorbed is brought into contact with a cleaning fluid heated to 40°C or above and regenerated.

Description

Membrane fouling causative adsorbent, water treatment method using the same, and adsorbent regeneration method

Related applications

This application claims the priority of Japanese Patent Application No. 2014-106855 filed on May 23, 2014 and the priority of Japanese Patent Application No. 2014-204547 filed on October 3, 2014. Cited as part of this application.

The present invention relates to a membrane fouling-causing substance adsorbing material that adsorbs a membrane fouling-causing substance (hereinafter sometimes simply referred to as a fouling-causing substance), a water treatment method using the same, and a method for regenerating the adsorbing material.

When water treatment is performed on raw water obtained from a natural environment or an artificial environment, organic carbon usually exists in such raw water, and dissolved in water dissolved in these organic carbon. Organic carbon (dissolved organic carbon, hereinafter referred to as DOC: Dissolved Organic Carbon) is included. According to Patent Document 1, DOC is a term encompassing organic carbon, organic colorants, and natural organic substances, and humic acid and fulvic acid, which is a mixture of organic compounds formed by decomposition of plant residues. This term also includes such humic substances. According to Patent Document 1, since the main compounds and materials constituting DOC are soluble, they cannot be easily separated from water. And in patent document 1, a. Adding an ion exchange resin having a cationic group to water containing dissolved organic carbon; b. Dispersing the resin in the water to allow adsorption of the dissolved organic carbon onto the resin; and c. The present invention proposes a method for removing dissolved organic carbon from water by separating the cationic resin loaded with the dissolved organic carbon from the water.

On the other hand, in membrane filtration, a phenomenon called membrane fouling, in which substances present in the supplied water adhere to the membrane surface and pores in the membrane, is a problem. In recent years, detailed analysis on fouling substances in membrane filtration has been made. In Non-Patent Document 1, the causative substance of physically irreversible membrane fouling is hydrophobic having an aromatic ring such as humic acid or fulvic acid. It has been reported that biopolymers such as polysaccharides and proteins, which are dissolved organic substances having relatively higher hydrophilicity than substances, are the main causes.

As for the adsorption removal technique of the causative substance of physically irreversible membrane fouling, for example, in Patent Document 2, zeolite or activated carbon is exemplified as an adsorbent, and the treated water from which TEP (transparent exopolymer particles) has been removed is heated, A method for regenerating an adsorbent used as washing water has also been proposed.
However, in the invention of Patent Document 2, since the scale component contained in the treated water adheres to an inorganic substance such as zeolite, the inorganic substance cannot be washed as a result.

Regarding the removal technology of biopolymers such as saccharides and proteins, for example, in Patent Document 3, particles made of a cationic polymer are added to water to be treated and adsorbed, and the water to be treated having been adsorbed is separated by a separation membrane. A method of separation processing has been proposed.

On the other hand, Patent Document 4 includes a pretreatment device having a pretreatment membrane that filters turbid components in raw water, and a reverse osmosis membrane device that produces fresh water by removing salt from the filtered water from the pretreatment device. Regarding the desalination apparatus provided, a method is described in which the pretreatment membrane is back-washed using the produced fresh water and chlorine.

Japanese National Patent Publication No. 10-504995 JP 2013-56286 A Japanese Patent No. 5282864 JP 2011-31121 A

However, in any of the cationic adsorbents of the inventions of Patent Documents 1 and 3, there is no description of adsorbing a membrane fouling-causing substance by paying attention to a specific cation group concentration. Moreover, in the cationic adsorbents described in Patent Documents 1 and 3, the cationic group concentration cannot be increased.

Further, the particles made of the cationic polymer disclosed in Patent Document 3 have a particle size in water of about 10 to 200 times (that is, 1000 to 200000%) with respect to the particle size when not swollen with water. Since it has extremely large swellability, it is not easy to handle during adsorption and regeneration.

Further, in the invention of Patent Document 4, it is only described as a pretreatment membrane for filtering the pollutant, and no specific treatment membrane is described.

An object of the present invention is to provide a membrane fouling-causing substance adsorbent and a water treatment method for efficiently adsorbing membrane fouling-causing substances in membrane filtration, particularly biopolymers such as polysaccharides and proteins, in treated water. is there.
Another object of the present invention is to adsorb membrane fouling causative substances that efficiently adsorb membrane fouling causative substances in membrane filtration, particularly biopolymers such as polysaccharides and proteins, even when the water to be treated contains salts. It is to provide a material and a water treatment method.
Still another object of the present invention is to provide a method for regenerating an adsorbent that can efficiently regenerate the adsorbent at a low cost.

As a result of intensive studies to solve the above problems, the present inventors have found the following points. That is, generally used cationic adsorbents can adsorb organic substances in water that are negatively charged in nature, but these cationic adsorbents increase the density of cationic groups. There has been no study on the effect of such density on the adsorption of membrane fouling substances. However, surprisingly, in the adsorbent, the density of the cationic group is 10 mmol / g to 30 mmol / g (the content of the cationic group is 10 to 30 mmol per gram of the dry weight. Applying an adsorbent with a region that is dry weight.) Cationic groups function cooperatively in the treated water, so membrane fouling-causing substances, especially biopolymers such as polysaccharides and proteins, can be efficiently Adsorption materials having a region where the density of the cationic group is 10 mmol / g to 30 mmol / g can be adsorbed, and the cationic group is cooperative even in treated water that contains salts and competes for adsorption of ionic components. Have been found to be able to efficiently adsorb membrane fouling-causing substances, especially biopolymers such as polysaccharides and proteins. It was completed a light.

That is, the first configuration of the present invention is an adsorbent containing a first polymer (or cation group-containing polymer) containing a cationic group, and the adsorbent has a cationic group density of 10 mmol. The film fouling-causing substance adsorbent has a region of / g to 30 mmol / g, preferably 11 mmol / g to 28 mmol / g, and has an adsorption ability for the film fouling-causing substance.

The cationic group is, for example, at least one selected from an amino group, a quaternary ammonium group, an imino group, an amidine group, a guanidino group, an imidazole group, a quaternary imidazolium group, a pyridyl group, and a quaternary pyridinium group. It may be a functional group.

Specifically, the first polymer may be at least one polymer selected from polyethyleneimine, polyallylamine, polyvinylamine, polyamidine, polyguanidine, polyamino acid, polypyridine, and salts thereof. .

The adsorbent may be an adsorbent in which the first polymer is introduced into the base material. For example, the adsorbent may be an adsorbent in which a first polymer is introduced into a base material having a predetermined shape by coating, impregnation, or the like; It may be an adsorbent introduced by being copolymerized as a copolymerization component; or it may be introduced by alloying the first polymer with a base material by mixing, kneading or the like. It may be an adsorbent.

The adsorbent may contain a second polymer in addition to the first polymer. For example, the adsorbent may be a polymer adsorbent in which the first polymer is introduced into a base material made of the second polymer.
Preferably, the second polymer constituting the base material may be a hydrophilic polymer, and particularly preferably, the second polymer may be an ethylene-vinyl alcohol copolymer.

In the adsorbent, the degree of swelling in water at 25 ° C. may be 20 to 500%, preferably 30 to 250%.

In the adsorbent, the membrane fouling-causing substance may contain a biopolymer. Here, the biopolymer is A fraction measured by the method described in Stefan A. Huber et al. Water Research 45 (2011) pp879-885, for example, retention time by LC-OCD is 25 minutes or more and 38 minutes or less. May be a component.

In the second configuration of the present invention, the water to be treated containing the membrane fouling cause substance is brought into contact with the adsorbent at the first contact temperature, and the film fouling cause substance contained in the water to be treated is adsorbed by the adsorbent. A water treatment method comprising at least a process.
The water treatment method may further include a membrane filtration step for subjecting the adsorption treated water obtained by the adsorption step to a membrane filtration treatment. The membrane filtration step includes an ultrafiltration (UF) membrane, a microfiltration ( MF) membranes, nanofiltration (NF) membranes, and reverse osmosis (RO) membranes may be used in one or more stages using at least one membrane selected from the group consisting of.

In the above water treatment method, the water to be treated may be water containing 0.1% by mass or more of salts. Examples of the salts include various alkali metal salts and alkaline earth metal salts, and sodium chloride may be particularly preferable. The salt concentration of the water to be treated may be, for example, 60% by mass or less. Alternatively, the sodium chloride concentration may be 27% by mass or less.

The water treatment method may further include a regeneration step in which the adsorbent that has adsorbed the membrane fouling-causing substance in the adsorption step is brought into contact with and regenerated at the second contact temperature. The second contact temperature may be higher than the first contact temperature. The second contact temperature may be 40 ° C. or higher.

Further, according to a third configuration of the present invention, a membrane fouling causative substance that regenerates the adsorbent by bringing the adsorbent adsorbing the membrane fouling causative substance into contact with a cleaning fluid heated to 40 ° C. or higher. This is a method for regenerating the adsorbent.

Various fluids can be used as the cleaning fluid, and for example, an aqueous solution containing metal ions may be used.

With the adsorbent of the present invention, it has been difficult to remove membrane fouling from the water to be treated, particularly polysaccharides and proteins that are considered to cause physical irreversible membrane fouling. The biopolymer can be efficiently adsorbed and removed in the water to be treated. Accordingly, it is possible to suppress the occurrence of membrane fouling, particularly physically irreversible membrane fouling, and maintain the water permeability of the filtration membrane for a long period of time. In particular, the adsorbent of the present invention is advantageous in that membrane fouling-causing substances can be removed even from water to be treated containing salts that has been difficult to adsorb.

In addition, when having a predetermined degree of swelling, the adsorbent can also be efficiently packed into a column. For example, in that case, in the water treatment method, the water permeability of the filtration membrane can be maintained over a long period of time by a simple method by combining the causative substance removal step using a column and the membrane filtration step.

Hereinafter, the present invention will be described in detail based on embodiments. In addition, embodiment described below does not limit this invention.

[Adsorbents capable of adsorbing substances that cause membrane fouling]
The adsorbent according to the first aspect of the present invention includes a cationic group-containing polymer containing a cationic group as the first polymer, and the adsorbent has a density of the cationic group of 10 mmol / g to It has a region that is 30 mmol / g. Since this adsorbent has an adsorbing ability for a membrane fouling-causing substance, it is useful as a membrane fouling-causing substance adsorbent.

(Adsorbent)
The adsorbent of the present invention contains a cation group-containing polymer as the first polymer, and has a region where the density of the cationic group is 10 mmol / g to 30 mmol / g derived from the first polymer. is doing.
Although the mechanism by which the adsorbent of the present invention acts is not clear, the following mechanism is presumed. (I) Many organic substances in water that are normally present in nature are negatively charged and can be removed with an adsorbent having a cationic group. (Ii) Commonly used cationic adsorption The material cannot remove organic matter in water efficiently even if it has a cationic group because the density of the cationic group is not high. (Iii) On the other hand, when the present inventors applied an adsorbent having a region where the density of the cationic group is 10 mmol / g to 30 mmol / g, the cationic group cooperates in a high concentration phase of the cationic group. Because of its function, it can efficiently adsorb membrane fouling-causing substances, especially biopolymers such as polysaccharides and proteins. (Iv) In particular, when there is a region where the density of the cationic group is high, the cationic group functions cooperatively even in treated water that contains salts and competes for adsorption of ionic components. For this reason, the aforementioned membrane fouling-causing substances (particularly biopolymers such as polysaccharides and proteins) can be adsorbed efficiently.

[Cationic group-containing polymer]
The adsorbent of the present invention contains a cation group-containing polymer as the first polymer, and the adsorbent of the present invention is derived from the cation group-containing polymer and has a density of cationic groups of 10 mmol / g to It has at least a part of a region (that is, a cationic group high concentration phase) that is 30 mmol / g (the content of cationic groups per gram of dry weight is 10 to 30 mmol).
As the cationic group, a nitrogen atom-containing cationic group [for example, amino group (primary amino group, secondary amino group, tertiary amino group), quaternary ammonium group, imino group, amidine group, guanidino group, imidazole group Quaternary imidazolium group, pyridyl group, quaternary pyridinium group], sulfonium group, phosphonium group and the like. They may exist in a salt state. These functional groups may be present alone or in combination of two or more. Among these, preferred functional groups include nitrogen atom-containing cationic groups, and more preferred functional groups include amino groups, quaternary ammonium groups, and salts thereof.

The cationic group-containing polymer is not particularly limited as long as a specific cationic group density region can be formed in the adsorbent, and is preferably composed of a typical element, more preferably a carbon atom, a hydrogen atom, or a nitrogen atom. , A sulfur atom, a phosphorus atom, and an oxygen atom, and more preferably a carbon atom, a hydrogen atom, a nitrogen atom, and an oxygen atom.
For example, preferable cationic group-containing polymers include polyethyleneimine, polyallylamine, polyvinylamine, polyamidine, polyguanidine, polyamino acid, polypyridine, and salts thereof. Such polymers may be used alone or in combination of two or more. Among these, more preferred cationic group-containing polymers include polyethyleneimine, polyallylamine, and polyvinylamine, and particularly preferred cationic group-containing polymers include polyethyleneimine and polyallylamine.

The density of the cationic group can be calculated based on, for example, the number of cationic groups (N) per unit molecular weight (M) (g / mol) of the polymer from the skeleton structure of the cationic group-containing polymer (the following formula) ).
Cationic group density = (N / M) × 1000 (mmol / g)
The density of the cationic group is not particularly limited as long as it is 10 mmol / g to 30 mmol / g, but is preferably 11 mmol / g to 28 mmol / g, and particularly preferably 12 mmol / g to 25 mmol / g. If the density of the cationic group is less than 10 mmol / g, the cationic group cannot function cooperatively in the water to be treated (especially, the water to be treated containing salts). There is a possibility that the adsorption rate of the substance is insufficient and the water permeability of the filtration membrane is poor. When it exceeds 30 mmol / g, it becomes difficult to produce a cationic group-containing polymer.
In addition, when the adsorbent is formed of a copolymer having a cationic group-containing polymer as a polymer component (for example, a block copolymer or a graft copolymer), the cationic group density is determined based on the polymer component. It can be calculated based on the skeletal structure.

The calculation example of the cationic group density at the time of using a polyethyleneimine is shown. Since polyethyleneimine is synthesized by ring-opening polymerization of aziridine, the unit molecular weight of the unit structure can be calculated based on the composition formula (C ₂ H ₅ N ₁ ) of aziridine. The number of cationic groups (N) present in the unit structure is 1. Therefore, the cationic group density can be calculated by the following formula.
Polyethyleneimine cationic group density =
(1 / 43.070) x 1000 (mmol / g) = 23.218 (mmol / g)

On the other hand, a calculation example of the cationic group density when chitosan is used is shown. The structural formula of chitosan is shown in the following general formula (1). Chitosan has a composition formula of unit structure of C ₆ H ₁₁ O ₄ N ₁ and has one amino group as a cationic group for each unit structure. Therefore, the unit molecular weight (M) is 161.1558 g / mol, and the number of cationic groups (N) is 1. Therefore, the cationic group density can be calculated by the following formula.
Chitosan cationic group density =
(1 / 161.1558) x 1000 (mmol / g) = 6.205 (mmol / g)

Regarding the method for estimating the cationic group density, in addition to the above calculation based on the skeleton structure of the cationic group-containing polymer, a method according to the following procedure is also possible. For example, the adsorbent samples of a given amount was added to 4% NaOH aqueous solution, after stirring, a cationic group OH ^- replacing the mold cationic groups. Next, after thoroughly washing the resin after the exchange to OH ⁻ type with ion exchange water, this adsorbent is added to 4% HCl aqueous solution, and after stirring, the cationic groups are exchanged with Cl ⁻ type cationic groups. To do. After the exchanged adsorbent is sufficiently washed with ion-exchanged water, a cross section of the adsorbent is cut out to produce a section having a predetermined size. The section was analyzed by transmission electron microscope (TEM) -energy dispersive X-ray spectroscopy (EDX) (for example, JEM-2100F, JED-2300T manufactured by JEOL). If it is uniform, arbitrary 5 points are selected, and if it is a phase separation structure, 5 high concentration phases are selected at random, and the Cl / C molar ratio is calculated.

Regarding the elements other than carbon atoms in the adsorbent sample, the molar ratio of each atom to carbon atom is grasped at the above-mentioned 5 points (or 5 points corresponding to selected sites), and the unit is based on these molar ratios. The cationic group concentration per molecular weight may be calculated by the following formula.
Cationic group density = 1 / [(1 / X) x (atomic weight of carbon atom) + {(molar ratio of target atom to carbon atom) x (total weight of target atom)}]

For elements other than carbon atoms, various analysis methods may be used as long as the molar ratio of the target atom to carbon atoms can be calculated. For example, in addition to the above-described TEM-EDX, mass spectrometry, You may determine the molar ratio of the object atom with respect to a carbon atom by various analyzes, such as an infrared absorption spectrum, a Raman scattering spectrum, and NMR.

For example, when the Cl / C molar ratio is X, the N / C molar ratio is Y, and the H / C molar ratio is Z, the cationic group concentration can be estimated by the following formula.
Cationic group density = 1 / {(1 / X) × C _C + (Y / X) × C _N + (Z / X) × C _H } × 1000
(Wherein C _C is the atomic weight of the carbon atom, C _N is the atomic weight of the nitrogen atom, and C _H is the atomic weight of the hydrogen atom)
It is possible to estimate with.
Specifically, the cationic group is Cl ^- polyethylene imine exchanged to mold cationic group (Cl / C molar ratio 0.5, N / C molar ratio 0.5, H / C molar ratio 2.5) In the case of a model, the cationic group density calculated from this is 23.21, which is substantially the same value as described above.
By this method, the density of the cationic group can be calculated even in a commercially available adsorbent whose skeleton structure is not clear.

If the distribution of Cl is uniform, the cation group density may be calculated by the following formula using the ion exchange capacity of the adsorbent, and may be used as an alternative value.
Cationic group density = ion exchange capacity (meq / ml) × resin dry weight per volume (ml / g)

If it is difficult to measure the density of the cationic group based on the skeleton structure in the adsorbent, for example, the present invention is an adsorbent including the first polymer containing a cationic group as one aspect, adsorbent, a cationic group Cl ^- in a state where the exchanged type cationic groups, on sections of a predetermined shape, a transmission electron microscope (TEM) - energy dispersive X-ray spectroscopy Cl measured by (EDX) / A film fouling-causing substance adsorbent having at least a region having a C molar ratio of 0.2 to 0.65 and having an adsorption ability for the film fouling-causing substance may also be included. For example, the Cl / C molar ratio may be about 0.2 to 0.65, preferably about 0.25 to 0.6, and more preferably about 0.28 to 0.55.

Further, the unit skeleton has a carbon atom and a hydrogen atom as main elements other than the cationic group, and preferably has other elements as desired. For example, in the unit skeleton, other elements for the carbon atom (for example, , Oxygen atoms, etc.) may be, for example, 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, and even more preferably 0.2 or less.

When the measurement sample shows a phase separation structure, the region having the predetermined range of Cl / C molar ratio may be about 1 to 70% as a ratio of the high concentration phase to the entire measurement area in the Cl mapping. Alternatively, it may be about 5 to 65%, more preferably about 8 to 60%.

The form of the adsorbent of the present invention is not particularly limited as long as it contains a cationic group-containing polymer. For example, the adsorbent may be a polymer adsorbent in which the cation group-containing polymer itself has both a base material function and an adsorptive function and constitutes the adsorbent as a simple substance. For example, such an adsorbent may be a polymer adsorbent obtained by insolubilizing a liquid or solid containing a cationic group-containing polymer by crosslinking or the like. Crosslinking can be carried out by known or conventional means, and for example, it may be carried out using a crosslinking agent described later.

On the other hand, the adsorbent may be formed in combination with a cationic group-containing polymer and a base material or another substance. In this case, the adsorbent of the present invention is derived from the cationic group-containing polymer and has at least a part of a region where the density of the cationic group is 10 mmol / g to 30 mmol / g (that is, a cationic group high concentration phase). Have. For example, the cation group-containing polymer contained in the adsorbent may be applied or introduced as a mixture of a cation group-containing polymer and another substance, or a cation group-containing polymer as long as a predetermined cationic group density can be achieved. It may be a material that has been removed.

[Base material]
The adsorbent of the present invention may be an adsorbent containing a cation group-containing polymer and a substrate. For example, the adsorbent may be an adsorbent in which a cation group-containing polymer is introduced into a substrate by coating, impregnation, or the cation group-containing polymer is copolymerized or alloyed in a substrate. It may be an adsorbent introduced by, for example.
The substrate is not particularly limited as long as it can be combined with the cationic group-containing polymer, and may be, for example, an inorganic substrate or a polymer substrate. Examples of the inorganic substrate include silica, alumina, hydroxyapatite, clay, molecular sieves and the like. These inorganic substrates may be used alone or in combination of two or more. Of these, silica is more preferable.
When an inorganic substrate is used, for example, the cationic group-containing polymer may be applied to the inorganic substrate by coating, impregnation, or the like. If necessary, the cation group-containing polymer may be fixed to the inorganic base material by chemical bonding using a silane coupling agent or a crosslinking agent.

From the viewpoint of easy introduction and excellent retention of the cationic group-containing polymer, the substrate is preferably a polymer substrate used as the second polymer.

When the cation group-containing polymer is an adsorbent introduced into a polymer substrate, the introduction method in this case includes a cation group-containing polymer (or a monomer capable of forming the polymer) and a polymer group. The material (or the monomer capable of forming the base material) may be copolymerized (preferably block copolymerization or graft copolymerization) by a known method, respectively, as a polymer component, or alloyed (for example, Alternatively, the cationic group-containing polymer and the polymer base material may be mixed or kneaded). If necessary, the introduced cationic group-containing polymer (and polymer base material) may be post-modified by crosslinking or the like. Crosslinking can be carried out by known or conventional means, and for example, it may be carried out using a crosslinking agent described later.
From the viewpoint of ease of introduction and imparting physical properties such as strength and swelling degree of the resulting polymer adsorbent, it is more preferable to introduce the polymer by alloying the cation group-containing polymer and the polymer substrate.

The alloying may be performed by, for example, (i) a method of preparing a mixed solution using a cation group-containing polymer, a polymer substrate, an optional component as necessary, and an appropriate solvent, and (ii) You may carry out by the method (solution shaping | molding) of melt-kneading a cationic group containing polymer, a polymer base material, and arbitrary components as needed using a kneading machine etc.

The polymer substrate may be a hydrophobic polymer or a hydrophilic polymer.
Hydrophobic polymers generally have a solubility parameter (δ) of less than 22 calculated using the following formula using the cohesive energy density (Ecoh) and molar molecular volume (V) calculated by the Fedor estimation method. It refers to a polymer.
δ = [ΣEcoh / ΣV] ^1/2

Specific examples of the hydrophobic polymer include styrene polymers such as polystyrene; polyolefin polymers such as polyethylene and polypropylene; poly (meth) acrylates such as polymethyl methacrylate; polysulfone and polyether. Examples thereof include polysulfone polymers such as sulfone; halogen vinyl polymers such as polyvinylidene fluoride. These polymers may be used alone or in combination of two or more. Of these, styrenic polymers and poly (meth) acrylic acid esters are preferred.

The weight average molecular weight of the hydrophobic polymer can be appropriately set in accordance with the type of polymer, but for example, the weight average molecular weight of the hydrophobic polymer is at least 5000 or more (for example, 5000 to 100,000), preferably 10,000 or more. In addition, a weight average molecular weight can be calculated | required, for example using GPC.

The polymer substrate may preferably be a hydrophilic polymer. The polymer adsorbent whose polymer substrate is a hydrophilic polymer has a membrane fouling-causing substance (especially polysaccharides) contained in raw water compared to a polymer adsorbent whose polymer substrate is a hydrophobic polymer. From the viewpoint of the adsorptivity of the substance causing the membrane fouling, it is excellent in the adsorptivity of biopolymers such as protein and protein.

The reason why the polymer adsorbent, whose polymer substrate is a hydrophilic polymer, is superior in adsorbability of substances that cause membrane fouling, is not clear, but by making the polymer substrate a hydrophilic polymer, it becomes wet with water. As a result, at least some of the components that cause membrane fouling, especially biopolymers such as polysaccharides and proteins, penetrate into the adsorbent, and the polymer substrate becomes a polymer adsorbent that is a hydrophobic polymer. In comparison, it is presumed that the cationic group-containing polymer acts effectively.

The hydrophilic polymer generally refers to a polymer having a solubility parameter (δ) calculated by the following formula of Fedor's estimation method of 22 or more. Preferably it is 23 or more, More preferably, it is 24 or more, 25 or more is still more preferable. The upper limit of the solubility parameter is not particularly limited, but may be about 35, for example.
δ = [ΣEcoh / ΣV] ^1/2
The hydrophilic polymer is not particularly limited as long as it satisfies the above-described solubility parameter. For example, the polymer having a hydrophilic group such as a hydroxyl group, an ether group, a cationic group, an anionic group, or an amide group in the repeating unit. Etc.

For example, as the hydrophilic polymer, vinyl acetate derivative polymer [eg, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal (eg, polyvinyl alcohol acetalized product with various aldehydes such as formaldehyde, acetaldehyde, butyraldehyde) ], Polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, poly (meth) acrylamide, polyacrylonitrile, cationic polymer (eg, polyethyleneimine, polyallylamine, polyvinylamine, polyamidoamine dendrimer, polypyridine, polyvinylpyridine , Polyamino acid, polydiallyldimethylammonium halide, polyvinylbenzyltrimethyla Monium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, polynucleotide, etc.), anionic polymer (eg, polystyrene sulfonic acid, polyvinyl sulfate, poly (meth) acrylic acid, polymaleic acid, polyamic acid), phenol At least one selected from the group consisting of a resin, polyamide, polyvinylpyrrolidone, cellulose derivative, dextrin, chitin, and chitosan is preferably used.
These polymers may have other comonomer units (eg, monomer units having unsaturated carboxylic acid units such as maleic acid, itaconic acid, acrylic acid, silanol groups, aldehyde groups, or sulfonic acid groups). Good.

Particularly preferred hydrophilic polymers include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal (eg, polyvinyl formal, polyvinyl butyral), polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, cation. Polymer, anionic polymer, phenol resin, polyvinyl pyrrolidone, dextrin, chitin, and chitosan are preferable, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal are more preferable, polyvinyl alcohol, ethylene-vinyl alcohol copolymer Combined and polyvinyl formal are particularly preferred, not only having water resistance, but also from the viewpoint of excellent durability, moldability and hydrophilicity Ethylene - vinyl alcohol copolymer is most preferable.

The weight average molecular weight of the hydrophilic polymer can be appropriately set in accordance with the type of the polymer. For example, the weight average molecular weight of the hydrophilic polymer is at least 5000 or more (for example, from 5000 to 100,000), preferably 10,000 or more. In addition, a weight average molecular weight can be calculated | required, for example using GPC.

The molecular weight of polyvinyl alcohol may be defined by the viscosity average degree of polymerization, and the viscosity average degree of polymerization determined from the viscosity of a 30 ° C. aqueous solution can be selected from a wide range of about 100 to 15,000, for example. From the viewpoint of improving durability, those having a high degree of polymerization are preferably used. In this case, for example, the viscosity average degree of polymerization is preferably about 800 to 13000, and more preferably about 1000 to 10,000.

The degree of saponification of polyvinyl alcohol can be appropriately selected according to the purpose and is not particularly limited. For example, it may be 88 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more. Good. In particular, from the viewpoint of improving durability, those having a saponification degree of 98 mol% or more are preferred.

In the ethylene-vinyl alcohol copolymer, the content of ethylene units is preferably 20 to 60 mol%, more preferably 25 to 55 mol% in all monomer units. If the ethylene content is too small, the durability may deteriorate. On the other hand, when there is too much ethylene content, there exists a possibility that hydrophilicity may fall.

[Mass ratio of cationic group-containing polymer to polymer substrate]
In the adsorbent of the present invention, the ratio of the cation group-containing polymer to the polymer substrate may be, for example, about 1/99 to 70/30, in terms of mass ratio, cation group-containing polymer / polymer substrate. Preferably, it may be about 5/95 to 65/45, more preferably about 8/92 to 60/40. If the amount of the cation group-containing polymer is too much, the water resistance may be lowered, and if the amount of the cation group-containing polymer is too small, the adsorption performance tends to be lowered. The cationic group-containing polymer is preferably dispersed in the polymer substrate.

[Other ingredients]
In the present invention, an adsorbent having an adsorptivity to a membrane fouling-causing substance contained in raw water, in particular, a biopolymer such as a polysaccharide or a protein, for example, a cross-linking agent, an antioxidant, etc. , Various additives such as stabilizers, lubricants, processing aids, antistatic agents, colorants, antifoaming agents, and dispersing agents may be included.

The cross-linking agent can be appropriately determined according to the type of the cationic group-containing polymer and the cross-linking reactive group of the substrate, for example, epoxy group, carboxyl group, halogen group, acid anhydride group, acid halide group, At least one or two or more functional groups selected from a formyl group, N-chloroformyl group, chloroformate group, amidinyl group, isocyanate group, vinyl group, aldehyde group, azetidine group, carbodiimide group, and the like Including compounds. Also, zirconyl-based crosslinking agents (zirconyl nitrate, zirconium ammonium carbonate, zirconyl chloride, zirconyl acetate, zirconyl sulfate), titanium-based crosslinking agents [titanium-based crosslinking agents, titanium lactate, titanium diisopropoxybis (triethanolamate)], etc. May be used. Such a cross-linking agent can use various commercially available cross-linking agents, and is not particularly limited, but is selected from epoxy groups, halogen groups, isocyanate groups, vinyl groups, aldehyde groups, azetidine groups, carbodiimide groups, and the like. A compound containing at least two functional groups of at least one kind or two or more kinds is preferred.

Further, the introduction of the crosslinked structure by the crosslinking agent may be introduced by adding the crosslinking agent to the aqueous solution of the cationic group-containing polymer.

Also, a crosslinked structure may be introduced by using a copolymer component such as divinyl monomer during the synthesis of the adsorbent.

Moreover, you may introduce a crosslinked structure by melt-kneading together with the structural component of a crosslinking agent and an adsorbent.
In the case of performing melt kneading, a method (melt kneading method) in which the constituent components of the adsorbent, the crosslinking agent, and if necessary, optional components are melt kneaded using a biaxial kneader or the like can be mentioned. According to the melt kneading method, there is an advantage that it is easy to obtain an adsorbent in which each component is uniformly dispersed.

Alternatively, the adsorbent material may be once molded by melt molding, solution molding, etc. to form molded bodies of various shapes, and then the crosslinked structure may be introduced by immersing the molded body in a solution containing a crosslinking agent. .

When performing melt molding, for example, the adsorbent material excluding at least the cross-linking agent is melt-kneaded using a biaxial kneader or the like, and molded articles of various shapes are obtained by extrusion molding, injection molding, or the like. After that, the molded body may be subjected to a crosslinking treatment by immersing it in a crosslinking agent-containing solution.
On the other hand, when performing solution molding, for example, a mixed solution is prepared from an adsorbent material excluding at least a cross-linking agent using an appropriate solvent, and cast film formation or dry spinning, wet spinning, etc. are performed using this mixed solution. Thus, after obtaining a film-like or fibrous shaped body, the shaped body may be subjected to a crosslinking treatment by immersing it in a crosslinking agent-containing solution.

(Characteristics of adsorbent)
The adsorbent can have various shapes as long as it can be used for adsorption treatment of membrane fouling-causing substances from treated water, in particular, biopolymers such as polysaccharides and proteins, for example, particulate, fibrous, Various three-dimensional shapes may be used. From the viewpoint of improving the adsorption efficiency, the adsorbent is preferably in the form of particles or fibers, and considering the method of packing and using the column, particles are more preferred from the viewpoint of the volume filling rate.

The adsorbent of the present invention is, for example, an adsorbent having a swelling degree of 20 to 500% (for example, 20 to 400%) in water at 25 ° C. from the viewpoint of the permeability of water to be treated and the handleability in the adsorption treatment. It may be. In this case, the degree of swelling is preferably 30 to 450% (eg, 30 to 250%), more preferably about 40 to 350% (eg, 40 to 300%), and even more preferably 40 to It may be about 250%, particularly preferably about 50 to 250% (for example, 50 to 200%). If the degree of swelling is too low, the adsorptivity of the adsorbent may be reduced, and if the degree of swelling is too high, the adsorbent may be deformed.

For example, the swellability of the adsorbent may be controlled by cross-linking with a cross-linking agent, or the cationic group-containing polymer may be controlled with a hydrophobic polymer substrate or with a hydrophilic high or low swellable or non-swellable. It may be controlled as an alloy material introduced into a molecular (eg, ethylene-vinyl alcohol copolymer, polyamide, etc.) substrate. Moreover, you may bridge | crosslink an alloy material as needed.

The adsorbent of the present invention is preferably an adsorbent that is excellent in packing properties in a column. The packing property to the column can be evaluated by the volume change rate of the adsorbent at a high temperature of 80 ° C. The volume change rate is preferably 1.2 times or less from the viewpoint of not affecting the column.
The volume change rate was determined by filling the adsorbent sufficiently swollen into a chromatographic column tube (made by Shibata Kagaku Co., Ltd.) with an inner diameter of 15.4 mm so that the height is 5 cm, and passing the acid solution through the washing. Then, the volume change rate of the adsorbent before and after the immersion when the entire chromatographic column is immersed in a water bath heated to 80 ° C. for 1 hour can be calculated according to the following formula.
Volume change rate (times) = Adsorbent height after heating at 80 ° C. (cm) / 5 cm

Also, the adsorbent preferably has hot water solubility at the use temperature of the regeneration medium used in the regeneration process. Here, the hot water solubility means that the solubility (X) represented by the following formula when the adsorbent is immersed in hot water at a predetermined temperature for 1 hour is 5% or less. It may be.

X = [(Y−Z) / (Y)] × 100 (%)
(In the formula, Y is the dry weight of the adsorbent dried and weighed at 105 ° C. for 4 hours before immersing the adsorbent in hot water, and Z is 1 in hot water at a predetermined temperature. (This is the dry weight measured after soaking for 4 hours and drying at 105 ° C. for 4 hours.)

(Cause of membrane fouling)
Although various fouling-causing substances exist in the raw water, the fouling-causing substances that have been difficult to be adsorbed by the adsorbent of the present invention can be adsorbed and removed. In particular, the adsorbent of the present invention efficiently adsorbs organic substances having a particle size of 0.45 μm or less (for example, aromatic-containing organic substances such as humic acid and fulvic acid, synthetic chemical substances such as surfactants, biopolymers, etc.). It is possible.

In the present specification, the fouling-causing substance means a substance that causes fouling. The fouling-causing substances include, for example, organic carbon, various bacteria, inorganic particles, and the like. In addition, as a fouling causative substance that can be adsorbed and removed by the adsorbent of the present invention, inorganic particles may be excluded. In this specification, organic carbon means carbon constituting organic substances existing in water [for example, dissolved organic carbon (DOC); particulate organic carbon (POC) such as TEP]. To do.
Organic carbon includes, for example, biopolymers such as polysaccharides and proteins, humic acid, fulvic acid, uronic acid, cuturonic acid, odor components (geosmin, 2-methylisoborneol), and the like. In addition, you may remove | eliminate an odor component as organic carbon which can be adsorbed and removed with the adsorbent of this invention.

The fouling-causing substance may be a substance that is difficult to remove by means such as physical backwashing when performing membrane filtration. Although specific causative substances are still under study, when the treated water that has undergone the adsorption process of the present invention is supplied to the membrane treatment process, the treated water is supplied to the membrane treatment process without going through the adsorption process. Thus, the lifetime of the film in the film processing step can be improved.
Therefore, even if the causative substance is not specifically identified, it is possible to confirm that the amount of causative substance that causes physically irreversible membrane fouling can be reduced by the adsorption process.

The adsorbent of the present invention is particularly excellent in removing biopolymers having high hydrophilicity among fouling-causing substances. A biopolymer is a kind of organic carbon present in various raw waters, and is generally a polysaccharide and protein having an apparent molecular weight of 100,000 Da or more.
In the present invention, as an index for distinguishing other organic carbons from biopolymers, for example, in LC-OCD in which a wet total organic carbon measuring instrument is connected to high performance liquid chromatography, from the retention time at which a humic signal peak appears. It may be defined as a substance that exhibits a signal peak in a short holding time.
In more detail, the biopolymer has an A fraction measured by the method described in Stefan A. Huber et al. Water Research 45 (2011) pp879-885, for example, a retention time by LC-OCD of 25 minutes to 38 minutes. The following components may be used. Further, the humic substance may be a B fraction in the measurement under the same conditions, for example, a component exceeding the holding time of 38 minutes and not more than 50 minutes.

Biopolymers are mainly composed of organic substances with few hydrophobic structures such as benzene rings and mainly high hydrophilicity. For example, biopolymers are composed of organic substances exhibiting an SUVA value of 1.0 [L / (m · mg)] or less. May be.
On the other hand, the humic substance contains not only a UV-absorbing structure because it contains a benzene ring, but also has a high hydrophobicity, for example, an SUVA value of 2.0 [L / (m · mg)] or more It may be composed of an organic material showing.

The SUVA value is obtained by the following formula.
SUVA (L / mg-C · m) = UV (m ⁻¹ ) / DOC (mg-C / L)

Here, each parameter for calculating the SUVA value was measured by the method described in Stefan A. Huber et al. Water Research 45 (2011) pp879-885, and "area value" The area value obtained by LC-OCD is expressed, “UV” indicates the absorbance at a wavelength of 254 nm, and “DOC” indicates the DOC concentration (mg-C / L) in the test sample.

UV value calculation method (i) UV of biopolymer = UV of entire test sample × area value of biopolymer in spectrum (holding time tb: 25 minutes ≦ tb ≦ 38 minutes) / area value of entire spectrum (ii) Humin Quality UV = UV of the entire test sample × area value of humic substance in the spectrum (holding time th: 38 minutes <th ≦ 50 minutes) / area value of the whole spectrum

DOC value calculation method (i) DOC of biopolymer = DOC of whole test sample × area value of biopolymer in spectrum (holding time tb: 25 minutes ≦ tb ≦ 38 minutes) / area value of whole spectrum (ii) Humin DOC of the quality = DOC of the entire test sample × Area value of humic substance in the spectrum (holding time th: 38 minutes <th ≦ 50 minutes) / Area value of the whole spectrum

For example, the adsorbent used in the present invention may have a biopolymer removal rate (or adsorption rate) from the water to be treated of, for example, 15% or more, preferably 20% or more, more preferably 30% or more. More preferably, it may be 50% or more, more preferably 80% or more, further preferably 85% or more, and particularly preferably 90% or more. In addition, a removal rate shows the value measured by the method described in the Example mentioned later.

The adsorbent used in the present invention is particularly excellent in biopolymer absorbability, and biopolymer model water at 25 ° C. (sodium alginate concentration: 4.3 mg-C / L sodium alginate aqueous solution) and humic substances In each model water (sodium humate concentration: 4.3 mg-C / L sodium humate aqueous solution), the ratio between the adsorption rate of sodium alginate (A) and the adsorption rate of sodium humate (B) is, for example, , (A) / (B) = about 0.3 to 10, preferably (A) / (B) = about 1.0 to 10, more preferably about 1.1 to 9, more preferably May be about 1.3 to 8. In each model water, sodium alginate is used as the biopolymer model, and sodium humate is used as the humic model. Moreover, each adsorption rate shows the value measured by the method described in the Example mentioned later.

In addition, the adsorbent used in the present invention has an adsorption rate (A) of sodium alginate in biopolymer model water (sodium alginate concentration: 4.3 mg-C / L sodium alginate aqueous solution) at 25 ° C., for example, 30 % Or more (for example, 30 to 100%), preferably 35% or more, more preferably 45% or more, still more preferably 60% or more, and particularly preferably 80% or more. Good. About the adsorption rate, the value measured by the method described in the Example mentioned later is shown.

Further, the adsorbent used in the present invention has an adsorption rate (A) of sodium humate in humic model water (sodium humate concentration: 4.3 mg-C / L sodium humate aqueous solution) at 25 ° C. For example, it may be 25% or more (for example, 25 to 90%), preferably 35% or more, more preferably 45% or more, and further preferably 50% or more. About the adsorption rate, the value measured by the method described in the Example mentioned later is shown.

[Water treatment method]
The present invention includes a water treatment method as another embodiment. The water treatment method includes at least an adsorption step in which water to be treated containing a membrane fouling-causing substance is brought into contact with the adsorbent of the present invention and the membrane fouling-causing substance contained in the water to be treated is adsorbed by the adsorbent. .
The water treatment method may further include a membrane filtration step of subjecting the adsorption treated water obtained in the adsorption step to membrane filtration treatment, as necessary. Further, the membrane filtration step uses at least one membrane selected from the group consisting of an ultrafiltration (UF) membrane, a microfiltration (MF) membrane, a nanofiltration (NF) membrane, and a reverse osmosis (RO) membrane. The water treatment method may be performed in one or more stages.

(Adsorption process)
The water to be treated in the water treatment method of the present invention is not particularly limited as long as various raw waters obtained in a natural environment and an artificial environment can be used as the water to be treated and contains a fouling-causing substance. The raw water includes general river water, lake water, seawater, soil elution water, irrigation water, biological treatment water, pretreatment of these (for example, sand filtration treatment, rough filtration treatment using a water treatment membrane, coagulation sedimentation treatment, ozone Treated water after treatment, adsorption treatment using existing adsorbent or activated carbon, biological treatment) and the like.
In addition, when the adsorption pretreatment is performed, for example, water from which particles having a particle diameter of 5 μm or more, preferably 1 μm or more, more preferably larger than 0.45 μm are excluded is used as the adsorption treated water. preferable.

The water to be treated is raw water containing fouling-causing substances, particularly polysaccharides and proteins that are considered to cause physically irreversible membrane fouling, and containing 0.1% by mass or more of sodium chloride. May be. Examples of such raw water include seawater (sodium chloride concentration of 2 to 4% by mass), brackish water (sodium chloride concentration of 0.5 to 2% by mass), and accompanying water generated when mining oil fields and gas fields. It may also be water with higher sodium chloride concentration obtained by treating these, and water containing various salts obtained from raw water in the natural environment is used as treated water May be.

For example, the raw water may have a sodium chloride concentration of 0.1% by mass or more (for example, about 0.5 to 30% by mass), 1% by mass or more, or 2% by mass or more. In addition to sodium chloride, the water to be treated may contain alkali metal salts such as potassium chloride; alkaline earth metal salts such as magnesium chloride, magnesium sulfate, calcium chloride, and calcium sulfate.

The temperature of the water to be treated in the adsorption treatment may be the first contact temperature (for example, near room temperature). Specifically, the vicinity of room temperature may be, for example, 0 ° C. or more and less than 40 ° C., The temperature may be preferably 5 to 38 ° C, more preferably 10 to 35 ° C.

In the adsorption process, it is not particularly limited as long as the water to be treated and the adsorbent can be brought into contact with each other. For example, as a batch type, the adsorbent is added to the water to be treated and, if necessary, stirred by a known method. The adsorbing treatment may be carried out by a method in which the water to be treated is passed through a column filled with an adsorbent as a continuous type. Further, the adsorption step may be a single step or a multi-step.

The amount of adsorbent used for the water to be treated can be appropriately selected according to the type of water to be treated, the form of the adsorbent, etc. For example, in the case of a batch type, the amount of adsorbent is The amount may be about 0.05 to 30 g, preferably about 0.1 to 10 g, per liter of treated water.

In addition, when the adsorbent is immersed in the water to be treated and stirred, the adsorbent may be stirred by mechanical stirring or bubble stirring. When performing mechanical stirring, the peripheral speed may be about 0.1 to 20 m / s, or about 0.3 to 15 m / s.

On the other hand, in the case of the continuous type, with respect to the adsorbent packed in the column, the flow rate of the water to be treated to the column is, for example, the superficial velocity that is a value obtained by dividing the treated water flow rate by the adsorbent volume. it may be about 0.5 ~ 200h ^-1, preferably about 1 ~ 150h ^-1.

By the adsorption treatment using the adsorbent of the present invention, the membrane fouling-causing substance in the water to be treated can be efficiently adsorbed, and in particular, the above-described biopolymer can be adsorbed efficiently. For example, in the adsorption treatment, the removal rate (or adsorption rate) of the biopolymer from the water to be treated may be, for example, 15% or more, preferably 20% or more, more preferably 25% or more. . In addition, a removal rate shows the value measured by the method described in the Example mentioned later. When the removal rate is too low, when the treated water after the adsorption treatment is supplied to the membrane filtration step, the effect of suppressing membrane contamination may not be sufficient.

(Membrane filtration process)
After the adsorption step, the adsorption-treated water (or supply water) subjected to the adsorption treatment is subjected to membrane filtration in the membrane filtration step as necessary. The membrane filtration step may be a single step or multiple steps. About the kind of film | membrane of a membrane filtration process, the same film | membrane may be used and a different kind of film | membrane may be combined. Membrane filtration may be combined to purify water according to the application.

The membrane filtration step is appropriately performed using a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a nanofiltration membrane (NF membrane), a reverse osmosis (RO) membrane, etc., depending on the purpose of water treatment. be able to. In the membrane filtration step, these membranes may be used alone or in one or more stages for membrane filtration, or a plurality of types of membranes may be combined, and each one or more stages may be used for membrane filtration.
When a plurality of types of membranes are combined, the membrane water may be further filtered with an NF membrane or a reverse osmosis (RO) membrane after membrane filtration treatment of the treated water supplied with the MF membrane or UF membrane.

The membrane material of the filtration membrane in the membrane filtration step is not particularly limited, and any known material can be applied. For example, examples of the film material for the UF film and the MF film include cellulose acetate, polyacrylonitrile, polyethylene, polyethersulfone, polysulfone, polypropylene, polyvinylidene fluoride, and ceramic. Examples of the film material of the NF film include polyamide-based, polypiperazine amide-based, polyester amide-based, or water-soluble vinyl polymer crosslinked. Examples of the membrane material for the RO membrane include cellulose acetate and polyamide.

The membrane form is not particularly limited, and may be any shape such as a flat membrane, a tubular membrane, and a hollow fiber membrane. For example, the film thickness may be in the range of 10 μm to 1 mm, and in the case of a hollow fiber membrane, the inner diameter may be about 0.2 to 2 mm and the outer diameter may be about 0.4 to 5 mm. The filtration membrane may have a fine porous structure such as a network structure, a honeycomb structure, or a fine gap structure.

These filtration membranes may be modularized. For example, in the case of a flat membrane, a spiral type, a pleat type, a plate-and-frame type, or a disc type in which discs are stacked may be used. It may be a hollow fiber membrane type bundled in an I shape and stored in a container.

The filtration flow rate can be set as appropriate according to the type of water supplied to the membrane, the type of filtration membrane, and the like. For example, when filtration is performed by the cross flow method, the filtration flow rate is flux 0.5 to 5 .0 ^{^(m} 3 / m ² / day) may be liquid passing respect filtration membrane, preferably may be ^{^{Flux1.0 ~ 4.0 (m 3 / m}} 2 / day).

In particular, since the adsorbent of the present invention functions effectively even if the water to be treated contains salts, the water to be treated containing salts is adsorbed with the adsorbent of the present invention, and then the RO membrane or the like. It may be supplied to a membrane treatment to remove salts in water.

By performing the adsorption process using the adsorbent of the present invention, membrane fouling-causing substances, particularly biopolymers such as polysaccharides and proteins, can be reduced from the water supplied to the filtration membrane. As a result, it is possible to suppress the occurrence of membrane fouling (particularly physically irreversible membrane fouling) in the filtration membrane, and it is possible to suppress the reduction of water permeability of the filtration membrane due to clogging of the filtration membrane. .
Furthermore, since the amount of the causative substance in the supply water can be reduced, it is possible to suppress the deterioration of the filtration membrane due to membrane fouling, thereby prolonging the service life of the membrane. In addition, since the amount of the causative substance in the supply water can be reduced, the frequency of cleaning the filtration membrane and the amount of cleaning chemicals used can also be reduced.

In the water treatment using the adsorbent of the present invention, it may be combined with an existing water treatment method as necessary within a range not impairing the effects of the invention. Examples of the existing water treatment method include sand filtration treatment, coarse filtration treatment, coagulation sedimentation treatment, ozone treatment, adsorption treatment using an existing adsorbent or activated carbon, biological treatment, and the like. These treatments may be performed singly or in combination of two or more. In addition, these water treatments may be appropriately performed before and / or after the adsorption treatment.

The adsorbent that has adsorbed the membrane fouling-causing substance in the adsorption step is separated by a known filtering means as necessary and is supplied to the regeneration step. On the other hand, the adsorption-treated water that has been subjected to solid-liquid separation by filtering the adsorbent may be used in a membrane filtration step as needed, and membrane filtered in the filtration step.

(Regeneration process)
The water treatment method of the present invention may include a regeneration step in which the adsorbent that has adsorbed the membrane fouling-causing substance in the adsorption step is regenerated by contacting with the cleaning fluid. The regeneration process is not particularly limited as long as the adsorbent adsorbing the membrane fouling-causing substance can be regenerated, and various regeneration processes can be performed.

Note that the present invention may include a method for regenerating the adsorbent. In this case, the regeneration step may be performed independently as a regeneration method. For example, the adsorbent regeneration method for regenerating the adsorbent that has adsorbed the membrane fouling-causing substance in the adsorption step by bringing it into contact with the cleaning fluid may be performed independently. Preferably, the adsorbent regeneration method may be performed by bringing the adsorbent adsorbing the membrane fouling-causing substance into contact with a cleaning fluid heated to 40 ° C. or more and regenerating the adsorbent. .

The cleaning fluid may be a medium composed of a liquid containing water as a main component (for example, 60% by mass or more). For example, purified water (water that has been purified by an appropriate treatment operation on raw water, For example, tap water, etc.), pure water (RO water, deionized water, distilled water, etc.), various raw waters described above in the adsorption step or related waters may be used, and these waters (purified water, pure water, raw water) are used as chemicals. Alternatively, an aqueous solution added to the related water) may be used. As the drug, for example, various acidic substances and salts thereof, various alkaline substances and the like can be used.
For example, as an acidic substance, various inorganic acids (for example, hydrochloric acid, hypochlorous acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, carbonic acid, phosphoric acid, hypobromous acid, hypoiodous acid, etc.), various organic acids ( For example, formic acid, acetic acid, propionic acid, butyric acid, stearic acid, citric acid, oxalic acid, lactic acid, maleic acid, tartaric acid, fumaric acid, malonic acid, succinic acid, malic acid, adipic acid, oleic acid, linoleic acid, linolenic acid And benzoic acid). The acidic substance salt may be, for example, an alkali metal salt such as a sodium salt or a potassium salt, or an organic salt such as an ammonium salt. Examples of the alkaline substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and ammonia water. These drugs may be used alone or in combination of two or more. The concentration of the drug in the cleaning fluid may be, for example, about 0.1 to 60% by mass, preferably about 0.1 to 30% by mass, more preferably 0.5 to 20%, as the ratio of the solute to water. It may be about mass%.
Further, the cleaning fluid is not limited to a liquid, and may be a gas such as air or heated steam, for example. That is, the cleaning fluid may be any fluid that can clean the adsorbent of the present invention and remove the fouling-causing substance attached to the surface. Further, the contact with the cleaning fluid in the regeneration step may be one stage or multiple stages. In the case of multiple stages, a plurality of types of cleaning fluids may be used separately.

A metal ion-containing aqueous solution is preferably used as the cleaning fluid. The metal ions used in the aqueous solution containing metal ions are not particularly limited as long as the causative substance can be eliminated, but typically, alkali metal ions such as lithium ions, sodium ions, and potassium ions are listed. Specifically, for example, an aqueous solution containing an alkali metal hydroxide, an alkali metal organic acid salt, or an alkali metal inorganic acid salt may be used. As the alkali metal hydroxide, organic acid and inorganic acid, various substances used as the above-mentioned chemicals may be used. Preferred metal ion-containing aqueous solutions include alkali metal salt aqueous solutions of inorganic acids, and specific examples include sodium chloride aqueous solution, potassium chloride aqueous solution, lithium chloride aqueous solution, sodium carbonate aqueous solution, potassium carbonate aqueous solution, lithium carbonate aqueous solution and the like. It is done. The cleaning fluid may be a metal ion-containing aqueous solution containing the same type of metal ions as the salts present in the water to be treated. The concentration of the metal ion-containing aqueous solution may be, for example, about 0.1 to 60% by mass, preferably about 0.1 to 30% by mass, more preferably 0.5 to 20% by mass as a solute ratio with respect to water. % May be sufficient.

Alternatively, the aqueous medium as the cleaning fluid may have a sodium chloride concentration of 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 2% by mass or more. Moreover, sodium chloride concentration may be 27 mass% or less, for example, and may be 20 mass% or less. As long as it is used at a predetermined temperature, it can be suitably used as a cleaning fluid.
In addition to sodium chloride, the cleaning fluid may contain alkali metal salts such as potassium chloride; alkaline earth metal salts such as magnesium chloride, magnesium sulfate, calcium chloride, and calcium sulfate.

As the raw water, the various raw waters described above in the adsorption process may be used, or a part of the raw water used in the adsorption process may be separated and used in the regeneration process. Alternatively, raw water different from the raw water used in the adsorption step may be used as a regeneration medium. Examples of raw water-related water include non-permeate water (for example, concentrated water obtained after RO membrane treatment) generated when various membrane treatments of raw water, treated water obtained after the raw water adsorption step, and the like.

The pH of the cleaning fluid may be, for example, about 5 to 14, preferably about 5.5 to 12, and more preferably about 6 to 11. When the pH is in the neutral range (pH 6 to 8), it is preferable for disposal of the cleaning fluid after the regeneration treatment, and when the pH is weakly basic (pH 8 to 11), the regeneration performance is good.

The temperature of the cleaning fluid used in the regeneration process is not particularly limited as long as the adsorbent can be regenerated. Depending on the type of cleaning fluid, it may be near room temperature, at the same temperature as the water to be treated, or at a temperature equal to or higher than the temperature of the water to be treated in the adsorption process. Preferably, it may be set to be higher than the temperature of the water to be treated in the adsorption step. By changing the temperature condition of the liquid in contact with the adsorbent between the adsorption process and the regeneration process, even if it is a causative substance adsorbed to the adsorbent in the adsorption process, the adsorbent can be more efficiently used in the regeneration process. It is possible to detach from.

For example, in the regeneration process (or regeneration method) of the adsorbent, the water to be treated containing the fouling-causing substance is brought into contact at the first contact temperature, and the film fouling-causing substance contained in the water to be treated is adsorbed. May be brought into contact with various cleaning fluids at a second contact temperature higher than the first contact temperature, and the adsorbent may be regenerated.
The first contact temperature and the second contact temperature may differ from each other by, for example, 10 ° C. or more (eg, about 10 to 90 ° C.), preferably about 15 to 80 ° C., more preferably 20 to 70 ° C. It may be different by about ° C.

As long as the causative substance can be desorbed, the temperature of the cleaning fluid in the regeneration process can be selected as an appropriate temperature as the second contact temperature. For example, it may be 40 to 110 ° C. (eg 50 to 110 ° C.), preferably 45 to 105 ° C. (eg 60 to 105 ° C.), more preferably 50 to 100 ° C. (eg 70 ° C.). ~ 100 ° C).

The cleaning fluid may have a temperature within the predetermined range, and the temperature of the cleaning fluid may decrease during the regeneration process. Or you may perform a reproduction | regeneration process using the washing | cleaning fluid heated by the predetermined heating means as needed. For example, as the heating means, any heat source can be targeted, such as heat pumps, electric heating means, combustion means using combustion heat such as gas or petroleum, natural heat sources such as solar heat and geothermal heat, etc. A secondary heat source derived from a heat source (for example, a heating heat medium heated by the heat source) may be used. These heat sources may be used alone or in combination of two or more.

Examples of the heating mode include a system in which piping through which the cleaning fluid flows is heated with various heat sources, and a system in which the cleaning fluid is stored in a heating tank provided with a heat source outside or inside. These methods may be used alone or in combination of two or more. For example, piping and a heating tank may be heated directly using a heat source, or may be heated using a secondary heat source such as steam used in a factory.
The heating tank that heats the cleaning fluid may be a container that performs a regeneration process, or may be a container that stores the cleaning fluid before the regeneration process. When the regeneration time is long (for example, 1 hour or longer), it is preferable to heat the container for performing the regeneration process in order to maintain the temperature of the cleaning fluid.

In the regeneration step, the treatment time is not particularly limited as long as the adsorbent can be regenerated, and can be set as appropriate according to the state and amount of the adsorbent and the regeneration medium. The regeneration treatment time may be, for example, 10 minutes or more, preferably 15 minutes or more, more preferably 20 minutes or more, and further preferably 30 minutes or more. . In addition, the regeneration processing time may be 36 hours or less, preferably 25 hours or less, from the viewpoint of improving the efficiency of the regeneration process.

The amount of the cleaning fluid used for the adsorbent can be appropriately selected according to the type of the cleaning fluid, the form of the adsorbent, the type of regeneration process (batch type or continuous type), and the like. When the adsorbent is immersed in the cleaning fluid and stirred, the adsorbent may be stirred by mechanical stirring, bubble stirring, or the like. When mechanical stirring is performed, the peripheral speed may be about 0.1 to 20 m / s, or about 0.3 to 18 m / s.

The regeneration step is not particularly limited as long as the cleaning fluid and the adsorbent can be brought into contact with each other. For example, as a batch type, the adsorbent is added to the cleaning fluid, and if necessary, stirred by a known method. The regeneration process may be carried out; as a continuous system, the regeneration process may be carried out by passing a washing fluid through a column filled with an adsorbent. Further, the regeneration step may be a single step or multiple steps.

The adsorbent regenerated by the regeneration step may be separated by a known filtering means as necessary and may be provided again to the adsorption step.

In the regeneration process, the adsorbent can be efficiently regenerated by contact with the cleaning fluid. For example, in the regeneration step, the adsorption rate of the adsorbent before and after the regeneration treatment can be evaluated as regeneration efficiency. For example, the regeneration efficiency may be 30% or more, preferably 50% or more, more preferably May be 80% or more, particularly preferably 90% or more. Note that the regeneration efficiency is a value measured by a method described in Examples described later.

The present invention may include the following contents as application examples.
That is, in the first application example of the present invention, water to be treated (for example, raw water) containing organic carbon (for example, a substance causing membrane fouling) and various adsorbents (preferably polymer adsorbents) are used. An adsorption step of contacting at a first contact temperature near room temperature and adsorbing at least a part of organic carbon by an adsorbent;
A regeneration step of regenerating the adsorbent by bringing the adsorbent adsorbed with the component into contact with a cleaning fluid (eg, an aqueous medium) heated to a second contact temperature of 40 ° C. or higher, which is higher than the first contact temperature. And a water treatment method comprising at least
In the water treatment method, since the regeneration medium is used by paying attention to the temperature of the aqueous medium, various cleaning fluids such as purified water, metal ion-containing aqueous solution, raw water (in particular, an aqueous medium containing organic carbon to be adsorbed) are used. Thus, the adsorbent can be efficiently regenerated.

In the water treatment method according to the first application example, various adsorbents (preferably polymer adsorbents) cause organic carbon contained in the water to be treated, particularly causative substances that cause physically irreversible membrane fouling (particularly Not only can adsorb highly hydrophilic biopolymers such as sugars and proteins), but it is already adsorbed on the adsorbent by bringing the adsorbent after the adsorption process into contact with a cleaning fluid that is hotter than the adsorption process. The adsorbed material can be regenerated by desorbing from the adsorbent. Then, the regenerated adsorbent can be effectively used again for the adsorption process.

Note that the regeneration step included in the water treatment method according to the first application example may be performed independently as a method for regenerating the adsorbent. That is, as a regeneration method, a regeneration method including regeneration in which an adsorbent adsorbing organic carbon is regenerated by bringing it into contact with a cleaning fluid may be performed independently.
Various processing conditions performed in this regeneration step (or regeneration method) include the various conditions described above in the present invention (type of cleaning fluid, temperature condition of cleaning fluid, heating means, regeneration processing time, cleaning fluid usage conditions, etc.). May be used as appropriate, or playback conditions described later may be used separately.

A second application example of the present invention is a water treatment method in which the component adsorbed in the adsorption step in the water treatment method according to the first application example includes a biopolymer.
According to a third application example of the present invention, in the water treatment method according to the first or second application example, the polymer adsorbent has at least one functional group selected from the group consisting of an amino group and a salt thereof. It has a water treatment method.
The fourth application example of the present invention is the water treatment method according to any one of the first to third application examples, wherein a polymer having a hydrophilic polymer as a main skeleton is used as a polymer adsorbent. It is.

According to a fifth application example of the present invention, in the water treatment method according to the fourth application example, the hydrophilic polymer that is the main skeleton of the polymer adsorbent is polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, polyvinyl acetal. , Polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, poly (meth) acrylamide, polyacrylonitrile, cationic polymer, anionic polymer, phenol resin, polyamide, polyvinyl pyrrolidone, dextrin, chitin, and chitosan A water treatment method comprising at least one selected from the group.

The sixth application example of the present invention is the water treatment method according to any one of the first to fifth application examples, wherein the adsorption treated water obtained by the adsorption step is further subjected to membrane filtration by membrane filtration treatment. A water treatment method including a filtration step.
According to a seventh application example of the present invention, in the water treatment method according to the sixth application example, the membrane filtration step includes an ultrafiltration (UF) membrane, a microfiltration (MF) membrane, a nanofiltration (NF) membrane, and The water treatment method is carried out in one or more stages using at least one membrane selected from the group consisting of reverse osmosis (RO) membranes.

The polymer adsorbent used in the first to seventh application examples is not particularly limited as long as it is an adsorbent that is formed of a polymer and adsorbs at least a part of organic carbon, and various polymer adsorbents. Can be used.

More specifically, the polymer adsorbent used in the application example includes a polymer adsorbent having a bond-forming group for causing causative substances that cause membrane fouling contained in raw water to be adsorbed to the adsorbent. Materials.
The bond-forming group can form various bonds (for example, hydrogen bond, coordination bond, ionic bond, etc.) with the adsorbing component. For example, examples of the bond-forming group include a hydrogen bond-forming group, a chelate-forming group, a cationic ion-exchange group, and an anionic ion-exchange group. These bond-forming groups can be used alone or in combination of two or more. May be. Preferably, it may have at least a cationic ion exchange group.

The bond-forming group may be a functional group containing at least one element selected from the group consisting of N, S, P and O, for example.
Specifically, such functional groups include amino groups (primary amino groups, secondary amino groups, tertiary amino groups), quaternary ammonium groups, iminium groups, imidazole groups, quaternary imidazolium groups, pyridyl groups. Group, quaternary pyridinium group, hydroxyl group, carboxyl group, sulfonate group, sulfonic acid group, sulfonium group, mercapto group, thiourea group, phosphonate group, phosphonic acid group, phosphonium group and the like. They may be present in a salt state. These functional groups may be present alone or in combination of two or more. Among these, preferred functional groups are primary amino group, secondary amino group, tertiary amino group, quaternary ammonium group, iminium group, imidazole group, quaternary imidazolium group, pyridyl group, and quaternary pyridinium group. And more preferably, an amino group (primary amino group, secondary amino group, tertiary amino group) and salts thereof.

The polymer adsorbent may have a hydrophobic polymer as a main skeleton together with the bond-forming group, or may have a hydrophilic polymer as a main skeleton.

Examples of the hydrophobic polymer adsorbent having a hydrophobic polymer as a main skeleton include a polymer adsorbent in which the above functional group is introduced with respect to the above-described hydrophobic polymer. The amount to be introduced may be, for example, 2 to 100 mol%, preferably 3 to 95 mol%, more preferably 5 to 90 mol% in all monomer units.

Such hydrophobic polymer adsorbents are, for example, “Purolite (registered trademark)” series from Purolite Co., Ltd .; “Sumichelate (registered trademark)” series, “Duolite (registered trademark)” from Sumika Chemtex Co., Ltd. Series: Launched as “Diaion (registered trademark)” series by Mitsubishi Chemical Corporation.

The hydrophilic polymer adsorbent has a hydrophilic polymer as a main skeleton, and the hydrophilic polymer itself may have a bond-forming group in its structure. In addition, a bond forming group may be introduced. In that case, the bond-forming group may be introduced by copolymerizing a monomer (or a derivative thereof) containing the bond-forming group when the hydrophilic polymer is produced, or the hydrophilic polymer is produced. Thereafter, a bond-forming group may be introduced by post-modification. When a functional group is introduced, the introduced bond-forming group may be a different type of functional group from the hydrophilic group of the hydrophilic polymer.
The amount to be introduced may be 2 to 100 mol%, preferably 3 to 95 mol%, more preferably 5 to 90 mol%, based on all monomer units.

In addition, the polymer adsorbent is composed of the above hydrophilic polymer or hydrophobic polymer as a matrix component and alloyed with a component having a bond-forming functional group (bond-forming group), thereby making the bond-forming group highly hydrophilic. It may be introduced into a molecule or a hydrophobic polymer. From the viewpoint of ease of introduction and imparting physical properties such as strength and swelling degree of the resulting polymer adsorbent, the polymer adsorbent is a polymer alloy of a bond-forming group-containing polymer and a matrix polymer (B). Is preferred.

[Bond-forming group-containing polymer]
For example, the bond-forming group-containing polymer is an anionic polymer such as polystyrene sulfonic acid (PSS), polyvinyl sulfate (PVS), polyacrylic acid (PAA), polymethacrylic acid (PMA), polymaleic acid, and polyamic acid. Polyethyleneimine, polyallylamine, polyvinylamine, polyamidoamine dendrimer, polypyridine, polyvinylpyridine, polyamino acid, polydiallyldimethylammonium halide, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride It may also be a cationic polymer such as a polynucleotide. Such polymers may be used alone or in combination of two or more.

Among these, in combination with the matrix polymer, from the viewpoint of more efficiently adsorbing the organic carbon contained in the raw water, particularly the causative substance that causes physically irreversible membrane fouling, the above-mentioned cationic polymer is preferable, Amino group-containing polymers, quaternary ammonium group-containing polymers, and quaternary pyridinium group-containing polymers are more preferred, and polymers having a high cation density (for example, polyethyleneimine, polyallylamine, etc.) are particularly preferred.

[Matrix polymer]
The matrix polymer may be either a hydrophobic matrix polymer or a hydrophilic matrix polymer as long as it can be polymerized with the bond-forming group-containing polymer. It may be a blend polymer. As the hydrophobic matrix polymer and the hydrophilic matrix polymer, the hydrophobic polymer and the hydrophilic polymer described in the above-described polymer base material may be used, respectively.

In the water treatment method and the adsorbent regeneration method in the present invention or its application examples, as described above, raw water or the like may be used as a cleaning fluid. In particular, when an aqueous medium containing organic carbon to be adsorbed is used as the cleaning fluid, reduction in water production cost and improvement in water production rate in the water treatment method are achieved. Hereinafter, a case where a cleaning fluid derived from non-purified water (non-fresh water) is used as the cleaning fluid will be described in detail.

If the cleaning fluid used in the regeneration process for the adsorbent (particularly the polymer adsorbent) has a second contact temperature heated to a specific temperature higher than the first contact temperature, It has been found that even if it is not purified water, it can be used as a cleaning fluid and recontamination by organic carbon can be suppressed. Since it is not necessary to use purified water as the cleaning fluid, the water treatment method of the present invention can reduce water production costs. In addition, purified water here is the water which performed the purification act by appropriate processing operation with respect to raw | natural water (For example, the water which satisfies the water quality standard which the water supply law in Japan at the time of application) satisfy | fills.

Conventionally, in order to regenerate the adsorbent while preventing re-contamination, it has been a natural knowledge of those skilled in the art to regenerate the adsorbent using fresh water or other fresh water as washing water. However, surprisingly, when an aqueous medium heated to a predetermined high temperature is applied to the adsorbent, organic carbon adheres to the adsorbent in the regeneration process, even if it is not purified water used for purification. It is possible to regenerate the adsorbent while suppressing the generation of water, and as a result, it is possible to reduce water production costs.

For example, as the cleaning fluid, it is possible to use the above-described various raw waters or related waters in the adsorption process. Examples of raw water-related water include non-permeate water (for example, concentrated water obtained after RO membrane treatment) generated when various membrane treatments of raw water, treated water obtained after the raw water adsorption step, and the like. The raw water may be used in the regeneration process by partially separating the raw water used in the adsorption process. Alternatively, raw water different from the raw water used in the adsorption process may be used as the cleaning fluid.

For example, the aqueous medium used as the cleaning fluid may have a total organic carbon (TOC) concentration of 0.01 mg-C / L or more, 0.05 mg-C / L or more, and 0. It may be 1 mg-C / L or more, 3.1 mg-C / L or more. In addition, TOC density | concentration means the TOC prescribed | regulated to JISK0101, and its measuring method here.
The TOC concentration is not particularly limited as long as it can be used as a cleaning fluid, but may be, for example, 20 mg-C / L or less.

The aqueous medium used as the cleaning fluid is not particularly limited as long as the organic carbon component adsorbed in the adsorption step can be desorbed from the adsorbent. For example, the turbidity of the aqueous medium used as the cleaning fluid is 200 NTU. (For example, 1 to 200 NTU), preferably 150 NTU or less (for example, 5 to 150 NTU), more preferably 100 NTU or less (for example, 10 to 100 NTU). Here, the turbidity of the aqueous medium is a value measured by a transmitted scattering light measurement method using formazine as a turbidity standard solution.

The aqueous medium used as the cleaning fluid may preferably be raw water from which particles having a particle size of 5 μm or more, preferably 1 μm or more, and more preferably 0.45 μm or more are excluded.

The cleaning fluid may be an aqueous solution in which a chemical is added to the raw water (for example, raw water containing organic carbon, particularly a causative substance that causes physically irreversible membrane fouling).
As the drug, for example, various acidic substances and salts thereof, various alkaline substances and the like can be used. For example, as an acidic substance, various inorganic acids (for example, hydrochloric acid, hypochlorous acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, carbonic acid, phosphoric acid, hypobromous acid, hypoiodous acid, etc.), various organic acids ( For example, formic acid, acetic acid, propionic acid, butyric acid, stearic acid, citric acid, oxalic acid, lactic acid, maleic acid, tartaric acid, fumaric acid, malonic acid, succinic acid, malic acid, adipic acid, oleic acid, linoleic acid, linolenic acid And benzoic acid). The acidic substance salt may be, for example, an alkali metal salt such as a sodium salt or a potassium salt, or an organic salt such as an ammonium salt. Examples of the alkaline substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and ammonia water. These drugs may be used alone or in combination of two or more.

Preferably, the cleaning fluid may be raw water containing metal ions (hereinafter referred to as metal ion-containing raw water). The metal ions used in the metal ion-containing raw water are not particularly limited as long as the causative substances can be eliminated, but typically, alkali metal ions such as lithium ions, sodium ions, potassium ions and the like can be mentioned. Specifically, for example, an aqueous solution containing an alkali metal hydroxide, an alkali metal organic acid salt, or an alkali metal inorganic acid salt may be used. As the alkali metal hydroxide, organic acid and inorganic acid, various substances used as the above-mentioned chemicals may be used. Preferred metal ion-containing raw water includes alkali metal salt-containing raw water of inorganic acid, specifically, sodium chloride-containing raw water, potassium chloride-containing raw water, lithium chloride-containing raw water, sodium carbonate-containing raw water, potassium carbonate-containing raw water, Examples include raw water containing lithium carbonate. The concentration of the drug in the raw water may be, for example, about 0.1 to 60% by mass, preferably about 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, as a solute ratio with respect to water. It may be a degree.

For example, the cleaning fluid may be an aqueous medium containing organic carbon, particularly a causative substance that causes physically irreversible film fouling, and containing 0.1% by mass or more of salts. Examples of such an aqueous medium include seawater (sodium chloride concentration of 2 to 4% by mass), brackish water (sodium chloride concentration of 0.5 to 2% by mass), and accompanying water generated when oil fields and gas fields are mined. Alternatively, water containing various salts obtained from raw water in the natural environment, such as water with a higher salt concentration obtained by treating them, may be used as the cleaning fluid.

The pH of the cleaning fluid may remain as an aqueous medium or may be adjusted using a pH adjuster with respect to the aqueous medium. The pH of the cleaning fluid may be, for example, about 5 to 14, preferably about 5.5 to 12, and more preferably about 6 to 11. When the pH is in the neutral range (pH 6 to 8), it is preferable for disposal of the cleaning fluid after the regeneration treatment, and when the pH is weakly basic (pH 8 to 11), the regeneration performance is good.

Furthermore, if necessary, the aqueous medium used in the regeneration step may be repeatedly used a plurality of times. By repeatedly using such a method, the concentration of organic carbon in the cleaning fluid may be concentrated to reduce the volume of the cleaning fluid as waste.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, “%” and “parts” represent “% by mass” and “parts by mass”, respectively, unless otherwise specified.

(Calculation of cationic group density)
The density of cationic groups, including commercially available ion exchange resins, was calculated based on the number of cationic groups (N) per unit molecular weight (M) (g / mol) of the polymer from the polymer skeleton structure (the following formula) ).
Cationic group density = (N / M) × 1000 (mmol / g)

(Measurement of Cl / C molar ratio)
0.1 g of the adsorbent was added to 30 g of 4% NaOH aqueous solution and stirred for 3 hours to exchange the cationic group to OH-type. Next, after thoroughly washing the resin after the exchange to OH − type with ion exchange water, 0.1 g of the adsorbent is added to 30 g of 4% HCl aqueous solution and stirred for 3 hours to remove the cationic group from the Cl − type. Was replaced. After the exchanged resin was sufficiently washed with ion-exchanged water, a cross section of the resin was cut out, and an ultrathin slice having a thickness of 100 nm, 3 μm × 3 μm square was prepared. The ultrathin section was analyzed by transmission electron microscope (TEM) -energy dispersive X-ray spectroscopy (EDX) (JEOL JEM-2100F, JED-2300T). If it was uniform, arbitrary 5 points were selected, and if it was a phase separation structure, 5 high-concentration phases were randomly selected, and the Cl / C molar ratio was calculated. If the Cl / C molar ratio was 0.2 or more, the point was determined to be a point containing a cationic group / C molar ratio of 0.2 or more.

(Biopolymer adsorption rate 1)
Adsorption evaluation of sodium alginate (manufactured by Wako Pure Chemical Industries, Ltd., model number: 199-09961) was carried out as a biopolymer model substance. 200 g of model sea water (concentration of sodium alginate: 4) is obtained by using 1.0 g of the adsorbent obtained in each of the Examples and Comparative Examples (the mass in the state dried in a vacuum dryer for 12 hours and the same in the following description). .3 mg-C / L, NaCl: 3.5%) and stirred with a magnetic hot stirrer (180 rpm, 25 ° C.). 40 ml of the supernatant liquid before and after stirring for 18 hours was evaluated by a total organic carbon meter, and the adsorption rate of the biopolymer by the adsorbent was evaluated as follows.
Biopolymer adsorption rate = (sodium alginate concentration before adsorption evaluation−sodium alginate concentration after adsorption evaluation) / sodium alginate concentration before adsorption evaluation × 100 (%)

(Evaluation of swelling degree)
After 1 g of the adsorbent is immersed in 25 ° C. water for 12 hours, the adsorbent is subjected to centrifugal dehydration and weighed (A), then dried at 105 ° C. for 4 hours and weighed (B). The degree of swelling was determined from the following formula.
Swelling degree = [(AB) / (B)] × 100 (%)

(Volume change rate of adsorbent)
After immersing 5.0 g of the adsorbent in water at 25 ° C. for 12 hours, the adsorbent was packed in a 15.4 mm inner diameter chromatographic column tube (manufactured by Shibata Kagaku Co., Ltd.) so that the height was 5 cm. After passing 1N HCl through 3BV, ion-exchanged water was passed through 3BV. After stopping the flow, the volume change rate of the adsorbent before and after immersion was calculated according to the following formula when the entire chromatographic column was immersed in a water bath heated to 80 ° C. for 1 hour.
Volume change rate (times) = Adsorbent height after heating at 80 ° C. (cm) / 5 cm
A case where the volume change rate was 1.2 times or less was evaluated as A, and a case where the volume change rate exceeded 1.2 times was evaluated as B.

(Water permeability evaluation of filtration membrane)
Surface water (organic carbon concentration = 3.6 mg-C / L, pH = 8.7) collected from Inba Marsh (Chiba Prefecture), first, stainless mesh cartridge filter (TMP-2, manufactured by Advanced Technology) with an exclusion diameter of 2 μm ) To remove insoluble matters, and 3.5% of NaCl was added to the filtered water. 5 g of the produced adsorbent was added to 1 L of the obtained liquid and shaken at 25 ° C. for 4 hours. After shaking, the adsorbent was filtered off to obtain an adsorption treatment liquid.
The obtained adsorption treatment liquid was passed through a filtration membrane with Flux 2.0 (m ³ / m ² / day) and reversely with pure water of Flux 3.0 m ³ / m ² / day) once every 30 minutes. Washing was performed, the pressure change when passing through the membrane was evaluated, the time (min) until reaching 60 kPa was determined, and long-term water permeability was evaluated according to the following criteria.
A: 900 minutes or more B: 600 minutes or more and less than 900 minutes C: Less than 600 minutes

(Regeneration of adsorbent)
After adsorbing sodium alginate, it was filtered and immersed in model seawater 1 set to a predetermined temperature and stirred for 1 hour to desorb sodium alginate and regenerate it. The regeneration efficiency was evaluated by the following formula.
Adsorbent regeneration efficiency = adsorption rate after regeneration process / adsorption rate before regeneration process x 100 (%)

(Heat resistant water solubility)
The adsorbent was dried at 105 ° C. for 4 hours, and its weight was weighed as Yg. The weighed adsorbent was recovered after being immersed in hot water maintained at a predetermined temperature at a bath ratio of 1/30 for 1 hour. The collected adsorbent was further dried at 105 ° C. for 4 hours, and its weight was weighed as Zg. did. The solubility (X) of this adsorbent was calculated by the following formula.
X = [(Y−Z) / (Y)] × 100 (%)
When X was 5% or less, it was determined that the adsorbent was soluble in hot water with respect to hot water at a predetermined temperature.

[Example 1-1]
Polyethyleneimine having a cationic group density of 23.2 (mmol / g) (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) and an epoxy compound (“Denacol EX-810” manufactured by Nagase ChemteX Corp.) After being used and cross-linked, it was crushed. The obtained pulverized product was stirred and washed with a large amount of hot water at 80 ° C. to obtain the target adsorbent 1-1 as shown in Table 1. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-1 in 25 ° C. water was 276%.

The obtained adsorbent 1-1 was immersed in model seawater and stirred, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating water permeability with a pore diameter of 0.1 μm, the long-term water permeability was A. The volume change rate of the adsorbent 1-1 with 80 ° C. hot water was B. The results are shown in Table 2.

[Example 1-2]
25 parts by mass of polyethyleneimine (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) having a cationic group density of 23.2 (mmol / g) and an ethylene-vinyl alcohol copolymer (hydrophilic polymer) 75 parts by mass of Kuraray Co., Ltd., “E-105”, δ = 28) was melt kneaded for 3 minutes at 180 ° C. using a Laboplast mill, and the resulting kneaded product was cooled and then pulverized to obtain particles. It was. Furthermore, this particle was subjected to a crosslinking treatment for 1 hour with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) at 25 ° C., filtered, and then stirred and washed with a large amount of hot water at 80 ° C. As a result, the target adsorbent 1-2 was obtained as shown in Table 1. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-2 in 25 ° C. water was 80%.

The obtained adsorbent 1-2 was immersed and stirred in model seawater, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh, and after the adsorption treatment, a UF membrane made of polyacrylonitrile (PAN) ( As a result of evaluating the water permeability of Asahi Kasei Co., Ltd., molecular weight cut-off 100 kDa), the long-term water permeability was A. The volume change rate of the adsorbent 1-2 with 80 ° C. hot water was A. The results are shown in Table 2.
When this adsorbent was analyzed by TEM-EDX, the high concentration phase Cl / C molar ratio was 0.45.

[Example 1-3]
10 parts by mass of polyethyleneimine (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) having a cationic group density of 23.2 (mmol / g) and an ethylene-vinyl alcohol copolymer (hydrophilic polymer) 90 parts by mass of Kuraray Co., Ltd. “F-101”, δ = 28) was melt-kneaded at 210 ° C. for 3 minutes with a Laboplast mill, and the resulting kneaded product was cooled and then pulverized to obtain particles. It was. Furthermore, this particle was subjected to a crosslinking treatment for 1 hour with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) at 25 ° C., filtered, and then stirred and washed with a large amount of hot water at 80 ° C. did. The obtained washed product was immersed in hydrochloric acid to obtain an adsorbent 1-3 substituted with a hydrochloride type. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-3 in 25 ° C. water was 40%.

The obtained adsorbent 1-3 was immersed and stirred in model seawater, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating water permeability with a pore diameter of 0.1 μm, the long-term water permeability was A. The volume change rate of the adsorbent 1-3 in 80 ° C. hot water was A. The results are shown in Table 2.

[Example 1-4]
35 parts by weight of polyallylamine (Nittobo Medical Co., Ltd., “PAA-15C”) having a cationic group density of 17.5 (mmol / g) and a hydrophilic polymer, an ethylene-vinyl alcohol copolymer ( Kuraray Co., Ltd., “G-156”, δ = 25) 65 parts by mass was melt kneaded at 180 ° C. for 3 minutes using a Laboplast mill, and the resulting kneaded product was cooled and then pulverized to give particles. Obtained. Furthermore, the particles were subjected to a crosslinking treatment with a 25% solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) for 1 hour, filtered and then immersed in a large amount of hot water at 80 ° C. The target adsorbent 1-4 was obtained by stirring and washing as shown in Table 1. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-4 in 25 ° C. water was 93%.

The obtained adsorbent 1-4 was immersed and stirred in model seawater, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating water permeability with a pore diameter of 0.1 μm, the long-term water permeability was A. The volume change rate of the adsorbent 1-4 in 80 ° C. hot water was A. The results are shown in Table 2.
When this adsorbent was analyzed by TEM-EDX, the Cl / C molar ratio of the high concentration phase was 0.3.

[Example 1-5]
A polyallylamine (Nitto Bo Medical Co., Ltd., “PAA-15C”) having a cationic group density of 17.5 (mmol / g) was used with an epoxy compound (Nagase ChemteX Co., Ltd., “Denacol EX-810”). After cross-linking, pulverization was performed. The obtained pulverized product was stirred and washed with a large amount of hot water at 80 ° C. to obtain the target adsorbent 1-5 as shown in Table 1. The adsorbent 1-5 had hot water solubility in 80 ° C. hot water. The degree of swelling of the obtained adsorbent 1-5 in 25 ° C. water was 346%.

The obtained adsorbent 1-5 was immersed and stirred in model seawater, and a sodium alginate adsorption test was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and the resulting treated water was used to make a PE MF membrane (Mitsubishi Rayon Co., Ltd.). As a result, the long-term water permeability was A. The volume change rate of the adsorbent 1-5 in 80 ° C. hot water was B. The results are shown in Table 2.

[Example 1-6]
Polymethyl methacrylate (manufactured by Kuraray Co., Ltd., “Parapet G”) was dissolved in DMSO to prepare a 5% solution. Polyethyleneimine having a cationic group density of 23.2 (mmol / g) was dissolved in DMSO (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) to prepare a 5% solution. 75 parts by mass of a 5% polymethyl methacrylate solution and 25 parts by mass of a 5% polyethyleneimine solution were mixed, and the resulting mixed solution was cast on a polyethylene film and dried to obtain a desired film. Next, after pulverizing the obtained film, it was subjected to a crosslinking treatment for 1 hour with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) at 25 ° C. As shown in Table 1, the intended adsorbent 1-6 was obtained by immersing in 80 ° C. hot water and washing with stirring. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-6 in 25 ° C. water was 40%.

The obtained adsorbent 1-6 was immersed and stirred in model seawater, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating the water permeability of the pore diameter of 0.1 μm, the long-term water permeability was B. The volume change rate of the adsorbent 1-6 in 80 ° C. hot water was A. The results are shown in Table 2.

[Example 1-7]
25 parts by mass of polyvinylamine (“PVAM-0595B”, manufactured by Mitsubishi Rayon Co., Ltd.) having a cationic group density of 23.2 (mmol / g) and an ethylene-vinyl alcohol copolymer (stock) 75 parts by mass of Kuraray Co., Ltd., “E-105”, δ = 28) was melt kneaded for 3 minutes at 180 ° C. using a lab plast mill, and the resulting kneaded product was cooled and pulverized to obtain particles. . Furthermore, this particle was subjected to a crosslinking treatment for 1 hour with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) at 25 ° C., filtered, and then stirred and washed with a large amount of hot water at 80 ° C. As a result, the target adsorbent 1-7 was obtained as shown in Table 1. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-7 in 25 ° C. water was 70%.

The obtained adsorbent 1-7 was immersed and stirred in model seawater, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating water permeability with a pore diameter of 0.1 μm, the long-term water permeability was A. The volume change rate of the adsorbent 1-7 in 80 ° C. hot water was A. The results are shown in Table 2.
When this adsorbent was analyzed by TEM-EDX, the high concentration phase Cl / C molar ratio was 0.4.

[Example 1-8]
12 g of commercially available fumed silica (manufactured by Aldrich, Silica, fumed, model number: S5505-100G) was dispersed in methanol to prepare a 10% methanol sol. While stirring 10% methanol sol, 3 mL of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) was added, reacted at 60 ° C. for 6 hours, Washing three times gave an epoxy-modified silica substrate.
An epoxy-modified silica group was obtained by heating 25 g of a 60 mass% aqueous solution of polyethyleneimine (Nippon Shokubai Co., Ltd., “Epomin SP-200”) having a cationic group density of 23.2 (mmol / g) to 80 ° C. 5 g of the material was gradually added and reacted for 1 h. The obtained particles were filtered, immersed in a large amount of hot water at 80 ° C., washed with stirring, and the target adsorbent 1-8 was obtained as shown in Table 1. In addition, the adsorbent had heat-resistant water solubility with respect to 80 degreeC hot water. The degree of swelling of the obtained adsorbent 1-8 in 25 ° C. water was 90%.

The amount of polyethyleneimine added to the adsorbent 1-8 obtained was calculated from the weight increase before and after the polyethyleneimine addition reaction, and the mass ratio of polyethyleneimine to the epoxy-modified silica substrate was 10/90.
The obtained adsorbent 1-8 was immersed in model seawater and stirred, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating the water permeability of the pore diameter of 0.1 μm, the long-term water permeability was B. The volume change rate of the adsorbent 1-8 in 80 ° C. hot water was A. The results are shown in Table 2.

[Comparative Example 1-1]
An adsorbent 1-9 was obtained by immersing a commercially available magnetic ion exchange resin (manufactured by Maezawa Kogyo Co., Ltd., “MIEX resin”) in a large amount of hot water at 80 ° C. and washing with stirring. The cationic group density of the adsorbent 1-9 was 4.9 (mmol / g) as a result of calculation based on the polymer skeleton structure described in Japanese Patent Application Laid-Open No. 10-504959. The degree of swelling in water was 170%.

The obtained adsorbent 1-9 was immersed in model seawater and stirred, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating the water permeability of the pore diameter of 0.1 μm, the long-term water permeability was C. The volume change rate of the adsorbent 1-9 in 80 ° C. hot water was A. The results are shown in Table 2.

[Comparative Example 1-2]
A commercially available anion exchange resin (“WA10” manufactured by Mitsubishi Chemical Corporation) was immersed in a large amount of hot water at 80 ° C., washed with stirring, and adsorbent 1-10 was obtained. The cationic group density of the adsorbent 1-10 was calculated based on the polymer skeleton structure described in the non-patent document Diaion 2 Ion Exchange Resin / Synthetic Adsorbent Manual, and was found to be 7.8 (mmol / g). Yes, the degree of swelling in water at 25 ° C. was 157%.

The obtained adsorbent 1-10 was immersed and stirred in model seawater, and an adsorption test for sodium alginate was performed. In addition, an adsorbent was added to a solution obtained by adding 3.5% NaCl to the surface water of Inba Marsh and adsorbed, and then the PVDF MF membrane (manufactured by Asahi Kasei Co., Ltd.) was used. As a result of evaluating the water permeability of the pore diameter of 0.1 μm, the long-term water permeability was C. The volume change rate of the adsorbent 1-10 in 80 ° C. hot water was A. The results are shown in Table 2.

[Comparative Example 1-3]
The adsorbent 1- 1 is obtained by immersing crosslinked chitosan particles having an amino group density of 6.2 (mmol / g) (“Kimikakitosan F”, manufactured by Kimika Co., Ltd.) in a large amount of hot water at 80 ° C. and washing with stirring. 11 was obtained. The degree of swelling in water at 25 ° C. was 166%.

The obtained adsorbent 1-11 was immersed in model seawater and stirred, and an adsorption test for sodium alginate was performed. As a result of evaluating the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm) using the treated water obtained after the adsorption test, the long-term water permeability was C. The volume change rate of the adsorbent 1-11 in 80 ° C. hot water was A. The results are shown in Table 2.

As shown in Table 2, in Examples 1-1 to 1-8, it is possible to efficiently adsorb the biopolymer, and thus it is possible to maintain high water permeability over a long period in the membrane filtration step. . On the other hand, as shown in Comparative Examples 1-1 to 1-3, when a polymer adsorbent having a low amino group density was used, biopolymer could not be adsorbed, and sufficient long-term water permeability could not be obtained. .

[Example 1-9]
According to Example 1-2, after adsorbing sodium alginate on the adsorbent 1-2, the adsorbent was filtered off. Subsequently, the adsorbent separated by filtration was immersed in pure water adjusted to 80 ° C., and regenerated by stirring for 1 hour. Thereafter, the regenerated adsorbent was collected by filtration, and the adsorption rate of sodium alginate was determined again in the same manner as in Example 1-2. The evaluation results are shown in Table 3.

[Example 1-10]
According to Example 1-3, after adsorbing sodium alginate on the adsorbent 1-3, the adsorbent was filtered off. Subsequently, the adsorbent separated by filtration was immersed in the above-described model seawater adjusted to 60 ° C. and regenerated by stirring for 24 hours. Thereafter, the regenerated adsorbent was collected by filtration, and the adsorption rate of sodium alginate was determined again in the same manner as in Example 1-3. The evaluation results are shown in Table 3.

As shown in Table 3, in Examples 1-9 and 1-10 where the regeneration treatment was performed on the adsorbent that adsorbed sodium alginate, the adsorbent after the regeneration treatment again had a high adsorption rate of sodium alginate. It is possible to adsorb. The regeneration efficiency of both Examples 1-9 and 1-10 is 90% or more.

(Biopolymer adsorption rate 2)
Adsorption evaluation of sodium alginate (manufactured by Wako Pure Chemical Industries, Ltd., model number: 199-09961) was carried out as a biopolymer model substance. 200 g of model river water 1 (sodium alginate concentration) was obtained from 1.0 g of the adsorbent obtained in each Example and Comparative Example (the mass in the state dried in a vacuum dryer for 12 hours and the same in the following description). : 4.3 mg-C / L) or model seawater 1 (sodium alginate concentration: 4.3 mg-C / L, NaCl: 3.5%), and stirred with a magnetic hot stirrer (180 rpm, 25 ° C.) . 40 ml of the supernatant liquid before and after stirring for 18 hours was evaluated by a total organic carbon meter, and the adsorption rate of the biopolymer by the adsorbent was evaluated as follows.
Biopolymer adsorption rate = (sodium alginate concentration before adsorption evaluation−sodium alginate concentration after adsorption evaluation) / sodium alginate concentration before adsorption evaluation × 100 (%)

(Humine adsorption rate)
Adsorption evaluation of sodium humate (manufactured by Aldrich, model number: H16752-100G) was performed as a model substance of humic substances. In each Example and Comparative Example, 1.0 g of the adsorbent obtained from 200 mL of model river water 2 (sodium humate concentration: 4.3 mg-C / L) or model seawater 2 (sodium humate concentration: 4.3 mg-) C / L, NaCl: 3.5%) and stirred with a magnetic hot stirrer (180 rpm, 25 ° C.). 40 ml of the supernatant before and after stirring for 18 hours was evaluated by a total organic carbon meter, and the adsorption rate of humic substances by the resin was evaluated as follows.
Humic acid adsorption rate = (sodium humate concentration before adsorption evaluation−sodium humate concentration after adsorption evaluation) / sodium humate concentration before adsorption evaluation × 100 (%)

(Ratio of adsorption rate of biopolymer and humic substance)
From the ratio of the adsorption rate of the biopolymer and the adsorption rate of the humic substance, the ratio of the adsorption rate of the biopolymer and the humic substance was calculated by the following formula.
Ratio of adsorption rate of biopolymer and humic substance = adsorption rate of biopolymer / adsorption rate of humic substance

(Water permeability evaluation of filtration membrane)
While passing liquid to the filtration membrane of water processed with Flux2.0 ^{^(m} 3 / m ² / day), the backwashing once Flux3.0m ³ / ^{m 2} / day) of pure water in 30 minutes The pressure change at the time of carrying through the membrane was evaluated, the time (min) until reaching 60 kPa was determined, and long-term water permeability was evaluated according to the following criteria.
A: 1000 minutes or more B: Less than 1000 minutes

[Reference Example 2-1]
A commercially available ion exchange resin (Purolite Co., Ltd., “Purolite A830W”) having a swelling degree in water at 25 ° C. of 113% is immersed in a large amount of hot water at 80 ° C., and washed with stirring. The adsorbent 2-1 shown in FIG. The adsorbent 2-1 was soluble in hot water with respect to 80 ° C. hot water. The adsorption test of sodium alginate and sodium humate was performed by using the adsorbent 2-1 soaking and stirring in model river water 1 and model river water 2, respectively. The results are shown in Table 5. When a sample of Purolite A830W was measured by TEM-EDX, Cl was uniformly distributed and the Cl / C molar ratio was 0.15. Moreover, since Cl is uniformly distributed, the amino group density was estimated from the ion exchange capacity. As a result, the cationic group concentration was 7.4 mmol / g.
After the adsorption process of sodium alginate from the model river water 1, the adsorbent was filtered, immersed in the model river water 1 adjusted to 80 ° C., stirred for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was again immersed and stirred in the model river water 1, and an adsorption test for sodium alginate was performed. Table 5 shows the results of adsorption evaluation after regeneration of the obtained adsorbent.

[Example 2-2]
Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP-200”) was crosslinked using an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”), and then pulverized. The obtained pulverized product was stirred and washed with a large amount of hot water at 80 ° C. to obtain the intended adsorbent 2-2 as shown in Table 4. The adsorbent 2-2 was soluble in hot water with respect to 80 ° C. hot water. The degree of swelling of the obtained adsorbent in 25 ° C. water was 276%.

The obtained adsorbent 2-2 was immersed and stirred in each of model river water 1 and model river water 2, and an adsorption test for sodium alginate and sodium humate was performed.
After the adsorption process of sodium alginate from the model river water 1, the adsorbent was filtered, immersed in the model river water 1 adjusted to 80 ° C., stirred for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was again immersed and stirred in the model river water 1, and an adsorption test for sodium alginate was performed. Table 5 shows the results of adsorption evaluation after regeneration of the obtained adsorbent.

[Example 2-3]
75 parts by mass of an ethylene-vinyl alcohol copolymer (“E-105” manufactured by Kuraray Co., Ltd.) and polyethyleneimine (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) 25 as hydrophilic polymers as the main skeleton A mass part was melt-kneaded at 180 ° C. with a lab plast mill, and the obtained kneaded product was cooled and then pulverized to obtain particles. Furthermore, this particle was subjected to a crosslinking treatment for 1 hour with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) at 25 ° C., filtered, and then stirred and washed with a large amount of hot water at 80 ° C. As a result, the intended adsorbent 2-3 was obtained as shown in Table 4. Note that the adsorbent 2-3 had solubility in hot water with respect to 80 ° C. hot water. The degree of swelling of the obtained adsorbent in 25 ° C. water was 80%.

The obtained adsorbent 2-3 was immersed and stirred in each of model seawater 1 and model seawater 2, and an adsorption test for sodium alginate and sodium humate was performed.
After the adsorption process of sodium alginate from model seawater 1, the adsorbent was filtered off, immersed in model water 1 adjusted to 90 ° C., stirred for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was again immersed and stirred in the model seawater 1, and an adsorption test for sodium alginate was performed. Table 5 shows the results of adsorption evaluation after regeneration of the obtained adsorbent.

[Example 2-4]
As shown in Table 6, the adsorption and regeneration were evaluated in the same manner as in Example 2-3, except that the model seawater 2 was used as the water for regeneration of the adsorbent 2-3. The evaluation results are shown in Table 5.

[Example 2-5]
As shown in Table 6, the adsorption and regeneration were evaluated in the same manner as in Example 2-3, except that the water used for regeneration of the adsorbent 2-2 was changed to model river water 1 at 50 ° C. The evaluation results are shown in Table 5.

[Example 2-6]
70 parts by mass of an ethylene-vinyl alcohol copolymer (“F-101” manufactured by Kuraray Co., Ltd.) and polyethyleneimine (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) 30 as hydrophilic polymers as the main skeleton A mass part was melt-kneaded at 210 ° C. for 3 minutes in a lab plast mill, and the obtained kneaded product was cooled and then pulverized to obtain particles. Furthermore, this particle was subjected to a crosslinking treatment for 1 hour with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corporation, “Denacol EX-810”) at 25 ° C., filtered, and then stirred and washed with a large amount of hot water at 80 ° C. As a result, as shown in Table 4, the intended adsorbent 2-4 was obtained. The adsorbent 2-4 had hot water solubility in hot water at 80 ° C. The degree of swelling of the obtained adsorbent in 25 ° C. water was 101%.

The obtained adsorbent 2-4 was immersed and stirred in each of model river water 1 and model river water 2, and an adsorption test for sodium alginate and sodium humate was performed.
After the adsorption step of sodium humate from the model river water 2, the adsorbent was filtered, immersed in the model river water 2 adjusted to 80 ° C., stirred for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was again immersed and stirred in the model river water 1, and an adsorption test for sodium humate was performed. Table 5 shows the results of adsorption evaluation after regeneration of the obtained adsorbent.

[Reference Example 2-7]
Adsorbent 2 is obtained by immersing styrene-based strongly basic anion exchange resin (organo Co., Ltd., “IRA400”) having a degree of swelling of 85% in water at 25 ° C. with a large amount of hot water at 80 ° C., stirring and washing. -5 was obtained. The adsorbent 2-5 had hot water solubility in 80 ° C. hot water. Using the adsorbent 2-5, the model river water 1 and the model river water 2 were immersed and stirred, respectively, and an adsorption test for sodium alginate and sodium humate was performed. The results are shown in Table 5. When the sample of IRA400 was measured by TEM-EDX, Cl was uniformly distributed and the Cl / C molar ratio was 0.05. Further, since Cl is uniformly distributed, the amino group density was estimated from the ion exchange capacity, and it was 3.7 mmol / g.
After the adsorption process of sodium alginate from the model river water 1, the adsorbent was filtered, immersed in the model river water 1 adjusted to 80 ° C., stirred for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was again immersed and stirred in the model river water 1, and an adsorption test for sodium alginate was performed. Table 5 shows the results of adsorption evaluation after regeneration of the obtained adsorbent.

[Example 2-8]
Polyallylamine (Nitto Bo Medical Co., Ltd., “PAA-15C”) was crosslinked using an epoxy compound (Nagase ChemteX Co., Ltd., “Denacol EX-810”), and then pulverized. The obtained pulverized product was stirred and washed with a large amount of hot water at 80 ° C. to obtain the intended adsorbent 2-6 as shown in Table 4. The adsorbent 2-6 had hot water solubility in 80 ° C. hot water. The degree of swelling of the obtained adsorbent in 25 ° C. water was 346%.

The obtained adsorbent 2-6 was immersed and stirred in each of model river water 1 and model river water 2, and an adsorption test for sodium alginate and sodium humate was performed.
After the adsorption process of sodium alginate from the model river water 1, the adsorbent was filtered, immersed in the model river water 1 adjusted to 80 ° C., stirred for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was again immersed in each model river water 1 and stirred, and an adsorption test for sodium alginate was performed. Table 5 shows the results of adsorption evaluation after regeneration of the obtained adsorbent.

[Comparative Example 2-1]
Adsorption was evaluated in the same manner as in Reference Example 2-1, except that the second adsorption test was performed without regenerating the adsorbent 2-1. The evaluation results are shown in Table 5. When the regeneration was not performed, the target product was hardly adsorbed by the second adsorption.

[Comparative Example 2-2]
Adsorption was evaluated in the same manner as in Reference Example 2-1, except that the adsorbent 2-1 was regenerated using model river water 1 at 25 ° C. and the second adsorption test was conducted. The evaluation results are shown in Table 5. Since room temperature reclaimed water was used, regeneration was insufficient, and the target product was hardly adsorbed by the second adsorption.

As shown in Table 5, in Reference Example 2-1, it is possible to adsorb both sodium alginate and sodium humate from the model river water, regenerate it with the hot model river water, and perform the second adsorption. I understood. In Examples 2-2 to 2-6, in the model river water or model seawater, the main skeleton of the adsorbent was composed of a hydrophilic polymer. In these examples, the ratio (A) / (B) of the adsorption rate (A) of sodium alginate and the adsorption rate (B) of sodium humate is 1.1 times or more. Therefore, the adsorbent of the present invention suggests that the biopolymer can be adsorbed efficiently even when, for example, more humic substances are present than the biopolymer. Also, it was found that both model river water and model seawater function in regeneration.
Reproduction efficiency was 90% or more in Reference Example 2-1 and Examples 2-2 to 2-4, 2-6 and 2-8, and Reference Example 2-7, and 40% or more in 2-5. In addition, when the temperature of the aqueous medium used in the regeneration treatment is 60 ° C. or higher, the regeneration efficiency tends to be high.

[Example 2-9]
(1) As raw water, surface water collected from Inba Marsh (Chiba Prefecture) (total organic carbon concentration = 4.0 mg-C / L, dissolved organic matter concentration = 3.6 mg-C / L, pH = 8.7, SUVA value of biopolymer: 0.21 (L / mg-C · m), biopolymer concentration: 0.50 (ppm-C), SUVA value of humic substance: 3.3 (L / mg-C · m) ), The concentration of humic substance: 1.8 (ppm-C), the raw water is first filtered through a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) with an exclusion diameter of 2 μm to remove insoluble matters, 5 g of adsorbent 2-3 was added to 1 L of the filtered water and stirred for 2 hours at 25 ° C. After stirring, the adsorbent was filtered off, and the resulting treated water was used to make PVDF MF module (Asahi Kasei Corporation, UNA-6 0A) result of the permeability was evaluated for long-term permeability was A. Table 6 shows the results.

(2) The adsorbent 2-3 after contacted with the raw water in (1) above is collected by filtration, and the water temperature is heated using surface water collected from Inba marsh (Chiba Prefecture) heated to 80 ° C. The mixture was stirred for 24 hours while being maintained, and then subjected to a regeneration treatment, and was again brought into contact with raw water at 25 ° C. in the same manner as in the above (1) to obtain treated water. As a result of evaluating the water permeability of the PVDF MF module (Ana-Chemical Co., Ltd., UNA-620A) using the treated water obtained, the long-term water permeability was A. The results are shown in Table 6. The surface water used for regeneration is in a state where insoluble matters are removed (turbidity: 200 NTU or less) by sampling with a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) having an exclusion diameter of 2 μm.

[Example 2-10]
(1) As raw water, surface water collected from Inba Marsh (Chiba Prefecture) as above (total organic carbon concentration = 4.0 mg-C / L, dissolved organic matter concentration = 3.6 mg-C / L, pH = 8.7), first, the raw water is filtered through a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) with an exclusion diameter of 2 μm to remove insoluble matter, and adsorbed to 1 L of the filtered water. 5 g of the material 2-3 was added and stirred at 25 ° C. for 2 hours. After stirring, the hydrophilic polymer adsorbent was filtered off, and the resulting treated water was used to evaluate the water permeability of a polyacrylonitrile (PAN) UF membrane (Asahi Kasei Co., Ltd., molecular weight cut off 100 kDa), The long-term water permeability was A. The results are shown in Table 6.

(2) The adsorbent 2-3 after contacted with the raw water in (1) above is collected by filtration and stirred for 1 hour using surface water collected from Inba marsh (Chiba Prefecture) heated to 80 ° C. After carrying out the regeneration treatment, treated water was obtained again at 25 ° C. in the same manner as in (1) above. As a result of evaluating the water permeability of a polyacrylonitrile (PAN) UF membrane (manufactured by Asahi Kasei Corporation, fractional molecular weight 100 kDa), the long-term water permeability was A. The results are shown in Table 6. The surface water used for regeneration is in a state where insoluble matters are removed (turbidity: 200 NTU or less) by sampling with a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) having an exclusion diameter of 2 μm.

(3) The adsorbent 2-3 after contacted with the raw water in (2) above is collected by filtration, and the concentrated water (non-permeated water) after being treated with the UF membrane in (2) above is heated to 80 ° C. After heating to reclaimed water and regenerating the adsorbent 2-3, it was again contacted with raw water at 25 ° C. in the same manner as in (1) above to obtain treated water. As a result of evaluating the water permeability of a polyacrylonitrile (PAN) UF membrane (Asahi Kasei Co., Ltd., molecular weight cut-off 100 kDa), the long-term water permeability was A. The results are shown in Table 6.

[Example 2-11]
(1) As raw water, surface water collected from Inba Marsh (Chiba Prefecture) as above (total organic carbon concentration = 4.0 mg-C / L, dissolved organic matter concentration = 3.6 mg-C / L, pH = 8.7), first, the raw water is filtered through a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) with an exclusion diameter of 2 μm to remove insoluble matter, and adsorbed to 1 L of the filtered water. 5 g of the material 2-3 was added and stirred at 25 ° C. for 2 hours. After stirring, the hydrophilic polymer adsorbent was filtered off, and the resulting treated water was used to evaluate the water permeability of a polyethersulfone (PES) UF membrane (Pentair, fractional molecular weight 100 kDa). The water permeability was A. The results are shown in Table 6.

(2) The adsorbent 2-3 after contacted with the raw water in (1) above is collected by filtration and stirred for 1 hour using surface water collected from Inba marsh (Chiba Prefecture) heated to 80 ° C. After carrying out the regeneration treatment, treated water was obtained again at 25 ° C. in the same manner as in (1) above. As a result of evaluating the water permeability of a polyethersulfone (PES) UF membrane (Pentair, fractional molecular weight 100 kDa), the long-term water permeability was A. The results are shown in Table 6. The surface water used for regeneration is in a state where insoluble matters are removed (turbidity: 200 NTU or less) by sampling with a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) having an exclusion diameter of 2 μm.

[Comparative Example 2-3]
The surface water is filtered without using an adsorbent and filtered through a stainless mesh cartridge filter (TMP-2, manufactured by Advantech) with a diameter of 2 μm, and the water permeability of PVDF MF module (Asahi Kasei Co., Ltd., UNA-620A) is evaluated. The evaluation was performed in the same manner as Reference Example 2-7 except that. The long-term water permeability was B because the causative substance causing film fouling was not removed by the adsorbent. The results are shown in Table 6.

According to the present invention, it is possible to provide an adsorbent that has an ability to adsorb a membrane fouling-causing substance and can efficiently treat water to be treated having the membrane fouling-causing substance. Further, the feed water treated with the adsorbent can suppress the deterioration of the filtration membrane due to membrane fouling, thereby prolonging the useful life of the membrane.

Although the preferred embodiments of the present invention have been described above by way of example, those skilled in the art can make various modifications, additions and substitutions without departing from the scope and spirit of the present invention disclosed in the claims. It will be understandable.

Claims

An adsorbent comprising a first polymer containing a cationic group, wherein the adsorbent has a cationic group density of 10 mmol / g to 30 mmol / g (content of cationic group per gram of dry weight) 10 to 30 mmol, hereinafter, g represents an absolute dry weight.), Preferably a film fouling causative substance having a region of 11 mmol / g to 28 mmol / g and having an adsorption ability for the film fouling causative substance Adsorbent.
The adsorbent according to claim 1, wherein the cationic group is selected from an amino group, a quaternary ammonium group, an imino group, an amidine group, a guanidino group, an imidazole group, a quaternary imidazolium group, a pyridyl group, and a quaternary pyridinium group. Membrane fouling causative agent adsorbent that is at least one functional group selected.
The adsorbent according to claim 1 or 2, wherein the first polymer is at least one selected from polyethyleneimine, polyallylamine, polyvinylamine, polyamidine, polyguanidine, polyamino acid, polypyridine, and salts thereof. Membrane fouling-causing substance adsorbent, which is a polymer.
The membrane fouling-causing substance adsorbent according to any one of claims 1 to 3, wherein the first polymer is introduced into the substrate.
5. The adsorbent according to claim 4, wherein the base material is a polymer base material made of a second polymer.
6. The adsorbent according to claim 5, wherein the second polymer is a hydrophilic polymer.
The adsorbent according to claim 5 or 6, wherein the adsorbent is a polymer alloy of a first polymer and a second polymer.
8. The adsorbent according to claim 7, wherein the second polymer constituting the substrate is an ethylene-vinyl alcohol copolymer.
The membrane fouling-causing substance adsorbent according to any one of claims 1 to 8, wherein the adsorbent has a degree of swelling in water at 25 ° C of 20 to 500%, preferably 30 to 250%.
The adsorbent according to any one of claims 1 to 9, wherein the membrane fouling-causing substance includes a biopolymer.
The adsorbent according to any one of claims 1 to 10, wherein the adsorbent comprises a group consisting of an ultrafiltration (UF) membrane, a microfiltration (MF) membrane, a nanofiltration (NF) membrane, and a reverse osmosis (RO) membrane. A membrane fouling causative agent adsorbent used to provide feed water for membrane filtration treatment with at least one selected membrane.
A treated water containing a membrane fouling-causing substance is brought into contact with the membrane fouling-causing substance adsorbent according to any one of claims 1 to 11 at a first contact temperature. An adsorption process for adsorbing the substances that cause membrane fouling;
It includes a membrane filtration step for membrane filtration treatment of the adsorption treated water obtained by the adsorption step, and the membrane filtration step is an ultrafiltration (UF) membrane, a microfiltration (MF) membrane, a nanofiltration (NF) membrane, and the reverse A water treatment method that is performed in one or more stages using at least one membrane selected from the group consisting of osmotic (RO) membranes.
The water treatment method according to claim 12, wherein the water to be treated is water containing 0.1% by mass or more of salts.
The water treatment method according to claim 12 or 13, wherein the adsorbent adsorbing the membrane fouling-causing substance in the adsorption step is regenerated by bringing the adsorbent into contact with the second fluid at a second contact temperature. A water treatment method provided at least.
The membrane fouling-causing substance adsorbent according to any one of claims 1 to 11, wherein the membrane fouling-causing substance is adsorbed, is contacted with a cleaning fluid heated to 40 ° C or higher to regenerate the adsorbent. A method for regenerating the adsorbent that causes membrane fouling.
16. The regeneration method according to claim 15, wherein the cleaning fluid is a metal ion-containing aqueous solution.