WO2015076371A1 - Hydrophilic polymeric adsorbent and water treatment method employing same - Google Patents

Abstract

Provided are: an adsorbent which has adsorptivity for organic carbon (in particular, substances causing membrane fouling) contained in raw water obtained from natural environments or artificial environments; and a water treatment method in which the adsorbent is used. The adsorbent is a hydrophilic polymeric adsorbent, has a degree of swelling in 25°C water of 20-500%, and has a functional group capable of forming a bond with at least some components of the organic carbon contained in water to be treated (hereinafter, referred to as bond-forming group). The water treatment method includes at least an adsorption step in which organic-carbon-containing water to be treated is brought into contact with the hydrophilic polymeric adsorbent to adsorb the organic carbon thereonto.

Description

Hydrophilic polymer adsorbent and water treatment method using the same Related applications

This application is based on the priority of Japanese Patent Application No. 2013-243150 filed on November 25, 2013, the priority of Japanese Patent Application No. 2014-053175 filed on March 17, 2014, and the patent application filed on March 17, 2014. This application claims the priority of application 2014-053176, which is incorporated by reference in its entirety as a part of this application.

The present invention relates to an adsorbent having adsorptivity to organic carbon (particularly a causative substance that causes membrane fouling) contained in raw water obtained from a natural environment or an artificial environment, and a water treatment using the same. Regarding the method.

When water treatment is performed on raw water obtained from a natural environment or an artificial environment, dissolved organic carbon (DOC) exists in such raw water. 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. Such humic substances are also included, and the main compounds and materials constituting the DOC are soluble and cannot be easily separated from water. And in patent document 1; a. Adding an ion exchange resin 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. It proposes a method for removing dissolved organic carbon from water by separating the resin loaded with the dissolved organic carbon from the water. And d. A process for regenerating a resin loaded with organic carbon has also been proposed.

On the other hand, ultrafiltration (UF) membrane, microfiltration (MF) membrane, nanofiltration (NF) membrane, reverse osmosis (RO) in the field of water treatment such as water purification, ultrapure water, pharmaceutical water, domestic water purification, wastewater purification, etc. Membranes are becoming popular. Although these membrane filtrations allow high-level water treatment, on the other hand, membranes used for water treatment cause membrane fouling as the operating time elapses.
Biofouling, which is membrane contamination with organic carbon, is a physically irreversible fouling and is currently a major problem in water treatment by membrane filtration.

Especially, there is an increasing social demand for a device that desalinates brine such as seawater using a reverse osmosis (RO) membrane. In the desalination of seawater by membrane filtration, membrane fouling due to inorganic substances and organic substances present in seawater is an important problem that leads to an increase in water production costs.

In order to solve the above problems, a water treatment method has been proposed in which an activated carbon treatment, an adsorption treatment with a porous inorganic adsorbent, a coagulation treatment, a treatment using ozone treatment, or the like is provided in the front stage of the filtration membrane. However, the adsorptivity of organic carbon is insufficient in the activated carbon treatment or the adsorption treatment with the porous inorganic adsorbent. In addition, the agglomeration treatment has a drawback that a large amount of an aggregating agent such as ferric chloride needs to be added when the organic carbon concentration increases. Further, there is a problem that aggregation of organic carbon having high hydrophilicity becomes incomplete. Ozone treatment has the problem of disinfection by-products such as bromic acid, and alternative techniques are required.

In recent years, detailed analysis has been made on fouling substances in membrane filtration. In Non-Patent Document 1, the causative substances of physically irreversible membrane fouling are aromatic carbons such as humic acid and fulvic acid among organic carbons. It has been reported that biopolymers such as saccharides and proteins, which are organic carbons having relatively higher hydrophilicity than hydrophobic substances having a family ring, are the main causes. Further, in Non-Patent Document 2, the phenomenon that the RO membrane permeation performance is reduced is caused by biofouling caused by the growth of microorganisms, and the biofouling is greatly contributed by polysaccharides that are nutrients for microorganisms. Has been reported.

For example, Patent Document 2 proposes a removal method using a colloidal adsorbent as a technique for adsorbing and removing saccharides. Patent Document 3 exemplifies zeolite and activated carbon, and a regeneration method is also proposed. Patent Document 4 proposes a method of using, as an adsorbent, particles made of a cationic polymer that swells in water and does not substantially dissolve in water.

Japanese National Patent Publication No. 10-504995 JP 2013-223847 A JP 2013-56286 A Japanese Patent No. 5218731

However, since the adsorbent of the invention of Patent Document 1 is mainly an adsorbent having a hydrophobic main skeleton, organic carbon having a high hydrophilicity, especially a causative substance of physically irreversible membrane fouling is used. It cannot be removed efficiently. Further, with the colloidal adsorbent used in the invention of Patent Document 2, it is difficult to regenerate the adsorbent. The invention of Patent Document 3 discloses a method for removing a biopolymer by physical adsorption using surface pores. However, in the case of physical adsorption using pores, physics using surface pores is disclosed. Since all organic carbon is adsorbed by adsorption, it is not possible to efficiently remove physically irreversible substances causing membrane fouling from the water to be treated. Furthermore, since it is difficult to regenerate if the adsorbent is adsorbed in a saturated state, it is virtually impossible to perform both adsorption and regeneration efficiently. In the first place, any of the adsorbents illustrated in the first place requires a large amount of adsorbent because the adsorption performance of the highly hydrophilic biopolymer is insufficient.

Further, in the inventions of Patent Documents 1 and 3, an adsorbent regeneration method is also exemplified. However, in the method described in Patent Document 1, an aqueous medium that is a regeneration medium is formed even inside an adsorbent having a hydrophobic resin as a main skeleton. Since the medium does not penetrate sufficiently, there is a concern that the reproduction efficiency is poor. Also in Patent Document 3, it is considered difficult to efficiently remove and regenerate the biopolymer clogged in the pores.

Further, the particles made of the cationic polymer disclosed in Patent Document 4 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 an extremely large swellability, it is difficult to handle during the adsorption and regeneration treatment, and has a problem that the liquid permeability is lowered due to adhesion between particles, particularly in a closed environment.

The object of the present invention is to efficiently adsorb organic carbon (especially biopolymer) having relatively high hydrophilicity, such as saccharides and proteins, which is a membrane contaminant of membrane filtration in view of the above-described circumstances. An object of the present invention is to provide a polymer adsorbent that can be used.

Another object of the present invention is to provide a water treatment method that not only enables efficient water treatment using such a polymer adsorbent, but also maintains the water permeability of the membrane over a long period of time. .

Still another object of the present invention is to provide organic carbon contained in raw water obtained from a natural environment or an artificial environment, in particular, a causative substance of physically irreversible membrane fouling, and a biopolymer reported to be the main cause thereof. It is to provide a water treatment method capable of efficiently adsorbing and adsorbing the adsorbent after adsorption by a simple method.

The inventors of the present invention have intensively studied to achieve the above object, and as a result, have found the following configurations.

That is, the first configuration of the present invention is as follows.
The degree of swelling in water at 25 ° C. is 20 to 500% (for example, 20 to 400%), has a hydrophilic polymer as a main skeleton, and at least a part of organic carbon in the water to be treated. It is a hydrophilic polymer adsorbent having a functional group capable of forming a bond with a component (hereinafter referred to as a bond forming group).

For example, in the hydrophilic polymer adsorbent, the bond-forming group has an ability to form at least one bond selected from the group consisting of a hydrogen bond, an ionic bond, and a chelate bond with respect to the adsorbed component. It may be. Further, the bond-forming group may be a different type from the hydrophilic group contained in the hydrophilic polymer.

The bond-forming group may be a bond-forming group containing at least one element selected from the group consisting of N, S, P and O, for example. For example, the bond-forming group is preferably at least one selected from the group consisting of amino groups, quaternary ammonium groups, and salts thereof.

The component adsorbed in the adsorption step may contain a biopolymer. In addition, the adsorbed components include components with a retention time of 25 to 38 minutes measured by the method described in Stefan A. Huber et al. Water Research 45 (2011) pp879-885. May be.

In the hydrophilic polymer adsorbent, when the component to be adsorbed is a biopolymer, the removal rate of the biopolymer may be 15% or more.

The hydrophilic polymer adsorbent preferably has higher biopolymer adsorbability than humic adsorbent, for example, biopolymer model water at 25 ° C. (sodium alginate concentration: 4.3 mg-C / L sodium alginate) Aqueous solution) and humic model water (sodium humate concentration: 4.3 mg-C / L sodium humate aqueous solution), sodium alginate adsorption rate (A), sodium humate adsorption rate (B), The ratio of (A) / (B) may be 1.0 to 10. In addition, in the hydrophilic polymer adsorbent, in the biopolymer model water (sodium alginate concentration: 4.3 mg-C / L sodium alginate aqueous solution) at 25 ° C., the adsorption rate (A) of sodium alginate is 30% or more. There may be.

For example, in the hydrophilic polymer adsorbent, the hydrophilic polymer is polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal (eg, polyvinyl formal, polyvinyl butyral), polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl. At least one selected from ether, polyalkylene oxide, poly (meth) acrylamide, cationic polymer, anionic polymer, phenol resin, polyamide, polyvinylpyrrolidone, cellulose derivative, dextrin, chitin, and chitosan Also good.

For example, the polymer adsorbent may have a hydrophilic polymer as a main skeleton, and a bond-forming group is introduced into the hydrophilic polymer. The polymer adsorbent may be a polymer alloy including a bond-forming group-containing polymer (A) and a hydrophilic matrix polymer (B).

In this case, the hydrophilic polymer or hydrophilic matrix polymer (B) includes polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal, polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, poly ( It may contain at least one selected from the group consisting of (meth) acrylamide, cationic polymer, anionic polymer, phenol resin, polyamide, polyvinylpyrrolidone, cellulose derivative, dextrin, chitin, and chitosan.

The second configuration of the present invention is as follows:
A water treatment method comprising at least an adsorption step in which water to be treated containing organic carbon is brought into contact with the hydrophilic polymer adsorbent to adsorb at least a part of the organic carbon. The water to be treated may be raw water obtained from a natural environment or an artificial environment, and may be, for example, fresh water or water containing salts.

The water treatment method may further include a membrane filtration step in which the adsorption treated water obtained in the adsorption step is subjected to membrane filtration by a membrane filtration treatment. The membrane filtration step is performed using 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. Or it may be performed in multiple stages.

The water treatment method may further include a regeneration step in which the adsorbent after the adsorption step is brought into contact with an aqueous medium to regenerate the adsorbent.

The aqueous medium used in the regeneration step may be water or a metal ion-containing aqueous solution (for example, an alkali metal ion-containing aqueous solution). The temperature of the aqueous medium may be about 40 ° C. to 110 ° C.

In addition, as another configuration, the present invention is a polymer adsorbent used for water treatment,
The polymer adsorbent is a hydrophilic polymer adsorbent having a degree of swelling of 20 to 500% in water at 25 ° C.,
The polymer adsorbent includes a polymer adsorbent that can adsorb at least a part of organic carbon contained in raw water and can be regenerated after the adsorption step. May be.

According to another aspect of the present invention, there is provided an adsorbent regeneration method in which the polymer adsorbent adsorbing at least part of organic carbon contained in raw water is regenerated by contact with an aqueous medium. It may be included.

In the first configuration of the present invention, by using a specific hydrophilic polymer adsorbent, organic carbon contained in raw water, which has been difficult to remove in the past, particularly physically irreversible membrane fouling is generated. Causative substances (especially highly hydrophilic biopolymers such as sugars and proteins) can be adsorbed efficiently.
In the second configuration of the present invention, by performing water treatment using the hydrophilic polymer adsorbent, organic carbon in the adsorption treated water (water subjected to the adsorption treatment), particularly the cause of membrane fouling. The amount of substance can be reduced.
If necessary, the adsorbent after the adsorption step can be regenerated by simply desorbing the adsorbent from the adsorbent by contact with an aqueous medium. Furthermore, if necessary, the regenerated adsorbent can be effectively used again for the adsorption treatment.

Furthermore, in the water treatment method of the second configuration of the present invention, when using the adsorption treated water that has undergone the adsorption treatment, when combined with various membrane filtration steps, membrane fouling, particularly physically, can be achieved by a simple method. It is possible to suppress the occurrence of irreversible membrane fouling and maintain the water permeability of the filtration membrane over a long period of time.

In particular, the hydrophilic polymer adsorbent can also be packed into a column. In that case, in the water treatment method, a simple method is obtained by combining the organic carbon removal step by using the column and the membrane filtration step. Thus, the water permeability can be maintained for a long time.

Organic matter measured by LC-OCD (manufactured by DOC-Labor) connected to a wet total organic carbon measuring instrument (OCD meter) to high performance liquid chromatography (HPLC) with respect to the water to be treated used in Example 1-3 It is a graph which shows the molecular weight distribution spectrum of carbon.

(Hydrophilic polymer adsorbent)
The hydrophilic polymer adsorbent which is the first embodiment of the present invention will be described.
The hydrophilic polymer adsorbent according to the first embodiment has a swelling degree of 20 to 500% in water at 25 ° C., and has a functionality capable of forming a bond with at least a part of the organic carbon in the water to be treated. It is a hydrophilic polymer adsorbent having a group (hereinafter referred to as a bond-forming group).

By using a hydrophilic polymer as the main skeleton, the wettability to water is increased, and at least some components of organic carbon, especially the causative substances that cause physically irreversible membrane fouling, are adsorbed by appropriate swelling. It can penetrate into the material. As a result, the internal adsorptive functional group can also be used effectively, and clogging with organic carbon is unlikely to occur, so that excellent organic carbon removing ability can be expressed.

Although the mechanism by which the hydrophilic polymer adsorbent used in the present invention acts is not clear, the following mechanism is assumed. (I) By using a hydrophilic polymer as the main skeleton, the wettability to water is increased, and at least a part of the organic carbon, particularly the causative substance that causes physically irreversible membrane fouling, can reach the inside of the adsorbent. (Ii) The infiltrated component is captured by an interaction such as a hydrogen bond, a coordination bond, a chelate bond, or an ionic bond by a group capable of forming a bond with this component (bond-forming group), and the adsorbent Efficiently removes at least some components of organic carbon, especially those that cause physically irreversible membrane fouling (especially biopolymers that are beginning to be considered to be highly hydrophilic and a concern for membrane contamination) It is presumed that it can be adsorbed. (Iii) In particular, since the degree of swelling of the hydrophilic polymer adsorbent in water at 25 ° C. is in a specific range, the bond-forming groups present in the adsorbent can be effectively used, and Since clogging hardly occurs, it is considered that excellent organic carbon removing ability can be expressed.
(Iv) On the other hand, since conventional ion exchange resins are provided with an adsorptive functional group using a hydrophobic polymer such as polystyrene as a main skeleton, organic carbon contained in the raw water (particularly highly hydrophilic) It is difficult for carbon (airframe) to approach hydrophobic polymers, and (v) in that case, it is not possible to approach, so that interactions such as hydrogen bonds, coordination bonds, and ionic bonds are expressed in the adsorbent. It is presumed that the adsorbent may not be able to adsorb the causative substance even if it has a functional group.

Furthermore, since the degree of swelling is controlled within a predetermined range, even when a hydrophilic polymer is used as the main skeleton, while suppressing the deterioration of the handleability of the adsorbent due to excessive swelling, It is possible to adsorb organic carbon efficiently.
For example, since the hydrophilic polymer adsorbent has a controlled degree of swelling, unlike the cationic polymer described in Patent Document 4 that swells in water and does not substantially dissolve in water, the hydrophilic polymer adsorbent is previously swollen in water. You may make it contact with to-be-processed water, without performing a process. Moreover, since swelling property is controlled, even if it is a water-containing state, it is excellent in the distribution | circulation property.

The hydrophilic polymer adsorbent is a functional group capable of forming a bond with at least a part of the organic carbon contained in the raw water (especially a causative substance that causes physically irreversible membrane fouling) ( Or a bond-forming group). The bond-forming group can form various bonds (for example, hydrogen bond, coordination bond, chelate bond, ionic bond, etc.) with the adsorbing component. By such various bonds, the component can be adsorbed to the adsorbent.
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 anion ion-exchange group. The organic carbon contained in the raw water with respect to the adsorbent, particularly physical There is no particular limitation as long as adsorbability to a causative substance that causes irreversible membrane fouling can be imparted.

The bond-forming group may be a bond-forming 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 include amino groups, quaternary ammonium groups, iminium groups, imidazole groups, quaternary imidazolium groups, pyridyl groups, quaternary pyridinium groups, and salts thereof, more preferably amino groups. Quaternary ammonium groups and their salts are mentioned.

The hydrophilic polymer adsorbent has a hydrophilic polymer as a main skeleton, and when the hydrophilic polymer is produced, a bond-forming group may be introduced by polymerization or post-modification. The bond-forming group may be introduced by alloying the component having a hydrophilic polymer component.

For example, the hydrophilic polymer adsorbent may have a hydrophilic polymer as a main skeleton, and the hydrophilic polymer itself may have a bond-forming group in its structure.
In that case, the hydrophilic polymer adsorbent can introduce a bond-forming group into the main chain or side chain by homopolymerizing or copolymerizing a monomer (or a derivative thereof) containing the bond-forming group. . The copolymerization may be a copolymerization of monomers (or derivatives thereof) containing a bond-forming group, a monomer (or derivative thereof) containing a bond-forming group, and a monomer (not containing a bond-forming group). Or copolymerization thereof).
Alternatively, the hydrophilic polymer adsorbent may have a hydrophilic polymer as a main skeleton, and a bond forming group may be introduced into the hydrophilic polymer. In that case, after forming a hydrophilic polymer, a bond-forming group may be introduced by post-modification. The bond-forming group to be introduced may be a different type of functional group from the hydrophilic group of the hydrophilic polymer.
The amount of the bond-forming group introduced is 2 to 100 mol%, preferably 3 to 95 mol%, more preferably 5 to 90 mol%, based on the total number of monomer units in the polymer. There may be.

Preferably, the polymer adsorbent may have a hydrophilic polymer as a main skeleton and a bond-forming group is introduced into the hydrophilic polymer. Alternatively, a polymer alloy in which a hydrophilic polymer as a main skeleton constitutes a matrix component may be used.
Here, the hydrophilic polymer has a solubility parameter (δ) calculated by the following formula using the cohesive energy density (Ecoh) and molar molecular volume (V) calculated by the Fedor's estimation method. A certain polymer may be sufficient. The solubility parameter (δ) is preferably 24 or more, and more preferably 25 or more. The upper limit of the solubility parameter is not particularly limited, but may be about 35, for example.
δ = [ΣEcoh / ΣV] ^1/2
Examples of the hydrophilic polymer include a polymer having a hydrophilic group such as a hydroxyl group, an ether group, a cationic group, an anionic group, and an amide group in a repeating unit.

Examples of the hydrophilic polymer include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal (eg, polyvinyl formal, polyvinyl butyral), polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, Poly (meth) acrylamide, cationic polymer (eg, polyethyleneimine, polyallylamine, polyvinylamine, polyamidoamine dendrimer, polypyridine, polyvinylpyridine, polyamino acid, polydiallyldimethylammonium halide, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide , Polydimethylaminoethyl methacrylate hydrochloride, polynucleotide ), Anionic polymers (for example, polystyrene sulfonic acid, polyvinyl sulfate, poly (meth) acrylic acid, polymaleic acid, polyamic acid), phenol resin, polyamide, polyvinyl pyrrolidone, cellulose derivatives, dextrin, chitin, and chitosan At least one selected from the above 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. The content of the comonomer unit is preferably 10 mol% or less, more preferably 5% mol or less in all monomer units.

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.

Particularly preferred hydrophilic polymers include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal (polyvinyl formal, polyvinyl butyral), and polyamide (for example, polyamide 6, polyamide 10, polyamide 6,6, polyamide 11, polyamide). 12, polyamide 6,12, polyamide 6,10, polyamide 6 / 6,6 copolymer, polyamide 6,6 / 6,10 copolymer, polyamide 6,11, polyamide 6,6 / 6,10 / 6 An ethylene-vinyl alcohol copolymer is particularly preferable from the viewpoint of not only water resistance but also excellent organic carbon (particularly biopolymer) adsorption performance, moldability and hydrophilicity.

In the ethylene-vinyl alcohol copolymer, the content of ethylene units is preferably 20 to 60 mol%, more preferably 25 to 55 mol% (for example, 25 to 50 mol%) in all monomer units. Good. 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.

The polyvinyl alcohol may be defined by the viscosity average degree of polymerization, and the viscosity average degree of polymerization obtained from the viscosity of the 30 ° C. aqueous solution can be selected from a wide range of about 100 to 15000, 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.

Further, 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.

Moreover, the polymer adsorbent of the present invention uses the above hydrophilic polymer as a matrix component and is alloyed with a component having a bond-forming functional group (bond-forming group) to convert the bond-forming group into a hydrophilic polymer. It may be introduced. From the viewpoint of ease of introduction, the polymer adsorbent is preferably a polymer alloy of a bond-forming group-containing polymer (A) and a hydrophilic polymer matrix (B).

[Bond Forming Group-Containing Polymer (A)]
For example, the bond-forming group-containing polymer (or chemisorbable functional group-containing polymer) (A) is polystyrene sulfonic acid (PSS), polyvinyl sulfate (PVS), polyacrylic acid (PAA), polymethacrylic acid (PMA). , Anionic polymers such as polymaleic acid and polyamic acid; polyethyleneimine, polyallylamine, polyvinylamine, polyamidoamine dendrimer, polypyridine, polyvinylpyridine, polyamino acid, polydiallyldimethylammonium halide, polyvinylbenzyltrimethylammonium halide Cationic polymers such as polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, and polynucleotide may be used. Such polymers may be used alone or in combination of two or more.

Among these, from the viewpoint of more efficiently adsorbing organic carbon contained in raw water, particularly causative substances (particularly biopolymers) that cause physically irreversible membrane fouling, in combination with a hydrophilic matrix polymer. In particular, a polymer having a high cation density (for example, polyethyleneimine, polyallylamine, etc.) is preferable.

[Hydrophilic matrix polymer (B)]
The hydrophilic matrix polymer (B) may be the predetermined hydrophilic polymer described above.

[Mass ratio between the bond-forming group-containing polymer (A) and the hydrophilic matrix polymer (B)]
In the hydrophilic polymer adsorbent of the present invention, the bond-forming group-containing polymer (A) and the hydrophilic matrix polymer (B) in the alloy of the bond-forming group-containing polymer (A) and the hydrophilic polymer matrix (B). ) Is not particularly limited as long as the polymer (A) is dispersed within a predetermined range. For example, the polymer (A) / polymer (B) is approximately 1/99 to 70/30 in mass ratio. It may be about 5/95 to 65/45, more preferably about 8/92 to 60/40. If the amount of the polymer (A) is too much, the water resistance may be lowered, and if the amount of the polymer (A) is too small, the adsorption performance tends to be lowered. The polymer (A) is preferably dispersed in the hydrophilic matrix polymer (B).

[Other ingredients]
In the present invention, the hydrophilic polymer adsorbent having organic carbon adsorptivity contains other polymer polymers as a resin component or a forming component within a range not impairing the effects of the present invention. Also good. In addition, the hydrophilic polymer adsorbent of the present invention is, for example, a cross-linking agent, an antioxidant, a stabilizer, a lubricant, a processing aid, an antistatic agent, a colorant, an antifoaming agent, a dispersing agent, etc. if necessary. These various additives may be included.

In the hydrophilic polymer adsorbent of the present invention, the degree of swelling at 25 ° C. is 20 to 500% (for example, 20 to 400) in terms of mass% from the viewpoint of enabling the adsorption of biopolymers and improving the handling properties. %), Preferably 30 to 450%, more preferably 40 to 400%. The swelling degree of the hydrophilic polymer adsorbent may be more preferably about 40 to 300% (for example, 40 to 200%), and still more preferably about 50 to 200% (for example, 50 to 160%). It may be. In addition, the swelling degree of a hydrophilic polymer adsorbent shows the value measured by the method described in the Example mentioned later.

If the degree of swelling is too small, contact with organic carbon, particularly a solution containing a causative substance that causes physically irreversible membrane fouling may be insufficient, or physically irreversible membrane fouling may be caused. If the resulting causative substance is poorly adsorbed and the degree of swelling is too large, the liquid permeability is impaired due to excessive swelling, and the column take-out property becomes insufficient.

For example, the swelling property of the hydrophilic polymer adsorbent may be controlled by crosslinking with a crosslinking agent and / or low swelling property or non-swelling property with respect to the bond-forming group-containing polymer (A). It may be controlled as an alloy material combining a hydrophilic matrix polymer (for example, ethylene-vinyl alcohol copolymer and polyamide).

In particular, the hydrophilic polymer adsorbent of the present invention is preferably crosslinked with a crosslinking agent from the viewpoint of controlling durability and swelling property. The crosslinking agent can be appropriately determined according to the type of the crosslinking reactive group of the hydrophilic polymer. For example, an epoxy group, a carboxyl group, a halogen group, an acid anhydride group, an acid halide group, a formyl group, N -A compound containing at least two functional groups of at least one or two or more selected from chloroformyl group, chloroformate group, amidinyl group, isocyanate group, vinyl group, aldehyde group, azetidine group, carbodiimide group, etc. It is done. Also, zirconyl crosslinking agents (zirconyl nitrate, ammonium zirconium carbonate, zirconyl chloride, zirconyl acetate, zirconyl sulfate), titanium crosslinking agents (titanium crosslinking agent, 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.

For example, the crosslinking structure may be introduced with a crosslinking agent by using a copolymer component such as a divinyl monomer during the synthesis of the hydrophilic polymer adsorbent.

Moreover, you may introduce | transduce a crosslinked structure by melt-kneading together with the structural component of a crosslinking agent and a hydrophilic polymer adsorption material.
In the case of performing melt kneading, a method (melt kneading method) in which the components of the hydrophilic polymer 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.

Also, once the hydrophilic polymer adsorbent material is molded by melt molding, solution molding, etc. to form molded bodies of various shapes, the molded body is immersed in a solution containing a crosslinking agent to introduce a crosslinked structure. Also good.
When performing melt molding, for example, a hydrophilic polymer adsorbent material excluding at least a crosslinking agent is melt-kneaded using a biaxial kneader or the like, and the melt-kneaded material is formed into various shapes by extrusion molding, injection molding, or the like. After obtaining a molded body, the molded body may be subjected to crosslinking treatment by dipping in a solution containing a crosslinking agent.
Further, when performing solution molding, for example, from a hydrophilic polymer adsorbent material excluding at least a cross-linking agent, a mixed solution is prepared using an appropriate solvent, and using this mixed solution, cast film formation or dry spinning, After obtaining a film-like or fibrous shaped body by wet spinning or the like, the shaped body may be dipped in a solution containing a crosslinking agent and subjected to a crosslinking treatment.

Such a polymer adsorbent is particularly excellent in absorbability of biopolymer, and biopolymer model water at 25 ° C. (sodium alginate concentration: 4.3 mg-C / L sodium alginate aqueous solution) and humic model water ( In each of the 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 1.0 to 10, preferably about 1.1 to 9, more preferably 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.

Further, the polymer 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, preferably 35% or more, and more preferably 45% or more. About the adsorption rate, the value measured by the method described in the Example mentioned later is shown.

(Shape of hydrophilic polymer adsorbent)
The hydrophilic polymer adsorbent can have various shapes as long as it can be used for adsorption treatment of at least a part of the organic carbon in the water to be treated (for example, biopolymer). It may be a shape, a fiber shape, various three-dimensional shapes or the like. From the viewpoint of improving the adsorption efficiency, the hydrophilic polymer adsorbent is preferably in the form of particles or fibers.

When the hydrophilic polymer adsorbent is in the form of particles, the particle diameter is not particularly limited, and can be selected from a wide range of 0.5 μm to 20 mm. For example, from the viewpoint of performing solid-liquid separation by filtration, for example, the particle diameter may be 1 μm or more, 10 μm or more, or 100 μm or more. On the other hand, the particle diameter may be 10 mm or less, 5 mm or less, 4 mm or less, or 3 mm or less.
From the viewpoint of handleability and adsorptivity, the particle size is preferably 1 μm to 5000 μm, more preferably 10 μm to 4000 μm, and most preferably 20 μm to 3000 μm. When the particle size is too small, handling is difficult, for example, the fine powder tends to fly. If the particle size is too large, sufficient adsorption performance may not be obtained. In addition, a particle diameter shows the value classified by sieving.

The average particle diameter of the polymer adsorbent in a swollen state in 25 ° C. water may be, for example, 1 μm or more depending on the purpose, and may be 5 μm or more, 50 μm or more, more than 100 μm (for example, 110 μm or more). It may be 150 μm or more, or 200 μm or more. The average particle diameter of the polymer adsorbent in a swollen state in 25 ° C. water may be 10 mm or less, 4.5 mm or less, 3.5 mm or less, or 3 mm. It may be the following. In addition, an average particle diameter shows the value measured by the method described in the Example mentioned later.

When the polymer adsorbent is fibrous, the average fiber diameter is not particularly limited, but can be selected from a wide range of 0.1 to 1000 μm, for example, 1 to 500 μm, preferably 2 It may be up to 200 μm. The average fiber diameter can be calculated as an average fiber diameter by measuring the fiber diameter at 10 locations of fibers in a standard state defined by JIS L 0105 with a micrometer.
Moreover, as a fiber, a continuous fiber may be sufficient and a short fiber may be sufficient. In the case of short fibers, the fiber length may be, for example, about 0.1 to 100 mm (for example, 1 to 100 mm), preferably about 0.5 to 80 mm (for example, 5 to 80 mm), more preferably 10 It may be about 50 mm.

[Water treatment method]
2nd Embodiment of this invention is equipped with the to-be-processed water containing organic carbon, and a specific hydrophilic polymer adsorbent, and is provided with the adsorption | suction process which adsorb | sucks at least one component of organic carbon at least. Water treatment method.
Preferably, the water treatment method may include a filtration step of performing membrane filtration on the adsorption-treated water subjected to the adsorption treatment.

(Adsorption process)
As long as the water to be treated can use various raw waters obtained in natural and artificial environments as water to be treated, it contains organic carbon, especially the causative substances that cause physically irreversible membrane fouling. Although not particularly limited, for example, as raw water, in general river water, lake water, seawater (salt content 2 to 4% by mass), brackish water (salt content 0.5 to 2% by mass), oil fields and gas fields Examples include associated water generated, soil elution water, irrigation water, biologically treated water, biologically treated water in sewage treatment and human waste treatment facilities, highly treated water such as tertiary treatment, and various factory effluents.

Moreover, the raw water that is the treated water may contain organic carbon, particularly a causative substance that causes physically irreversible membrane fouling, and water that contains 0.5% by mass or more of salt, For example, water containing various salts obtained from raw water in the natural environment, such as water with higher salt concentration, obtained by treating the raw water such as seawater, is used as raw water that is to be treated. Can do. In that case, the water to be treated may have a salt concentration of 0.5% by mass or more (for example, about 0.5 to 30% by mass), 1% by mass or more, or 2% by mass or more.
Examples of the salt in the water to be treated include alkali metal salts such as sodium chloride and potassium chloride; alkaline earth metal salts such as magnesium chloride, magnesium sulfate, calcium chloride, and calcium sulfate. Can be calculated as the concentration of the total amount of these salts. The salt may be a salt that makes the aqueous solution neutral.

Here, the organic carbon contained in the raw water usually means an organic compound constituting the total organic carbon (TOC) contained in the raw water described above. The organic carbon includes dissolved organic carbon (Dissolved Organic carbon) and particulate organic carbon (POC).
In addition, the causative substance that causes physically irreversible membrane fouling is a kind of organic carbon, and it is difficult to remove substances that are difficult to remove by means such as physical backwashing when performing membrane filtration. I mean. 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.

Although various compounds can be considered as causative substances, the causative substances adsorbed in the adsorption process belong to organic substances having a particle diameter of 0.45 μm or less that are considered difficult to desorb when physically adsorbed. It may be a substance.
Examples of organic substances having a particle size of 0.45 μm or less include aromatic-containing organic substances such as humic acid and fulvic acid, synthetic chemical substances such as surfactants, biopolymers, etc. In the adsorption process of the present invention, for example, high It is sufficient that at least a part of the causative substance is adsorbed by the molecular adsorbent.
For example, the adsorbed component is a hydrophilic compound having 100,000 daltons or more, and the retention time during which a humic signal peak appears in LC-OCD in which a wet total organic carbon measuring instrument is connected to high performance liquid chromatography. It may be a substance that exhibits a signal peak in a shorter holding time.

In the adsorption step, it is preferable to adsorb at least the biopolymer as a component of at least a part of the causative substance by the polymer adsorbent.

Biopolymers are compounds (for example, polysaccharides and proteins) having hydrophilic high molecular weight (for example, 100,000 daltons or more). More specifically, the A fraction measured by the method described in Stefan A. Huber et al. Water Research 45 (2011) pp879-885, for example, the retention time by LC-OCD is 25 to 38 minutes. There may be. In the examples, a component having a holding time of 25 minutes or more and 38 minutes or less is measured as a biopolymer in the analysis of LC-OCD (manufactured by DOC-Labor) based on the above-described method. 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 t _b : 25 minutes ≦ t _b ≦ 38 minutes) / area value of entire spectrum (ii ) humic humic substance of UV = test sample total UV × in the spectrum of (holding time _t h: 38 min <area value / spectrum total area values of _{t h} ≦ 50 minutes)

DOC value calculation method (i) DOC of biopolymer = DOC of the entire test sample x area value of biopolymer in the spectrum (holding time t _b : 25 minutes ≤ t _b ≤ 38 minutes) / area value of the entire spectrum (ii ) Humic DOC = DOC of the entire test sample x area value of humic substance in the spectrum (holding time t _h : 38 minutes <t _h ≤ 50 minutes) / area value of the entire spectrum

The ion-exchange resins and chelate resins mainly composed of hydrophobic polymers such as styrene that are currently on the market have organic carbon contained in raw water, especially physically irreversible membrane fouling. The resulting causative substance cannot be adsorbed efficiently. However, in the present invention, by using a specific hydrophilic polymer adsorbent, for example, even hydrophilic organic carbon can be adsorbed efficiently.

In the adsorption step, it is not particularly limited as long as the water to be treated and the hydrophilic polymer adsorbent can be brought into contact. For example, as a batch type, the adsorbent is added to the water to be treated, and known as necessary. The adsorption treatment may be carried out by stirring by a method; or the adsorption treatment may be carried out by passing water to be treated through a column filled with a hydrophilic polymer adsorbent as a continuous type. Further, the adsorption step may be a single step or a multi-step.
In the adsorption step, after the adsorption treatment, the solid-liquid separation step may be performed by a known method as necessary, and the adsorbent after the adsorption treatment may be removed from the adsorption treatment liquid by the solid-liquid separation step. .

The temperature of the water to be treated in the adsorption step can be selected as long as the causative substance can be adsorbed. The temperature of the water to be treated is, for example, 0 to 40 ° C. from the viewpoint of adsorptivity. It may be 5 to 35 ° C, more preferably 10 to 33 ° C.

When the water to be treated contains salts, the temperature of the water to be treated may be, for example, 10 to 40 ° C., preferably 15 to 35 ° C., more preferably 18 to 33 ° C. from the viewpoint of adsorptivity. May be.

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 It can be selected from a wide range of 0.05 to 50 g per liter of treated water, and may be, for example, about 0.05 to 30 g, preferably about 0.1 to 10 g. When the water to be treated contains salts, the amount of the adsorbent may be about 0.1 to 50 g, preferably about 0.5 to 30 g, per liter of water to be treated. *

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 ~ 500h ^-1 (for example, about 0.5 ~ 200h ^-1), preferably about 1 ~ 300h ^-1 (for example, about 1 ~ 150h ^-1).

In the adsorption process, organic carbon in the water to be treated, particularly the causative substance that causes physically irreversible membrane fouling, can be efficiently adsorbed, and in particular, the biopolymer can be adsorbed efficiently as described above. Can do. For example, in the adsorption step, 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 30% or more. . In addition, a removal rate shows the value measured by the method described in the Example mentioned later. If the removal rate is too low, the effect of suppressing membrane contamination in the subsequent membrane filtration step may not be sufficient.

(Membrane filtration process)
After the adsorption step, the adsorption-treated water (or supply water) subjected to the adsorption treatment may be subjected to membrane filtration in the membrane filtration step, if necessary. By combining such membrane filtration, it is possible to purify water according to the application. 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.

The membrane filtration step is performed appropriately 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 present invention, the adsorption process can reduce the amount of organic carbon contained in the raw water, particularly the causative substance that causes physically irreversible membrane fouling. It is possible to efficiently suppress the occurrence of membrane fouling.

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 appropriately set 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 from flux 0.5 to The liquid may be passed through the filtration membrane at 5.0 (m ³ / m ² / day), and may preferably be from Flux 1.0 to 4.0 (m ³ / m ² / day).

In the water treatment method of the present invention, by performing a specific adsorption step, organic carbon that is a causative substance of membrane fouling, particularly a physically irreversible membrane fouling, is caused from water supplied to the filtration membrane. Substances can be reduced. 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, membrane fouling can be suppressed, the frequency of cleaning, the amount of cleaning chemical used can be reduced, and the life of the membrane can be extended.

The water treatment method of the present invention 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. Further, these water treatments may be appropriately performed before and / or after the adsorption treatment.

Further, for example, water from which particles having a particle diameter of 5 μm or more, preferably particles of 1 μm or more, more preferably particles larger than 0.45 μm are excluded by pretreatment for adsorption is used as water to be treated in the adsorption step. preferable.

The adsorbent that has adsorbed at least a part of the organic carbon 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)
In the regeneration step, the adsorbent may be regenerated by bringing an adsorbent that has adsorbed at least a part of the organic carbon into contact with an aqueous medium.

The aqueous medium is a medium composed of a liquid containing water as a main component (for example, 50% by mass or more), and may be, for example, water or an aqueous solution containing metal ions. Further, the contact with the aqueous medium in the regeneration step may be one stage or multiple stages, and in the case of multiple stages, a plurality of types of aqueous media may be used separately.

The metal ion used in the metal ion-containing aqueous solution is not particularly limited as long as the causative substance can be eliminated, but typically includes an alkali metal ion, specifically, an aqueous sodium chloride solution, Examples include potassium chloride aqueous solution, lithium chloride aqueous solution, sodium carbonate, potassium carbonate, lithium carbonate and the like. The aqueous medium 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 can be selected from a wide range of, for example, about 0.1 to 50% by mass as a solute ratio with respect to water, and a low concentration (for example, about 0.1 to 10% by mass, preferably 0.3 to 8% by mass, more preferably about 0.5 to 8% by mass), and high concentration (for example, about 10 to 50% by mass, preferably 15 to 45% by mass, more preferably 20 to 40% by mass).

The temperature of the aqueous medium used in the regeneration step may be equal to or higher than the temperature of the liquid to be treated in the adsorption step, and preferably set to be higher than the temperature of the liquid to be treated in the adsorption step. Good. 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.

The regeneration step is not particularly limited as long as the aqueous medium and the hydrophilic polymer regeneration material can be brought into contact with each other. For example, as a batch type, an adsorbent is added to the aqueous medium, and if necessary, a known method is used. The regeneration treatment may be carried out by stirring; or as a continuous type, the regeneration treatment may be carried out by passing an aqueous medium through a column filled with a polymer adsorbent. Further, the regeneration step may be a single step or multiple steps.

As the temperature of the aqueous medium in the regeneration step, an appropriate temperature can be selected as long as the causative substance can be eliminated, but the temperature of the aqueous medium is, for example, 40 to 110 ° C. from the viewpoint of elimination. The temperature may be 45 to 100 ° C, more preferably 50 to 90 ° C.

The amount of the aqueous medium used for the adsorbent can be appropriately selected according to the type of the aqueous medium, the form of the adsorbent, the type of regeneration process (batch type or continuous type), and the like. When the adsorbent is immersed in an aqueous medium 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 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 aqueous medium. 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.

In the present invention, as another embodiment, an adsorption step in which raw water containing organic carbon is brought into contact with a polymer adsorbent, and at least a part of the organic carbon is adsorbed by the polymer adsorbent; ,
A water treatment method comprising at least a regeneration step of bringing the adsorbent adsorbing the components into contact with an aqueous medium and regenerating the adsorbent,
The polymer adsorbent may include a water treatment method that is a hydrophilic polymer adsorbent having a hydrophilic polymer as a main skeleton and having a specific functional group.

In this case, (i) wettability to water is increased by using a hydrophilic polymer as a main skeleton, and at least a part of organic carbon, particularly a causative substance that causes physically irreversible membrane fouling is adsorbed. (Ii) The infiltrated component is, for example, an adsorbent having a group capable of forming a bond with this component (bond-forming group) such as a hydrogen bond, a coordinate bond, an ionic bond, or a chelate bond. Captured by interaction, adsorbents are beginning to be considered at least some components of organic carbon, especially causative agents that cause physically irreversible membrane fouling (especially highly hydrophilic and a concern for membrane contamination) (Iii) Furthermore, the adsorbent after the adsorption treatment can be efficiently regenerated because the bond is broken by contacting with an aqueous medium. It is estimated.

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.

(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 (%)

(Average particle size)
The average particle size of the adsorbents used in Examples and Comparative Examples was measured with a laser diffraction / scattering particle size distribution analyzer (manufactured by Horiba, Ltd.) after being immersed in water at 25 ° C. for 12 hours.

(Average fiber diameter)
As for the average fiber diameter described in the examples, the fiber diameter was measured at 10 points of the obtained fiber with a micrometer, and the average value was defined as the average fiber diameter.

(Measurement method of organic components)
The concentration of the organic component is measured by LC-OCD (manufactured by DOC-Labor) in which a wet total organic carbon meter (OCD meter) is connected to high performance liquid chromatography (HPLC). Stefan A. Huber et al. “Characterisation of aquatic humic and non-humic matter with size-exclusion chromatography -organic carbon detection -organic nitrogen detection (LC-OCD-OND)” Water Research 45 (2011) pp879-885 Was carried out under the following conditions.
Flow rate: 1.1 mL / min
Sample injection volume: 1 mL
Column: 250 mm x 20 mm, TSK HW50S
UV wavelength: 254 nm
OCD meter: Acid injection rate 0.2mL / min
Eluent: pH 6.85 Phosphate buffer acidified solution: Add 4 mL O-phosphoric acid (85%) and 0.5 g potassium peroxodisulfate to 1 L ultrapure water

(Removal rate of organic components)
Add 5 g of adsorbent (but as dry weight) to 1 L of the liquid to be treated with organic carbon, infiltrate it at 25 ° C. for 4 h, perform the adsorption treatment, filter the adsorbent, and obtain an adsorption treatment liquid. It was. The organic carbon removal rate (%) of the adsorption treatment liquid was calculated as follows.
The supernatant before and after the adsorption treatment was analyzed using LC-OCD (manufactured by DOC-Labor), and the removal rate of biopolymer (retention time 25 to 38 minutes) and humic substances (retention time 38 to 50 minutes) ( %) Was calculated by the following formula.
(I) Biopolymer removal rate = (Biopolymer concentration before adsorption step−Biopolymer concentration after adsorption step) / (Biopolymer concentration before adsorption step) × 100 (%)
(Ii) Removal rate of humic substance = (humic substance concentration before adsorption process−humic substance concentration after adsorption process) / (humic substance concentration before adsorption process) × 100 (%)

(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: 1200 minutes or more B: 900 minutes or more and less than 1200 minutes C: 600 minutes or more and less than 900 minutes D: Less than 600 minutes

[Example 1-1]
Polyvinyl alcohol (“PVA-117” manufactured by Kuraray Co., Ltd.) 88 parts by mass and polyallylamine (“PAA-15C” manufactured by Nitto Bo Medical Co., Ltd.) 12 parts by mass are used, and these resins are dissolved in water. I let you. The solution was wet-spun into a saturated sodium sulfate bath at 40 ° C. from a nozzle having a diameter of 0.08 mm and a pore number of 1000, and taken up at a speed of 15 m / min. The formed yarn was further wet-drawn 2 times, dried at 130 ° C., and subjected to dry heat drawing 5 times at 230 ° C. This fiber was further immersed in a 40 ° C. solution of 1% glutaraldehyde and 2% maleic acid to perform a crosslinking treatment to obtain a target adsorbent (fiber diameter 10 μm, fiber length 3 cm). The degree of swelling of the obtained adsorbent at 25 ° C. was 65%.
Surface water (organic carbon concentration = 3.6 mg-C / L, pH = 8.7) collected from Inba Marsh (Chiba Prefecture) was used as the water to be treated. The insoluble matter was removed by filtering with a mesh cartridge filter (TMP-2, manufactured by Advantech), and 5 g of the obtained hydrophilic polymer adsorbent was added to 1 L of the filtered water at 25 ° C. for 4 hours. Shake. After shaking, the hydrophilic polymer adsorbent was separated by filtration, and the resulting treated water was used to evaluate the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm). The sex was B. The results are shown in Table 1.

[Example 1-2]
Laboplast mill contains 60 parts by mass of an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “F-101B”) and 40 parts by mass of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP-200”). After being melt-kneaded at 210 ° C., pulverization was performed to obtain a composite having a particle size of 0.6 to 1.2 mm. Further, this composite was subjected to a crosslinking treatment with a 2% solution of an epoxy compound (Denacol EX-810 (trade name) manufactured by Nagase ChemteX Corp.) at 25 ° C. to obtain a target adsorbent (particle diameter of 0.6 to 1). 0.2 mm). The degree of swelling of the obtained adsorbent in 25 ° C. water was 125%.
As the water to be treated, surface water (organic carbon concentration = 3.6 mg-C / L, pH = 8.7) collected from Inba Marsh (Chiba Prefecture) was used. The insoluble matter was removed by filtering with a stainless mesh cartridge filter (TMP-2, manufactured by Advantech), and 5 g of the obtained hydrophilic polymer adsorbent was added to 1 L of the filtered water at 4 ° C. Shaking time. After shaking, the hydrophilic polymer adsorbent was separated by filtration, and the resulting treated water was used to evaluate the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm). The sex was A. The results are shown in Table 1.

[Example 1-3]
75 parts of ethylene-vinyl alcohol copolymer (“E-105B” manufactured by Kuraray Co., Ltd.) and 25 parts of polyethyleneimine (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd.) were tested at 210 After melt-kneading at 0 ° C., a pulverization treatment was performed to obtain a composite having a particle size of 0.1 to 0.2 mm. This composite was subjected to a crosslinking treatment with a 25% solution of an epoxy compound (Denacol EX-810 (trade name) manufactured by Nagase ChemteX Corp.) at 2% to obtain a target adsorbent (particle diameter of 0.1 to 0.2 mm). ) The degree of swelling of the obtained adsorbent in 25 ° C. water was 82%.
Using the adsorbent, the water to be treated was adsorbed and filtered in the same manner as in Example 1-2. As a result of evaluating the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm) used for the filtration treatment, the long-term water permeability was A. The results are shown in Table 1.
When the molecular weight distribution of the organic substance contained in the water to be used used in Example 1-3 was measured by LC-OCD, a spectrum as shown in FIG. 1 was obtained.

[Example 1-4]
A vinyl alcohol polymer having a mercapto group at the end was synthesized by the method described in JP-A-59-187005. The content (degree of saponification) of the vinyl alcohol unit determined by 1H-NMR measurement was 98.5 mol%, and the viscosity average degree of polymerization measured according to JIS K6726 was 1500.
Next, 563 g of water and 110 g of the above-mentioned terminal mercapto group-containing polyvinyl alcohol were charged, and the mixture was heated to 95 ° C. with stirring in a nitrogen atmosphere to dissolve the polyvinyl alcohol, and then cooled to room temperature. After adding 57.1 g of vinylbenzyltrimethylammonium chloride to the aqueous solution with stirring, the solution was heated to 70 ° C., and 88.8 mL of a 2.5% aqueous solution of potassium persulfate was added over 1.5 hours. The polymerization was continued for 1 hour at 75 ° C. to obtain an aqueous solution of a water-soluble polymer which is a copolymer of polyvinyl alcohol-polyvinylbenzyltrimethylammonium chloride having a solid content concentration of 20%.
A part of the obtained aqueous solution was dried and then dissolved in heavy water and subjected to 1H-NMR measurement. As a result, the content of the polymerizable unsaturated monomer in the copolymer, that is, in the polymer was measured. The ratio of the number of vinylbenzyltrimethylammonium chloride monomer units to the total number of monomer units was 10 mol%.
50 g of an aqueous solution of the polymer was added, and ion exchange water was added to prepare a solid concentration of 15%. This aqueous solution was cast on a polyethylene terephthalate film using an applicator and dried at 80 ° C. for 30 minutes. The film thus obtained was heat treated at 170 ° C. for 30 minutes to cause physical crosslinking. Next, the membrane was immersed in 1 L of an aqueous solution in which 350 g of sodium sulfate was dissolved, concentrated sulfuric acid was added to the aqueous solution so that the pH was 1, and the membrane was further immersed as a 3% aqueous solution of glutaraldehyde. Crosslinking treatment was carried out at 3 ° C. for 3 hours. After the crosslinking treatment, the membrane was washed with ion exchange water and dried to obtain a membrane having a thickness of 70 μm. This film was cut into 2 mm squares to form adsorbents. The degree of swelling of the obtained adsorbent in water at 25 ° C. was 30%.
Using the adsorbent, the water to be treated was adsorbed and filtered in the same manner as in Example 1-2. As a result of evaluating the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm) used for the filtration treatment, the long-term water permeability was B. The results are shown in Table 1.

[Comparative Example 1-1]
As a result of evaluating the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size: 0.1 μm) by performing water treatment in the same manner as in Example 1-2 except that no organic carbon adsorption treatment was performed. The water permeability was D. The results are shown in Table 1.

[Comparative Example 1-2]
As an adsorbent, water treatment was performed in the same manner as in Example 1-2 except that a commercially available granular activated carbon (Charcoal activated, manufactured by Wako Pure Chemical Industries, Ltd.) having a swelling degree in water at 25 ° C. of 58% was used. As a result of evaluating the water permeability of the manufactured MF membrane (Asahi Kasei Co., Ltd., pore size: 0.1 μm), the long-term water permeability was C. The results are shown in Table 1.

[Comparative Example 1-3]
PVDF MF was prepared by performing water treatment in the same manner as in Example 1-2 except that a commercially available anion adsorbent (Amberlite IR A400, manufactured by Sigma-Aldrich) having a degree of swelling of 98% in water at 25 ° C. was used. As a result of evaluating the water permeability of the membrane (manufactured by Asahi Kasei Co., Ltd., pore size: 0.1 μm), the long-term water permeability was C. The results are shown in Table 1.

 

[Example 1-5]
As a result of evaluating the water permeability of a polyacrylonitrile (PAN) UF membrane (Asahi Kasei Co., Ltd., molecular weight cut off 100 kDa) using treated water adsorbed with the adsorbent used in Example 1-3, long-term water permeability The sex was A. The results are shown in Table 2.

 

[Comparative Example 1-4]
A mineral oil emulsion of Akogel C (manufactured by MT Aqua Polymer Co., Ltd.) was washed with hexane and dried to obtain particles having a quaternary ammonium group. When trying to use the particles as they are in the organic carbon adsorption process, the dry particles have a very small particle size, so that not only the stirring ability to the water to be treated is bad, but also after swelling with the water to be treated, Since the particles swelled to 1000% or more and it was difficult to stir the particles well, the test was stopped.

As seen in Experimental Examples 1-1 to 1-5, a process for removing organic carbon in water using a hydrophilic polymer adsorbent having a degree of swelling in water at 25 ° C. of 20 to 500% is provided. In this case, it can be seen that the biopolymer which is organic carbon having high hydrophilicity can be efficiently removed, and the water permeability of the filtration membrane is stable for a long time.

On the other hand, as seen in Comparative Example 1-1, long-term water permeability cannot be obtained unless a process for removing organic carbon is provided. Further, as seen in Comparative Examples 1-2 and 1-3, when an adsorbent mainly composed of a hydrophobic structure such as commercially available activated carbon or ion exchange resin is used, part of organic carbon can be removed. However, since the removal ability of biopolymer is low, sufficient long-term water permeability cannot be obtained. The crosslinked polymer having quaternary ammonium as in Comparative Example 1-4 has a problem that the degree of swelling is too high.

In Examples 2-1 to 2-10, Comparative Examples 2-1 to 2-5, Examples 3-1 to 3-5, and Comparative Examples 3-1 to 3-3, the adsorption characteristics and regeneration characteristics of the adsorbents are shown. evaluated. The evaluation of the degree of swelling, the average particle diameter of the adsorbent, and the average fiber diameter were evaluated by the methods performed for Examples 1-1 to 1-5.

(Adsorption rate of biopolymer)
Adsorption evaluation of sodium alginate (manufactured by Wako Pure Chemical Industries, Ltd., model number: 199-09961) was carried out as a biopolymer model substance. 1 L of model river water 1 (concentration of sodium alginate) was obtained from 5.0 g of the adsorbent obtained in each Example and Comparative Example (the mass in the state dried in a vacuum dryer for 12 hours, 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%) or model brackish water 1 (sodium alginate concentration: 4.3 mg-C / L), NaCl: 2.0%) and shaken at 25 ° C. for 4 hours. The supernatant before and after shaking was analyzed by LC-OCD, and the adsorption rate of sodium alginate as a 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, 5.0 g of the adsorbent obtained from 1 L 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%) or model brackish water 2 (sodium humate concentration: 4.3 mg-C / L, NaCl: 2.0%) and shaken at 25 ° C. for 4 hours. The supernatant before and after shaking was analyzed by LC-OCD, and the adsorption rate of sodium humate as humic substance by the adsorbent 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

(Regeneration of adsorbent)
After adsorbing sodium alginate, it is filtered and immersed in pure water set to a predetermined temperature or an aqueous solution of 0.25% NaCl or 2.5% Na ₂ CO ₃ and stirred for a predetermined time to desorb sodium alginate. Recycled. The regeneration efficiency was evaluated by the following formula.
Adsorption rate of adsorbent = adsorption rate after regeneration treatment / adsorption rate before regeneration treatment × 100 (%)

(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

[Example 2-1]
70 parts by mass of ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “F-101”, δ = 28) and polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP”) are hydrophilic polymers that are the main skeleton. -200 ") 30 parts by mass in a Laboplast mill at 210 ° C. for 3 minutes, the obtained kneaded product was cooled, pulverized, and classified using a sieve to obtain a particle size of 0.4 Particles of ~ 0.7 mm were obtained. Further, this particle was subjected to a crosslinking treatment with a 25% solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”) for 1 hour, filtered and stirred with a large amount of hot water at 80 ° C. By washing, the target adsorbent 2-1 was obtained as shown in Table 3. The obtained adsorbent had a degree of swelling in 25 ° C. water of 105% and an average particle size of 0.7 mm.

The obtained adsorbent 2-1 was immersed and shaken 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 model river water 1 for sodium alginate, the adsorbent was filtered off, immersed in a 0.25% NaCl aqueous solution adjusted to 60 ° C., and shaken for 24 hours to regenerate the adsorbent. Thereafter, the regenerated adsorbent was collected by filtration.
The regenerated adsorbent collected by filtration was immersed and infiltrated in the model river water 1, and the sodium alginate adsorption test was performed again.
Table 4 shows the adsorption rate of sodium alginate and sodium humate of the obtained adsorbent and the adsorption rate of sodium alginate of the regenerated adsorbent.

[Example 2-2]
75 parts by mass of ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “E-105”, δ = 26) and polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP”) are hydrophilic polymers as the main skeleton. -200 ") 25 parts by mass were melt-kneaded at 210 ° C in a lab plast mill, and the obtained kneaded product was cooled and then pulverized. The obtained pulverized product was classified using a sieve to obtain particles having a particle size of 0.4 to 0.7 mm. Further, this particle was subjected to a crosslinking treatment with a 25% solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”) for 1 hour, filtered and stirred with a large amount of hot water at 80 ° C. By washing, the target adsorbent 2-2 was obtained as shown in Table 3. The obtained adsorbent had a degree of swelling in 25 ° C. water of 88% and an average particle size of 0.6 mm.

The obtained adsorbent 2-2 was immersed and shaken 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 water adjusted to 80 ° C., shaken 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 immersed in the model river water 1 and shaken, and an adsorption test for sodium alginate was performed again. Table 4 shows evaluation results of adsorption and regeneration of the obtained adsorbent.

[Example 2-3]
As shown in Table 4, the adsorption and regeneration were evaluated in the same manner as in Example 2-2, except that the sample was immersed in a 0.25% NaCl aqueous solution adjusted to 25 ° C. and shaken for 24 hours. It was. The evaluation results are shown in Table 4.

[Example 2-4]
Adsorption and regeneration were evaluated in the same manner as in Example 2-2, except that the sample was immersed in water adjusted to 70 ° C. and shaken for 1 hour. The evaluation results are shown in Table 4.

[Example 2-5]
90 parts by mass of an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “G-156”, δ = 25) and polyallylamine (manufactured by Nitto Bo Medical Co., Ltd., “PAA— 15C ") 10 parts by mass was melt-kneaded for 3 minutes at 210 ° C in a lab plast mill, and the resulting kneaded product was cooled and then pulverized. The obtained pulverized product was classified using a sieve to obtain particles having a particle size of 0.1 to 0.5 mm. Furthermore, this particle was subjected to a crosslinking treatment with a 25% solution of an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”) at 25 ° C. for 1 hour, filtered, and then immersed in a large amount of hot water at 80 ° C. By stirring and washing, the target adsorbent 2-3 was obtained as shown in Table 3. The resulting adsorbent had a degree of swelling in 25 ° C. water of 46% and an average particle size of 0.5 mm.

The obtained adsorbent 2-3 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 adsorbing sodium alginate in model river water 1, the adsorbent is filtered off, immersed in a 2.5% Na ₂ CO ₃ aqueous solution adjusted to 60 ° C. and shaken for 24 hours to regenerate the adsorbent. went. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent collected by filtration was immersed in the model river water 1 and shaken, and an adsorption test for sodium alginate was performed again. Table 4 shows evaluation results of adsorption and regeneration of the obtained adsorbent.

[Example 2-6]
In Example 2-1, Example 2 was performed except that the adsorbent after the crosslinking treatment was washed with a large amount of 3.5% NaCl 80 ° C. hot water and Model Seawater 1 and Model Seawater 2 were used. The adsorption test was conducted in the same manner as -1.
After the adsorption process of sodium alginate from the model seawater 1, the adsorbent was filtered off, immersed in water adjusted to 90 ° C., shaken for 1 hour, and the adsorbent was regenerated. Thereafter, the regenerated adsorbent that had been regenerated was collected by filtration.
The regenerated adsorbent was immersed in the model seawater 1 and shaken, and an adsorption test for sodium alginate was performed again. Table 4 shows evaluation results of adsorption and regeneration of the obtained adsorbent.

[Comparative Example 2-1]
Commercially available ion exchange resin (Made by Mitsubishi Chemical Co., Ltd., “Diaion WA-20”, average particle size 0.5 mm, main skeleton polymer) Adsorbent 2-4 was obtained by immersing polystyrene and δ = 20) in a large amount of hot water at 80 ° C. and washing with stirring. Using the adsorbent 2-4, 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 4 and had almost no adsorption performance for sodium alginate.
After the adsorption process of sodium alginate from the model river water 1, the adsorbent was filtered, immersed in water adjusted to 80 ° C., shaken 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 immersed in the model river water 1 and shaken, and an adsorption test for sodium alginate was performed again. The results of adsorption evaluation after regeneration of the obtained adsorbent are shown in Table 4, and almost no sodium alginate was adsorbed.

[Comparative Example 2-2]
Commercial granular activated carbon (Kuraray Chemical Co., Ltd., “Kuraray Coal GW20 / 40”, average particle size 0.5 mm) having a swelling degree in water at 25 ° C. of 50% is immersed and stirred in a large amount of hot water at 80 ° C. After washing, adsorbent 2-5 was obtained. Using the adsorbent 2-5, the model river water 1 and the model river water 2 were immersed and shaken, and the adsorption test of sodium alginate and sodium humate was performed. The results are shown in Table 4 and had almost no adsorption performance for sodium alginate.

[Comparative Example 2-3]
Commercially available anion adsorbent having a swelling degree in water at 25 ° C. of 150% (manufactured by Dow Chemical Japan Co., Ltd., “MARATHON MSA”, average particle size: 0.6 mm, main skeleton polymer is polystyrene, and δ = 20) was immersed in a large amount of 80 ° C. hot water, washed with stirring, and adsorbent 6 was obtained. Using the adsorbent 6, the model river water 1 and the model river water 2 were immersed and shaken, and an adsorption test of sodium alginate and sodium humate was performed. The results are shown in Table 4, and it was found that the adsorption performance of humic substances was higher than that of sodium alginate.

As shown in Table 4, Examples 2-1 to 2-5 can adsorb both sodium alginate and sodium humate from the model river water, and are particularly excellent in sodium alginate adsorbability. . In these examples, the ratio (A) / (B) of the adsorption rate (A) of sodium alginate and the adsorption rate (B) of sodium humate is 1.5 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.
In Example 2-6, sodium alginate can be adsorbed at a high adsorption rate even from model seawater 1.
Furthermore, in Examples 2-1 to 2-6, when the regeneration treatment is performed on the adsorbent on which sodium alginate is adsorbed, the adsorbent after the regeneration treatment again adsorbs sodium alginate with a high adsorption rate. The regeneration efficiency is 70% or more in Examples 2-1 to 2-2 and 2-4 to 2-6, and in particular, Examples 2-1 to 2-2 and 2-5 to In 2-6, it is 95% or more. Moreover, when the temperature of the aqueous medium used in the regeneration treatment is 50 ° C. or higher, the regeneration efficiency tends to be high.

[Example 2-7]
As raw water, surface water collected from Inba Marsh (Chiba Prefecture) (organic carbon concentration = 3.6 mg-C / L, pH = 8.7, biopolymer SUVA value: 0.21 (L / mg-C · m), using a humic SUVA value: 3.3 (L / mg-C · m), and first filtering raw water through a stainless mesh cartridge filter (TMP-2, manufactured by Avantech) with an exclusion diameter of 2 μm. Insoluble matter was removed by 1 and 5 g of adsorbent 2-2 was added to 1 L of the filtered water and shaken for 4 hours at 25 ° C. After shaking, the hydrophilic polymer adsorbent was filtered off. 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, the long-term water permeability was A. The results are shown in Table 5.

[Example 2-8]
The adsorbent 2-2 after contact with the raw water in Example 2-7 was recovered by filtration, and the NaCl ₂ . After regenerating for 24 hours using a 5% aqueous solution, it was again contacted with raw water in the same manner as in Example 2-7 to obtain treated water. 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, the long-term water permeability was A. The results are shown in Table 6.

[Example 2-9]
As raw water, surface water (organic carbon concentration = 3.6 mg-C / L, pH = 8.7) collected from Inba Marsh (Chiba Prefecture) is used. The raw water is first a stainless mesh cartridge filter with an exclusion diameter of 2 μm. (TMP-2, manufactured by Advantech) was used to remove insoluble matter, and 5 g of adsorbent 2-2 was added to 1 L of the filtered water and stirred at 25 ° C. for 4 hours. After stirring, the hydrophilic polymer adsorbent was filtered off, and the water permeability of the polyacrylonitrile (PAN) UF membrane (Asahi Kasei Co., Ltd., molecular weight cut off 100 kDa) was evaluated using the resulting treated water. The long-term water permeability was A. The results are shown in Table 5.

[Example 2-10]
The adsorbent 2-2 that had been brought into contact with the raw water in Example 2-9 was collected by filtration, regenerated for 1 hour using water at 80 ° C., and then again with the raw water as in Example 2-7. It was made to contact and the treated water was obtained. 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.

[Comparative Example 2-4]
Surface water is removed without using an adsorbent, filtered through a stainless steel mesh cartridge filter (TMP-2, manufactured by Advantech) with a diameter of 2 μm, and then permeable to PVDF MF membrane (Asahi Kasei Co., Ltd., pore size: 0.1 μm). Evaluation was conducted in the same manner as in Example 2-7, except that The long-term water permeability was B because the causative substance that causes physically irreversible membrane fouling with the adsorbent was not removed. The results are shown in Table 5.

[Comparative Example 2-5]
Evaluation was performed in the same manner as in Example 2-7, except that a commercially available granular activated carbon (manufactured by Kuraray Chemical Co., Ltd., “Kuraray Coal GW20 / 40”) was used as the adsorbent. The long-term water permeability was B. The results are shown in Table 5.

As shown in Table 5, when the filtration process was performed using the treated water obtained by treating the raw water with the adsorbents obtained in Examples 2-7 and 2-9, the MF membrane was not the UF membrane. Even in both cases, it is possible to prolong the water permeability of the membrane. On the other hand, when the adsorbent is not used (Comparative Example 2-4) and when the commercially available granular activated carbon is used as the adsorbent (Comparative Example 2-5), the water permeability of the filter membrane cannot be prolonged.

As shown in Table 6, in Examples 2-8 and 2-10, it is shown that the adsorptivity can be maintained even if the adsorbent is subjected to the regeneration treatment after the adsorption. That is, when the filtration process is performed using the treated water obtained by treating the raw water with the regenerated adsorbent, it is possible to prolong the permeability of the filtration membrane in both the MF membrane and the UF membrane. Is possible.

[Example 3-1]
80 parts by weight of ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “F-104”, δ = 28) and polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd. -200 ") 20 parts by mass was melt-kneaded for 3 minutes at 210 ° C in a lab plast mill, and the resulting kneaded product was cooled and then pulverized. The obtained pulverized product was classified using a sieve to obtain particles having a particle size of 0.4 to 0.7 mm. Further, the particles were subjected to a crosslinking treatment with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”) at 25 ° C. for 1 hour, and after filtration, a large amount of NaCl 3.5 ° C. at 80 ° C. As shown in Table 7, the intended adsorbent 3-1 was obtained by immersing in a 100% aqueous solution and washing with stirring. The degree of swelling of the obtained adsorbent in 25 ° C. water was 97% and the average particle size was 0.7 mm.

The obtained adsorbent 3-1 was immersed and shaken in each of model seawater 1 and model 2, and the adsorption rate of sodium alginate and sodium humate was determined. The evaluation results are shown in Table 8.

[Example 3-2]
As a hydrophilic polymer which is the main skeleton, ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “E-105”, δ = 26) 75 parts by weight and polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP”) -200 ") 25 parts by mass was melt-kneaded for 3 minutes at 210 ° C in a lab plast mill, and the resulting kneaded product was cooled and then pulverized. The obtained pulverized product was classified using a sieve to obtain particles having a particle size of 0.4 to 0.7 mm. Further, the particles were subjected to a crosslinking treatment with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”) at 25 ° C. for 1 hour, and after filtration, a large amount of NaCl 3.5 ° C. at 80 ° C. As shown in Table 7, the intended adsorbent 3-2 was obtained by immersing in a 100% aqueous solution and washing with stirring. The obtained adsorbent had a degree of swelling in 25 ° C. water of 88% and an average particle size of 0.6 mm.

The obtained adsorbent 3-2 was immersed and shaken in each of model seawater 1 and model seawater 2, and the adsorption rate of sodium alginate and sodium humate was determined. The evaluation results are shown in Table 8.

[Example 3-3]
65 parts by weight of an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “G-156”, δ = 25) and polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP”) are hydrophilic polymers as the main skeleton. −200 ”) 35 parts by mass was melt-kneaded at 210 ° C. for 3 minutes in a lab plast mill, and the obtained kneaded product was cooled and then pulverized. The obtained pulverized product was classified using a sieve to obtain particles having a particle size of 0.4 to 0.7 mm. Further, the particles were subjected to a crosslinking treatment with a solution of 2% of an epoxy compound (manufactured by Nagase ChemteX Corp., “Denacol EX-810”) at 25 ° C. for 1 hour, and after filtration, a large amount of NaCl 3.5 ° C. at 80 ° C. As shown in Table 7, the intended adsorbent 3-3 was obtained by immersion in an aqueous solution of 100% and washing with stirring. The obtained adsorbent had a degree of swelling in 25 ° C. water of 110% and an average particle diameter of 0.8 mm.

The obtained adsorbent 3-3 was immersed and shaken in each of model brackish water 1 and model brackish water 2, and the adsorption rate of sodium alginate and sodium humate was determined. The evaluation results are shown in Table 8.

[Example 3-4]
88 parts by mass of polyvinyl alcohol (“PVA-117” manufactured by Kuraray Co., Ltd., δ = 33), 12 parts by mass of polyallylamine (“PAA-15C” manufactured by Nitto Bo Medical Co., Ltd.) The resin composition was such that these resins were dissolved in water. The solution was wet-spun into a saturated sodium sulfate bath at 40 ° C. from a nozzle having a diameter of 0.08 mm and a pore number of 1000, and taken up at a speed of 15 m / min. The formed yarn was further wet-drawn 2 times, dried at 130 ° C., and subjected to dry heat drawing 5 times at 230 ° C. This fiber was further immersed in a 40 ° C. solution of 1% glutaraldehyde and 2% maleic acid for crosslinking treatment, then washed with water, then washed with an aqueous NaOH solution, and further immersed in an aqueous 3.5% NaCl solution. The target adsorbent 3-4 (average fiber diameter 10 μm, fiber length 3 cm) was obtained by washing with stirring. The degree of swelling of the obtained adsorbent in 25 ° C. water was 65%.

The obtained adsorbent 3-4 was immersed and shaken in each of model seawater 1 and model seawater 2, and the adsorption rate of sodium alginate and sodium humate was determined. The evaluation results are shown in Table 8.

[Example 3-5]
A vinyl alcohol polymer having a mercapto group at the end was synthesized by the method described in JP-A-59-187005. ^The vinyl alcohol unit content (degree of saponification) determined by ¹ H-NMR measurement was 98.5 mol%, and the viscosity average degree of polymerization measured according to JIS K6726 was 1500.
Next, 563 g of water and 110 g of the above-mentioned terminal mercapto group-containing polyvinyl alcohol were charged, and the mixture was heated to 95 ° C. with stirring in a nitrogen atmosphere to dissolve the polyvinyl alcohol, and then cooled to room temperature. After adding 57.1 g of vinylbenzyltrimethylammonium chloride to the aqueous solution with stirring, the solution was heated to 70 ° C., and 88.8 mL of a 2.5% aqueous solution of potassium persulfate was added over 1.5 hours. The polymerization was continued for 1 hour at 75 ° C. to obtain an aqueous solution of a water-soluble polymer which is a copolymer of polyvinyl alcohol-polyvinylbenzyltrimethylammonium chloride having a solid content concentration of 20%.
A portion of the obtained aqueous solution was dried and then dissolved in heavy water and subjected to ¹ H-NMR measurement. As a result, the content of the polymerizable unsaturated monomer in the copolymer, that is, in the polymer The ratio of the number of vinylbenzyltrimethylammonium chloride monomer units to the total number of monomer units was 10 mol%.
50 g of an aqueous solution of the polymer was added, and ion exchange water was added to prepare a solid concentration of 15%. This aqueous solution was cast on a polyethylene terephthalate film using an applicator and dried at 80 ° C. for 30 minutes. The film thus obtained was heat treated at 170 ° C. for 30 minutes to cause physical crosslinking. Next, the membrane was immersed in 1 L of an aqueous solution in which 350 g of sodium sulfate was dissolved, concentrated sulfuric acid was added to the aqueous solution so that the pH was 1, and the membrane was further immersed as a 3% aqueous solution of glutaraldehyde. Crosslinking treatment was carried out at 3 ° C. for 3 hours. After the crosslinking treatment, the membrane was washed with ion-exchanged water and a 3.5% aqueous solution of NaCl and dried to obtain a membrane having a thickness of 70 μm. This membrane was cut into 2 mm squares to obtain the intended adsorbent 3-5 as shown in Table 7. The degree of swelling of the obtained adsorbent in water at 25 ° C. was 30%.

The obtained adsorbent 3-5 was immersed and shaken in each of model seawater 1 and model seawater 2, and the adsorption rate of sodium alginate and sodium humate was determined. The evaluation results are shown in Table 8.

[Comparative Example 3-1]
A commercially available ion exchange resin (Made by Mitsubishi Chemical Co., Ltd., “Diaion WA-20”, average particle diameter: 0.5 mm) having a swelling degree in water at 25 ° C. of 82%, the main polymer is Adsorbent 3-6 was obtained by immersing polystyrene and δ = 20) in a large amount of an aqueous solution of 3.5% 80 ° C NaCl, stirring and washing. The obtained adsorbent 3-6 was immersed and shaken in each of model seawater 1 and model seawater 2, and the adsorption rates of sodium alginate and sodium humate were determined. The evaluation results are shown in Table 8. Adsorbent 3-6 had almost no adsorption performance for sodium alginate.

[Comparative Example 3-2]
Commercially available synthetic zeolite with a degree of swelling in water at 25 ° C. of 27% (manufactured by Tosoh Corporation, “synthetic zeolite F-9”, average particle size: 0.9 mm) in a large amount of 80 ° C. NaCl 3.5% aqueous solution. After soaking, stirring and washing, an adsorbent 3-7 was obtained.
The obtained adsorbent 3-7 was immersed and shaken in each of model seawater 1 and model seawater 2, and the adsorption rate of sodium alginate and sodium humate was determined. The evaluation results are shown in Table 8, and the adsorbent 3-7 had little adsorption performance for sodium alginate.

[Comparative Example 3-3]
Commercially available anion adsorbent having a swelling degree in water at 25 ° C. of 150% (manufactured by Dow Chemical Japan Co., Ltd., “MARATHON MSA”, average particle size: 0.6 mm), the main polymer is polystyrene, and δ = 20 ) Was immersed in a large amount of 80 ° C. NaCl 3.5% aqueous solution, washed with stirring, and adsorbent 3-8 was obtained. The adsorbent 3-8 was immersed and shaken in each of model seawater 1 and model seawater 2, and the adsorption rate of sodium alginate and sodium humate was determined. The results are shown in Table 8. In this case, it was found that not only the adsorption rate of sodium alginate was lower than that in Examples, but also the adsorption performance of humic substances was higher than that of sodium alginate.

As shown in Table 8, in Examples 3-1 to 3-5, both sodium alginate and sodium humate can be adsorbed from the model water containing sodium chloride. Are better. In these examples, the ratio (A) / (B) of the adsorption rate (A) of sodium alginate and the adsorption rate (B) of sodium humate is 1.5 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.
In particular, in Examples 3-1 to 3-3, it is possible to adsorb sodium alginate with a high adsorption rate because an ethylene-vinyl alcohol copolymer is used as the main skeleton as the hydrophilic polymer. . Further, as shown in Example 3-4, sodium alginate can be adsorbed at a high adsorption rate even in a fibrous form.

[Example 3-6]
According to Example 3-1, after adsorbing sodium alginate on the adsorbent 3-1, using model water 1, the adsorbent was filtered off. Next, the adsorbent separated by filtration was immersed in pure water adjusted to 80 ° C. and shaken for 1 hour to perform a regeneration treatment. Thereafter, the regenerated adsorbent was collected by filtration, and the adsorption rate of sodium alginate was obtained again using model water 1 in the same manner as in Example 3-1. Table 9 shows the evaluation results.

[Example 3-7]
In accordance with Example 3-2, model water 1 was used to adsorb sodium alginate on the adsorbent 3-2, and then the adsorbent was filtered off. Next, the adsorbent separated by filtration was immersed in pure water adjusted to 90 ° C. and shaken for 1 hour to perform a regeneration treatment. Thereafter, the regenerated adsorbent was collected by filtration, and the adsorption rate of sodium alginate was obtained again using model water 1 in the same manner as in Example 3-1. Table 9 shows the evaluation results.

[Example 3-8]
According to Example 3-3, model a brackish water 1 was used to adsorb sodium alginate on the adsorbent 3-3, and then the adsorbent was filtered off. Subsequently, the adsorbent separated by filtration was immersed in a 0.25% NaCl aqueous solution adjusted to 60 ° C. and shaken for 24 hours to perform a regeneration treatment. Thereafter, the regenerated adsorbent was collected by filtration, and the adsorption rate of sodium alginate was determined again using model brackish water 1 in the same manner as in Example 3-1. Table 9 shows the evaluation results.

As shown in Table 9, in Examples 3-6 to 3-8 in which regeneration treatment was performed on the adsorbent that adsorbed sodium alginate, the adsorbent after regeneration treatment again had a high adsorption rate of sodium alginate. It is possible to adsorb. The regeneration efficiency is 95% or more in each of Examples 3-6 to 3-8.

According to the present invention, it is possible to provide a hydrophilic polymer adsorbent capable of adsorbing organic carbon, and in particular, capable of efficiently adsorbing biopolymers that have been difficult to adsorb conventionally. Such a composition can be effectively used as an organic carbon adsorbent (particularly, a biopolymer adsorbent) when various raw waters are treated with water.

As described above, the preferred embodiments of the present invention have been described with reference to the drawings. However, those skilled in the art can easily assume various changes and modifications within the obvious range by looking at the present specification. I will. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

Claims (14)

1. Swelling degree in water at 25 ° C. is 20 to 500%, has a hydrophilic polymer as the main skeleton, and can form bonds with at least some of the organic carbon in the water to be treated. A hydrophilic polymer adsorbent having a functional group (hereinafter referred to as a bond-forming group).
2. The hydrophilic polymer adsorbent according to claim 1, wherein the bond-forming group has an ability to form at least one kind of bond selected from the group consisting of a hydrogen bond, an ionic bond, and a chelate bond with respect to the adsorbed component. , Hydrophilic polymer adsorbent.
3. 3. The hydrophilic polymer adsorbent according to claim 1, wherein the bond-forming group is a bond-forming group containing at least one element selected from the group consisting of N, S, P and O. .
4. The hydrophilic polymer adsorbent according to any one of claims 1 to 3, wherein the adsorbed component contains a biopolymer, and the removal rate of the biopolymer is 15% or more.
5. 5. The hydrophilic polymer adsorbent according to claim 1, wherein biopolymer model water (sodium alginate concentration: 4.3 mg-C / L sodium alginate aqueous solution) and humic model water (humin) at 25 ° C. The ratio of the sodium alginate adsorption rate (A) to the sodium humate adsorption rate (B) for each of the sodium acid concentration: 4.3 mg-C / L sodium humate aqueous solution) is (A) /(B)=1.0-10, hydrophilic polymer adsorbent.
6. The hydrophilic polymer adsorbent according to any one of claims 1 to 5, wherein the hydrophilic polymer is polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetal, polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether. , A polyalkylene oxide, poly (meth) acrylamide, cationic polymer, anionic polymer, phenol resin, polyamide, polyvinyl pyrrolidone, cellulose derivative, dextrin, chitin, and hydrophilic which is at least one selected from chitosan Polymer adsorbent.
7. The hydrophilic polymer adsorbent according to any one of claims 1 to 6, wherein the hydrophilic polymer adsorbent comprises at least a polymer (A) having a bond-forming group and a hydrophilic polymer (B). Hydrophilic polymer adsorbent, which is an alloy material.
8. 8. The hydrophilic polymer adsorbent according to claim 7, wherein the hydrophilic polymer (B) is an ethylene-vinyl alcohol copolymer.
9. An adsorption step in which water to be treated containing organic carbon is brought into contact with the hydrophilic polymer adsorbent according to any one of claims 1 to 8 to adsorb at least a part of the organic carbon; A water treatment method comprising at least a water treatment method.
10. The water treatment method according to claim 9, further comprising a membrane filtration step of membrane-filtering the adsorption-treated water obtained by the adsorption step by membrane filtration.
11. The water treatment method according to claim 9 or 10, wherein the water to be treated is fresh water or water containing salts.
12. The water treatment method according to any one of claims 9 to 11, further comprising a regeneration step of regenerating the adsorbent by bringing the adsorbent after the adsorption step into contact with an aqueous medium.
13. The water treatment method according to claim 12, wherein the aqueous medium used in the regeneration step is water or a metal ion-containing aqueous solution.
14. The water treatment method according to claim 12 or 13, wherein the temperature of the aqueous medium used in the regeneration step is 40 ° C to 110 ° C.

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