TWI555571B - Reverse osmosis membrane lift rate enhancer, barrier rate lifting method and reverse osmosis membrane - Google Patents

Description

Reverse osmosis membrane blocking rate increasing agent, blocking rate lifting method and reverse osmosis membrane

The present invention relates to a reverse osmosis (RO) membrane, in particular to an aromatic polyamine-based RO membrane, and the present invention relates to a barrier ratio-enhancing agent which does not permeate an RO membrane having a reduced barrier ratio (desalting rate) during use thereof. A water-blocking rate is significantly reduced, and a blocking rate-enhancing agent having a high blocking rate-increasing effect is obtained. In particular, it is used as a beverage water, a living water, and a concentrated water system is discharged into the environment as a reference for the blocking rate of the RO film. In the lifting process, even if it leaks to the water-permeable side, it is safe, and even if it is discharged to the concentrated side, it does not cause a high load on the RO membrane.

The present invention further relates to a method for improving the barrier rate of an RO film using the barrier ratio improving agent, and an RO film which has been treated by the blocking rate enhancer.

At present, in order to make up for the shortage of water supply in the world, the desalination and water recovery of seawater and salt water are carried out using the RO membrane system. In the RO membrane system, in the pretreatment step, chlorine (sodium hypochlorite or the like) or hydrogen peroxide is added to the raw water (treated water of the RO membrane, hereinafter referred to as "RO feed water") in the pretreatment step. Oxidizer.

However, it is known that such an oxidizing agent has a strong oxidative decomposition effect, and after the addition of such an oxidizing agent, if the raw water is supplied to the RO membrane in a state where the reduction treatment is insufficient, the RO membrane is deteriorated.

Further, it is also known that in order to decompose the oxidizing agent in the raw water, a reducing agent such as sodium hydrogen sulfite is added to the raw water to supply the RO film, but in the reducing environment in which sodium hydrogen sulfite is excessively added, in the raw water. When a metal such as Cu or Co coexists, the RO film is deteriorated and the barrier ratio is lowered (Patent Document 1 and Non-Patent Document 1).

In the past, as a method for improving the barrier rate of the RO film, there are proposals as follows, but each has its own problems, and it is desired to improve it.

(i) A method of increasing the blocking ratio of the RO film by attaching an anionic or cationic ionic polymer compound to the surface of the film (Patent Document 2).

This method has an effect of improving the barrier ratio of the electrolyte for the RO film having less deterioration or the RO film which is not used. However, the barrier rate of the RO film which is improved by the non-electrolyte is increased or the deterioration is high, and the effect is low.

(ii) A method of increasing the blocking ratio of the RO film by adhering a compound having a polyalkylene glycol chain to the surface of the film (Patent Document 3).

This method also has an effect on the increase in the barrier rate of the non-electrolyte, but the effect of lowering the barrier ratio of the RO film having a large deterioration is lower, and there is a problem that the permeation beam is lowered, compared with the unused RO film. The flow through the stream will be reduced by more than 20%.

(iii) A method of adsorbing a nonionic surfactant for an RO membrane (Patent Document 4).

Among the nonionic surfactants, those containing a polyalkylene glycol chain are covered by Patent Document 3, but in the nature of the surfactant, since the surfactant has a hydrophobic group, it is adsorbed to the RO membrane. Dramatically reduce the flow through the stream.

(iv) A method of improving the salt rejection by attaching tannic acid or the like to the RO membrane (Non-Patent Document 2).

The effect of improving the barrier rate by the method is not large. For example, the method is used to improve the desalination rate of the ES20 (manufactured by Nitto Denko Corporation) and SUL-G20F (manufactured by Toray Industries, Inc.) of the deteriorated RO film. The solute concentration of the permeated water of the film after the film cannot be 1/2 or less of the permeated water solute concentration of the film before the improvement.

(v) A method of increasing the blocking ratio of the RO membrane by adding tannic acid and a polymer (polyvinyl methyl ether) (Non-Patent Document 3).

In this method, it is judged that the effect is better than that of the tannic acid only method, but the average flow rate is reduced by about 20%, and the blocking rate improvement effect is also that the salt rejection rate of the RO membrane which reduces the salt rejection rate to 90.5% becomes 92.5%, etc., there is also a case where the solute concentration of the permeated water cannot be 1/2 or less.

In addition, it is known that a carboxyl group is oxidatively degraded by a chlorine-based oxidizing agent to form a carboxyl group (Non-Patent Documents 4 and 5), and the inventors have found that, on the surface of the aromatic polyamine-based RO film, for example, The carboxyl group is also used, and the film is also deteriorated due to a major factor other than a chlorine-based oxidizing agent such as a base or hydrogen peroxide, and the carboxyl group is increased. Therefore, the detection of a carboxyl group can be carried out by an XPS method in which surface modification is carried out to increase the sensitivity of detection of a carboxyl group.

(vi) based on the presence of a carboxyl group in the RO membrane, which increases due to deterioration The inventors of the present invention have found a method of increasing the blocking ratio of an RO membrane by using a compound having an amine group and bonding it to a carboxyl group (Patent Documents 5 and 6). The basic technical idea of these Patent Documents 5 and 6 is that since a carboxyl group is present in a portion where the deterioration is intense, a point at which the amine group-containing compound having a molecular weight of 1,000 or less is focused on is adsorbed.

Moreover, the present inventors have found that it is indispensable for the low molecular compound to adsorb to the RO membrane system in the improvement of the barrier ratio of the RO membrane (Patent Document 7).

That is, the aromatic polyamine-based RO membrane has an isopropyl alcohol (1PA) blocking ratio of 80 to 95%. Since the molecular weight of IPA is 60, it can be judged that the separation molecular weight of the RO membrane is about 60 for the non-electrolyte. In consideration of the decrease in the blocking ratio of the RO film due to the widening of the gap of the dense layer of the RO film, it is preferable to bury the gap of the dense layer of the widened RO film with a substance which is somewhat larger than the molecular weight. Further, since the size of the gap is various, it is more preferable to use a substance having a complex molecular weight. Finally, it is considered that the low molecular fixed attachment is carried out by using a substance having a relatively large molecular weight than the lower molecules.

The method for improving the barrier rate of the RO film of Patent Document 7 is to pass an aqueous solution containing a first organic compound having a molecular weight of less than 200, a second organic compound having a molecular weight of 200 or more and less than 500, and a third organic compound having a molecular weight of 500 or more. In the case of the reverse osmosis membrane, the first and second organic compounds are preferably amino acid or amino acid derivatives, and as the third organic compound, a functional group having a function of a carboxyl group of the film (cation group: 1) can be used. ~4 amine group), and a compound having an amine group in a blocking rate enhancer (anionic group: carboxyl group, sulfo group, aromatic hydroxyl group (phenolic hydroxyl group) Base)), a functional group (hydroxyl group) which interacts with a polyamide membrane, or has a cyclic structure.

The repair mechanism of the deteriorated film by Patent Document 7 will be described below with reference to Figs.

The normal guanamine bond of the RO membrane, such as an aromatic polyamine-based RO membrane, is the configuration shown in the normal membrane of FIG. When the film is deteriorated by an oxidizing agent such as chlorine, the C-N bond of the guanamine bond is broken, and finally the structure shown in the deteriorated film of Fig. 1 is obtained.

As shown in the deteriorated film of Fig. 1, the amine group disappears due to the breakage of the indole bond, but at least a part of the broken portion forms a carboxyl group.

When the deterioration progresses, the gap of the dense layer of the RO film becomes large, and gaps of various sizes are formed. As for the RO film, as shown in FIG. 2, the first to third organic compounds A to C having different molecular weights (the molecular weight is the order of the organic compound A < the organic compound B < the organic compound C) by the size of the gap Fixing the adhesion, repairing the pores of various sizes of the deteriorated film (the gap of the dense layer), and restoring the barrier ratio of the film.

In Patent Document 7, by infiltrating an aqueous solution containing a plurality of kinds of amine-based compounds (first and second organic compounds) having different molecular weights or skeletons (structures) into the deteriorated film, each compound becomes an obstacle to each other when permeating through the film. By prolonging the residence time of the deteriorated portion in the film, the contact probability of the carboxyl group of the film with the amine group of the low molecular weight amine compound becomes high, and the repair efficiency of the film is improved. Further, by using a third organic compound having a molecular weight of 500 or more in combination, the large deteriorated portion of the film can be blocked, and the repair efficiency can be further improved.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Publication No. 7-308671

Patent Document 2: JP-A-2006-110520

Patent Document 3: JP-A-2007-289922

Patent Document 4: JP-A-2008-86945

Patent Document 5: International Publication WO2011/040354A1 Booklet

Patent Document 6: Japanese Patent Application No. 2011-051525 (JP-A-2012-187468)

Patent Document 7: Japanese Patent Application No. 2011-051530 (JP-A-2012-187469)

Non-patent literature

Non-Patent Document 1: Nagai et al. Desalination, Vol. 96 (1994), 291-301

Non-Patent Document 2: Sato, Tamura, Proceedings of Chemical Engineering, Vol. 34 (2008), 493-498

Non-Patent Document 3: S.T. Mitrouli, A.J. Karabelas, N.P. Isaias, D.C. Sioutopoulos, and A.S. Al Rammah, Reverse Osmosis Membrane Treatment Improves Salt-Rejection Performance, IDA Journal I Second Quarter 2010, P22-34

Non-Patent Document 4: Uemura et al., Bulletin of the Society of Sea Water Science, Japan. 57, 498-507 (2003)

Non-Patent Document 5: Shenshan Yikang, Surface, vol. 31. No. 5 (1993), 408-418

According to the blocking rate increasing method of Patent Document 7, although the blocking ratio of the RO film can be effectively increased, when a plurality of organic compounds having different molecular weights are mixed and dissolved in an aqueous solution, aggregates are formed to adhere to the chemical solution tank, causing The flow path of the membrane module is hindered, and there is a problem that the effect as a medicine is lowered. Further, some organic compounds have problems such as low solubility in water and considerable insolubility. Further, when an organic compound having a guanamine bond or an ester bond is stored in the form of an aqueous solution, hydrolysis may occur and the chemical may be deteriorated. In addition, when it is stored as an aqueous solution, there is a problem that precipitation occurs due to a decrease in the storage temperature, and there is a problem of proliferation of microorganisms due to an increase in the storage temperature.

The present invention has been made in view of the above problems, and an object of the present invention is to provide agglomeration of a barrier ratio-enhancing agent for preventing an RO film containing two or more kinds of organic compounds having different molecular weights, or a problem of poor solubility in water, hydrolysis, and the like. The blocking rate enhancer is effectively used in the technique of the barrier rate lifting treatment of the RO film.

In order to solve the above problems, the present inventors repeated the dedicated review and obtained the following findings.

(1) Among the plurality of organic compounds used in the blocking ratio improving agent, for example, an organic compound having a pH of 7 or more in an aqueous solution alone dissolved in water is mixed with an organic compound having a pH of not more than 7 at a high concentration. When dissolved in water, it will form agglomerates. The organic compound having a pH of substantially 7 or more is basic, and the organic compound having less than 7 is acidic. The organic compound having an amine group can be said to be a weakly basic substance. On the other hand, the organic compound used in combination with this is weakly acidic, and when the molecular weight is large, when it is a high-concentration aqueous solution, an insoluble salt is formed, and this is an aggregate. Therefore, when the organic compound contained in the blocking ratio-improving agent is two or more types, aggregation does not occur at a high concentration, and it is necessary to divide into two at the stage before the dissolution, that is, at the stage of the powder. For example, when arginine and tannic acid are each dissolved in water at a concentration of 1% by weight, aggregates are formed, and therefore it is necessary to divide into a powder containing arginine and a powder containing tannic acid.

(2) The substance in which the methyl ester of the aspartame-based phenylalanine and the aspartic acid are bonded to the decylamine has a low solubility in water, but the solubility in the aqueous alkaline solution increases. Therefore, if it is mixed with an organic compound having a pH of 7 or more when dissolved in water to form a mixed powder with arginine or the like, the aqueous solution can be prepared by using the mixed powder to improve dissolution in an aqueous solution. Sex. Further, if aspartame is stored under alkaline conditions for a long period of time, it is hydrolyzed, and it can be inhibited by hydrolysis by storage in a powder state. Here, although the arginine-based organic compound is used, the pH after dissolution can be adjusted by an inorganic compound such as a carbonate or a phosphate.

(3) When the blocking rate of the RO film is increased by using a powdery drug which is divided into two, it is uniform if it is dissolved in water to a concentration of 0.1 to 200 mg/L which is actually used. The aspect of the aqueous solution has no effect. On the other hand, if two organic compounds are brought into contact with each other in a high concentration state, there is a risk of formation of aggregates. So this Preferably, the two powdery medicaments are temporarily dissolved at 1 to 200 g/L, and then become a diluted aqueous solution. Further, as the above-mentioned substance having a guanamine bond or an ester bond, since it is likely to be hydrolyzed under alkaline conditions or acidic conditions, it must be diluted as quickly as possible to the use concentration after being dissolved in water, and used for The RO film barrier rate lifting process. Therefore, when the concentration of each organic compound is 1 to 200 g/L, the two powdery drug systems dissolved are diluted to a concentration of 0.1 to 200 mg/L in the next stage. When the concentration of the organic compound is 0.1 to 200 mg/L, even if all the organic compounds are present in the same aqueous solution, the concentration of the expected salt is below the solubility, and no aggregate is formed. Therefore, an aqueous solution in which all the organic compounds have been dissolved can be used for the barrier rate raising treatment of the RO film. Further, as another method, an aqueous solution of two powdery pharmaceutical agents dissolved at a concentration of each organic compound of 1 to 200 g/L may be injected into a line and diluted and mixed in a line. Further, after dissolving two powdery chemicals so that the concentration of each organic compound is 1 to 200 g/L, the concentration of each organic compound after mixing may be diluted to 0.1 to 200 mg/L to be in contact with the RO membrane. The method.

The present invention has been made based on the findings of the above, and the following is the gist of the present invention.

[1] A reverse osmosis membrane blocking rate-enhancing agent comprising a reverse osmosis membrane blocking ratio-enhancing agent containing two or more organic compounds having different molecular weights, characterized in that at least a molecular weight of the organic compound as the two or more kinds is contained In the reverse osmosis membrane blocking rate enhancer of an organic compound having an amine group of 60 or more and less than 500 and tannic acid, the organic compound having an amine group and the tannic acid are two powders different from each other. Pharmacy tube.

[2] The reverse osmosis membrane blocking rate-increasing agent according to [1], wherein when the two powdery medicaments each have an aqueous solution having a concentration of each organic compound of 1 to 200 g/L, the organic group having the aforementioned amine group is contained. The pH of the aqueous solution of the powdery drug of one of the compounds is 7 or more, and the pH of the aqueous solution containing the powdery drug of the other of the above-mentioned tannic acid is less than 7.

[3] A method for improving the barrier ratio of a reverse osmosis membrane, which is a method for improving a barrier ratio of a reverse osmosis membrane of a reverse osmosis membrane by using an aqueous solution of a barrier ratio-enhancing agent such as [1] or [2], which is characterized by comprising Dissolving a powdery drug of at least one of the two powdery drugs in water to prepare an organic compound concentration (when the powdery drug contains two or more organic compounds, the organic compound concentration means each The organic compound concentration is a step of an aqueous solution of 1 to 200 g/L, and the concentration of the organic compound in the aqueous solution (when the powdery agent contains two or more organic compounds, the organic compound concentration means the respective organic compound) The concentration is adjusted to 0.1 to 200 mg/L, and the aqueous solution is diluted.

[4] A method for improving a barrier ratio of a reverse osmosis membrane, which is a method for improving a barrier ratio of a reverse osmosis membrane of a reverse osmosis membrane by using an aqueous solution of a barrier ratio-enhancing agent such as [1] or [2], which is characterized by comprising A step of preparing an aqueous solution having a concentration of each organic compound of 1 to 200 mg/L by dissolving each of the two powdery chemicals in water and mixing the obtained aqueous solution.

[5] A method for improving a barrier ratio of a reverse osmosis membrane, which is a method for improving a barrier ratio of a reverse osmosis membrane of a reverse osmosis membrane by using an aqueous solution of a barrier ratio-enhancing agent such as [1] or [2], which is characterized by comprising : making the above two powders Each of the agents is dissolved in water, and each of the obtained aqueous solutions is injected into a line from a different position to dilute and mix.

[6] A reverse osmosis membrane using a barrier ratio-enhancing agent such as [1] or [2] for a barrier increase treatment.

[7] A reverse osmosis membrane which is subjected to a barrier ratio lifting treatment by a barrier ratio lifting method according to any one of [3] to [5].

According to the present invention, it is possible to achieve the following effects, and prevent the formation of aggregates of the barrier ratio improving agent of the RO film containing two or more kinds of organic compounds having different molecular weights, or the dissolution in water, hydrolysis, etc., and the blocking ratio The lifting agent is effectively used in the RO film blocking rate lifting treatment, and the efficient RO film blocking rate lifting treatment can be performed.

(i) when an organic compound having an amine group and a tannic acid which are constituents of a barrier-enhancing agent which is likely to form agglomerates at a high concentration are separated into two powders and dissolved in water to prepare an aqueous solution By first dissolving each organic compound at a concentration of 1 to 200 g/L, and diluting the mixture so that the concentration of each organic compound becomes 0.1 to 200 mg/L, the formation of aggregates can be suppressed. Therefore, the aforementioned problems due to the agglomerates can be avoided.

(ii) dissolving a component which constitutes a hard-to-dissolve blocking rate enhancer at a usual pH of an organic compound having an amine group, and mixing with a substance exhibiting basicity or acidity, and easily preparing an aqueous solution having a concentration of 1 to 200 g/L. .

(iii) by having a guanamine bond or an ester bond and easily growing in an aqueous solution The constituent component of the biohydrogen barrier ratio improving agent is stored in a powder form, and hydrolysis can be suppressed, and the effect of the drug by hydrolysis can be prevented from being lowered.

(iv) Since it is stored as a powder, it is possible to avoid problems such as the formation of a precipitate accompanying a decrease in temperature during storage as an aqueous solution or the proliferation of microorganisms accompanying an increase in temperature. This is particularly effective when the organic compound is a food additive.

1‧‧‧ container

1A‧‧‧ Raw Water Room

1B‧‧‧through water room

2‧‧ ‧ flat membrane unit

3‧‧‧Agitator

4‧‧‧ pump

5‧‧‧ stirrer

6‧‧‧ pressure gauge

7‧‧‧ switch valve

11, 12, 13‧‧‧ piping

Fig. 1 is an explanatory view showing a chemical structural formula of a normal film and a deteriorated film.

FIG. 2 is an explanatory view showing a chemical structural formula of a mechanism of the barrier ratio lifting process of Patent Document 7.

Fig. 3 is a schematic view showing a flat film test apparatus used in the examples.

The best form of invention

Hereinafter, embodiments of the present invention will be described in detail.

[blocking rate enhancer]

The RO film blocking rate enhancer of the present invention is a reverse osmosis membrane blocking rate enhancer containing two or more organic compounds having different molecular weights, and has a molecular weight of at least 60 or more as the organic compound of the two or more types. An organic compound having an amine group of less than 500 and tannic acid are stored as two powdery medicines containing mutually different organic compounds.

The organic compound having an amino group having a molecular weight of 60 or more and less than 500, which is a constituent component of the blocking rate-improving agent of the present invention (hereinafter also referred to as "low-molecular-weight amine-based compound"), may, for example, be as follows.

The aromatic amine-based compound is, for example, an aniline (molecular weight 93) or a diaminobenzene (molecular weight: 108) having a benzene skeleton and an amine group.

Aromatic aminocarboxylic acid compounds: for example, 3,5-diaminobenzoic acid (molecular weight 152), 3,4-diaminobenzoic acid (molecular weight 152), 2,4-diaminobenzoic acid (molecular weight 152) , 2,5-diaminobenzoic acid (molecular weight 152), 2,4,6-triaminobenzoic acid (molecular weight 167), etc. having a benzene skeleton and two or more amine groups and a carboxyl group having a smaller number than the amine group .

Aliphatic amine-based compounds: for example, methylamine (molecular weight 31), ethylamine (molecular weight 45), octylamine (molecular weight 129), 1,9-diaminodecane (also referred to as "NMDA" in this specification) (C ₉ H ₁₈ (NH ₂ ) ₂ ) (molecular weight 158), etc. having a linear hydrocarbon group having from 1 to 20 carbon atoms and one or more amine groups, and 1-aminopentane (also in this specification) Referred to as "IAAM") (NH ₂ (CH ₂ ) ₄ CH ₃ ) (molecular weight 87), 2-methyl-1,8-octanediamine (also referred to as "MODA" in this specification) (NH ₂ CH ₂ CH ( CH ₃ )(CH ₂ ) ₆ NH ₂ ) (molecular weight 158) or the like having a branched hydrocarbon group having about 1 to 20 carbon atoms and one or more amine groups.

Aliphatic amino alcohol: 4-amino-2-methyl-1-butanol (also referred to as "AMB" in this specification) (NH ₂ (CH ₂ ) ₂ CH(CH ₃ )CH ₂ OH) (molecular weight 103 And the like having an amine group and a hydroxyl group on a hydrocarbon group having 1 to 20 carbon atoms in a straight chain or a branch.

Heterocyclic amine based compound: tetrahydrofurfurylamine (also referred to as abbreviated in this specification) "FAM") (the following structural formula) (molecular weight 101), etc. having a heterocyclic ring and an amine group.

Amino acid compound: for example, a basic amino acid compound such as arginine (molecular weight 174) or aminic acid (molecular weight 146), aspartic acid (molecular weight 132) or glutamic acid (molecular weight 146) Other amino acid compounds such as an amino acid compound, glycine (molecular weight 75) or phenylalanine (molecular weight 165).

These low molecular weight amine-based compounds may be used alone or in combination of two or more. In the present invention, among the low molecular weight amino compound, it is preferred to use the first low molecular weight of less than 200. The molecular weight amine compound and the second low molecular weight amine compound having a molecular weight of 200 or more and less than 500, and the first low molecular weight amine compound is preferably an amino acid or an amino acid compound, for example, a basic amino group. Acid, arginine (molecular weight 174), lysine (molecular weight 146) or histidine (molecular weight 155) or lower molecular weight glycine (molecular weight 75). As the second low molecular weight amino group compound, for example, as a peptide or a derivative thereof, aspartame (molecular weight 294) of a methyl ester of a dipeptide of phenylalanine and aspartic acid is preferable.

The amino acid generally has high solubility in water, and the aqueous solution is stable, reacts with the carboxyl group of the membrane, and bonds to the RO membrane to form an insoluble salt, and blocks the membrane. The resulting pores are deteriorated, thereby increasing the barrier ratio of the film.

These low molecular weight amine compounds may be used singly or in combination of two or more. When an aqueous solution containing two or more kinds of low molecular weight amine-based compounds having different molecular weights or skeleton structures is permeated through the RO membrane, each compound becomes an obstacle to each other when permeating through the membrane, and the residence time in the deteriorated portion in the membrane becomes long. The contact probability of the carboxyl group with the amine group of the low molecular weight amine compound becomes high, and the repair efficiency of the film is improved.

Further, by using a combination of tannic acid having a molecular weight of 500 or more together with such a low molecular weight amine compound, the large deteriorated portion of the film can be blocked, and the repair efficiency can be improved.

In the present invention, the low molecular weight amine compound and the tannic acid are stored in two powdery medicines which are different from each other. When the powdery drug is used as an aqueous solution having a concentration of each organic compound contained in the powdery drug of 1 to 200 g/L, it is preferable to contain an amine group. The pH of the aqueous solution of the powdery drug in one of the organic compounds is 7 or more, and the pH of the aqueous solution of the powdery drug containing the other of the tannic acid is less than 7 in combination.

In the case of the aqueous solution, the basic organic compound having a pH of 7 or higher and the acidic organic compound having a pH of less than 7 are stored as the respective powdery chemicals, and by preparing the respective aqueous solutions, the reaction can be prevented. The formation of aggregates.

As described above, since the solubility of aspartame in an alkaline aqueous solution is relatively high, it is preferably mixed with a low molecular weight amine compound which becomes an alkaline aqueous solution having a pH of 7 or higher when dissolved in water, such as arginine, to be in a powder form. Pharmacy, The mixed powder was dissolved in water to prepare an aqueous solution. Further, when the low molecular weight amine-based compound is dissolved in water, an inorganic compound such as a carbonate or a phosphate can be used as the pH adjuster, and the pH can be adjusted to a pH having a high solubility. Therefore, the pH adjuster can be previously low. The molecular weight amine compound is mixed to form a powdery medicament.

In the blocking rate improving agent of the present invention, the content ratio of the two or more organic compounds in the powdery drug containing two or more kinds of organic compounds is suitable as long as it is used as a blocking rate improving agent. The ratio of the content of the powdery medicament corresponding to the use ratio may be adjusted by using the ratio.

[Blocking rate improvement method]

The method for improving the barrier rate of the RO film of the present invention is to use a barrier rate-enhancing agent of the present invention comprising the two powder-formed agents as described above to perform a RO film blocking rate improvement process, specifically by using The aqueous solution of the barrier increase agent of the invention passes water to the RO membrane to increase the barrier ratio of the deteriorated RO membrane. Hereinafter, the aqueous solution of the blocking rate increasing agent that passes the water to the RO membrane for the RO film blocking rate raising treatment is referred to as "blocking rate lifting treatment water".

In the method for improving the barrier ratio of the present invention, the concentration of the low molecular weight amine compound and the tannic acid constituting the component of the blocking rate enhancer in the water in the treatment rate is preferably from 1 to 200 mg/L, more preferably It is 1~100mg/L. The concentration of each component in the water in the treatment rate is lower than the above lower limit, and a sufficient blocking rate improvement effect cannot be obtained, which is more than the above upper limit. High, there is a flaw in the formation of aggregates.

As described above, when the barrier ratio lifting treatment of the RO film is carried out using the barrier ratio improving agent of the present invention, the two powdery medicaments of the barrier ratio-enhancing agent of the present invention are used to directly modulate the above-described thin concentration blocking ratio lifting treatment. In the case of water, it is not appropriate to have a uniform aqueous solution.

Therefore, it is preferred to use two powdery chemicals, and first prepare a high-concentration aqueous solution having a concentration of each organic compound of 1 to 200 g/L, and use these to have an organic compound concentration of 1 to 200 mg when passing through the RO membrane. Dilute and mix in the form of an aqueous solution of /L.

Therefore, for example, when it is a blocking ratio improving agent composed of the powdery agent A and the powdery agent B, it is preferred to carry out dissolution and mixing dilution of water by the following aspects I, II or III.

I: using the powdery agent A, preparing an aqueous solution having an organic compound concentration (when the powdery drug A contains two or more kinds of organic compounds, the concentration of the organic compound means the concentration of each organic compound) is 1 to 200 g/L. On the other hand, the powdery agent B is used to prepare an organic compound concentration (when the powdery drug B contains two or more organic compounds, the concentration of the organic compound means the concentration of each organic compound) is 1 to 200 g/L. The aqueous solution is diluted and mixed with the aqueous solution to obtain a blocking ratio-enhancing treatment water having a concentration of each organic compound of 0.1 to 200 mg/L.

II: using a powdery agent A to prepare an aqueous solution having an organic compound concentration (when the powdery drug A contains two or more organic compounds, the concentration of the organic compound means the concentration of each organic compound) is 1 to 200 g/L. On the other hand, the powdery agent B is used to modulate the concentration of organic compounds. (When the powdery drug B contains two or more organic compounds, the concentration of the organic compound means the concentration of each organic compound) is an aqueous solution of 1 to 200 g/L, and the aqueous solutions are each diluted to mix the diluted aqueous solution. The formation rate of each organic compound is 0.1 to 200 mg/L, and the treated water is treated.

III: using the powdery agent A to prepare an aqueous solution having an organic compound concentration (when the powdery drug A contains two or more organic compounds, the concentration of the organic compound means the concentration of each organic compound) is 1 to 200 g/L. On the other hand, the powdery agent B is used to prepare an organic compound concentration (when the powdery drug B contains two or more organic compounds, the concentration of the organic compound means the concentration of each organic compound) is 1 to 200 g/L. The aqueous solution is injected into the supply pipe of the RO water supply from the different positions, and the treatment rate of the organic compound is 0.1 to 200 mg/L.

Further, the ratio C _min / C _max of the concentration C _min of the organic compound having the lowest concentration among the organic compounds in the blocking rate-increasing treatment water to the concentration C _max of the organic compound having the highest concentration is preferably 0.1 to 1.0. If the value is smaller than 0.1, the size of the repairable hole is biased. The concentration of each organic compound may also be equal.

Further, an inorganic electrolyte such as a salt (NaCl), a neutral organic substance such as isopropyl alcohol or glucose, or a low molecular polymer such as polymaleic acid may be added as a tracer in the barrier-enhancement treatment water. The degree of repair of the membrane can be confirmed by analyzing the penetration of salt or glucose into the permeation water of the reverse osmosis membrane.

The blocking rate increases the feed water pressure when the treated water passes through the RO membrane. If the water pressure is too high, there is a problem that the adsorption proceeds to the undegraded portion. If the adsorption is not performed to the deteriorated portion, the normal operating pressure of the RO membrane is preferably 20 ~150%, especially good 50~130%. When the membrane of the RO membrane is an ultra-low pressure membrane, the inlet pressure of the device is preferably 0.1 to 1.0 MPa. When the membrane of the RO membrane is a low pressure membrane, the inlet pressure of the device is preferably 0.1 to 2.0 MPa. When the membrane of the RO membrane is a seawater desalination membrane, the inlet pressure of the apparatus is preferably 0.1 to 7.0 MPa.

Further, in the present invention, the membrane was calculated by the following formula the minimum amount per unit area in contact with the organic compound is 2500mg / m ² or more, preferably 2500 ~ 1000000mg / m ^2, particularly preferably 3000 ~ 100000mg / m ² of the embodiment The blocking rate is increased by the treatment water to the RO membrane, that is, it is preferably transmitted.

Minimum organic compound contact amount (mg/m ² ) = [minimum organic compound concentration (mg/L) × treatment time (hr) × permeate water amount (m ³ /hr) / membrane area (m ² )] × 1000

Here, the minimum organic compound concentration is a barrier ratio which increases the concentration of the organic compound having the lowest concentration among the organic compounds in the treated water.

By becoming the minimum amount of organic compound contact, the blocking ratio of the RO film is sufficiently increased. For example, using two kinds of the aforementioned low molecular weight amine-based compounds, the blocking ratio of the first low molecular weight amine compound is increased as the C ₁ (mg/L), and the blocking ratio of the second low molecular weight amine compound is increased. The concentration in the treated water is taken as C ₂ (mg/L), the blocking rate of tannic acid is increased as the C ₃ (mg/L), and the lowest concentration in C ₁ ~ C ₃ is taken as C _min . The minimum organic compound contact amount per unit area of the film was calculated by the following formula.

Contact amount of the smallest organic compound per unit area of the film = [(C _min ) × treatment time (Hr) × amount of permeate water (m ³ /Hr) / membrane area (m ² )] × 1000

In the method of the present invention, the linear velocity of the RO membrane permeating water during the barrier ratio raising treatment is related to the pressure, the water temperature, the shape of the membrane, and the like, but is preferably 0.1 to 5 m/d. The reason is the same as the above, because the adsorption is progressing to the undegraded portion, and the contact efficiency at the deteriorated portion is deteriorated.

Further, the blocking rate of the barrier rate raising treatment is preferably a normal temperature, for example, about 10 to 35 ° C. When the water temperature is too low, the amount of water passing through is lowered, and the contact efficiency is deteriorated. The blocking rate increases the temperature of the treated water too high, and the film material has denaturation.

The time during which the blocking rate is increased by the treatment water is preferably the time during which the organic compound sufficiently penetrates the RO film. When the RO membrane device is not operating normally, the passage rate is increased by the treatment water, preferably from about 3 to 100 hours, and particularly preferably from 6 to 50 hours. When the passage time is too short, the fixing property of the organic compound is not obtained, and the treatment is terminated, and the adhered organic compound is peeled off.

The barrier rate lifting process can also be performed during normal operation of the RO membrane device, for example, by adding an aqueous solution prepared by the barrier ratio lifting treatment agent to the RO feed water during normal operation of the RO membrane device. The time for adding the aqueous solution of the blocking rate-increasing treatment agent to the RO water supply is preferably about 1 to 500 hours, and the aqueous solution of the blocking rate-enhancing treatment agent is usually added to the RO feed water.

Due to the long-term operation of the RO membrane device, membrane fouling occurs. When the stream is lowered, the barrier rate lifting treatment may be performed after the membrane is washed.

Examples of the membrane cleaning agent used in this case include mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid, and organic acids such as citric acid and oxalic acid. Examples of the alkali washing include sodium hydroxide, potassium hydroxide, and the like. Generally, the acid wash is set near pH 2, and the alkali wash is set near pH 12.

[RO film]

In the present invention, the membrane structure of the RO membrane which is a target of the treatment for the barrier rate-up treatment is a polymer membrane such as an asymmetric membrane or a composite membrane. Examples of the material of the RO film include a polyamide-based material such as an aromatic polyamine, an aliphatic polyamine, a composite material thereof, or a cellulose-based material such as cellulose acetate. Among these, in the RO film having a majority of carboxyl groups due to the breakage of the CN bond due to deterioration of the RO film of the aromatic polyamide material, it is particularly preferable to use the barrier ratio improving agent and the barrier ratio raising method of the present invention, especially The method of the present invention can be suitably used when the salt rejection rate of the RO membrane before the barrier ratio raising treatment is 95% or less, particularly 90% or less.

The form of the RO membrane module is not particularly limited, and examples thereof include a tubular membrane module, a planar membrane module, a spiral membrane module, and a hollow fiber membrane module.

[Water treatment method]

The water treatment method of the present invention uses the RO film which has been subjected to the barrier rate lifting treatment by the barrier ratio improving agent or the barrier ratio lifting method of the present invention, and can be effectively applied to the field of electronic device manufacturing, semiconductor manufacturing, and the like. Recovery of TOC-containing wastewater from high to low concentrations discharged from the industrial field. Reuse water treatment, or ultra-pure water from industrial water or domestic water, water treatment in other fields.

The water to be treated which is treated by the RO membrane device of the present invention is not particularly limited, but is preferably water containing an electrolyte, and is preferably water containing organic matter having a conductivity of 2 to 10000 mS/m, preferably about 10 to 7,000 mS/m. The water containing such an organic material may be, for example, an electronic device manufacturing plant drainage, a transportation machinery manufacturing plant drainage, an organic synthesis plant drainage, a printing plate making, a painting factory drainage, or the like, or the like, but not the same. And so on.

Example

Hereinafter, the present invention will be more specifically described by way of Comparative Examples and Examples.

Hereinafter, as the performance evaluation device, the flat film test apparatus shown in Fig. 3 was used.

In the flat film test apparatus, the flat film unit 2 is disposed at an intermediate position in the height direction of the bottomed lid-shaped cylindrical container 1, and the inside of the container is partitioned into a raw water chamber 1A and a permeated water chamber 1B, and the container 1 is placed in a stirring state. In the device 3, the water to be treated is supplied to the raw water chamber 1A through the pipe 11 by the pump 4, and the stirrer 5 in the container 1 is rotated to stir the inside of the raw water chamber 1A, and the permeated water is taken out from the permeated water chamber 1B through the pipe 12. At the same time, the concentrated water is taken out from the raw water chamber 1A through the pipe 13. A pressure gauge 6 and an on-off valve 7 are provided on the concentrated water take-out pipe 13.

Further, the RO permeation flux, the salt rejection ratio (NaCI removal rate), and the IPA removal rate of the evaluation film were each calculated by the following formula.

Permeation flux ^{[m 3 / (m 2 d} )] = permeated water [m ³ / d] / membrane area [m ^2] × temperature conversion coefficient [-]

Desalination rate [%] = (1 - conductivity of permeated water [mS / m] / conductivity of concentrated water [mS / m]) × 100

IPA removal rate [%] = (1 - TOC through water (mg / L) / TOC [mg / L] of concentrated water × 100

[Blocking rate increase test I]

The following deteriorated film was used as the film of the flat film unit 2 of the flat film test apparatus, and the test was carried out using the following barrier ratio improving agent, performance evaluation water to be treated, and performance evaluation conditions.

Deteriorated film: An ultra-low pressure reverse osmosis membrane ES20 manufactured by Nitto Denko Corporation was immersed in an aqueous solution containing 1% by weight of hydrogen peroxide and 1 mg/L of ferric chloride as an iron fraction to accelerate deterioration. The permeation flux, the salt rejection rate, and the IPA removal rate of the deteriorated film were 1.1 m ³ /(m ² .d), 90%, and 72%, respectively, and the permeated stream of the original film (new undegraded ES20 film) The salt rejection rate and the IPA removal rate were 0.8 m ³ /(m ² .d), 98%, and 88%, respectively.

The components of the barrier-enhancing agent: arginine (manufactured by Ajinomoto, Supply, molecular weight 174), aspartame (manufactured by Ajinomoto, Supply, molecular weight 294), tannic acid AL (the following tannic acid, Fuji) Chemical industry, molecular weight of 500 or more), all food additives

Performance evaluation treated water: dissolved in ultra-pure water NaCl 500mg / L, IPA 100mg / L

Performance evaluation conditions: operating pressure 0.75MPa, temperature 24 °C ± 2 ° C

<Comparative Example 1>

The three components constituting the blocking rate enhancer were dissolved in pure water directly from the powder so as to be 10 g/L each, and as a result, an insoluble aggregate was formed, which was not provided in the barrier rate raising treatment.

<Example 1>

The arginine and the aspartame were directly mixed in a powder ratio of 1:1, and the tannic acid was dissolved in pure water in addition to the components of 10 g/L. Aspartame is easily dissolved due to its coexistence with arginine. The pH of the aqueous solution containing aspartame and arginine was 9.0, and the pH of the aqueous solution containing tannic acid was 3.7.

Then, the two aqueous solutions were dropped into pure water so as to have a concentration of 50 mg/L, and the mixture was diluted and mixed to obtain a clear aqueous solution.

The obtained mixed aqueous solution was passed through water for 5 hours to a deteriorated film to carry out a barrier ratio raising treatment. As a result, the permeated flow, the salt rejection rate, and the IPA removal rate of the treated RO membrane were restored to 0.8 m ³ /(m ² .d), respectively. 98.5%, 87%.

[Block Rate Improvement Test II]

The following deteriorated film was used as the film of the flat film unit 2 of the flat film test apparatus, and the test was carried out using the following barrier ratio improving agent, performance evaluation water to be treated, and performance evaluation conditions.

Deteriorated film: An ultra-low pressure reverse osmosis membrane ES20 manufactured by Nitto Denko Corporation was immersed in an aqueous solution containing 1% by weight of hydrogen peroxide and 1 mg/L of ferric chloride as an iron fraction to accelerate deterioration. The permeation flux, the salt rejection rate, and the IPA removal rate of the deteriorated film were 0.95 m ³ /(m ² .d), 95%, and 81%, respectively. The permeate flow, the salt rejection rate, and the IPA removal rate of the original film (new undegraded ES20 film) are as described above.

The components of the barrier-enhancing agent: glycine (manufactured by Wako Pure Chemical Industries, molecular weight 75), arginine (manufactured by Ajinomoto, supply MW), and tannic acid AL (the following tannic acid, manufactured by Fuji Chemical Industry) , molecular weight of 500 or more)

Performance evaluation treated water: dissolved in ultra-pure water NaCl 500mg / L, IPA 100mg / L

Performance evaluation conditions: operating pressure 0.75MPa, temperature 24 °C ± 2 ° C

<Comparative Example 2>

Each of glycine, arginine, and tannic acid was dissolved in pure water so as to be 30 g/L, and these were mixed so that the respective concentrations became 10 g/L, and as a result, coagulation was formed immediately after mixing. The item cannot be provided for the blocking rate improvement process.

<Comparative Example 3>

Each of glycine, arginine, and tannic acid was dissolved in pure water so as to be 30 g/L, and each was stored at -5 ° C for one month, and each of them was frozen. Let these return to normal temperature to melt, and the result is born in an aqueous solution of tannic acid. It is precipitated and cannot be provided for the barrier increase treatment.

<Comparative Example 4>

The same amount of glycine, arginine, and tannic acid was mixed in a powder state. When the obtained mixed powder was stored at -5 ° C for 1 month, no change was observed in the powder state, but when the mixed powder was dissolved in pure water so that the respective concentrations became 10 g/L, aggregates were formed. Unable to provide for blocking rate boost processing.

<Example 2>

Glycine and arginine were mixed in a powder at a ratio of 1:1, and the tannic acid was separately in a powder state. Each powdered drug was stored at a temperature of -5 ° C for one month. Then, each of the two powdery chemicals was dissolved in pure water so that the concentration of each component became 10 g/L. The pH of the aqueous solution containing glycine and arginine was 9.6, and the pH of the aqueous tannic acid solution was 3.7. Using this glycine ‧ arginine aqueous solution and an aqueous tannic acid solution, the barrier film lifting treatment of the deteriorated film was carried out by the following method.

In other words, the flow rate of the water to be treated is adjusted so that the flow rate of each of the aqueous solutions is 1/5000, that is, the concentration of each component after the combined flow of the treated water is 2 mg/L, and is in the flow path of the treated water. The aqueous solution of glycine ‧ arginine and the aqueous solution of tannic acid were respectively injected into the pipeline. After the start of the injection, the performance of the deteriorated film was changed. After 72 hours, the permeation flux, the salt rejection rate, and the IPA removal rate were 0.8 m ³ /(m ² .d), 98.7%, and 89%, respectively.

[investigation]

From the above results, the following are known.

(i) mixing arginine with aspartame to form a powdery agent. On the other hand, the tannic acid is directly used as a powdery agent, and each of them is made into a high-concentration aqueous solution, and then mixed by such dilution. , without generating aggregates, can be effectively used in the RO film barrier rate lifting process.

(ii) mixing glycine and arginine to form a powdery drug. On the other hand, when tannic acid is directly stored as a powdery drug, it is not dissolved after being dissolved in water. The material can be prepared into a uniform and stable aqueous solution, and these dilutions are mixed by pipeline injection without generating aggregates, and can be effectively used for the RO membrane blocking rate raising treatment.

While the invention has been described in detail, the embodiments of the invention may be

Furthermore, the present application is based on a Japanese invention patent application filed on April 9, 2012 (Japanese Patent Application No. 2012-088478), the entire disclosure of which is incorporated herein by reference.

Claims (6)

A polyamidamide-based reverse osmosis membrane blocking rate-enhancing agent which is a polyamidamide-based reverse osmosis membrane blocking ratio-enhancing agent containing two or more organic compounds having different molecular weights, and is characterized in that it is contained in two or more kinds. The organic compound having at least a molecular weight of 60 or more and less than 500, and having a polyamine amine-based reverse osmosis membrane blocking rate enhancer of tannic acid, the aforementioned organic compound having an amine group and the aforementioned tannic acid It is stored as two powdery medicines different from each other. The polyamine-based reverse osmosis membrane blocking rate enhancer according to claim 1, wherein when the two powdery medicaments are each an aqueous solution having a concentration of each organic compound of 1 to 200 g/L, the organic group having the aforementioned amine group is contained. The pH of the aqueous solution of the powdery drug of one of the compounds is 7 or more, and the pH of the aqueous solution containing the powdery drug of the other of the above-mentioned tannic acid is less than 7. A method for improving a barrier rate of a polyamidamide-based reverse osmosis membrane, which comprises treating a polyamidamide-based reverse osmosis membrane with an aqueous solution of a barrier ratio-enhancing agent according to claim 1 or 2, characterized in that it comprises: The powdery agent of at least one of the bulk chemicals is dissolved in water to prepare an aqueous solution having an organic compound concentration of 1 to 200 g/L, and the concentration of the organic compound of the aqueous solution is 0.1 to 200 mg/L. The step of releasing the aqueous solution, the concentration of the organic compound in the above two steps is the concentration of each organic compound when the powdery drug contains two or more organic compounds. A method for improving the blocking rate of a polyamidamide-based reverse osmosis membrane, which comprises treating a polyamidamide-based reverse osmosis membrane with an aqueous solution of a blocking rate enhancer according to claim 1 or 2, characterized in that it comprises: Each of the powdery chemicals is dissolved in water, and the obtained aqueous solution is mixed to prepare an aqueous solution having a concentration of each organic compound of 1 to 200 mg/L. A method for improving a barrier rate of a polyamidamide-based reverse osmosis membrane, which comprises treating a polyamidamide-based reverse osmosis membrane with an aqueous solution of a barrier ratio-enhancing agent according to claim 1 or 2, characterized in that it comprises: Each of the bulk chemicals is dissolved in water, and each of the obtained aqueous solutions is injected into a line from a different position to dilute and mix. A polyamidamide-based reverse osmosis membrane which uses a barrier ratio-enhancing agent as claimed in claim 1 or 2 for a barrier increase treatment.