JP2017018842A - Hydrophilic polymer adsorbent material and water treatment method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a hydrophilic polymer adsorbent material that can efficiently adsorb fouling substances in membrane filtration; and a water treatment method by membrane filtration in which the water permeability can be maintained for a long period of time.SOLUTION: The hydrophilic polymer adsorbent material is a hydrophilic polymer adsorbent material in which a chemisorptive functional group is introduced, has a swelling degree in 25°C water of 20 to 400%, and has excellent adsorptivity of dissolved organic matter in water to be treated. The water treatment method at least includes an adsorption step of bringing water to be treated containing dissolved organic matter, and the hydrophilic polymer adsorbent material into contact to adsorb dissolved organic matter, and a filtration step of membrane-filtering the adsorption treated water.SELECTED DRAWING: None

Description

  The present invention relates to a water treatment method by membrane filtration that can remove fouling substances in membrane filtration and maintain water permeability for a long period of time.

Ultrafiltration (UF) membrane, microfiltration (MF) membrane, nanofiltration (NF) membrane, reverse osmosis (RO) membrane in the field of water treatment such as water purification, ultrapure water, pharmaceutical water, domestic water purification, wastewater purification, etc. It is 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.
In particular, biofouling, which is membrane fouling by dissolved organic matter, is a physically irreversible fouling and is currently a major problem in water treatment by membrane filtration.

  In order to solve the above problem, a water treatment method has been proposed in which an activated carbon treatment, an adsorption treatment using a porous inorganic adsorbent, a coagulation treatment, a treatment using ozone treatment, and the like are provided in the front stage of the filtration membrane. However, the adsorptivity of the dissolved organic matter is insufficient in the adsorption treatment with the activated carbon treatment or 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 dissolved organic matter concentration becomes high. In addition, there is a problem that aggregation of dissolved organic matter having high hydrophilicity becomes incomplete. Ozone treatment has the problem of disinfection by-products such as bromic acid, and alternative techniques are required.

  As such an alternative technique, for example, Patent Documents 1 and 2 propose a method for removing dissolved organic substances centering on a hydrophobic adsorbent.

  Patent Document 3 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.

  On the other hand, in recent years, detailed analysis has been made on fouling substances in membrane filtration. In Non-Patent Document 1, irreversible fouling causes substances such as saccharides and proteins which are dissolved organic substances having relatively higher hydrophilicity than humin. It has been reported that biopolymers such as

JP 2013-223847 A Japanese Patent No. 3839477 Japanese Patent No. 5218731

Yoshinori Watanabe, Membrane, 38 (5), 207-214 (2013)

In addition, any of the methods described in Patent Documents 1 and 2 still have a biofouling problem with respect to dissolved organic matter.
Furthermore, the particle | grains which consist of a cationic polymer currently disclosed by patent document 3 are said that the particle diameter in water is about 10-200 times (namely, 1000-200000%) with respect to the particle diameter when not swollen with water. Since it has an extremely large swellability, the handleability during the adsorption treatment is poor, and in particular in a closed environment, there is a problem that the filterability is reduced due to adhesion between particles.

  In view of the circumstances described above, the present invention provides a polymer adsorbent capable of efficiently adsorbing dissolved organic substances that are membrane contaminants of membrane filtration, particularly dissolved organic substances having relatively high hydrophilicity such as sugars and proteins. The purpose is to do.

  Another object of the present invention is to provide a water treatment method that can efficiently perform water treatment using such a polymer adsorbent and can maintain the water permeability of the membrane over a long period of time. To do.

As a result of intensive studies to solve the above problems, the present inventors have found that when a hydrophilic polymer adsorbent whose degree of swelling in water at 25 ° C. is in a specific range is used, dissolved organic matter reaches the inside of the adsorbent by appropriate swelling. As a result, it was found that the internal adsorptive functional group can be used effectively and clogging by dissolved organic matter is difficult to occur, so that it exhibits excellent ability to remove dissolved organic matter. Further, the present inventors have found that such a hydrophilic polymer adsorbent has a high affinity for biopolymers because of its high affinity with biopolymers having particularly high hydrophilicity.
As a result, by adding an adsorption step of dissolved organic matter using the adsorbent to the previous step of the membrane filtration step, in particular, a biopolymer adsorption step with high hydrophilicity, membrane contamination can be suppressed, and water permeability can be maintained over a long period of time. It came to propose the water treatment method by membrane filtration which can be maintained.

  That is, the first embodiment of the present invention is a hydrophilic polymer adsorbent into which a chemisorbable functional group is introduced, having a swelling degree of 20 to 400% in water at 25 ° C. and dissolved in water to be treated. It is a hydrophilic polymer adsorbent that excels in adsorbability of organic matter.

  In the hydrophilic polymer adsorbent, the dissolved organic matter to be adsorbed may be a biopolymer, and in particular, the removal rate of the biopolymer may be 15% or more.

  A preferred hydrophilic polymer adsorbent is a hydrophilic polymer as a matrix, and the hydrophilic polymer is polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl butyral, polyvinyl acetal, polyvinyl alkyl alcohol, polyalkylene glycol, It may be at least one selected from any of polyvinyl alkyl ether, polyalkylene oxide, poly (meth) acrylamide, cationic polymer, anionic polymer, polyamide, cellulose derivative, dextrin, chitin, and chitosan.

  Further, the chemisorbable functional group may be a chemisorbable functional group containing at least one element selected from the group consisting of N, S, P and O, for example, an amino group, a quaternary ammonium group, and It is preferably at least one chemisorbable functional group selected from the group consisting of those salts.

  A preferable hydrophilic polymer adsorbent may be an alloy material composed of at least a polymer (A) having a chemically adsorbing functional group and a hydrophilic polymer (B). B) may be an ethylene-vinyl alcohol copolymer.

A second embodiment of the present invention is an adsorption step in which water to be treated containing dissolved organic matter is brought into contact with the hydrophilic polymer adsorbent to adsorb dissolved organic matter;
A water treatment method comprising at least a filtration step of subjecting the adsorption treated water to membrane filtration.

  By using a hydrophilic polymer adsorbent having a degree of swelling in water at 25 ° C. in a specific range as a material for adsorbing dissolved organic substances (especially highly hydrophilic biopolymers such as sugars and proteins), a hydrophilic polymer is obtained. Not only can the adsorbent be efficiently used for water treatment, but also the dissolved organic matter in the treated water can be reduced by highly adsorbing dissolved organic matter from the water to be treated.

  Furthermore, in the water treatment method of the present invention, the water permeability of the filtration membrane can be maintained over a long period of time by a simple method when combined with various membrane filtration steps by using the adsorption treated water that has undergone the adsorption treatment. It is.

  In particular, the hydrophilic polymer adsorbent can be packed into a column. In that case, in the water treatment method, a combination of a dissolved organic substance removal step using a column and a membrane filtration step can be performed by a simple method. The water permeability can be maintained for a long time.

About the to-be-processed water used in Example 4, the molecular weight of the dissolved organic substance measured by LC-OCD (made by DOC-Labor) which connected the wet total organic carbon measuring device (OCD meter) to the high performance liquid chromatography (HPLC). It is a graph which shows a distribution spectrum.

Hereinafter, the present invention will be described in detail based on embodiments. Note that the embodiments described below do not limit the present invention.
[Water treatment method]
The water treatment method of the present invention comprises an adsorption step in which water to be treated containing dissolved organic matter and a specific hydrophilic polymer adsorbent are brought into contact with each other to adsorb dissolved organic matter,
A filtration step of performing membrane filtration on the adsorption-treated water subjected to the adsorption treatment.

(Adsorption process)
The water to be treated is not particularly limited as long as various waters obtained in natural and artificial environments can be used as the water to be treated and contain dissolved organic matter. For example, general river water, lake water, soil Examples include elution water, irrigation water, biologically treated water, biologically treated water in sewage treatment and human waste treatment facilities, advanced treated water such as tertiary treatment, and various factory effluents.

  In such water to be treated, various dissolved organic substances exist. However, in the water treatment method of the present invention, dissolved organic substances that have conventionally been difficult to adsorb in the adsorption step, particularly organic substances having a particle size of 0.45 μm or less. (For example, aromatic-containing organic substances such as humic acid and fulvic acid, synthetic chemical substances such as surfactants, biopolymers, etc.) can be adsorbed efficiently.

In the adsorption process of the present invention, it is excellent in removing a biopolymer having a high hydrophilicity among dissolved organic substances. Biopolymers are a kind of dissolved organic substances present in various raw waters. Generally, biopolymers are polysaccharides and proteins having an apparent molecular weight of 100,000 Da or more.
In the present invention, as an index for distinguishing other dissolved organic substances from biopolymers, a component having a retention time of 25 minutes to 35 minutes in the analysis of LC-OCD (manufactured by Hubers, DOC-Labor) shown in Examples. Is defined as biopolymer. The humic substance is a component with a retention time of 35 minutes to 46 minutes.

Since biopolymers have few unsaturated bonds such as benzene rings, biopolymers are mainly composed of highly hydrophilic organic substances. For example, the SUVA value is 1.0 [L / (m · mg)] or less. It may be composed of an organic material showing.
On the other hand, since the humic substance includes a UV-absorbing structure such as a benzene ring, the humic substance is mainly composed of an organic substance having high hydrophobicity. For example, the SUVA value is 2.0 [L / (M · mg)] It may be composed of an organic material having the above.

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

UV value calculation method (i) UV of biopolymer = UV of full spectrum × Area value of biopolymer (holding time: 25 to 35 minutes) / Area value of full spectrum (ii) UV of humic substance = UV of full spectrum × Area value of humic substances (holding time: 35 to 46 minutes) / area value of all spectra

DOC value calculation method (i) DOC of biopolymer = DOC of full spectrum × Area value of biopolymer (holding time: 25 to 35 minutes) / Area value of full spectrum (ii) DOC of humic substance = DOC of full spectrum Area value of humic substances (holding time: 35 to 46 minutes) / area value of all spectra

  Styrenic and acrylic ion exchange resins and chelate resins that are currently commercially available cannot efficiently adsorb such hydrophilic dissolved organic substances. However, in the present invention, by using a specific hydrophilic polymer adsorbent, even such a hydrophilic dissolved organic substance can be adsorbed efficiently.

The adsorption step is not particularly limited as long as the water to be treated and the hydrophilic polymer adsorbent can be brought into contact with each other. For example, the adsorption treatment is performed by adding the adsorbent to the water to be treated and stirring it by a known method. The adsorption treatment may be carried out by passing water to be treated through a column filled with a hydrophilic polymer adsorbent. 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. .

  In the adsorption step, dissolved organic matter in the water to be treated can be adsorbed efficiently, and in particular, the biopolymer can be adsorbed efficiently as described above. For example, in the adsorption step, the removal 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.

(Hydrophilic polymer adsorbent)
The hydrophilic polymer adsorbent of the present invention will be described.
The hydrophilic polymer adsorbent of the present invention is a hydrophilic polymer adsorbent into which a chemisorbable functional group is introduced, and has a swelling degree of 20 to 400% in 25 ° C. water. Preferably, the hydrophilic polymer adsorbent is an adsorbent into which an adsorptive functional group is introduced using a hydrophilic polymer as a base.

  Since the hydrophilic polymer adsorbent of the present invention is a hydrophilic polymer, the dissolved organic matter penetrates to the inside, the adsorptive functional group can be effectively used, and the dissolved organic matter can be adsorbed efficiently. In conventional ion exchange resins, a hydrophobic polymer such as polystyrene is used as a base and an adsorptive functional group is added. Compared with such a hydrophobic polymer, the hydrophilic polymer adsorbent of the present invention is It is possible to efficiently adsorb dissolved organic substances in water, in particular, biopolymers that are highly hydrophilic and have begun to be considered as substances that cause membrane contamination.

On the other hand, since the degree of swelling is controlled within a predetermined range, even in the case where the hydrophilic polymer is used as a base material, while suppressing the deterioration of the handling property of the adsorbent due to excessive swelling, It is possible to efficiently adsorb dissolved organic matter.
For example, since the hydrophilic polymer adsorbent has a controlled degree of swelling, unlike the cationic polymer described in Patent Document 6 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 refers to a polymer having a hydrophilic group such as a hydroxyl group, an ether group, a cationic group, an anionic group or an amide group in a repeating unit. For example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl butyral, polyvinyl acetal, polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, poly (meth) acrylamide, cationic polymer (for example, polyethyleneimine, Polyallylamine, polypyridine, polyvinylpyridine, polyamino acid, polydiallyldimethylammonium halide, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, polynucleotide, etc.), anionic polymer (eg, polystyrene sulfone) Acid, polyvinyl sulfate, poly (meth) acrylic acid, polymer Phosphate, polyamic acid), polyamide, cellulose derivatives, dextrin, chitin, and at least one is preferably used selected from the group consisting of chitosan. 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.

  As the hydrophilic polymer, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polyamide are preferable, and from the viewpoint of water resistance and biopolymer removal performance, ethylene-vinyl alcohol copolymer is more preferable. At this time, the content of ethylene units is preferably 20 to 60 mol%, more preferably 25 to 50 mol% in all monomer units. If the ethylene content is less than 20 mol%, the water resistance may deteriorate. On the other hand, when the ethylene content exceeds 60 mol%, production is difficult.

  The polymer adsorbent of the present invention has a chemisorbable functional group that interacts with dissolved organic matter. Examples of the functional group having chemical adsorptivity include chelate-forming groups, cationic ion exchange groups, anionic ion exchange groups, and the like, and are not particularly limited as long as they have adsorptivity to dissolved organic substances.

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

  The chemical adsorptive functional group may be introduced by polymerization or post-modification when the hydrophilic polymer is produced, and is introduced by alloying with a component having the chemisorbable functional group. May be. From the viewpoint of ease of introduction, introduction is preferably performed by alloying the chemically adsorbing functional group-containing polymer (A) and the hydrophilic polymer matrix (B).

[Chemically Adsorbing Functional Group-Containing Polymer (A)]
For example, the chemisorbable functional group-containing polymer (A) is an anion such as polystyrene sulfonic acid (PSS), polyvinyl sulfate (PVS), polyacrylic acid (PAA), polymethacrylic acid (PMA), polymaleic acid, polyamic acid, etc. Polyethyleneimine, polyallylamine, polypyridine, polyvinylpyridine, polyamino acid, polydiallyldimethylammonium halide, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, poly It may be a cationic polymer such as a nucleotide. Such polymers may be used alone or in combination of two or more.

  Among these, from the viewpoint of more efficiently adsorbing a biopolymer in combination with a hydrophilic matrix polymer, the above-described cationic polymer is preferable, and particularly a strong basic polymer (a quaternary ammonium group-containing polymer, a quaternary polymer). Pyridinium group-containing polymers) and polymers having high cation density (for example, polyethyleneimine, polyallylamine, etc.) are preferable.

[Hydrophilic matrix polymer (B)]
The hydrophilic matrix polymer (B) is not particularly limited. For example, the hydrophilic matrix polymer (B) includes polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl alkyl alcohol, polyalkylene glycol, and polyvinyl alkyl ether. (Meth) acrylic polymers, polyalkylene oxides, polyacrylamides, polyamides, cellulose derivatives, dextrin, chitin, chitosan and the like. These polymers may be used alone or in combination of two or more.

  These polymers may have other comonomer units, and the content of the comonomer units is preferably 10 mol% or less, more preferably 5% mol or less in all monomer units. .

  The weight average molecular weight of the hydrophilic matrix polymer (B) can be appropriately set in accordance with the type of the polymer. From the viewpoint of maintaining inside the molecule (B), for example, the weight average molecular weight of the hydrophilic matrix polymer (B) may be at least 5,000 or more (for example, 5,000 to 100,000), preferably 10,000 or more. May be. In addition, a weight average molecular weight can be calculated | required, for example using GPC.

  Preferred hydrophilic matrix polymers (B) include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl butyral, polyvinyl acetal, 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 copolymer From the viewpoint of being excellent in both moldability and hydrophilicity, an ethylene-vinyl alcohol copolymer is particularly preferable.

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

  Polyvinyl alcohol may be defined by the viscosity average degree of polymerization, and is not particularly limited as long as the chemically adsorbable functional group-containing polymer (A) can be dispersed with a predetermined dispersion diameter, and is determined from the viscosity of a 30 ° C. aqueous solution. The viscosity average polymerization degree can be selected from a wide range of about 100 to 15000, for example. From the viewpoint of improving the durability as a matrix polymer, it is preferable to use a polymer having a high degree of polymerization. In this case, for example, the average degree of polymerization is preferably about 800 to 13000, more preferably about 1000 to 10,000. Also good.

  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.

[Mass ratio between the chemisorbable functional group-containing polymer (A) and the hydrophilic matrix polymer (B)]
In the hydrophilic polymer adsorbent of the present invention, the chemically adsorbing functional group-containing polymer (A) and the hydrophilic matrix in the alloy of the chemically adsorbing functional group-containing polymer (A) and the hydrophilic polymer matrix (B) The ratio of the polymer (B) is not particularly limited as long as the polymer (A) is dispersed within a predetermined range. For example, the polymer (A) / polymer (B) = 1/99 to 70 in terms of mass ratio. It may be about / 30, preferably 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 small, the adsorption performance tends to be lowered.

[Other ingredients]
In the present invention, the hydrophilic polymer adsorbent having the adsorptivity of dissolved organic matter is used as a resin component within the range that does not impair the effects of the present invention. A polymer polymer other than the matrix polymer (B) may be included. 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 maintained in the range of 20 to 400% from the viewpoint of enabling the adsorption of the biopolymer and improving the handleability. The degree of swelling of the hydrophilic polymer adsorbent may be preferably about 40 to 200%, more preferably about 50 to 160%. 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 less than 20%, the contact with the solution containing the biopolymer becomes insufficient, or the biopolymer adsorbability becomes poor, and if it exceeds 200% by mass, excessive swelling occurs. The liquid permeability is impaired, and the column take-out property becomes insufficient.

  For example, the swellability of the hydrophilic polymer adsorbent may be controlled by crosslinking with a crosslinking agent, and may be low or non-swellable with respect to the chemisorbable functional group-containing polymer (A). You may control as an alloy material which combined a certain hydrophilic matrix polymer (for example, ethylene-vinyl alcohol copolymer, polyamide, etc.).

  In particular, the hydrophilic polymer adsorbent of the present invention is preferably crosslinked with a crosslinking agent from the viewpoint of controlling durability and swellability. 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 agents, titanium lactate, titanium diisopropoxybis (triethanolamate)), etc. May be used. Such a cross-linking agent can use various commercially available cross-linking agents, and is not particularly limited, but is selected from epoxy groups, halogen groups, isocyanate groups, vinyl groups, aldehyde groups, azetidine groups, carbodiimide groups, and the like. A compound containing at least two functional groups of at least one kind or two or more kinds is preferred.

  For example, the crosslinking structure may be introduced by crosslinking with a divinyl monomer during 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.

(Shape of hydrophilic polymer adsorbent)
The hydrophilic polymer adsorbent can have various shapes as long as it can be used for the adsorption treatment of the biopolymer from the water to be treated. For example, the hydrophilic polymer adsorbent may be in the form of particles, fibers, various three-dimensional shapes, etc. . 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, but the particle diameter 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.

  When the hydrophilic polymer adsorbent is fibrous, the 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 It may be 2 to 200 μm. The fiber diameter can be obtained, for example, by sampling a short fiber randomly, observing a cross section of the fiber with an electron microscope, and measuring the fiber diameter.

(Filtration process)
After the adsorption step, the adsorption-treated water subjected to the adsorption treatment is subjected to membrane filtration in the filtration step. 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 can be performed using a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a nanofiltration membrane (NF membrane) or the like depending on the purpose of water treatment. In the filtration step, membrane filtration may be performed using one or more of these membranes alone, or a plurality of types of membranes may be combined and membrane filtration may be performed using one or more of each.
For example, when a plurality of types of membranes are combined, the water to be treated supplied with an MF membrane or a UF membrane may be subjected to membrane filtration treatment, and then further membrane filtration treatment may be performed with an NF 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. The membrane form is not particularly limited and may be any shape such as a flat membrane, a tubular membrane, a hollow fiber membrane and the like. 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, the filtration flow rate is Flux 0.5 to 5.0 (m ³ / m ² / Day) may be passed through the filtration membrane, preferably Flux 1.0 to 4.0 (m ³ / m ² / day). In the water treatment method of the present invention, since the biopolymer can be reduced from the water supplied to the filtration membrane by performing a specific adsorption step, the filtration treatment can be performed while suppressing biofouling of the filtration membrane. It becomes possible.

  In the water treatment method of this invention, you may combine with the existing water treatment method as needed in the range which does not impair the effect of invention. Examples of the existing water treatment method include sand 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.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by 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 = [(A−B) / (B)] × 100 (%)

(Measurement method of biopolymer)
The biopolymer concentration is measured by LC-OCD (manufactured by DOC-Labor) in which a wet total organic carbon measuring instrument (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 dissolved organic matter)
After performing the adsorption process using the adsorbent with respect to the to-be-processed liquid which has a dissolved organic substance, the adsorbent was filtered and the adsorption process liquid was obtained. The dissolved organic matter removal rate (%) of the adsorption treatment liquid was calculated as follows.
The supernatant liquid before and after the adsorption treatment was analyzed using LC-OCD (manufactured by Hubers, DOC-Labor), and the removal rate (%) of the biopolymer (retention time 25 to 35 minutes) was calculated by the following equation. .
(I) Biopolymer removal rate = (Biopolymer concentration before adsorption step−Biopolymer concentration after adsorption step) / (Biopolymer concentration before adsorption step) × 100 (%)

(Water permeability evaluation of filtration membrane)
The water to be treated is passed through the filtration membrane at Flux 2.0 (m ³ / m ² / day), and reverse with pure water of Flux 3.0 m ³ / m ² / day once every 30 minutes. Washing was performed, the pressure change when passing through the membrane was evaluated, the time (min) until reaching 60 kPa was determined, and long-term water permeability was evaluated according to the following criteria.
A: 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]
(Production of hydrophilic polymer adsorbent)
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. 30 parts by mass of the particles and 70 parts of an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “G-156”) were melt-kneaded in a lab plast mill, and then pulverized to give a particle size of 0.4 to A 0.7 mm composite was obtained. The degree of swelling of the obtained adsorbent in 25 ° C. water was 80%.
Surface water collected from Inba Marsh (Chiba) (dissolved organic matter concentration = 3.6 mg-C / L, biopolymer's SUVA value: 0.21 (L / mg-C · m), humic substance Using a stainless mesh cartridge filter (TMP-2, manufactured by Avantech) having an exclusion diameter of 2 μm. The SUVA value of 3.3 (L / mg-C · m), pH = 8.7) was used. The insoluble matter was removed by filtration at, and 5 g of the obtained hydrophilic polymer adsorbent was added to 1 L of the filtered water, followed by stirring at 25 ° C. for 2 hours. After stirring, the hydrophilic polymer adsorbent is filtered off, and the obtained adsorption treated water is used to make a PE MF membrane (Mitsubishi Rayon Co., Ltd., pore size 0.1 μm) Flux 2.0 (m ³ / m ² / day) and the water permeability of the MF membrane was evaluated over time. As a result, the long-term permeability of the MF membrane was A. The results are shown in Table 1.

[Comparative Example 1]
As a result of evaluating the water permeability of the PE MF membrane (Mitsubishi Rayon Co., Ltd., pore diameter: 0.1 μm) by performing water treatment in the same manner as in Example 1 except that the dissolved organic matter is not adsorbed. Was D. The results are shown in Table 1.

[Example 2]
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%.
The surface water (dissolved organic matter 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 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 and stirred at 25 ° C. for 2 hours. did. After stirring, the hydrophilic polymer adsorbent was filtered off, and the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm) was evaluated using the resulting treated water. Was B. The results are shown in Table 2.

[Example 3]
Laboplast mill with 60 parts by mass of 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 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 0.6 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 (dissolved organic matter concentration = 3.6 mg-C / L, pH = 8.7) collected from Inba Marsh (Chiba Prefecture) was used. Insoluble matter is removed by filtering with a mesh cartridge filter (TMP-2, manufactured by Advantech), and 5 g of the obtained hydrophilic polymer adsorbent is added to 1 L of the filtered water at 25 ° C. for 2 hours. Stir. After stirring, the hydrophilic polymer adsorbent was filtered off, and the water permeability of the PVDF MF membrane (Asahi Kasei Co., Ltd., pore size 0.1 μm) was evaluated using the resulting treated water. Was A. The results are shown in Table 2.

[Example 4]
75 parts of ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., “E-105B”) and 25 parts of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., “Epomin SP-200”) are 210 After melt-kneading at 0 ° C., a pulverization process 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 treatment water was adsorbed and filtered in the same manner as in Example 3. 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 2.
In addition, when the molecular weight distribution of the organic substance contained in the water to be used used in this example was measured by LC-OCD, a spectrum as shown in FIG. 1 was obtained.

[Example 5]
A vinyl alcohol polymer having a mercapto group at the terminal was synthesized by the method described in JP-A-59-187005. The content (degree of saponification) of the vinyl alcohol unit 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 allowed to proceed for 1 hour at 75 ° C. to obtain an aqueous solution of a water-soluble polymer which is a polyvinyl alcohol-polyvinylbenzyltrimethylammonium chloride copolymer 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 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 performed 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 treatment water was adsorbed and filtered in the same manner as in Example 3. 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 2.

[Comparative Example 2]
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 3 except that the dissolved organic matter is not adsorbed, long-term water permeability is D. The results are shown in Table 2.

[Comparative Example 3]
As an adsorbent, water treatment was performed in the same manner as in Example 3 except that a commercially available granular activated carbon (Charcol activated, manufactured by Wako Pure Chemical Industries, Ltd.) having a swelling degree in water of 25 ° C. of 58% was used, and PVDF MF was obtained. 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 2.

[Comparative Example 4]
A water treatment was performed in the same manner as in Example 3 except that a commercially available anion adsorbent (Amberlite IRA400, manufactured by Sigma-Aldrich) having a degree of swelling in 25 ° C. water of 98% was used, and a PVDF MF membrane ( As a result of evaluating the water permeability of Asahi Kasei Co., Ltd. (pore diameter 0.1 μm), the long-term water permeability was C. The results are shown in Table 2.

[Example 6]
As a result of evaluating the water permeability of polyacrylonitrile (PAN) UF membrane (Asahi Kasei Co., Ltd., molecular weight cut off 100 kDa) using treated water adsorbed with the adsorbent used in Example 4, long-term water permeability is A. The results are shown in Table 3.

[Comparative Example 5]
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 dissolved organic matter adsorption step, the particles in the dry state have a very small particle size, so that not only the stirring ability with respect to the water to be treated is poor, but also the particles after swelling with the water to be treated Swelled to 250% or more, and it was difficult to satisfactorily stir the particles, so the test was stopped.

  As seen in Experimental Examples 1 to 6, when a process for removing dissolved organic substances in water using a hydrophilic polymer adsorbent having a degree of swelling of 20 to 400% in water at 25 ° C. is efficient It can be seen that biopolymers, which are dissolved organic substances with high hydrophilicity, can be removed, and the water permeability of the filtration membrane is stable for a long time.

  On the other hand, as seen in Comparative Examples 1 and 2, long-term water permeability cannot be obtained unless a process for removing dissolved organic matter is provided. In addition, as seen in Comparative Examples 3 and 4, when an adsorbent mainly composed of a hydrophobic structure such as commercially available activated carbon or ion exchange resin is used, some dissolved organic matter can be removed, but biopolymer Therefore, sufficient long-term water permeability cannot be obtained. The crosslinked polymer having quaternary ammonium as in Comparative Example 5 has a problem that the degree of swelling is too high.

Claims (9)

  A hydrophilic polymer adsorbent having a chemically adsorbing functional group introduced therein, having a swelling degree of 20 to 400% in water at 25 ° C., and having excellent adsorptivity of dissolved organic matter in water to be treated .   The hydrophilic polymer adsorbent according to claim 1, wherein the dissolved organic matter to be adsorbed is a biopolymer.   The hydrophilic polymer adsorbent according to claim 2, wherein the biopolymer removal rate is 15% or more.   The hydrophilic polymer adsorbent according to any one of claims 1 to 3, wherein the hydrophilic polymer is a matrix, and the hydrophilic polymer is polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, polyvinyl butyral, polyvinyl. Acetal, polyvinyl alkyl alcohol, polyalkylene glycol, polyvinyl alkyl ether, polyalkylene oxide, poly (meth) acrylamide, cationic polymer, anionic polymer, polyamide, cellulose derivative, dextrin, chitin, and chitosan A hydrophilic polymer adsorbent which is at least one kind.   The hydrophilic polymer adsorbent according to any one of claims 1 to 4, wherein the chemisorbable functional group includes at least one element selected from the group consisting of N, S, P and O. A hydrophilic polymer adsorbent that is a base.   The hydrophilic polymer adsorbent according to any one of claims 1 to 5, wherein the chemisorbable functional group is selected from the group consisting of an amino group, a quaternary ammonium group, and a salt thereof. A hydrophilic polymer adsorbent that is a functional group.   The hydrophilic polymer adsorbent according to any one of claims 1 to 6, wherein the hydrophilic polymer adsorbent is at least a polymer (A) having a chemically adsorbing functional group and a hydrophilic polymer (B). A hydrophilic polymer adsorbent that is a structured alloy material.   The hydrophilic polymer adsorbent according to claim 7, wherein the hydrophilic polymer (B) is an ethylene-vinyl alcohol copolymer. An adsorption process for contacting water to be treated containing dissolved organic matter with the hydrophilic polymer adsorbent according to any one of claims 1 to 8, and adsorbing dissolved organic matter;
A water treatment method comprising at least a filtration step of subjecting the adsorption treated water to membrane filtration.

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