JPH04214741A - Mildewproofing ion exchange membrane, production thereof and recovery of sulfuric acid - Google Patents

Abstract

PURPOSE:To obtain an ion exchange resin especially effective for recovering sulfuric acid, preventing reduction in performance of membrane resulting from occurrence of mold, stably usable for a long period of time by adding a mildewproofing agent or an antimicrobial agent to a specific ion exchange polymer and forming a film. CONSTITUTION:(B) 0.001-30%, preferably 0.01-10% mildewproofing agent or antimicrobial agent (e.g. pentachlorophenol or tributyltin laurate) is blended and dissolved in (A) an ion exchange polymer comprising an aromatic polymer which is a polymer consisting of an aromatic ring and a connecting group and contains a group shown by formula I [X and Y are O or S; Ar is group shown by formula II, formula III, etc. (w is single bond, 0, S, etc.; R1 to R3 are 1-8C hydrocarbon group; a is 0-3; b+c is 0-7)] wherein an anion exchange group or cation exchange group is introduced to the aromatic ring to give an ion exchange membrane. A sulfuric acid/iron solution containing an organic substance is introduced to one chamber divided by an anion exchange membrane, water is fed to the other chamber, sulfuric acid is selectively permeated to recover sulfuric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion exchange membrane that adsorbs or permeates and separates specific components from a mixed fluid.

More specifically, it relates to ion exchange membranes useful for electrodialysis such as seawater concentration and desalination of brine water, and diffusion dialysis such as acid or alkali recovery. The present invention relates to ion exchange membranes useful for such applications.

[Prior Art] Many documents and patents have been reported regarding ion exchange, but the most practical and useful one is an ion exchange membrane made of styrene-divinylbenzene copolymer.

In addition to their chemical resistance and heat resistance, ion exchange properties and selective permselectivity can be controlled by changing the content of divinylbenzene, a crosslinking agent, so a wide variety of products have been synthesized and developed for various uses. .

[Problem to be solved by the invention] However, in new applications, for example, when organic compounds are used in the food industry, organic drug industry, or inorganic drug synthesis, salts are removed from systems where organic compounds are present in the processing liquid. Mold and bacteria are generated in the dialysis tank during the concentration or removal of acid or alkali, reducing the permeability of the ion exchange membrane and impeding the fluid flow of the dialysis tank, resulting in unstable operation. There is a problem that cannot be done.

As a method to solve this problem, it has been proposed to sterilize the fluid flowing through the dialysis tank in advance. However, although heat sterilization is highly effective, it denatures useful substances and is not economical in terms of energy, and ultraviolet irradiation sterilization
Although it is simple and economical, the bactericidal effect is not sufficient. Furthermore, although the method of adding a fungicide or bactericide is highly effective, it has the drawbacks of contaminating the liquid and requiring a large amount of the agent.

In other words, in order to incorporate an antifungal agent or antibacterial agent into a conventional styrene-divinylbenzene ion exchange membrane, the ion exchange membrane is immersed in the antifungal agent to impregnate it, or the antifungal agent is mixed into the monomer solution. However, with the former, not only does impregnation cause a decline in membrane properties, but the antifungal agent etc. eluted during use and the effect is not sustainable, and with the latter, polymerization is inhibited and the performance is degraded. Either a good film cannot be obtained, or the antifungal agent is denatured during polymerization or during the ion exchange group introduction reaction (chloromethylation-amination reaction or sulfonation reaction), making it impossible to achieve the objective.

[Means for Solving the Problems] The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to solve the problems of separation and recovery of valuable compounds,
In the ion exchange membrane separation method useful for removing harmful substances,
The aim is to provide ion exchange membranes that prevent membrane performance degradation and can operate stably for long periods of time.In particular, we aim to provide ion exchange membranes and membrane separation that can be applied to applications that have traditionally been difficult due to the generation of mold and bacteria. The purpose is to provide a method.

The present invention provides an ion exchange membrane in which an ion exchange group is introduced into the aromatic ring of a polymer substantially composed of an aromatic ring and a linking group, in which an antifungal or antibacterial agent is contained in the ion exchange polymer. This is achieved by an ion exchange membrane characterized by containing.

The ion exchange membrane of the present invention basically contains an antifungal agent or an antibacterial agent within the above-mentioned specific ion exchange membrane, but this is based on new knowledge not found in conventional ideas. It is.

As a result of intensive research on high-performance ion exchange membranes that have anti-fungal and anti-bacterial properties, the inventor has found that by incorporating anti-fungal agents into ion-exchange polymers, the deactivation of anti-fungal agents can be prevented. , a high-performance ion-exchange membrane can be obtained by using a polymer in which an ion-exchange group is introduced into the aromatic ring of a polymer that is substantially composed of an aromatic ring and a linking group as an ion-exchange polymer. They discovered this and completed the present invention.

To explain the present invention in more detail below, the ion-exchangeable polymer used in the present invention is a polymer substantially composed of an aromatic ring and a linking group, and at least the repeating unit contains the general formula (1) - X=Ar-Y- (However, in the formula, X and Y are the same or different -O-
, -S-. Ar is a hydrocarbon group in which R1 to R5 are the same or different from each other and have 1 to 8 carbon atoms. a is 0-3, b+c is 0-7, d+e is 0
~5. R6 and R7 represent hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. ), the aromatic ring contains
Any ion-exchangeable polymer into which an anion-exchange group or a cation-exchange group has been introduced can be used without any problems, and after introducing a haloalkyl group into a polymer such as Examples include anion-exchangeable polymers with sulfone groups and cation-exchangeable polymers with sulfone groups introduced therein.

However, more preferably, the aromatic polymer is a copolymer consisting of at least two types of repeating units, one of which has the general formula (2) consisting of a block copolymer having the general formula (1) ( However, in the formula, X, Y, and Ar are the same as in general formula (1).Z
are -SO2-, -O-, -S-.

R8 to R11 have 1 to 8 carbon atoms that are the same or different from each other
hydrocarbon group. f-i are 0-4. l represents 0 to 1, m and n represent integers of 2 to 200, and m/n represents 0.1 to 100. ) The use of an ion-exchangeable polymer consisting of an aromatic block copolymer represented by Polyphenylene oxide/polyethersulfone copolymer, polyphenylene sulfide/polyethersulfone copolymer are preferably used in terms of controllability, improvement of mechanical strength of membrane, and high performance ion exchange with high ion exchange capacity. , polysulfone/polyethersulfone copolymer, etc., but especially X
, Y is -O-, Z is -S-, aromatic polysulfone/polythioethersulfone can be obtained as a high molecular weight copolymer,
In addition, the number of segments m and n and the segment ratio m/n are easily controlled, and the block copolymer is exemplified as a preferable block copolymer from the viewpoints of moldability, mechanical strength, and chemical resistance, and is disclosed in Japanese Patent Application Laid-Open No. 1983-1991 by the present applicant. -72020, JP-A-61-765
23 and JP-A-61-168629.

The method for introducing anion exchange groups into these polymers is as follows: (a) Introducing an aminoalkyl group, and converting to quaternization with an alkyl halide if necessary.

(b) After introducing a haloalkyl group, amination with NH3 and a primary to tertiary amine can be used, but the reaction is easy and a wide variety of anion exchange membranes with unique membrane properties can be obtained. So, (b)
The haloalkylation-amination reaction is preferably used.

As a method for introducing a haloalkyl group, reactions such as chlorination and bromination can also be used when using a polymer whose aromatic ring is substituted with an alkyl group, but in general, chloromethylmethyl -X of the block copolymer by electrophilic chloromethylation reaction such as ether, 1,4-bis(chloromethoxy)butane, 1-chloromethoxy-4-chlorobutane, formalin-hydrogen chloride, paraformaldehyde-hydrogen chloride, etc. -Ar-Y- It can be selectively introduced into the aromatic ring of the repeating unit.

The chloromethylated polymer thus obtained can be made into an anion exchange membrane by containing a fungicide, preferably by the following method.

(1) A chloromethyl polymer is made into a solution, an antifungal agent and the like are added and mixed, and then cast and formed into a membrane, which is then brought into contact with an aminating agent to form an anion exchange membrane.

(2) After the chloromethylated polymer is made into a solution, an aminating agent is added to form an anion exchange resin solution. After adding and mixing a fungicide, etc., the anion exchange membrane is cast and formed into a membrane shape. shall be.

(3) An anion exchange resin obtained by aminating a chloromethylated polymer is made into a solution, a fungicide and the like are added and mixed, and then formed into a membrane by casting.

In addition, for the introduction of cation exchange groups, -SO3H, -C
Examples include F2COOH, phosphoric acid group, and -COOH, but -SO3H group is particularly preferred since it has ion exchange properties over a wide range of pH and also introduces an ion exchange group. As a method for introducing a sulfonic acid group, methods for sulfonating aromatic rings such as concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, sulfuric anhydride, and sulfuric anhydride-triethyl phosphate complex can be used.

Thus, the obtained sulfonated polymer is made into a solution,
After adding and mixing a preservative, etc. and casting, it is formed into a membrane to form a cation exchange membrane.

Next, the fungicides and antibacterial agents used in the present invention include agricultural chemicals and
Fungicides, fungicides used in foods, clothing, wood products, paints, etc., and fungicides for plastics can be used without limit, but preferably they have good heat resistance, alkali resistance, and acid resistance, and are mildewproofing agents. and those having a broad antibacterial spectrum against bacteria are used. For example, pentachlorophenol, p-chloro-m-xylenol, dihydrodiethylaminopentachlorophenol, 4-chloro-2-phenylphenol, N-(trichloromethylthio)phthalimide, N-(fluorodichloromethylthio)phthalimide, N,N-dimethyl -N'-phenyl(N'-fluorodichloromethylthio)sulfamide, N-(trichloromethylthio)-4-cyclohexene-1,2-carboximide, 2-methoxycarbonylaminobenzimidazole, 2,4,5,6-tetra Chloro-iso-phthalonitrile, bis(tri-n-butyltin) oxide, tributyltin laurate, 10,10'-oxybisbisphenoxyarsine, thiabendazole, 2,3,5
, 6-tetrachloro-4-(methylsulfonyl)pyridine, 1,2-benzisothiazolin-3-one, etc., and can be conveniently selected depending on the microorganisms that propagate.

Such antifungal agents and antibacterial agents are effective against ion exchange polymers.
0.001 to 30%, preferably 0.001% to 30%, preferably 0.00% from the viewpoint of effectiveness.
The content should be 0.1% or more, and 10% or less in order to prevent a decrease in film properties, especially mechanical strength.

The ion exchange membrane containing the antifungal agent obtained in this way can be used alone or laminated with another ion exchange membrane layer (for example, one that does not contain the antifungal agent) to control the elution rate of the preservative. , it is also possible to improve membrane performance.

In addition to processing ion-exchangeable polymers into membranes,
In order to provide practical strength such as dimensional stability and handleability, it can be reinforced with a porous base material.

Such a porous substrate can be used as a reinforced composite ion exchange membrane by being embedded in an ion exchanger layer, or it can be used by combining a thin layer of ion exchanger with a porous substrate layer in order to increase the permeability of the membrane. It can be a multilayer ion exchange membrane.

The shape of the membrane is not limited to the general flat shape, but especially for diffusion dialysis, it is used in the shape of a bag, hollow fiber, hollow tube, etc.

The ion exchange membrane of the present invention thus obtained can be used as a separation membrane for electrodialysis or diffusion dialysis in known applications, but the ion exchange membrane of the present invention can be used in applications where the characteristics of the ion exchange membrane of the present invention can be exhibited. It can be used as a separation circuit for valuables and for removing harmful substances from solutions where microorganisms are likely to occur.For example, desalting milk whey, desalting soy sauce, adjusting the acidity of juice, concentrating and separating animal and plant extracts, etc. is exemplified.

In addition, the anion exchange membrane of the present invention can be used to solve the problem of performance deterioration due to the growth of mold and fungi in acid diffusion dialysis using anion exchange membranes, particularly in sulfuric acid recovery systems and iron-containing solution treatment systems. By using it, stable operation can be achieved without deterioration of permeation performance. The reason for this is thought to be to prevent the growth of microorganisms such as sulfate-reducing bacteria, sulfur bacteria, or iron bacteria that use the organic matter contained in the treatment system as a nutrient source. However, this explanation is provided for understanding the present invention, and the present invention is not limited by this explanation.

EXAMPLES Next, the present invention will be explained with reference to examples, but the present invention is not limited to these examples.

[Examples] Example 1 4,4-diphenol and dichlorodiphenylsulfone were reacted in the same manner as in the synthesis method described in JP-A No. 61-168629 to prepare a monomer of aromatic polysulfone with an intrinsic viscosity of 0.22. A precursor was synthesized, and then the precursor was reacted with dichlorodiphenyl sulfone and sodium sulfide to obtain a block copolymer A containing equimolar aromatic polysulfone and polythioether sulfone and having an intrinsic viscosity of 0.65.

Next, the copolymer A was dissolved in 1,1,2,2,tetrachloroethane, chloromethyl methyl ether and anhydrous tin chloride were added, and after reacting at 110°C for 4 hours, methyl alcohol After precipitation and washing, chloromethylated copolymer B was obtained.

NMR measurement of Copolymer B revealed that chloromethyl groups were introduced into 95% of the aromatic rings of diphenol.

The thus obtained copolymer B was dissolved in dimethylformamide, and then trimethylamine was added to obtain an anion exchange resin solution C having an ion exchange capacity of 2.0 mil equivalent/g resin. Next, 1,2-benzisothiazoline-3- was added and dissolved in the anion exchange resin in an amount of 5% to obtain an anion exchange resin solution D.

After casting the D solution, it was heated and dried at 50° C. for 16 hours to form a cast film with a thickness of 25 μm.

Next, a polypropylene nonwoven fabric with a porosity of 60% was laminated on one side of the cast membrane using the anion exchange resin liquid as an adhesive to obtain a multilayer membrane with a thickness of 100 μm.

7N sulfuric acid and 0.7N sulfuric acid and 0.7
A solution containing M iron sulfate and beef tallow (a glyceride mixture of stearic acid and areic acid) is introduced, pure water is supplied to the other chamber, and diffusion dialysis is performed at 25°C, and sulfuric acid is dialyzed on the pure water side. It was collected.

The acid permeation rate is 9 mol/m2. hr. Δc, the ratio of iron ion to acid permeation rate, was 0.2 and remained stable for 3 months, and although the dialysis tank was dismantled, there was no abnormality in the membrane.

Comparative Example 1 In Example 1, 1,2-benzisothiazoline-3
A membrane was formed in exactly the same manner except that anion exchange resin solution C to which no -one was added was used, and diffusion dialysis was performed.

Initially, the acid permeation rate was 8 mol/m2. hr. Δc, the ratio of iron ion to acid permeation rate was 0.01, but after 3 months, the permeation rate was 5.5 mol/m2. hr. Δc, the ratio of iron ion to acid permeation rate decreased to 0.02, so when the dialysis tank was disassembled, the membrane surface on the side to which water was supplied was
3 had mold on it.

After washing and removing the mold, it was put back into the dialysis tank and subjected to diffusion dialysis, which showed its initial performance, but after one month, the dialysis performance decreased again.

Example 2 Using the anion exchange resin liquid C obtained in Example 1, a film thickness of 2
After creating a μm cast membrane, anion exchange resin solution D was cast on the cast membrane and dried, and a 2 μm ion exchange membrane not containing 1,2-benzisothiazolin-3-one and 1,2-benzisothiazoline An ion exchange membrane containing -3-one was made into a multilayer ion exchange membrane with a thickness of 23 μm, then laminated with a nonwoven fabric and subjected to diffusion dialysis in the same manner as in Example 1.

The acid permeation rate is 8.5 mol/m2. hr. Δc, the ratio of iron ion to acid permeation rate, stabilized at 0.01, and after 3 months, the tank was dismantled, but no mold was observed on the membrane surface.

Example 3 2, 3, 5, 6 was added to the anion exchange resin liquid C obtained in Example 1.
Add 5% of tetrachloro-4(methylsulfonyl)pyridine to the ion exchange resin to create anion exchange resin solution E.
An anion exchange membrane was obtained by forming a membrane in the same manner as in Example 1, except that an anion exchange membrane was prepared. The acid permeation rate is 8.5 mol/m2. hr. Δ
c, the ratio of iron ion to acid permeation rates was 0.02.

Example 4 In Example 3, 2,3,5,6tetrachloro-4(methylsulfonyl)pyridine was added to the ion exchange resin at 2
An anion exchange membrane was obtained by forming a membrane in the same manner as in Example 3 except that 5% was added. The membrane turned white and opaque, and the acid permeation rate was 7.5 mol/m2. hr. Δc, the ratio of iron ion to acid permeation rates, was 0.03.

Agent Akira Uchida Agent Ryoichi Hagiwara Agent Atsuo Anzai

Claims (8)

[Claims] Claim 1: An ion exchange membrane in which an ion exchange group is introduced into the aromatic ring of a polymer substantially composed of an aromatic ring and a linking group, wherein the ion exchange polymer contains an antifungal agent or an antibacterial agent. An ion exchange membrane characterized by containing an agent. Claim 2: The fungicide is pentachlorophenol, p-
Chloro-m-xylenol, dihydrodiethylaminopentachlorophenol, 4-chloro-2-phenylphenol, N-(trichloromethylthio)phthalimide,
N-(fluorodichloromethylthio)phthalimide, N,
N-dimethyl-N-phenyl (N'-fluorodichloromethylthio)sulfamide, N-(trichloromethylthio)-4-cycloexene-1,2-dicarboximide,
2-methoxycarbonylaminobenzimidazole, 2
, 4,5,6-tetrachloro-iso-phthalonitrile,
Bis(tri-n-butyltin) oxide, tributyltin laurate, 10,10'-oxybisbiphenoxyarsine, thiabendazole, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, 1
, 2-benzisothiazolin-3-one. 3. A polymer substantially composed of an aromatic ring and a linking group has at least one repeating unit having the general formula (1) -X=Ar-Y- (wherein X and Y are mutually Same or different -O-
, -S-. Ar is a hydrocarbon group in which R1 to R6 are the same or different from each other and have 1 to 8 carbon atoms. a represents a hydrocarbon group of 0 to 3, and b+c represents a hydrocarbon group of 0 to 7. ), the aromatic ring contains
The ion exchange membrane according to claim 1, wherein the ion exchange membrane into which an anion exchange group or a cation exchange group is introduced contains an antifungal agent or an antibacterial agent in the ion exchange polymer. Claim 4: The aromatic polymer is a copolymer consisting of at least two types of repeating units, one of which has the general formula (3) consisting of a block copolymer having the general formula (1) (provided that , where X, Y, and Ar are the same as in general formula (1).Z
are -SO2-, -O-, -S-. R6 to R11 have 1 to 8 carbon atoms, which are the same or different from each other
hydrocarbon group. f-i are 0-4. l is an integer of 0 to 1, m and n are integers of 2 to 200. m/n represents 0.1 to 100. ) An ion exchange membrane consisting of an aromatic block copolymer represented by The ion exchange membrane according to claim 1 or 3, which contains a fungicidal agent. 5. In general formula (2), X and Y are -O-. In an ion exchange membrane consisting of an aromatic polysulfone/polythioethersulfone block copolymer in which Z is -S-, and an anion exchange group or a cation exchange group is introduced into the aromatic ring, the Claim (1), (3) or (4) that contains an antifungal agent or an antibacterial agent.
ion exchange membrane. 6. Claims (1), (3), and (4), characterized in that the ion exchange polymer containing the antifungal agent or the antibacterial agent is present in a layered form inside the ion exchange membrane. or (5)
ion exchange membrane. 7. The antifungal agent or antibacterial agent is mixed and dissolved with a polymer into which an anion exchange group or a cation exchange group has been introduced, and the solution is formed into a film so that the antifungal agent or antibacterial agent is contained in the ion exchange polymer. Claims (1), (3),
The method for producing an ion exchange membrane according to (4) or (5). Claim 8: In one chamber partitioned by an anion exchange membrane,
Claims (1), (3), (4), (5)
, (6) or (7), a method for recovering sulfuric acid using an ion exchange membrane.