A kind of anti-pollution ion exchange membrane and its preparation method and application

Abstract

The invention discloses an anti-pollution ion exchange membrane and a preparation method and application thereof, belonging to the technical field of water treatment membranes. The preparation method comprises the following steps: (1) immersing an ion exchange membrane in a dopamine solution, and obtaining an ion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction; (2) placing the ion exchange membrane with the polydopamine intermediate layer deposited thereon in a monomer solution for a grafting reaction, and obtaining the anti-pollution ion exchange membrane; when the ion exchange membrane is an anion exchange membrane, the monomer solution is a negatively charged monomer solution, and when the ion exchange membrane is a cation exchange membrane, the monomer solution is a positively charged monomer solution; the preparation method has a simple process and low equipment requirements, and the obtained anti-pollution ion exchange membrane can reduce the pollution of the ion exchange membrane itself by charged pollutants while realizing the separation of inorganic salts and organic matter, and is particularly suitable for application in an electrodialysis process.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment membranes, and in particular to an anti-pollution ion exchange membrane and a preparation method and application thereof. Background Art

[0002] The resource utilization and near-zero discharge of industrial saline organic wastewater has become an inevitable trend in the current development of industrial wastewater treatment. In recent years, a three-stage combined process route of pretreatment + membrane concentration and reduction + evaporation and crystallization has been basically formed for the treatment of industrial saline organic wastewater. Among them, membrane concentration and reduction, that is, salt concentration, is the key process to achieve wastewater reduction. Electrodialysis technology has attracted much attention due to its high salt concentration ratio and low energy consumption in membrane concentration and reduction.

[0003] Electrodialysis utilizes the selective permeability of ion exchange membranes to anions and cations, and causes the cations and anions to migrate in a directional manner under the action of a DC electric field, thereby achieving separation, concentration, and dilution of electrolyte ions. The ion exchange membrane is the core component of the electrodialysis device, and is composed of a polymer skeleton, a fixed group, and movable ions on the fixed group. During the operation of the electrodialysis device, certain components in the raw liquid will be deposited on the membrane surface through physical and chemical reactions with the ion exchange membrane, causing the ion exchange membrane resistance to increase and the separation selectivity to decrease. Usually, ion exchange membrane pollution mainly includes inorganic pollution, organic pollution, and biological pollution.

[0004] In the prior art, surface modification is usually used to improve the anti-pollution performance of ion exchange membranes.

[0005] A Chinese patent document with publication number CN111135876A discloses a method for preparing a pollution-resistant aliphatic PVC anion exchange membrane. The method uses a one-step immersion method to complete the quaternization and cross-linking of the PVC membrane. The anion exchange membrane obtained after immersion has a hydrophilic membrane surface and an aliphatic membrane matrix. The hydrophilic membrane surface avoids contact between organic pollutants and the membrane surface, and the aliphatic membrane body can reduce the adsorption of organic pollutants because it does not contain aromatic rings.

[0006] A Chinese patent document with publication number CN112759041A discloses a method for preparing an anti-fouling ion exchange membrane. The invention uses the universal adhesion of dopamine and polyethylene glycol with hydrophilic anti-fouling properties to construct an anti-fouling coating on the surface of the ion exchange membrane by immersion. A Chinese patent document with publication number CN114192000A discloses an ion exchange membrane, which includes a substrate and a polymer membrane layer embedded with a transition metal catalyst. During use, the electric field can induce the catalyst loaded on the ion exchange membrane to electrolyze water, produce -OH and other strong oxidants, and decompose the refractory organic matter in the wastewater into biodegradable small molecules or carbon dioxide and water, effectively improving the anti-fouling ability of the membrane. Summary of the invention

[0007] The present invention provides a method for preparing an anti-pollution ion exchange membrane, which has low equipment requirements and simple process. The prepared anti-pollution ion exchange membrane can reduce the pollution of the ion exchange membrane by positively charged pollutants or negatively charged pollutants while realizing the separation of inorganic salts and organic matter.

[0008] The following two technical solutions are specifically adopted:

[0009] Method 1: A method for preparing an anti-pollution ion exchange membrane, comprising the following steps:

[0010] (1) immersing the anion exchange membrane in a dopamine solution to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0011] (2) placing the anion exchange membrane deposited with the polydopamine intermediate layer in a negatively charged monomer solution for grafting reaction to obtain an anti-fouling anion exchange membrane;

[0012] The negatively charged monomer is at least one of 2-acrylamide-2-methylpropanesulfonic acid, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-acrylamide dodecanesulfonic acid, methacrylic acid, sodium methacrylate, acrylic acid and sodium acrylate.

[0013] The present invention constructs a polydopamine intermediate layer containing -NH2 on the surface of the anion exchange membrane, and the amino groups on the membrane surface undergo a one-to-one Michael addition reaction with the double bonds in the negatively charged monomers, thereby constructing a single-molecule negatively charged organic pollution resistance layer on the polydopamine intermediate layer. The negatively charged monomer monolayer can increase the anti-pollution performance of the ion exchange membrane without affecting the membrane surface morphology and roughness.

[0014] The components of the anion exchange membrane include at least two of polyethylene, polyvinyl chloride, polyvinyl alcohol, polypropylene, polytetrafluoroethylene, styrene, divinylbenzene, polystyrene and chloromethyl ether.

[0015] The preparation method of the dopamine solution is: prepare 10mmol / L Tris-HCl buffer, adjust the pH value to 8.5-8.8, add dopamine to the Tris-HCl buffer to obtain the dopamine solution; in the dopamine solution, the concentration of dopamine is 0.5-2mg / mL.

[0016] In step (1), the anion exchange membrane is immersed in the dopamine solution for 12-48 hours.

[0017] In step (2), the mass percentage of the negatively charged monomer in the negatively charged monomer solution is 0.1-1wt%; and the grafting reaction time is 10-240min. The above-mentioned negatively charged monomer concentration range and grafting time can ensure that the negatively charged monomer and the amino group on the polydopamine intermediate layer form a uniform and continuous single-molecule negatively charged organic pollution-resistant layer. If the mass concentration of the negatively charged monomer is too low or the grafting time is too short, it will result in that a sufficient number of negatively charged monomers cannot be grafted onto the membrane surface.

[0018] Method 2: A method for preparing an anti-pollution ion exchange membrane, comprising the following steps:

[0019] (1) immersing the cation exchange membrane in a dopamine solution to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0020] (2) placing a cation exchange membrane deposited with a polydopamine intermediate layer in a positively charged monomer solution for grafting reaction to obtain an anti-fouling cation exchange membrane;

[0021] The positively charged monomer is at least one of trimethylallylammonium chloride, trimethylallylammonium bromide, 2-methacryloyloxyethyltrimethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium bromide, dimethyldiallylammonium chloride, dimethyldiallylammonium bromide, acryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium bromide, (3-acrylamidopropyl)trimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium bromide, allyltributylphosphine chloride, allyltriphenylphosphine chloride and allyltriphenylphosphine bromide.

[0022] The present invention constructs a polydopamine intermediate layer containing -NH2 on the surface of the cation exchange membrane, and the amino groups on the membrane surface undergo a one-to-one Michael addition reaction with the double bonds in the positively charged monomers, thereby constructing a monomolecular positively charged anti-organic pollution layer on the polydopamine intermediate layer. The monomolecular layer of the positively charged monomer can increase the anti-pollution performance of the ion exchange membrane without affecting the surface morphology and roughness of the membrane.

[0023] The components of the cation exchange membrane include at least two of polyethylene, polyvinyl chloride, polyvinyl alcohol, polypropylene, polytetrafluoroethylene, styrene, divinylbenzene and polystyrene.

[0024] The preparation method of the dopamine solution is: prepare 10mmol / L Tris-HCl buffer, adjust the pH value to 8.5-8.8, add dopamine to the Tris-HCl buffer to obtain the dopamine solution; in the dopamine solution, the concentration of dopamine is 0.5-2mg / mL.

[0025] In step (1), the cation exchange membrane is immersed in the dopamine solution for 12-48 hours.

[0026] In step (2), the mass percentage of the positively charged monomer in the positively charged monomer solution is 0.1-1wt%; and the grafting reaction time is 10-240min. The above positively charged monomer concentration range and grafting time can ensure that the positively charged monomer and the amino group on the polydopamine intermediate layer form a uniform and continuous single-molecule positively charged anti-organic pollution layer. If the mass concentration of the positively charged monomer is too low or the grafting time is too short, it will result in the failure to graft a sufficient number of positively charged monomers on the membrane surface.

[0027] The present invention also provides an anti-pollution ion exchange membrane prepared by the preparation method of the anti-pollution ion exchange membrane. The anti-pollution ion exchange membrane has a three-layer structure. A polydopamine middle layer is adhered to the ion exchange membrane body, and an anti-pollution charged small molecule monomer layer is grafted onto the polydopamine middle layer.

[0028] The surface physical and chemical properties of the anti-pollution ion exchange membrane are the main factors for its anti-pollution performance. The anti-pollution ion exchange membrane prepared by the present invention can achieve the anti-pollution effect of the membrane by relying on its hydrophilicity and the electrostatic interaction between the charged monomers grafted on the membrane surface and the charged pollutants.

[0029] The invention also provides application of the anti-pollution ion exchange membrane in an electrodialysis process.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The method of the present invention has low equipment requirements, and the preparation method of the anti-pollution ion exchange membrane is simple, which is convenient for improvement on the basis of the traditional ion exchange membrane preparation process to achieve scaled-up preparation and production. The anti-pollution ion exchange membrane obtained has broad application prospects in the field of water treatment.

[0032] (2) The anti-pollution ion exchange membrane prepared by the method of the present invention can achieve the separation of inorganic salts and organic matter while reducing the pollution of positively charged pollutants on the cation exchange membrane and the pollution of negatively charged pollutants on the anion exchange membrane, thereby increasing the service life of the membrane. In addition, polydopamine is connected to the charged monomer by a covalent bond, and the modified layer has good bonding strength with the original membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a graph showing the anti-fouling performance of the original membrane of Example 1, and the anti-fouling anion exchange membranes prepared in Examples 1-2, Example 4, and Example 6.

[0034] Figure 2 This is a graph showing the anti-fouling performance of the original membrane of Example 9, and the anti-fouling cation exchange membranes prepared in Examples 9-11 and Example 14.

[0035] Figure 3 1 and 2 are SEM images of the original membrane of Example 1 and the anti-fouling anion exchange membranes prepared in Examples 1-3, wherein A is the original membrane of Example 1, and BD are the anti-fouling anion exchange membranes of Examples 1-3, respectively.

[0036] Figure 4 SEM images of the original membrane of Example 8, and the anti-fouling cation exchange membranes prepared in Example 8 and Examples 10-11, wherein A is the original membrane of Example 8, B is the anti-fouling cation exchange membrane of Example 8, and C and D are the anti-fouling cation exchange membranes of Examples 10 and 11, respectively. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0038] In the embodiment of the present invention, the anion exchange membrane and the cation exchange membrane are both purchased from Hangzhou Lvhe Environmental Protection Technology Co., Ltd.

[0039] Example 1

[0040] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 0.5 mg / mL. An anion exchange membrane prepared by mixing polyvinyl chloride, styrene, divinylbenzene and chloromethyl ether was immersed in the dopamine solution for 12 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a self-polymerization reaction of dopamine.

[0041] A 0.1 wt % 2-acrylamide-2-methylpropanesulfonic acid negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 10 minutes to obtain an anti-pollution anion exchange membrane.

[0042] Example 2

[0043] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5, and dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL; an anion exchange membrane prepared by mixing polyethylene, styrene, divinylbenzene, and chloromethyl ether was immersed in the dopamine solution for 24 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0044] A 1 wt % sodium 3-allyloxy-2-hydroxy-1-propanesulfonate negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 120 minutes to obtain an anti-pollution anion exchange membrane.

[0045] Example 3

[0046] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 1 mg / mL. An anion exchange membrane prepared by mixing polyvinyl alcohol, styrene, divinylbenzene and chloromethyl ether was immersed in the dopamine solution for 24 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0047] A 0.5 wt % 2-acrylamidododecanesulfonic acid negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 180 min to obtain an anti-pollution anion exchange membrane.

[0048] Example 4

[0049] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.8, and dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL; an anion exchange membrane prepared by mixing polypropylene, styrene, divinylbenzene, and chloromethyl ether was immersed in the dopamine solution for 48 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0050] A 1 wt % methacrylic acid negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 240 minutes to obtain an anti-pollution anion exchange membrane.

[0051] Example 5

[0052] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL. An anion exchange membrane prepared by mixing polytetrafluoroethylene, styrene, divinylbenzene, and chloromethyl ether was immersed in the dopamine solution for 48 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0053] A 0.5 wt % sodium methacrylate negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 120 minutes to obtain an anti-pollution anion exchange membrane.

[0054] Example 6

[0055] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5, and dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL; an anion exchange membrane prepared by mixing polystyrene and chloromethyl ether was immersed in the dopamine solution for 24 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0056] A 1 wt % acrylic acid negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 120 minutes to obtain an anti-pollution anion exchange membrane.

[0057] Example 7

[0058] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.8, and dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL; an anion exchange membrane prepared by mixing polyethylene, styrene, divinylbenzene, and chloromethyl ether was immersed in the dopamine solution for 24 hours to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0059] A 1 wt % sodium acrylate negatively charged monomer solution was prepared, and the anion exchange membrane deposited with the polydopamine intermediate layer was immersed in the negatively charged monomer solution for grafting reaction for 120 minutes to obtain an anti-pollution anion exchange membrane.

[0060] Example 8

[0061] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 0.5 mg / mL. A cation exchange membrane prepared by mixing polyvinyl chloride, styrene and divinylbenzene was immersed in the dopamine solution for 12 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0062] A positively charged monomer solution was prepared, wherein the concentration of the positively charged monomers trimethylallyl ammonium chloride and trimethylallyl ammonium bromide was 0.1 wt %. The cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 10 minutes to obtain an anti-pollution cation exchange membrane.

[0063] Example 9

[0064] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL. A cation exchange membrane prepared by mixing polyethylene, styrene and divinylbenzene was immersed in the dopamine solution for 24 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0065] A positively charged monomer solution was prepared, wherein the concentration of the positively charged monomers 2-methacryloyloxyethyltrimethylammonium chloride and 2-methacryloyloxyethyltrimethylammonium bromide were both 1 wt %, and the cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 120 min to obtain an anti-pollution cation exchange membrane.

[0066] Example 10

[0067] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 1 mg / mL. A cation exchange membrane prepared by mixing polyvinyl alcohol, styrene and divinylbenzene was immersed in the dopamine solution for 24 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0068] A positively charged monomer solution was prepared, wherein the concentration of the positively charged monomers dimethyldiallylammonium chloride and dimethyldiallylammonium bromide were both 0.5 wt %. The cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 180 min to obtain an anti-pollution cation exchange membrane.

[0069] Embodiment 11

[0070] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL. A cation exchange membrane prepared by mixing polypropylene, styrene and divinylbenzene was immersed in the dopamine solution for 48 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0071] A positively charged monomer solution was prepared, wherein the concentration of the positively charged monomers acryloyloxyethyltrimethylammonium chloride and acryloyloxyethyltrimethylammonium bromide were both 1 wt %, and the cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 240 min to obtain an anti-pollution cation exchange membrane.

[0072] Example 12

[0073] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5. Dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL. A cation exchange membrane prepared by mixing polytetrafluoroethylene, styrene and divinylbenzene was immersed in the dopamine solution for 48 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction.

[0074] A positively charged monomer solution was prepared, wherein the concentration of the positively charged monomers (3-acrylamidopropyl)trimethylammonium chloride and (3-acrylamidopropyl)trimethylammonium bromide were both 0.5 wt %. The cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 120 min to obtain an anti-pollution cation exchange membrane.

[0075] Example 13

[0076] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.5, and dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL; a cation exchange membrane prepared by mixing polyvinyl chloride and polystyrene was immersed in the dopamine solution for 24 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0077] A positively charged monomer solution was prepared, wherein the concentration of the positively charged monomers allyl tributylphosphine chloride and allyl triphenylphosphine chloride were both 1 wt %, and the cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 120 min to obtain an anti-pollution cation exchange membrane.

[0078] Embodiment 14

[0079] A 10 mmol / L Tris-HCl buffer solution was prepared, and the pH value was adjusted to 8.8, and dopamine was added to the Tris-HCl buffer solution to obtain a dopamine solution with a concentration of 2 mg / mL; a cation exchange membrane prepared by mixing polyethylene, styrene, and divinylbenzene was immersed in the dopamine solution for 24 hours to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction;

[0080] A 1 wt % allyl triphenylphosphonium bromide positively charged monomer solution was prepared, and the cation exchange membrane deposited with the polydopamine intermediate layer was immersed in the positively charged monomer solution for grafting reaction for 120 minutes to obtain an anti-pollution cation exchange membrane.

[0081] Sample analysis

[0082] The hydrophilic performance test results of the anti-fouling ion exchange membrane prepared by the method of the present invention are shown in Table 1 and Table 2: wherein the original membrane refers to a blank membrane that has not been treated with dopamine and charged monomers.

[0083] Table 1 Test results of hydrophilicity of anti-pollution ion exchange membranes prepared in Examples 1-7

[0084]

[0085] Table 2 Test results of hydrophilicity of anti-pollution ion exchange membranes prepared in Examples 8-14

[0086]

[0087] The anti-pollution effects of the original membrane of Example 1, the anti-pollution anion exchange membranes prepared in Examples 1-2, Examples 4 and Example 6, and the anti-pollution effects of the original membrane of Example 9, the anti-pollution cation exchange membranes prepared in Examples 9-11 and Example 14 were tested, and the results were as follows: Figure 1 and Figure 2 shown.

[0088] The test device consists of a desalination chamber, a concentration chamber, a polarization chamber, a peristaltic pump, a liquid pool, electrodes, a temperature control system, and other parts. During the test, first, 120 mL of 0.2 mol / L sodium chloride solution was added to the concentration chamber, and 120 mL of a mixed solution of 0.2 mol / L sodium chloride and 0.6 g / L sodium dodecylbenzene sulfonate was added to the desalination chamber (anion exchange membrane), or 120 mL of a mixed solution of 0.2 mol / L sodium chloride and 0.2 g / L hexadecyltrimethylammonium bromide was added to the desalination chamber (cation exchange membrane). The temperature control system was turned on to maintain the system temperature at 25 °C, and the effective area of ​​7.067 cm 2 The ion exchange membranes were placed in the membrane pool in a certain arrangement, and the flow rate of the feed liquid was controlled to be 300 mL / min and the current density to be 7 mA / cm 2 .

[0089] The membrane resistance of the ion exchange membrane is R = ΔU / I, where ΔU is the voltage across the ion exchange membrane and I is the current density × membrane area.

[0090] pass Figure 1 and Figure 2 It can be seen that the anti-pollution ion exchange membrane prepared by the method of the present invention has excellent performance. In the pollution experiment, the increase in voltage on both sides of the membrane is smaller, and the rising trend of voltage is slower, which reduces the pollution of charged pollutants to the ion exchange membrane itself, indicating that the prepared anti-pollution ion exchange membrane has better anti-pollution effect.

[0091] The SEM images of the original membrane of Example 1 and the anti-fouling anion exchange membranes prepared in Examples 1-3 are as follows: Figure 3 As shown, A is the original membrane of Example 1, and BD are the anti-fouling anion exchange membranes of Examples 1-3 respectively. The SEM images of the original membrane of Example 8 and the anti-fouling cation exchange membranes prepared in Examples 8 and 10-11 are shown in Figure 4 As shown, A is the original membrane of Example 8, B is the anti-fouling cation exchange membrane of Example 8, C and D are the anti-fouling cation exchange membranes of Examples 10 and 11, respectively. The above SEM results prove that the membrane modification of the method of the present invention is successful.

[0092] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an anti-pollution ion exchange membrane for electrodialysis, characterized in that: The following steps are involved: (1) immersing the anion exchange membrane in a dopamine solution to obtain an anion exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction; (2) placing the anion exchange membrane deposited with the polydopamine intermediate layer in a negatively charged monomer solution for grafting reaction to obtain an anti-pollution ion exchange membrane; The negatively charged monomer is at least one of 2-acrylamide-2-methylpropanesulfonic acid, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-acrylamide dodecanesulfonic acid, methacrylic acid, sodium methacrylate, acrylic acid and sodium acrylate; In the dopamine solution, the concentration of dopamine is 0.5-2 mg / mL; In step (1), the immersion time is 12-48 hours; In the negatively charged monomer solution, the mass percentage of the negatively charged monomer is 0.1-1wt%; the grafting reaction time is 10-240min; The anion exchange membrane is made of at least two of polyethylene, polyvinyl chloride, polyvinyl alcohol, polypropylene, polytetrafluoroethylene, styrene, divinylbenzene, polystyrene and chloromethyl ether.

2. A method for preparing an anti-pollution ion exchange membrane for electrodialysis, characterized in that: The following steps are involved: (1) immersing the cation exchange membrane in a dopamine solution to obtain a cation exchange membrane with a polydopamine intermediate layer deposited thereon through a dopamine self-polymerization reaction; (2) placing a cation exchange membrane deposited with a polydopamine intermediate layer in a positively charged monomer solution for grafting reaction to obtain an anti-fouling ion exchange membrane; The positively charged monomer is at least one of trimethylallylammonium chloride, trimethylallylammonium bromide, 2-methacryloyloxyethyl trimethylammonium chloride, 2-methacryloyloxyethyl trimethylammonium bromide, dimethyldiallylammonium chloride, dimethyldiallylammonium bromide, acryloyloxyethyl trimethylammonium chloride, acryloyloxyethyl trimethylammonium bromide, (3-acrylamidopropyl)trimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium bromide, allyltributylphosphine chloride, allyltriphenylphosphine chloride and allyltriphenylphosphine bromide; In the dopamine solution, the concentration of dopamine is 0.5-2 mg / mL; In step (1), the immersion time is 12-48 hours; In the positively charged monomer solution, the mass percentage of the positively charged monomer is 0.1-1wt%; the grafting reaction time is 10-240min; The cation exchange membrane is made of at least two of polyethylene, polyvinyl chloride, polyvinyl alcohol, polypropylene, polytetrafluoroethylene, styrene, divinylbenzene and polystyrene.

3. The method for preparing an anti-pollution ion exchange membrane for electrodialysis according to claim 1 or 2, characterized in that: The preparation method of the dopamine solution is: prepare a Tris-HCl buffer, adjust the pH value to 8.5-8.8, and add dopamine into the Tris-HCl buffer to obtain the dopamine solution.

4. The anti-fouling ion exchange membrane obtained according to the method for preparing an anti-fouling ion exchange membrane for electrodialysis according to claim 1 or 2.

5. Use of the anti-fouling ion exchange membrane according to claim 4 in an electrodialysis process.

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