阅读说明：本技术 一种单价阴离子交换膜的制备方法 (Preparation method of monovalent anion exchange membrane ) 是由 赵严 沈江南 沈鹏鑫 王利祥 于 2019-09-11 设计创作，主要内容包括：本发明涉及一种单价阴离子交换膜的制备方法,所述制备方法采用图1所示交流电膜组装装置,所述制备方法包括如下步骤：(1)利用交流电电场中膜表面组装技术,在不具有单多价阴离子选择性分离性能的阴离子交换膜表面构建由左旋多巴聚合物与对氨基苯磺酸钠进行酰胺反应而形成的带负电荷的单体层；(2)在步骤(1)得到的带负电荷的单体层表面构建由壳聚糖季铵盐所构成的带正电荷的HACC层；(3)根据需要继续交替进行步骤(1)和(2)的操作,得到单价阴离子交换膜,其中最内层和最外层均为由左旋多巴聚合物与对氨基苯磺酸钠进行酰胺反应而形成带负电荷的单体层。本发明制备工艺简便,操作易行,制得的膜具有高效的单价阴离子选择分离性能。(The invention relates to a preparation method of a monovalent anion exchange membrane, which adopts an alternating current membrane assembly device shown in figure 1 and comprises the following steps: (1) constructing a monomer layer with negative charges formed by carrying out amide reaction on levodopa polymer and sodium sulfanilate on the surface of an anion exchange membrane without single-polyvalent anion selective separation performance by utilizing a membrane surface assembly technology in an alternating-current electric field; (2) constructing a HACC layer with positive charge formed by chitosan quaternary ammonium salt on the surface of the monomer layer with negative charge obtained in the step (1); (3) and (3) continuing to alternately perform the operations in the steps (1) and (2) according to requirements to obtain the monovalent anion exchange membrane, wherein the innermost layer and the outermost layer are monomer layers which are negatively charged by the amide reaction of the levodopa polymer and the sodium sulfanilate. The preparation method is simple and convenient in preparation process and easy to operate, and the prepared membrane has high-efficiency monovalent anion selective separation performance.)

1. A method for preparing a monovalent anion exchange membrane, comprising: the preparation method adopts an alternating current electric film assembly device, the alternating current electric film assembly device comprises an anode plate, a cathode plate, a film A and a film B, the anode plate, the film A, the film B and the cathode plate are sequentially arranged at intervals to form an anode chamber, a feed liquid chamber and a cathode chamber, a stirring device is arranged in the feed liquid chamber, and the anode plate and the cathode plate are respectively connected with an alternating current power supply, and the preparation method comprises the following steps:

(1) constructing a monomer layer with negative charges formed by carrying out amide reaction on levodopa polymer and sodium sulfanilate on the surface of an anion exchange membrane without single-polyvalent anion selective separation performance by utilizing a membrane surface assembly technology in an alternating-current electric field; the specific construction method comprises the following steps:

the first step, an anion exchange membrane without the single-multivalent anion selective separation performance is vertically placed at the positions of a membrane A and a membrane B of an alternating current membrane assembly device, and the surface to be modified faces a feed liquid chamber;

secondly, dissolving levodopa and NaCl into a mixed solution of Tris-HCl and copper sulfate with the pH value of 6-9 and the copper sulfate concentration of 1-10mM, wherein the addition amount of the levodopa and NaCl is 0.1-0.6 g/150mL and 1-10 g/150mL based on the volume of the mixed solution of Tris-HCl and copper sulfate, so as to obtain a mixed solution; dropwise adding hydrogen peroxide into the mixed solution, wherein the volume ratio of the mixed solution to the hydrogen peroxide is 150: 0.01-1, and then quickly pouring into a material liquid chamber;

thirdly, starting a stirring device of the feeding liquid chamber, controlling the rotating speed to be 50-600 rpm, circulating 1-40 g/L of NaCl aqueous solution serving as electrode liquid to the anode chamber and the cathode chamber, and switching on an alternating current power supply to carry out alternating current electric field membrane surface assembly;

fourthly, after the assembly is finished, turning off an alternating current power supply, removing the feed liquid, pouring ionized water into the feed liquid chamber, fully washing the surface of the membrane by the deionized water, and removing the deionized water in the feed liquid chamber after the washing is finished;

dissolving sodium sulfanilate and NaCl in deionized water, adding 1-ethyl-3- (3-dimethylamine-nitrosyl) carbodiimide hydrochloride and N-hydroxysuccinimide to obtain a mixed solution, and pouring the mixed solution into a material liquid chamber; the mass ratio of the sodium sulfanilate to the NaCl to the 1-ethyl-3- (3-dimethylamine-nitrosyl) carbodiimide hydrochloride to the N-hydroxysuccinimide to the deionized water is 0.05-0.5: 1-10: 0.05-0.45: 0.03 to 0.27: 150;

sixthly, starting a stirring device of the feed liquid chamber, controlling the rotating speed to be 50-600 rpm, controlling the electrode solution to be 1-40 g/LNaCl, and switching on an alternating current power supply to carry out alternating current electric field membrane surface assembly;

seventhly, turning off the alternating current power supply after the assembly is finished, removing the feed liquid, pouring ionized water into the feed liquid chamber, and fully washing the surface of the membrane by using the deionized water, so that a monomer layer with negative charges, which is formed by the amide reaction of the levodopa polymer and the sodium sulfanilate, is obtained on the surface of the membrane;

(2) constructing a positively charged HACC layer composed of chitosan quaternary ammonium salt on the surface of the monomer layer with negative charges obtained in the step (1) by using a membrane surface assembly technology in an alternating current electric field, wherein the specific construction method is as follows:

①, vertically placing the membrane at the positions of the membrane A and the membrane B of the alternating current membrane assembly device, and enabling the surface to be modified to face a feed liquid chamber;

②, dissolving chitosan quaternary ammonium salt and NaCl in deionized water, wherein the feeding mass ratio of the chitosan quaternary ammonium salt to the NaCl to the deionized water is 0.05-0.5: 1-10: 150, and quickly pouring the mixture into a material liquid chamber;

③, starting a stirring device of the feed liquid chamber, controlling the rotating speed to be 50-600 rpm, controlling the electrode solution to be 1-40 g/LNaCl, and switching on an alternating current power supply to carry out alternating current electric field membrane surface assembly;

④, turning off an alternating current power supply after the assembly is finished, removing the feed liquid, then pouring ionized water into the feed liquid chamber, and fully washing the membrane surface by using the deionized water, thereby obtaining a HACC layer with positive charges, which is composed of chitosan quaternary ammonium salt;

(3) and (3) continuously carrying out the operation of the step (1) on the surface of the HACC layer with the positive charge obtained in the step (2) or alternately carrying out the operations of the steps (1) and (2) according to requirements to obtain the monovalent anion-exchange membrane, wherein the innermost layer and the outermost layer are monomer layers which are formed by carrying out amide reaction on the levodopa polymer and the sodium sulfanilate to form the negative charge.

2. The method of claim 1, wherein: the anion exchange membrane without the single-polyvalent anion selective separation performance is a homogeneous membrane.

3. The method of claim 1, wherein: the monovalent anion exchange membrane has a total number of layers of negatively charged monomer layers and positively charged polymer layers of 3, 5, or 7.

4. The method of claim 2, wherein: the monovalent anion exchange membrane has a total number of layers of negatively charged monomer layers and positively charged polymer layers of 3, 5, or 7.

5. The method according to any one of claims 1 to 4, wherein: the mixture of Tris-HCl and copper sulfate had a pH of 8.5, with a copper sulfate concentration of 5 mM.

6. The method according to any one of claims 1 to 4, wherein: in the second step, the concentration of the hydrogen peroxide is 30%.

7. The method according to any one of claims 1 to 4, wherein:

the parameters of the film surface assembly in the third step were set as: the alternating current frequency is 40-60 Hz, the alternating current voltage is 1-30V, and the assembling time is 10-100 min;

the parameters of the film surface assembly in the sixth step were set as: the alternating current frequency is 40-60 Hz, the alternating current voltage is 1-30V, and the assembling time is 12-48 hours;

the parameters of the film surface assembly in the ③ th step are set as that the alternating current frequency is 40-60 Hz, the alternating current voltage is 1-30V, and the assembly time is 10-100 min.

Technical Field

The invention relates to a preparation method of a monovalent anion exchange membrane.

Technical Field

In recent years, resource shortage and environmental pollution and human health have become serious challenges facing the world. On the one hand, with the shrinkage of fossil mineral reserves and the shortage of water resources, the search for extraction of abundant ions or fresh water resources from salt lake brine and seawater, such as calcination, salting out, solvent extraction, precipitation and adsorption and extraction of useful ions, has been promoted. However, this presents an unavoidable environmental pollution problem, which limits the use of these methods in the context of sustainable development. On the other hand, drinking water contains many harmful ions, such as bromide ions, which must be removed from the water. Membrane separation techniques, particularly ion exchange membranes, have an economical, environmentally friendly and highly selective ion separation process that can achieve selective separation of corresponding ions from concentrated aqueous solutions containing chemically similar ions. Much research has been devoted in recent years to many new methods and techniques concerning how to effectively perform mono-and divalent ion separations. The mechanism underlying the major monovalent anion selective separation is currently: 1) electrostatic repulsion effects; 2) pore size sieving effect and 3) nature of the adsorption membrane groups of the ions. The common method at present is to add one or several negatively charged layers on the surface of the film, but this method will increase the surface resistance or instability of the modified layer. In addition, the preparation of nanoscopically restricted membranes, while producing efficient and selective separations, the low flux of ions in desalination processes limits the industrial application of such membranes. Therefore, the experiment utilizes the action of an alternating current electric field, combines the size screening and the electrostatic repulsion principle of an ion channel, and selectively assembles multiple layers to prepare the ion exchange membrane with high-efficiency selective separation of monovalent anions.

Disclosure of Invention

The invention aims to prepare a simple and convenient anion exchange membrane with high monovalent anion selectivity.

The invention is realized by the following technical scheme:

a preparation method of a monovalent anion exchange membrane adopts an alternating current membrane assembly device, the alternating current membrane assembly device comprises an anode plate, a cathode plate, a membrane A and a membrane B, the anode plate, the membrane A, the membrane B and the cathode plate are sequentially arranged at intervals to form an anode chamber, a feed liquid chamber and a cathode chamber, an agitating device is arranged in the feed liquid chamber, and the anode plate and the cathode plate are respectively connected with an alternating current power supply, and the preparation method comprises the following steps:

(1) constructing a monomer layer (LPDA-ABS) with negative charge formed by amide reaction of a Levodopa Polymer (LPDA) and sodium sulfanilate (ABS) on the surface of an anion exchange membrane without single-polyvalent anion selective separation performance by utilizing a membrane surface assembly technology in an alternating current electric field; the specific construction method comprises the following steps:

the first step, an anion exchange membrane without the single-multivalent anion selective separation performance is vertically placed at the positions of a membrane A and a membrane B of an alternating current membrane assembly device, and the surface to be modified faces a feed liquid chamber;

dissolving levodopa (L-dopa) and NaCl into a mixture of Tris-HCl and copper sulfate, wherein the pH value of the mixture is 6-10 (preferably 8.5), and the copper sulfate concentration of the mixture is 1-10M (preferably 5M), and the addition amount of the levodopa and the NaCl is 0.1-0.6 g/150mL and 1-10 g/150mL based on the volume of the mixture of Tris-HCl and copper sulfate to obtain a mixed solution; dropwise adding 30 wt% of hydrogen peroxide into the mixed solution, wherein the volume ratio of the mixed solution to the hydrogen peroxide is 150: 0.01-1, and then quickly pouring into a material liquid chamber;

thirdly, starting a stirring device of the feeding liquid chamber, controlling the rotating speed to be 50-600 rpm, circulating 1-40 g/L of NaCl aqueous solution serving as electrode liquid to the anode chamber and the cathode chamber, and switching on an alternating current power supply to carry out alternating current electric field membrane surface assembly;

fourthly, after the assembly is finished, turning off an alternating current power supply, removing the feed liquid, pouring ionized water into the feed liquid chamber, fully washing the surface of the membrane by the deionized water, and removing the deionized water in the feed liquid chamber after the washing is finished;

fifthly, dissolving ABS and NaCl in deionized water, then adding 1-ethyl-3- (3-dimethylamine-nitrosyl) carbodiimide hydrochloride and N-hydroxysuccinimide to obtain a mixed solution, and pouring the mixed solution into a material liquid chamber; the mass ratio of the ABS to the NaCl to the 1-ethyl-3- (3-dimethylamine-nitrosyl) carbodiimide hydrochloride to the N-hydroxysuccinimide to the deionized water is 0.05-0.5: 1-10: 0.05-0.45: 0.03 to 0.27: 150;

sixthly, starting a stirring device of the feed liquid chamber, controlling the rotating speed to be 50-600 rpm, controlling the electrode solution to be 1-40 g/LNaCl, and switching on an alternating current power supply to carry out alternating current electric field membrane surface assembly;

seventhly, turning off an alternating current power supply after the assembly is finished, removing the feed liquid, then pouring ionized water into the feed liquid chamber, and fully washing the surface of the membrane by using deionized water, so as to obtain a negatively charged monomer layer (LPDA-ABS) formed by performing amide reaction on a Levodopa Polymer (LPDA) and sodium sulfanilate (ABS) on the surface of the membrane;

(2) constructing a positively charged monomer layer (HACC) layer composed of chitosan quaternary ammonium salt (HACC) on the surface of the negatively charged monomer layer obtained in the step (1) by using a membrane surface assembly technology in an alternating current electric field, wherein the specific construction method is as follows:

①, vertically placing the membrane at the positions of the membrane A and the membrane B of the alternating current membrane assembly device, and enabling the surface to be modified to face a feed liquid chamber;

②, dissolving HACC and NaCl in deionized water, wherein the feeding mass ratio of HACC, NaCl and deionized water is 0.05-0.5: 1-10: 150, and quickly pouring the mixture into a material liquid chamber;

③, starting a stirring device of the feed liquid chamber, controlling the rotating speed to be 50-600 rpm, controlling the electrode solution to be 1-40 g/LNaCl, and switching on an alternating current power supply to carry out alternating current electric field membrane surface assembly;

④, turning off an alternating current power supply after the assembly is finished, removing the feed liquid, pouring ionized water into the feed liquid chamber, and fully washing the surface of the membrane by using the deionized water to obtain a HACC layer with positive charges, which is composed of chitosan quaternary ammonium salt;

(3) and (3) continuously carrying out the operation of the step (1) on the surface of the HACC layer with the positive charge obtained in the step (2) or alternately carrying out the operations of the steps (1) and (2) according to requirements to obtain the monovalent anion exchange membrane, wherein the innermost layer and the outermost layer are monomer layers with negative charge formed by carrying out amide reaction on a Levodopa Polymer (LPDA) and sodium sulfanilate (ABS).

In the present invention, the anion exchange membrane having no selective separation performance of mono-polyvalent anions can use a commercial membrane, preferably a homogeneous membrane. The hydrogen peroxide used in the second step may be a commercially available product, such as 30% hydrogen peroxide.

In the present invention, the number of layers of the modified layer has an important influence on the selective separation performance of the prepared monovalent anion exchange membrane. Preferably, the total number of layers of negatively charged monomer layer and positively charged polymer layer in the monovalent anion exchange membrane is 3 layers (1.5 bilayers), 5 layers (2.5 bilayers) or 7 layers (i.e. 3.5 bilayers), most preferably 7 layers.

According to the alternating current electric field membrane surface assembly, a person skilled in the art can set alternating current parameters and assembly time according to the membrane area and actual needs in the alternating current electric field membrane assembly device.

As a preference, the first and second liquid crystal compositions are,

the parameters of the film surface assembly in the third step were set as: the alternating current frequency is 40-60 Hz, the alternating current voltage is 1-30V, and the assembling time is 10-100 min;

the parameters of the film surface assembly in the sixth step were set as: the alternating current frequency is 40-60 Hz, the alternating current voltage is 1-30V, and the assembly time is 12-48 hours;

the parameters of the film surface assembly in the ③ th step are set as that the alternating current frequency is 40-60 Hz, the alternating current voltage is 1-30V, and the assembly time is 10-100 min.

Preferably, each membrane in the AC membrane assembly device has an effective membrane area of 20-40cm²。

In the preparation step of the monovalent anion exchange membrane, the concentration of various solutions and the charging ratio of various substances are changed within the set range, the selective separation performance of the prepared monovalent anion exchange membrane is not greatly influenced, and a person skilled in the art can set appropriate conditions according to actual conditions.

Compared with the prior art, the invention has the beneficial effects that: based on the mechanical property of anions in an alternating current electric field, the invention utilizes an alternating current assembly technology and target ions to control the assembly of a membrane surface monovalent anion selective separation layer, and constructs a positively charged HACC layer alternate assembly structure LPDA-ABS # (HACC # LPDA-ABS) which is formed by performing an amide reaction on a Levodopa Polymer (LPDA) and sodium sulfanilate (ABS) to form a negatively charged LPDA-ABS layer and a chitosan quaternary ammonium salt (HACC)_nAn anion exchange membrane, thereby enabling the membrane to have efficient monovalent anion selective separation performance. The preparation process is simple and convenient, and the operation is easy.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic diagram of an AC electric field monovalent anion membrane surface assembly system of the present invention, wherein 1-AC power supply, 2-mechanical stirrer, 3-electrode liquid chamber, 4-feed liquid chamber, 5-anion exchange membrane, 6-ruthenium iridium electrode plate.

FIG. 2 is a chemical structural diagram of a negatively charged LPDA-ABS layer prepared according to the present invention.

FIG. 3 is a chemical structural diagram of a positively charged HACC layer prepared according to the present invention.

FIG. 4 is a schematic diagram of the ion exchange membrane polarization current-voltage curve testing equipment and process of the invention, wherein 1-anion exchange membrane, 2-cation exchange membrane, 3-voltmeter, 4-silver electrode, and 5-ruthenium iridium electrode plate.

FIG. 5 is a schematic diagram of the selectivity test equipment and process of monovalent anion of anion exchange membrane of the present invention, wherein 1-anion exchange membrane, 2-cation exchange membrane, 3-cathode ruthenium iridium electrode plate, 4-anode ruthenium iridium electrode plate, 5-electrode chamber, 6-desalination chamber, 7-concentration chamber.

FIG. 6 is a schematic diagram of the current-voltage curve of commercial membrane polarization and the selective separation effect of single and multiple anion separations.

FIG. 7 shows a sample containing LPDA-ABS # (HACC # LPDA-ABS) prepared according to the present invention₀The scanning electron microscope, the current-voltage curve effect and the single and multi-valence anion separation selective separation effect of the layer anion exchange membrane are shown schematically.

FIG. 8 shows a sample containing LPDA-ABS # (HACC # LPDA-ABS) prepared according to the present invention₁The scanning electron microscope, the current-voltage curve effect and the single and multi-valence anion separation selective separation effect of the layer anion exchange membrane are shown schematically.

FIG. 9 shows a sample containing LPDA-ABS # (HACC # LPDA-ABS) prepared according to the present invention₃The scanning electron microscope, the current-voltage curve effect and the single and multi-valence anion separation selective separation effect of the layer anion exchange membrane are shown schematically.

FIG. 10 shows a sample containing LPDA-ABS # (HACC # LPDA-ABS) prepared according to the present invention₅The scanning electron microscope, the current-voltage curve effect and the single and multi-valence anion separation selective separation effect of the layer anion exchange membrane are shown schematically.

Detailed Description

The invention is described in further detail below with reference to the following figures and embodiments: