Preparation method of plant-based ion exchange membrane and application of plant-based ion exchange membrane in rare earth element recovery

Abstract

The invention discloses a preparation method of a plant-based ion exchange membrane and application of the plant-based ion exchange membrane in rare earth element recovery, and relates to the technical field of ion exchange membranes. When the plant-based ion exchange membrane is prepared, shell powder sequentially reacts with N-[3-(trimethoxysilyl) propyl] ethylenediamine, dicyandiamide and 9-allyl-9H-carbazole, and functionalized shell powder is prepared; the preparation method comprises the following steps: reacting microcrystalline cellulose with thionyl chloride, carbazole and sulfamic acid in sequence to prepare functionalized microcrystalline cellulose; the preparation method comprises the following steps: reacting 2, 7-bis (trifluoromethyl)-9H-carbazole with p-bromobenzaldehyde to prepare a functional monomer; and reacting the functionalized microcrystalline cellulose, N-(4-benzaldehyde)-carbazole, the functionalized shell powder, N, N-dimethylformamide and a functional monomer, and molding to prepare the plant-based ion exchange membrane. The plant-based ion exchange membrane prepared by the invention has good antibacterial, corrosion-resistant and thermal stability capabilities.

Description

Technical Field

[0001] The present invention relates to the technical field of ion exchange membranes, and specifically to a preparation method of a plant-based ion exchange membrane and its application in rare earth element recovery. Background Art

[0002] With the continuous expansion of the application fields of rare earths and the continuous growth of demand, people have gradually realized that rare earths, as non-renewable resources, are increasingly difficult to supply in large quantities for a long time. Therefore, people achieve effective reuse of resources through recycling, effectively saving natural resources. Ion exchange membranes are a commonly used means for rare earth element recovery. Ion exchange membranes are composed of a polymer matrix, in which ionic groups are fixed on the polymer backbone. According to the charge of the ionic groups, ion exchange membranes are divided into anion exchange membranes and cation exchange membranes. Among them, the commonly used ion exchange membranes for rare earth element recovery are cation exchange membranes. In diffusion dialysis and electrodialysis technologies, cation exchange membranes can selectively permeate cations, block anions and other impurities, thereby realizing the purification and recovery of rare earth elements.

[0003] The most widely used extraction process for ionic rare earth ores is the in-situ leaching method. Although the leaching process is simple and the rare earth leaching rate is relatively high, there is a problem of high acidity of the leaching solution. Being in such an environment for a long time may cause irreversible damage to the membrane. Moreover, Escherichia coli, Staphylococcus aureus, etc. in the environment can attach to the membrane surface and then secrete extracellular polymers to form a dense biofilm. This biofilm will cover the membrane surface and block the pores of the membrane, hindering the permeation of ions, and the biofilm may cause irreversible pollution on the membrane surface, and the performance can only be restored by replacing the membrane or performing deep cleaning. Therefore, this application introduces a plant-based ion exchange membrane with antibacterial and corrosion resistance capabilities. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a plant-based ion exchange membrane and a lithium-ion battery to solve the problems existing in the prior art.

[0005] A preparation method of a plant-based ion exchange membrane, wherein the preparation method of the plant-based ion exchange membrane is obtained by reacting functionalized microcrystalline cellulose, N-(4-benzaldehydyl)-carbazole, functionalized shell powder, N,N-dimethylformamide and a functional monomer, and then making a mold.

[0006] The functionalized microcrystalline cellulose is obtained by sequentially reacting microcrystalline cellulose with thionyl chloride, carbazole and sulfamic acid.

[0007] The functionalized shell powder is obtained by sequentially reacting shell powder with N-[3-(trimethoxysilyl)propyl]ethylenediamine, dicyandiamide and 9-allyl-9H-carbazole.

[0008] The functional monomer is prepared by reacting 2,7-bis(trifluoromethyl)-9H-carbazole with p-bromobenzaldehyde.

[0009] As an optimization, the preparation method of the plant-based ion exchange membrane mainly includes the following preparation steps:

[0010] (1) Mix modified shell powder, 9-allyl-9H-carbazole, and acetone at a mass ratio of 1:0.08 - 0.12:14 - 16, stir at 45 - 55°C and 200 - 300 r / min for 38 - 42 h, filter, wash with acetone 3 - 5 times, and vacuum dry at -10 - 0°C for 22 - 26 h to obtain functionalized shell powder.

[0011] (2) Mix pre-modified microcrystalline cellulose, dimethyl sulfoxide, and carbazole at a mass ratio of 1:25 - 35:0.18 - 0.22, stir at 85 - 95°C and 200 - 300 r / min for 11 - 13 h, pour into deionized water, let stand for 20 - 30 min, filter, wash with acetone 3 - 5 times, and vacuum dry at 45 - 55°C for 11 - 13 h to obtain modified microcrystalline cellulose.

[0012] (3) Mix 2,7-bis(trifluoromethyl)-9H-carbazole, p-bromobenzaldehyde, and N,N-dimethylformamide at a molar ratio of 1:1:14 - 16, stir at 200 - 300 r / min, 55 - 65°C under nitrogen protection for 25 - 35 min, cool to room temperature, and vacuum dry at -10 - 0°C for 22 - 26 h to obtain the functional monomer.

[0013] (4) Uniformly coat the casting solution on a clean and dry glass plate with a thickness of 450 - 550 μm, dry at 75 - 85°C for 5 - 7 h, scrape off, place in a zeolite mixture, let stand for 20 - 30 min, take out, wash with deionized water 5 - 7 times, and vacuum dry at -10 - 0°C for 22 - 26 h to obtain the ion exchange membrane.

[0014] As an optimization, the modified shell powder in step (1) is prepared by mixing pre-modified shell powder and 0.8 mol / L dilute hydrochloric acid at a mass ratio of 1:4 - 6, microwave at 200 - 300 r / min, 45 - 55°C, and 400 W microwave power for 8 - 12 min to obtain a pre-modified shell powder mixture. Mix dicyandiamide and deionized water at a mass ratio of 1:4 - 6 to obtain a dicyandiamide solution. Mix the pre-modified shell powder mixture and the dicyandiamide solution at a mass ratio of 1:0.18 - 0.22, adjust the pH to 1 with 0.8 mol / L dilute hydrochloric acid, microwave at 200 - 300 r / min, 95 - 105°C, and 400 W microwave power for 13 - 17 min, pour into ethanol, let stand for 18 - 22 min, filter, wash with ethanol 3 - 5 times, and vacuum dry at -10 - 0°C for 22 - 26 h.

[0015] As an optimization, the reaction mechanism is as follows:

[0016]

[0017] As an optimization, the pre-modified shell powder is prepared by mixing 200-mesh shell powder, N-[3-(trimethoxysilyl)propyl]ethylenediamine and isopropanol in a mass ratio of 1:0.14-0.16:14-16, adjusting the pH to 3.8-4.2 with 0.1 mol / L acetic acid aqueous solution, stirring at 85-95 °C and 200-300 r / min for 5-7 h, filtering, washing with deionized water for 3-5 times, and drying at 90-100 °C for 2-4 h.

[0018] As an optimization, the pre-modified microcrystalline cellulose in step (2) is prepared by mixing microcrystalline cellulose and N,N-dimethylformamide in a mass ratio of 1:20-30, stirring at 250-350 r / min and 85-95 °C for 8-12 min, adding thionyl chloride which is 0.17-0.18 times the volume of N,N-dimethylformamide uniformly within 8-12 min, continuing to stir for 2-3 h, pouring into deionized water, stirring at 300-400 r / min for 10-20 min, filtering, washing with deionized water for 6-8 times, and vacuum drying at 45-55 °C for 11-13 h.

[0019] As an optimization, the casting solution in step (4) is prepared by mixing functionalized microcrystalline cellulose, N-(4-benzaldehydyl)-carbazole, functionalized shell powder, N,N-dimethylformamide, functional monomer and ferric chloride in a mass ratio of 10-14:2-3:3-5:140-160:1:1, stirring at 75-85 °C and 200-300 r / min for 10-14 min, and centrifuging at 8-12 °C and 7000-9000 r / min for 8-12 min.

[0020] As an optimization, the functionalized microcrystalline cellulose is prepared by mixing sulfamic acid, N,N-dimethylformamide and modified microcrystalline cellulose in a mass ratio of 1:4-6:0.18-0.22, stirring at 75-85 °C and 200-300 r / min for 1-2 h, pouring into deionized water, standing for 20-30 min, filtering, washing with acetone for 3-5 times, and vacuum drying at 45-55 °C for 11-13 h.

[0021] As an optimization, the zeolite mixture in step (4) is prepared by mixing zeolite and deionized water evenly in a mass ratio of 1:5-7.

[0022] Application of a plant-based ion exchange membrane prepared by the preparation method of the plant-based ion exchange membrane according to any one of claims 1-8 in rare earth element recovery.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0024] When preparing the plant-based ion exchange membrane of the present invention, shell powder is successively reacted with N-[3-(trimethoxysilyl)propyl]ethylenediamine, dicyandiamide, and 9-allyl-9H-carbazole to obtain functionalized shell powder; microcrystalline cellulose is successively reacted with thionyl chloride, carbazole, and sulfamic acid to obtain functionalized microcrystalline cellulose; 2,7-bis(trifluoromethyl)-9H-carbazole is reacted with p-bromobenzaldehyde to obtain a functional monomer; the functionalized microcrystalline cellulose, N-(4-benzaldehydyl)carbazole, functionalized shell powder, N,N-dimethylformamide, and functional monomer are reacted and molded to obtain the plant-based ion exchange membrane.

[0025] First, shell powder is successively reacted with N-[3-(trimethoxysilyl)propyl]ethylenediamine, dicyandiamide, and 9-allyl-9H-carbazole to obtain functionalized shell powder; a biguanide structure is formed on the surface of the shell powder through the reaction of dicyandiamide with amino groups. Biguanide can specifically interact with the ribosomal RNA part of bacteria, blocking the normal chain reaction required for protein synthesis. It can also interact with the circular structure of bacterial DNA, blocking its replication and repair processes, resulting in the breakage and damage of bacterial DNA strands, affecting the replication and reproduction of bacteria, and enhancing the antibacterial effect of the material.

[0026] Second, microcrystalline cellulose is successively reacted with thionyl chloride, carbazole, and sulfamic acid to obtain functionalized microcrystalline cellulose; 2,7-bis(trifluoromethyl)-9H-carbazole is reacted with p-bromobenzaldehyde to obtain a functional monomer; the functionalized microcrystalline cellulose, N-(4-benzaldehydyl)carbazole, functionalized shell powder, N,N-dimethylformamide, and functional monomer are reacted and molded to obtain the plant-based ion exchange membrane; carbazole is introduced onto the surface of cellulose through the reaction of cellulose with thionyl chloride and carbazole, and then reacts with the carbazole on the surface of the functionalized shell powder, N-(4-benzaldehydyl)carbazole, and functional monomer to form polycarbazole. The functional monomer in the polycarbazole is rich in trifluoromethyl groups. The carbon-fluorine bond in the trifluoromethyl group is a very strong chemical bond with high bond energy and short bond length, making the prepared membrane have high chemical stability and being difficult to be destroyed in chemical reactions. Moreover, the high electronegativity of the trifluoromethyl group enables it to attract the surrounding electrons, making the carbon atom carry a certain positive charge, and the fluorine atom radius in the trifluoromethyl group is relatively small, which makes its influence on the molecular volume relatively small when substituting other atoms in the compound, further enhancing the corrosion resistance of the membrane; by forming polycarbazole, the carbazole monomer, functionalized microcrystalline cellulose, and functionalized shell powder are crosslinked to enhance the thermal stability of the membrane, and polycarbazole, as a stable polymer with benzene rings, can also enhance the thermal stability of the membrane. Detailed implementation manners

[0027] The following will combine with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] Example 1

[0029] A preparation method of a plant-based ion exchange membrane mainly includes the following preparation steps:

[0030] (1) Mix 200-mesh shell powder, N-[3-(trimethoxysilyl)propyl]ethylenediamine and isopropanol according to a mass ratio of 1:0.14:14, adjust the pH to 3.8 with 0.1 mol / L acetic acid aqueous solution, stir at 85 °C and 200 r / min for 5 h, filter, wash 3 times with deionized water, and dry at 90 °C for 2 h to obtain pre-modified shell powder;

[0031] Mix the pre-modified shell powder and 0.8 mol / L dilute hydrochloric acid evenly according to a mass ratio of 1:4, microwave at 200 r / min, 45 °C and 400 W microwave power for 8 min to obtain a pre-modified shell powder mixture. Mix dicyandiamide and deionized water evenly according to a mass ratio of 1:4 to obtain a dicyandiamide solution. Mix the pre-modified shell powder mixture and the dicyandiamide solution according to a mass ratio of 1:0.18, adjust the pH to 1 with 0.8 mol / L dilute hydrochloric acid, microwave at 200 r / min, 95 °C and 400 W microwave power for 13 min, pour it into ethanol, let it stand for 18 min, filter, wash 3 times with ethanol, and vacuum dry at -10 °C for 22 h to obtain modified shell powder;

[0032] Mix the modified shell powder, 9-allyl-9H-carbazole and acetone according to a mass ratio of 1:0.08:14, stir at 45 °C and 200 r / min for 38 h, filter, wash 3 times with acetone, and vacuum dry at -10 °C for 22 h to obtain functionalized shell powder;

[0033] (2) Mix microcrystalline cellulose and N,N-dimethylformamide according to a mass ratio of 1:20, stir at 250 r / min and 85 °C for 8 min, add thionyl chloride 0.17 times the volume of N,N-dimethylformamide uniformly within 8 min, continue to stir for 2 h, pour it into deionized water, stir at 300 r / min for 10 min, filter, wash 6 times with deionized water, and vacuum dry at 45 °C for 11 h to obtain pre-modified microcrystalline cellulose;

[0034] Mix pre-modified microcrystalline cellulose, dimethyl sulfoxide and carbazole in a mass ratio of 1:25:0.18, stir at 85 °C and 200 r / min for 11 h, pour into deionized water, let stand for 20 min, filter, wash with acetone 3 times, and vacuum dry at 45 °C for 11 h to obtain modified microcrystalline cellulose;

[0035] Mix sulfamic acid, N,N-dimethylformamide and modified microcrystalline cellulose in a mass ratio of 1:4:0.18, stir at 75 °C and 200 r / min for 1 h, pour into deionized water, let stand for 20 min, filter, wash with acetone 3 times, and vacuum dry at 55 °C for 11 h to obtain functionalized microcrystalline cellulose;

[0036] (3) Mix 2,7-bis(trifluoromethyl)-9H-carbazole, 4-bromobenzaldehyde and N-N dimethylformamide in a molar ratio of 1:1:14, stir at 200 r / min, 55 °C under nitrogen protection for 25 min, cool to room temperature, and vacuum dry at -10 °C for 22 h to obtain a functional monomer;

[0037] (4) Mix zeolite and deionized water in a mass ratio of 1:5 to obtain a zeolite mixture; Mix functionalized microcrystalline cellulose, N-(4-formylphenyl)-carbazole, functionalized shell powder, N,N-dimethylformamide, functional monomer and ferric chloride in a mass ratio of 10:2:3:140:1:1, stir at 75 °C and 200 r / min for 10 min, centrifuge at 8 °C and 7000 r / min for 8 min to obtain a casting solution; Spread the casting solution evenly on a clean and dry glass plate with a thickness of 450 μm, dry at 75 °C for 5 h, scrape off, place in the zeolite mixture, let stand for 20 min, take out, wash with deionized water 5 times, and vacuum dry at -10 °C for 22 h to obtain an ion exchange membrane.

[0038] Example 2

[0039] A preparation method of a plant-based ion exchange membrane mainly includes the following preparation steps:

[0040] (1) Mix 200-mesh shell powder, N-[3-(trimethoxysilyl)propyl]ethylenediamine and isopropanol in a mass ratio of 1:0.15:15, adjust the pH to 4 with 0.1 mol / L acetic acid aqueous solution, stir at 90 °C and 250 r / min for 6 h, filter, wash with deionized water 4 times, and dry at 95 °C for 3 h to obtain pre-modified shell powder;

[0041] Mix the pre-modified shell powder and 0.8 mol / L dilute hydrochloric acid evenly at a mass ratio of 1:5, and microwave for 10 min at 250 r / min, 50 °C, and a microwave power of 400 W to obtain a pre-modified shell powder mixture. Mix dicyandiamide and deionized water evenly at a mass ratio of 1:5 to obtain a dicyandiamide solution. Mix the pre-modified shell powder mixture and the dicyandiamide solution at a mass ratio of 1:0.2, adjust the pH to 1 with 0.8 mol / L dilute hydrochloric acid, and microwave for 14 min at 250 r / min, 100 °C, and a microwave power of 400 W. Pour it into ethanol, let it stand for 20 min, filter, wash it 4 times with ethanol, and vacuum dry it at -5 °C for 24 h to obtain the modified shell powder;

[0042] Mix the modified shell powder, 9-allyl-9H-carbazole, and acetone at a mass ratio of 1:0.1:15, stir at 50 °C and 250 r / min for 40 h, filter, wash it 4 times with acetone, and vacuum dry it at -5 °C for 24 h to obtain the functionalized shell powder;

[0043] (2) Mix microcrystalline cellulose and N,N-dimethylformamide at a mass ratio of 1:25, stir at 300 r / min and 90 °C for 10 min, add thionyl chloride 0.175 times the volume of N,N-dimethylformamide evenly within 10 min, continue to stir for 2.5 h, pour it into deionized water, stir at 350 r / min for 15 min, filter, wash it 7 times with deionized water, and vacuum dry it at 50 °C for 12 h to obtain the pre-modified microcrystalline cellulose;

[0044] Mix the pre-modified microcrystalline cellulose, dimethyl sulfoxide, and carbazole at a mass ratio of 1:30:0.2, stir at 90 °C and 250 r / min for 12 h, pour it into deionized water, let it stand for 25 min, filter, wash it 4 times with acetone, and vacuum dry it at 50 °C for 12 h to obtain the modified microcrystalline cellulose;

[0045] Mix sulfamic acid, N,N-dimethylformamide, and the modified microcrystalline cellulose at a mass ratio of 1:5:0.2, stir at 80 °C and 250 r / min for 1.5 h, pour it into deionized water, let it stand for 25 min, filter, wash it 4 times with acetone, and vacuum dry it at 50 °C for 12 h to obtain the functionalized microcrystalline cellulose;

[0046] (3) Mix 2,7-bis(trifluoromethyl)-9H-carbazole, p-bromobenzaldehyde, and N-N dimethylformamide at a molar ratio of 1:1:15, stir at 250 r / min, 60 °C under nitrogen protection for 30 min, cool to room temperature, and vacuum dry it at -5 °C for 24 h to obtain the functional monomer;

[0047] (4) Mix zeolite and deionized water at a mass ratio of 1:6 to obtain a zeolite mixture; mix functionalized microcrystalline cellulose, N-(4-benzaldehydyl)-carbazole, functionalized shell powder, N,N-dimethylformamide, functional monomer and ferric chloride at a mass ratio of 12:2.5:4:150:1:1, stir at 80 °C and 250 r / min for 12 min, centrifuge at 10 °C and 8000 r / min for 10 min to obtain a casting solution; evenly apply the casting solution on a clean and dry glass plate with a thickness of 500 μm, dry at 80 °C for 6 h, scrape it off, place it in the zeolite mixture, let it stand for 25 min, take it out, wash it 6 times with deionized water, and vacuum dry it at -5 °C for 24 h to obtain an ion exchange membrane.

[0048] Example 3

[0049] A preparation method of a plant-based ion exchange membrane mainly includes the following preparation steps:

[0050] (1) Mix 200-mesh shell powder, N-[3-(trimethoxysilyl)propyl]ethylenediamine and isopropanol at a mass ratio of 1:0.16:16, adjust the pH to 4.2 with 0.1 mol / L acetic acid aqueous solution, stir at 95 °C and 300 r / min for 7 h, filter, wash 5 times with deionized water, and dry at 100 °C for 4 h to obtain pre-modified shell powder;

[0051] Mix the pre-modified shell powder and 0.8 mol / L dilute hydrochloric acid evenly at a mass ratio of 1:6, microwave at 300 r / min, 55 °C and 400 W microwave power for 12 min to obtain a pre-modified shell powder mixture; mix dicyandiamide and deionized water evenly at a mass ratio of 1:6 to obtain a dicyandiamide solution; mix the pre-modified shell powder mixture and the dicyandiamide solution at a mass ratio of 1:0.22, adjust the pH to 1 with 0.8 mol / L dilute hydrochloric acid, microwave at 300 r / min, 105 °C and 400 W microwave power for 17 min, pour it into ethanol, let it stand for 22 min, filter, wash 5 times with ethanol, and vacuum dry at 0 °C for 26 h to obtain modified shell powder;

[0052] Mix the modified shell powder, 9-allyl-9H-carbazole and acetone at a mass ratio of 1:0.12:16, stir at 55 °C and 300 r / min for 42 h, filter, wash 5 times with acetone, and vacuum dry at 0 °C for 26 h to obtain functionalized shell powder;

[0053] (2) Mix microcrystalline cellulose and N,N-dimethylformamide at a mass ratio of 1:30, stir at 350 r / min and 95 °C for 12 min, add thionyl chloride which is 0.18 times the volume of N,N-dimethylformamide uniformly within 12 min, continue stirring for 3 h, pour into deionized water, stir at 400 r / min for 20 min, filter, wash with deionized water 8 times, and vacuum dry at 55 °C for 13 h to obtain pre-modified microcrystalline cellulose;

[0054] Mix pre-modified microcrystalline cellulose, dimethyl sulfoxide and carbazole at a mass ratio of 1:35:0.22, stir at 95 °C and 300 r / min for 13 h, pour into deionized water, let stand for 30 min, filter, wash with acetone 5 times, and vacuum dry at 55 °C for 13 h to obtain modified microcrystalline cellulose;

[0055] Mix sulfamic acid, N,N-dimethylformamide and modified microcrystalline cellulose at a mass ratio of 1:6:0.22, stir at 85 °C and 300 r / min for 2 h, pour into deionized water, let stand for 30 min, filter, wash with acetone 5 times, and vacuum dry at 55 °C for 13 h to obtain functionalized microcrystalline cellulose;

[0056] (3) Mix 2,7-bis(trifluoromethyl)-9H-carbazole, p-bromobenzaldehyde and N-N-dimethylformamide at a molar ratio of 1:1:16, stir at 300 r / min, 65 °C under nitrogen protection for 35 min, cool to room temperature, and vacuum dry at 0 °C for 26 h to obtain a functional monomer;

[0057] (4) Mix zeolite and deionized water at a mass ratio of 1:7 to obtain a zeolite mixture; Mix functionalized microcrystalline cellulose, N-(4-formylphenyl)-carbazole, functionalized shell powder, N,N-dimethylformamide, functional monomer and ferric chloride at a mass ratio of 14:3:5:160:1:1, stir at 85 °C and 300 r / min for 14 min, centrifuge at 12 °C and 9000 r / min for 12 min to obtain a casting solution; Spread the casting solution evenly on a clean and dry glass plate with a thickness of 550 μm, dry at 85 °C for 7 h, scrape off, place in the zeolite mixture, let stand for 30 min, take out, wash with deionized water 7 times, and vacuum dry at 0 °C for 26 h to obtain an ion exchange membrane.

[0058] Comparative Example 1

[0059] A preparation method of a plant-based ion exchange membrane mainly includes the following preparation steps:

[0060] The difference between the preparation method of the plant-based ion exchange membrane in Comparative Example 1 and that in Example 2 is only that the shell powder is not modified. The remaining steps are the same as those in Example 2.

[0061] Comparative Example 2

[0062] A preparation method of a plant-based ion exchange membrane mainly includes the following preparation steps:

[0063] The difference between the preparation method of the plant-based ion exchange membrane of Comparative Example 2 and that of Example 2 lies in the absence of steps (3) and (4). Step (4) is changed to: Mix zeolite and deionized water in a mass ratio of 1:6 to obtain a zeolite mixture; Mix functionalized microcrystalline cellulose, N-(4-benzaldehydyl)-carbazole, functionalized shell powder, N,N-dimethylformamide and ferric chloride in a mass ratio of 12:2.5:4:150:1, stir at 80 °C and 250 r / min for 12 min, centrifuge at 10 °C and 8000 r / min for 10 min to obtain a casting solution; Uniformly apply the casting solution on a clean and dry glass plate with a thickness of 500 μm, dry at 80 °C for 6 h, scrape off, place it in the zeolite mixture, let it stand for 25 min, take it out, wash it 6 times with deionized water, and vacuum dry it at -5 °C for 24 h to obtain an ion exchange membrane. The remaining steps are the same as those in Example 2.

[0064] Comparative Example 3

[0065] A preparation method of a plant-based ion exchange membrane mainly includes the following preparation steps:

[0066] The difference between the preparation method of the plant-based ion exchange membrane of Comparative Example 3 and that of Example 2 lies in the absence of steps (3) and (4). Step (4) is changed to: Mix zeolite and deionized water in a mass ratio of 1:6 to obtain a zeolite mixture; Mix functionalized microcrystalline cellulose, functionalized shell powder, and N,N-dimethylformamide in a mass ratio of 12:4:150, stir at 80 °C and 250 r / min for 12 min, centrifuge at 10 °C and 8000 r / min for 10 min to obtain a casting solution; Uniformly apply the casting solution on a clean and dry glass plate with a thickness of 500 μm, dry at 80 °C for 6 h, scrape off, place it in the zeolite mixture, let it stand for 25 min, take it out, wash it 6 times with deionized water, and vacuum dry it at -5 °C for 24 h to obtain an ion exchange membrane. The remaining steps are the same as those in Example 2.

[0067] Test Example 1

[0068] Ion exchange capacity test

[0069] Test method: Cut the samples of each example and comparative example into specimens with a diameter of 5 cm and a thickness of 200 μm, record the dry weight of the membrane, then soak the membrane in a 10% hydrochloric acid aqueous solution for 24 h, soak it in deionized water for 48 h, then soak the membrane in a 1 mol / L sodium chloride aqueous solution for 24 h, and then prepare a sodium hydroxide aqueous solution. Using phenolphthalein as an indicator, the content of hydrogen ions in the soaked sodium chloride aqueous solution was measured by molar titration, and the ion exchange capacity was calculated. The ion exchange capacity = the concentration of the sodium hydroxide aqueous solution × the volume of the sodium hydroxide aqueous solution / the dry weight of the membrane. The results are shown in Table 1.

[0070] Table 1

[0071] Ion exchange capacity Example 1 1.78 meq. / g Example 2 1.80 meq. / g Example 3 1.76 meq. / g Comparative Example 1 1.75 meq. / g Comparative Example 2 1.79 meq. / g Comparative Example 3 1.76 meq. / g

[0072] From the comparison of the experimental data in Table 1, it can be found that the plant-based ion exchange membrane prepared by the present invention has a good ion exchange capacity.

[0073] Test Example 2

[0074] Corrosion resistance test

[0075] Test method: Cut the membranes prepared in each example and comparative example into specimens with a radius of 5 cm and a thickness of 200 μm, weigh them, then soak the specimens in a 1 M sodium hydroxide aqueous solution at 80 °C for 2 h, wash them 5 times with deionized water, and freeze-dry them in a vacuum at -5 °C to test the mass loss rate. The mass loss rate = [(initial mass - mass after alkali corrosion) / initial mass] × 100%. The results are shown in Table 2.

[0076] Table 2

[0077]

[0078]

[0079] From the comparison of the experimental data in Table 2, it can be found that the plant-based ion exchange membrane prepared by the present invention has good corrosion resistance.

[0080] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2 in Table 2, it can be found that the mass loss rates of Examples 1, 2 and 3 are low. The difference between Comparative Example 2 and the examples is that no functional monomer was added, indicating that by polymerizing polycarbazole, trifluoromethyl was introduced onto the membrane. The carbon-fluorine bond of trifluoromethyl is a very strong chemical bond with a high bond energy and a short bond length, making the prepared membrane have high chemical stability and being difficult to be destroyed in chemical reactions. Moreover, the high electronegativity of trifluoromethyl enables it to attract the surrounding electrons, making the carbon atom carry a certain positive charge, and the fluorine atom in the trifluoromethyl group has a small radius, which makes the influence on the molecular volume small when it replaces other atoms in the compound, further enhancing the stability of the membrane and improving its corrosion resistance.

[0081] Test Example 3

[0082] Antibacterial Test

[0083] Test method: The membranes prepared in each example and comparative example were crushed to 80 mesh, and 1 g was taken for testing according to GB / T 31402-2015. The selected bacterial strains were Staphylococcus aureus and Escherichia coli. The results are shown in Table 3.

[0084] Table 3

[0085]

[0086]

[0087] It can be found from the comparison of the experimental data in Table 3 that the plant-based ion exchange membrane prepared by the present invention has good antibacterial ability.

[0088] It can be found from the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 1 in Table 3 that the antibacterial rates of Examples 1, 2, and 3 are high. The difference between Comparative Example 1 and the examples is that the shell powder was not modified. It shows that the biguanide structure formed on the surface of the shell powder through the reaction of dicyandiamide and amino groups can specifically interact with the ribosomal RNA part of bacteria, block the normal chain reaction required for protein synthesis, and can also interact with the circular structure of bacterial DNA, block its replication and repair process, cause the breakage and damage of bacterial DNA strands, affect the replication and reproduction of bacteria, and increase the antibacterial rate of the material.

[0089] Test Example 4

[0090] Thermal Stability Test

[0091] Test method: The membranes prepared in each example and comparative example were made into specimens with a radius of 5 cm and a thickness of 200 μm. The thermal stability of the prepared specimens was characterized by thermogravimetric analysis. Under nitrogen protection, the membrane samples were tested from 30 °C to 300 °C by a synchronous thermal analyzer at a heating rate of 10 °C / min, and the mass loss rate was measured, where the mass loss rate = [(initial mass - mass at 400 °C) / initial mass] × 100%. The results are shown in Table 4.

[0092] Table 4

[0093] Mass loss rate Example 1 25.8％ Example 2 25.5％ Example 3 25.7％ Comparative Example 1 25.6％ Comparative Example 2 31.3％ Comparative Example 3 48.8％

[0094] It can be found from the comparison of the experimental data in Table 4 that the plant-based ion exchange membrane prepared by the present invention has good thermal stability.

[0095] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 3 in Table 4, it can be found that the mass loss rates of Examples 1, 2, and 3 are low. The difference between Comparative Example 3 and the Examples is that polycarbazole is not formed, indicating that by forming polycarbazole, the material is crosslinked, enhancing the thermal stability of the film. Moreover, as a stable polymer with benzene rings, polycarbazole can also enhance the thermal stability of the film.

[0096] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a plant-based ion exchange membrane, characterized in that, The preparation method of the plant-based ion exchange membrane is obtained by reacting functionalized microcrystalline cellulose, N-(4-benzaldehydyl)-carbazole, functionalized shell powder, N,N-dimethylformamide and a functional monomer, and then making a mold. The functionalized microcrystalline cellulose is obtained by successively reacting microcrystalline cellulose with thionyl chloride, carbazole and sulfamic acid. The functionalized shell powder is obtained by successively reacting shell powder with N-[3-(trimethoxysilyl)propyl]ethylenediamine, dicyandiamide and 9-allyl-9H-carbazole. The functional monomer is obtained by reacting 2,7-bis(trifluoromethyl)-9H-carbazole with p-bromobenzaldehyde.

2. The preparation method of a plant-based ion exchange membrane according to claim 1, characterized in that, The preparation method of the plant-based ion exchange membrane mainly includes the following preparation steps: (1) Mix modified shell powder, 9-allyl-9H-carbazole and acetone according to a mass ratio of 1:0.08 - 0.12:14 - 16, stir at 45 - 55 °C and 200 - 300 r / min for 38 - 42 h, filter, wash with acetone 3 - 5 times, and vacuum dry at -10 - 0 °C for 22 - 26 h to obtain functionalized shell powder. (2) Mix pre-modified microcrystalline cellulose, dimethyl sulfoxide and carbazole according to a mass ratio of 1:25 - 35:0.18 - 0.22, stir at 85 - 95 °C and 200 - 300 r / min for 11 - 13 h, pour into deionized water, let stand for 20 - 30 min, filter, wash with acetone 3 - 5 times, and vacuum dry at 45 - 55 °C for 11 - 13 h to obtain modified microcrystalline cellulose. (3) Mix 2,7-bis(trifluoromethyl)-9H-carbazole, p-bromobenzaldehyde and N-N dimethylformamide according to a molar ratio of 1:1:14 - 16, stir at 200 - 300 r / min, 55 - 65 °C under nitrogen protection for 25 - 35 min, cool to room temperature, and vacuum dry at -10 - 0 °C for 22 - 26 h to obtain the functional monomer. (4) Uniformly apply the casting solution on a clean and dry glass plate with a thickness of 450 - 550 μm, dry at 75 - 85 °C for 5 - 7 h, scrape off, place in a zeolite mixture, let stand for 20 - 30 min, take out, wash with deionized water 5 - 7 times, and vacuum dry at -10 - 0 °C for 22 - 26 h to obtain the ion exchange membrane.

3. The preparation method of a plant-based ion exchange membrane according to claim 2, characterized in that, The modified shell powder in step (1) is prepared by mixing pre-modified shell powder and 0.8 mol / L dilute hydrochloric acid according to a mass ratio of 1:4 - 6, mixing evenly, microwave at 200 - 300 r / min, 45 - 55 °C and 400 W microwave power for 8 - 12 min to obtain a pre-modified shell powder mixture. Mix dicyandiamide and deionized water according to a mass ratio of 1:4 - 6 to obtain a dicyandiamide solution. Mix the pre-modified shell powder mixture and the dicyandiamide solution according to a mass ratio of 1:0.18 - 0.22, adjust the pH to 1 with 0.8 mol / L dilute hydrochloric acid, microwave at 200 - 300 r / min, 95 - 105 °C and 400 W microwave power for 13 - 17 min, pour into ethanol, let stand for 18 - 22 min, filter, wash with ethanol 3 - 5 times, and vacuum dry at -10 - 0 °C for 22 - 26 h.

4. The preparation method of a plant-based ion exchange membrane according to claim 3, characterized in that, The pre-modified shell powder is prepared by mixing 200-mesh shell powder, N-[3-(trimethoxysilyl)propyl]ethylenediamine and isopropanol in a mass ratio of 1:0.14-0.16:14-16, adjusting the pH to 3.8-4.2 with 0.1 mol / L acetic acid aqueous solution, stirring at 85-95 °C and 200-300 r / min for 5-7 h, filtering, washing with deionized water 3-5 times, and drying at 90-100 °C for 2-4 h.

5. The preparation method of a plant-based ion exchange membrane according to claim 2, characterized in that, The pre-modified microcrystalline cellulose described in step (2) is prepared by mixing microcrystalline cellulose and N,N-dimethylformamide in a mass ratio of 1:20-30, stirring at 250-350 r / min and 85-95 °C for 8-12 min, adding thionyl chloride in an amount 0.17-0.18 times the volume of N,N-dimethylformamide uniformly within 8-12 min, continuing to stir for 2-3 h, pouring into deionized water, stirring at 300-400 r / min for 10-20 min, filtering, washing with deionized water 6-8 times, and vacuum drying at 45-55 °C for 11-13 h.

6. The preparation method of a plant-based ion exchange membrane according to claim 2, characterized in that, The casting solution described in step (4) is prepared by mixing functionalized microcrystalline cellulose, N-(4-formylphenyl)-carbazole, functionalized shell powder, N,N-dimethylformamide, functional monomer and ferric chloride in a mass ratio of 10-14:2-3:3-5:140-160:1:1, stirring at 75-85 °C and 200-300 r / min for 10-14 min, and centrifuging at 8-12 °C and 7000-9000 r / min for 8-12 min.

7. The preparation method of a plant-based ion exchange membrane according to claim 6, characterized in that, The functionalized microcrystalline cellulose is prepared by mixing sulfamic acid, N,N-dimethylformamide and modified microcrystalline cellulose in a mass ratio of 1:4-6:0.18-0.22, stirring at 75-85 °C and 200-300 r / min for 1-2 h, pouring into deionized water, standing for 20-30 min, filtering, washing with acetone 3-5 times, and vacuum drying at 45-55 °C for 11-13 h.

8. The preparation method of a plant-based ion exchange membrane according to claim 2, characterized in that, The zeolite mixture described in step (4) is prepared by mixing zeolite and deionized water evenly in a mass ratio of 1:5-7.

9. Application of a plant-based ion exchange membrane prepared by the preparation method of the plant-based ion exchange membrane according to any one of claims 1-8 in the recovery of rare earth elements.

Images