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CN-121972036-A - Preparation method of efficient monolithic bipolar membrane

CN121972036ACN 121972036 ACN121972036 ACN 121972036ACN-121972036-A

Abstract

The invention relates to the technical field of bipolar membranes, in particular to a preparation method of a high-efficiency monolithic bipolar membrane, which comprises the following steps of preparing a co-supporting base membrane; the technical scheme of the invention realizes the span-type improvement of the comprehensive performance of the bipolar membrane and has remarkable practical application value. Through the optimization and synergistic effect of the technical scheme, the cation migration number of the bipolar membrane prepared by the invention is higher than 0.96, the hydrolysis voltage is lower than 0.85V, the tensile strength is higher than 28MPa, and the core problems of poor ion selectivity, high energy loss and insufficient mechanical stability of the existing bipolar membrane are synchronously solved. Compared with the traditional preparation method, the preparation method has the advantages that complicated equipment is not needed, parameters of each step are controllable, the preparation method is suitable for large-scale production, meanwhile, the stable structure of the catalytic layer is firmly combined with the membrane layer, and the service life of the bipolar membrane is prolonged.

Inventors

  • TAN YUANQING
  • DONG ZHUYONG
  • TONG YAN
  • TANG XUANNAN
  • FENG XUE

Assignees

  • 杭州科锐环境能源技术有限公司

Dates

Publication Date
20260505
Application Date
20260304

Claims (10)

  1. 1. The preparation method of the high-efficiency monolithic bipolar membrane is characterized by comprising the following steps of: Preparing a co-supporting substrate film, namely dissolving the sulfonated polyether-ether-ketone containing amino into N-methyl pyrrolidone, adding polyvinylidene fluoride accounting for 10-20wt% of the total mass of the substrate film raw material, performing ultrasonic dispersion for 30-60min, performing tape casting to form a film, and performing vacuum drying at 80-100 ℃ for 12-18h to obtain a homogeneous substrate film; The functionalization of the cation exchange layer, namely, soaking one side of the basement membrane in 0.5-1.0mol/L of 1, 3-propane sultone/ethanol sulfonation reagent, reacting for 4-8 hours at 60-80 ℃, hydrolyzing by NaOH solution, washing with deionized water to be neutral, and drying to form the cation exchange layer; Preparing and coating a modified bentonite-based catalytic layer, namely mixing ZnO-ZrO 2 loaded modified bentonite with a SPEEK binder according to a mass ratio of 7:3, adding N-methylpyrrolidone, performing ultrasonic dispersion for 2-3 hours to form catalytic slurry, coating the catalytic slurry on the surface of the cation exchange layer, controlling the thickness of the coating to be 5-10 mu m, and pre-drying at 60 ℃ for 3 hours; The functionalization of the anion exchange layer, namely casting an anion exchange resin solution of brominated 1-vinyl-3-methylimidazole modified SPEEK on the surface of the catalytic layer, and drying for 6-8 hours at 40-50 ℃ to form the anion exchange layer; And (3) composite solidification, namely hot-pressing the membrane materials sequentially forming the cation exchange layer, the catalytic layer and the anion exchange layer for 30-60min at 120-140 ℃ and 0.5-1.0MPa, and naturally cooling to room temperature to obtain the high-efficiency monolithic bipolar membrane.
  2. 2. The method according to claim 1, wherein in the 1, 3-propane sultone/ethanol sulphonation reagent in step S2, the volume ratio of 1, 3-propane sultone to ethanol is 1:3-5.
  3. 3. The preparation method according to claim 1, wherein the preparation step of the ZnO-ZrO 2 -supported modified bentonite in step S3 comprises: Crushing natural bentonite, sieving with a 200-mesh sieve, adding 5-10wt% hydrochloric acid solution, refluxing and stirring at 80 ℃ for 4-6h, filtering and washing to neutrality, adding 5-8wt% sodium hydroxide solution, stirring at 60 ℃ for 2-3h, filtering and washing to neutrality, and drying at 105 ℃ for 8h to obtain activated bentonite; Adding deionized water into the activated bentonite, performing ultrasonic dispersion to form a suspension with the weight of 5-10%, adding cetyltrimethylammonium bromide with the weight of 15-25% of the activated bentonite, stirring for 3-5 hours at 70-80 ℃, performing centrifugal separation, washing until no Cl - is detected, and performing vacuum drying for 6 hours at 60 ℃ to obtain the organic intercalation bentonite; And (3) loading active components, namely adding the organic intercalation bentonite into a mixed solution of zinc nitrate and zirconium chloride, regulating the pH to 8-9, stirring for 4-6h at 50 ℃, standing for precipitation, filtering, washing until no nitrate radical is detected, and roasting for 2-3h at 450-550 ℃ to obtain the organic intercalation bentonite.
  4. 4. The method according to claim 3, wherein the molar ratio of zinc nitrate to zirconium chloride in the mixed solution of zinc nitrate and zirconium chloride is 1:1, and the total concentration is 0.2-0.5mol/L.
  5. 5. The method according to claim 3, wherein the cetyl trimethylammonium bromide is added dropwise at a rate of 1-2mL/min.
  6. 6. The preparation method according to claim 1, wherein the loading amount of ZnO-ZrO 2 on the modified bentonite in the step S3 is 25-35% of the mass of the modified bentonite, and the particle size of ZnO-ZrO 2 is 20-50nm.
  7. 7. The method of claim 1, wherein the SPEEK binder in step S3 has a degree of sulfonation of 50-70%.
  8. 8. The method according to claim 1, wherein the viscosity of the catalytic slurry at 25 ℃ in step S3 is 500-1500 mPa-S and the shear rate is 100S -1 .
  9. 9. The preparation method according to claim 1, wherein the concentration of the anion exchange resin solution in step S4 is 15 to 25wt%.
  10. 10. The preparation method according to claim 1, wherein nitrogen is introduced during the hot pressing in step S5.

Description

Preparation method of efficient monolithic bipolar membrane Technical Field The invention relates to the technical field of bipolar membranes, in particular to a preparation method of a high-efficiency monolithic bipolar membrane. Background The bipolar membrane is used as a special ion exchange composite membrane and plays an irreplaceable role in the fields of electrodialysis acid and alkali preparation, wastewater treatment and recovery resources, energy storage and the like. The method has the core advantages that water molecules can be efficiently dissociated under the action of an electric field to generate hydrogen ions and hydroxyl ions, and the conversion of salt to acid and alkali or the advanced treatment of pollutants are realized, so that the method becomes a key material in the fields of green chemical industry and environmental protection. However, the current bipolar membrane preparation technology still faces a plurality of practical application problems, and the large-scale popularization and the performance improvement of the bipolar membrane are limited. Firstly, the traditional substrate film is mostly prepared from conventional polymer materials, the problems of swelling, cracking and the like are easy to occur in the long-term electrolysis process, the service life of the film is shortened due to insufficient mechanical stability, and the novel problem of increased ion transmission resistance is caused by poor component compatibility of part of the composite substrate film. Secondly, the performance of the hydrolytic-separation catalytic layer is a core for determining the efficiency of the bipolar membrane, but the existing catalytic layer often has the defects of uneven dispersion of active components and low loading capacity, and the conventional metal oxide catalyst is easy to agglomerate, so that the hydrolytic-separation voltage is higher and the energy loss is larger. Moreover, the insufficient bonding strength between the membrane layers is a common problem, and the phenomenon of stripping of the cation exchange layer, the catalytic layer and the anion exchange layer is easy to occur in both the bonding method and the conventional hot pressing method, so that the catalyst is lost and the performance is fast attenuated. These problems lead to the difficulty in combining high ion selectivity, low water dissociation voltage and excellent mechanical stability of the existing bipolar membrane, and limit the application effect of the bipolar membrane in industrial scenes. In order to solve the technical bottleneck, developing a bipolar membrane preparation method capable of synchronously optimizing the supporting performance of a substrate membrane, the activity of a catalytic layer and the combination stability of a membrane layer becomes an important research direction in the current field. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a preparation method of a high-efficiency monolithic bipolar membrane. The preparation method of the high-efficiency monolithic bipolar membrane comprises the following steps: Preparing a co-supporting substrate film, namely dissolving the sulfonated polyether-ether-ketone containing amino into N-methyl pyrrolidone, adding polyvinylidene fluoride accounting for 10-20wt% of the total mass of the substrate film raw material, performing ultrasonic dispersion for 30-60min, performing tape casting to form a film, and performing vacuum drying at 80-100 ℃ for 12-18h to obtain a homogeneous substrate film; The functionalization of the cation exchange layer, namely, soaking one side of the basement membrane in 0.5-1.0mol/L of 1, 3-propane sultone/ethanol sulfonation reagent, reacting for 4-8 hours at 60-80 ℃, hydrolyzing by NaOH solution, washing with deionized water to be neutral, and drying to form the cation exchange layer; Preparing and coating a modified bentonite-based catalytic layer, namely mixing ZnO-ZrO 2 loaded modified bentonite with a SPEEK binder according to a mass ratio of 7:3, adding N-methylpyrrolidone, performing ultrasonic dispersion for 2-3 hours to form catalytic slurry, coating the catalytic slurry on the surface of the cation exchange layer, controlling the thickness of the coating to be 5-10 mu m, and pre-drying at 60 ℃ for 3 hours; The functionalization of the anion exchange layer, namely casting an anion exchange resin solution of brominated 1-vinyl-3-methylimidazole modified SPEEK on the surface of the catalytic layer, and drying for 6-8 hours at 40-50 ℃ to form the anion exchange layer; And (3) composite solidification, namely hot-pressing the membrane materials sequentially forming the cation exchange layer, the catalytic layer and the anion exchange layer for 30-60min at 120-140 ℃ and 0.5-1.0MPa, and naturally cooling to room temperature to obtain the high-efficiency monolithic bipolar membrane. As a further technical scheme, in the 1, 3-propane sultone/ethanol sulfonation reag