3D printing ion exchange membrane for acid recovery as well as preparation method and application of 3D printing ion exchange membrane

Abstract

The invention relates to a 3D printing ion exchange membrane for acid recovery and a preparation method and application thereof, and the preparation method comprises the following steps: dissolving an ion exchange membrane matrix material and carbon quantum dots (CQDs) in an organic solvent to prepare a membrane casting solution; adding a first cross-linking agent (epoxy resin cross-linking agent) into the membrane casting solution; preparing an ion exchange membrane by adopting a 3D printing technology; soaking the printed ion exchange membrane in a second cross-linking agent (isocyanate cross-linking agent) solution for cross-linking treatment; and cleaning and drying to obtain the 3D printing ion exchange membrane. Compared with the prior art, the pore size and porosity of the membrane can be accurately controlled through a 3D printing technology, the performance of the ion exchange membrane in an acid recovery electrodialysis process is improved, and the mechanical strength and chemical resistance of the membrane can be further improved through carbon quantum dot modification and cross-linking agent modification.

Description

Technical Field

[0001] The present invention relates to the field of acid recovery, and particularly to a 3D printed ion exchange membrane for acid recovery, its preparation method and application. Background Art

[0002] In the field of acid recovery, the electrodialysis process is a commonly used effective means. As the core component of the electrodialysis process, the performance of the ion exchange membrane plays a key role in the acid recovery efficiency and quality. Traditional methods for preparing ion exchange membranes are difficult to precisely control the pore size and porosity of the membrane, resulting in difficulties in achieving the optimal balance of the ion selectivity, conductivity and mechanical properties of the membrane, which affects the acid recovery effect. The 3D printing technology has the characteristics of layer-by-layer manufacturing and precise control of material distribution, providing a new way for the preparation of high-performance ion exchange membranes.

[0003] Chinese Patent CN108786482A discloses a quaternary ammonium salt type anion exchange membrane based on the photocuring 3D printing technology. By mixing a certain proportion of 4-vinylbenzyl chloride, bisphenol A epoxy acrylate, isooctyl methacrylate and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to prepare a photosensitive resin, and then printing it into a flat film by a photocuring 3D printer, and then reacting with trimethylamine to prepare quaternary ammonium salt type anion exchange membranes (QPAEK) with different ion exchange capacities. The obtained anion exchange membranes have characteristics such as high ion conductivity and good mechanical properties, but their stability and chemical resistance limit their use in engineering. Summary of the Invention

[0004] The purpose of the present invention is to provide a 3D printed ion exchange membrane for acid recovery, its preparation method and application, and the performance of the prepared ion exchange membrane in the acid recovery electrodialysis process is effectively improved.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] On the one hand, the present invention provides a preparation method of a 3D printed ion exchange membrane for acid recovery, including the following steps:

[0007] S1: Mix an ion exchange membrane matrix material and carbon quantum dots (Carbon Quantum Dots, CQDs). Carbon quantum dots are a new type of carbon nanomaterial with a size below 10 nanometers and are spherical carbon particles. Compared with metal quantum dot materials, carbon quantum dots are almost non-toxic and have little harm to the environment. Dissolve them in an organic solvent to prepare a casting solution;

[0008] S2: Add a first cross-linking agent to the casting solution;

[0009] S3: Use 3D printing technology to prepare an ion exchange membrane;

[0010] S4: Immerse the printed ion exchange membrane in a second crosslinking agent solution for crosslinking treatment;

[0011] S5: Wash and dry.

[0012] Preferably, in step S1, in the casting solution, the content of the ion exchange membrane matrix material is 0.4 - 0.5 g / mL, and the content of the carbon quantum dots is 0.05 - 0.08 g / mL.

[0013] Preferably, in step S1, the ion exchange membrane matrix material includes sulfonated polyether ether ketone and quaternized polysulfone, and the organic solvents include dimethylacetamide and N - methylpyrrolidone.

[0014] More preferably, in step S1, when the 3D - printed ion exchange membrane is a cation exchange membrane, the ion exchange membrane matrix material is sulfonated polyether ether ketone, and the organic solvent is dimethylacetamide.

[0015] More preferably, in step S1, when the 3D - printed ion exchange membrane is an anion exchange membrane, the ion exchange membrane matrix material is quaternized polysulfone, and the organic solvent is N - methylpyrrolidone.

[0016] Preferably, in step S2, the addition amount of the first crosslinking agent added to the casting solution is 0.05 - 0.07 g / mL.

[0017] Preferably, in step S2, the first crosslinking agent is an epoxy resin - type crosslinking agent.

[0018] In the present invention, the role of the epoxy resin - type crosslinking agent is mainly to weave epoxy resin molecules into a three - dimensional network structure through chemical reactions, enhancing the overall performance of the material. Through complex chemical reactions, the crosslinking agent can form a firm network structure between molecules, thereby significantly improving the mechanical strength, heat resistance, and chemical stability of the material. This process is like tying countless strong knots to the originally loose ropes, turning them into an indestructible net. Simply put, the role of the crosslinking agent is to weave the matrix material molecules into a three - dimensional network structure through chemical reactions. This network structure greatly enhances the overall performance of the material, making it more robust, stable, and durable.

[0019] More preferably, in step S2, the epoxy resin - type crosslinking agent includes ethylene glycol diglycidyl ether (EGTA).

[0020] Preferably, in step S3, the 3D printing technology includes fused deposition modeling or stereolithography.

[0021] Further preferably, in step S3, the printing speed is 10 - 150 mm / s, the precision is within 0.01 mm to 0.2 mm, the wire diameter is 1 - 3 mm, the layer thickness is 0.05 - 5 mm, and it is optimized according to the curing speed and fluidity of the material to ensure the stability of the printing process and the structural precision.

[0022] Further preferably, in step S3, the wire diameter is 1 mm.

[0023] Further preferably, in step S3, when the 3D printing technology adopts the fused deposition modeling technology, the nozzle diameter is less than 0.5 mm.

[0024] Further preferably, in step S3, when the 3D printing technology adopts the fused deposition modeling technology, the nozzle diameter is less than 0.05 mm.

[0025] Even more preferably, in step S3, when the 3D printing technology adopts the fused deposition modeling technology, the nozzle diameter is 0.05 mm.

[0026] Further preferably, in step S3, when the 3D printing technology adopts the stereolithography apparatus technology, the spot size is 0.05 - 0.2 mm to ensure the precise deposition and curing of the material and form the expected film structure.

[0027] In the present invention, by setting the nozzle diameter less than 0.5 mm, the wire diameter of 1 - 3 mm, and regulating the three parameters of the printing speed of 10 mm / s to 150 mm / s, the precision within 0.01 mm to 0.2 mm, and the layer thickness within 0.05 - 5 mm, precise regulation within the range of the membrane pore diameter of 10 - 500 nm and the porosity of 20% - 80% can be achieved.

[0028] In the present invention, when the printing speed is relatively slow, the smoothness of the printed ion exchange membrane is better and the printing precision is better. Different from the prior art, the specially made 1 mm wire diameter and the nozzle diameter less than 0.05 mm in the present invention can further improve the printing precision, making the printing precision reach 0.01 mm to 0.2 mm, thereby realizing the precise regulation of the membrane pore diameter and the porosity.

[0029] In the present invention, the layer thickness of the 3D printed ion exchange membrane is adjusted according to the required pore diameter and porosity of the membrane. A smaller layer thickness helps to form a finer structure and achieve more precise pore diameter control.

[0030] In the present invention, the fused deposition modeling (FDM) or stereolithography (SLA) technology is selected according to the material properties and the design requirements of the membrane. For example, for SPEEK (sulfonated polyether ether ketone)-based cationic membrane materials, if the material has a relatively low melting point and good fluidity, the FDM mode can be selected; if the material is sensitive to light of a specific wavelength and has good curing performance, the SLA mode can be selected.

[0031] Preferably, before the 3D printing, computer-aided design (CAD) software is used to design the membrane structure, and a membrane structure model with a specific pore size and porosity is designed.

[0032] Preferably, in step S4, the concentration of the second cross-linking agent solution is 0.1 - 0.2 g / mL, the solvent includes ethyl acetate, the cross-linking treatment time is 2 - 3 h, and the temperature is 50 - 60 °C.

[0033] Preferably, in step S4, the second cross-linking agent is an isocyanate-based cross-linking agent.

[0034] More preferably, in step S4, the isocyanate-based cross-linking agent includes toluene diisocyanate (TDI).

[0035] In the present invention, an isocyanate-based cross-linking agent is used as the second cross-linking agent, and the isocyanate group therein reacts with the hydroxyl group or other functional groups on the surface of the carbon quantum dots to form a stable cross-linked structure, which is used for the mechanical strength and chemical resistance of the matrix material.

[0036] In the present invention, the 3D-printed ion exchange membrane is cross-linked to improve the chemical stability and mechanical strength of the membrane.

[0037] Preferably, in step S5, the cleaning refers to repeatedly cleaning with deionized water to remove residual solvents and impurities.

[0038] Preferably, in step S5, the drying refers to vacuum drying, the drying temperature is 30 - 45 °C, and the time is 18 - 24 h.

[0039] In a second aspect, the present invention also provides a 3D-printed ion exchange membrane for acid recovery prepared according to the described preparation method.

[0040] Preferably, the membrane pore size of the 3D-printed ion exchange membrane is 10 - 500 nm, and the porosity is 20% - 80%.

[0041] Preferably, the 3D-printed ion exchange membrane includes a honeycomb, porous columnar or gradient pore structure.

[0042] Further preferably, when the 3D printed ion exchange membrane is used in the acid recovery process that requires high ion selectivity, the pore size can be designed as a gradient structure that gradually decreases from the feed side to the discharge side to promote the directional transport of ions.

[0043] In a third aspect, the present invention also provides an application of the 3D printed ion exchange membrane for acid recovery in acid recovery.

[0044] Preferably, the acid recovery refers to acid recovery by an electrodialysis process.

[0045] For acids with various different molecular weights, such as sulfuric acid, phosphoric acid, etc., the effective treatment of the acid treatment solution can be reasonably achieved by adjusting parameters such as the 3D printing speed, the layer thickness of the ion exchange membrane, and the nozzle diameter. Especially for acid treatment solutions with different phosphorus-sulfur ratios, this customized method can better meet specific requirements.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The performance of the 3D printed ion exchange membrane obtained by the preparation method of the present invention in the acid recovery electrodialysis process has been effectively improved.

[0048] (2) The 3D printed ion exchange membrane of the present invention is prepared to have a relatively high recovery rate of phosphate and sulfate acids and a relatively high aluminum ion retention rate. The recovery rate of phosphate is greater than 55%, the recovery rate of sulfate acid can reach 87%, and the aluminum ion retention rate can reach 90%.

[0049] (3) Through the printing technology and precise parameter setting of the present invention, by setting the nozzle diameter to be less than 0.5 mm and the wire diameter to be 1 - 3 mm, regulating the printing speed to be 10 mm / s - 150 mm / s, with an accuracy of 0.01 mm - 0.2 mm, and the layer thickness to be 0.05 - 5 mm, the precise regulation of the membrane pore size within the range of 10 - 500 nm and the porosity within the range of 20% - 80% can be achieved, meeting the performance requirements of different acid recovery processes for ion exchange membranes.

[0050] (4) The 3D printed ion exchange membrane adopts an optimized pore size and porosity structure, making the ion exchange membrane have higher ion selectivity and lower resistance, improving the ion transport efficiency in the acid recovery electrodialysis process, and thus enhancing the acid recovery efficiency.

[0051] (5) Through the combination of crosslinking modification and carbon quantum dot modification, the present invention significantly enhances the mechanical strength of the membrane, enabling it to withstand greater pressure and shear force during the electrodialysis process and extending the service life of the membrane.

[0052] (6) The 3D printed ion exchange membrane of the present invention has good chemical resistance and stability, which can support its use in sulfuric acid or occasions where the sulfuric acid concentration is lower than 15%, thus improving the service life of the membrane.

[0053] (7) The present invention uses 3D printing technology to prepare ion exchange membranes, which has the characteristics of layer-by-layer manufacturing and precise control of material distribution, providing a new way for the preparation of high-performance ion exchange membranes. Detailed implementation mode

[0054] The following details the embodiments of the present invention. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0055] Unless otherwise specified, the reagents, methods, instruments, and equipment used in the present invention are conventional reagents, methods, instruments, and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0056] A preparation method of a 3D printed ion exchange membrane for acid recovery includes the following steps:

[0057] S1: Dissolve the ion exchange membrane matrix material and carbon quantum dots in an organic solvent to prepare a casting solution;

[0058] S2: Add a first cross-linking agent to the casting solution;

[0059] S3: Use 3D printing technology to prepare an ion exchange membrane;

[0060] S4: Immerse the printed ion exchange membrane in a second cross-linking agent solution for cross-linking treatment;

[0061] S5: Wash and dry.

[0062] The membrane pore size of the 3D printed ion exchange membrane prepared according to the preparation method is 10 - 500 nm, and the porosity is 20% - 80%.

[0063] The following details the present invention with specific embodiments.

[0064] Example 1

[0065] A 3D printed ion exchange membrane for acid recovery is prepared as follows:

[0066] (1) Material preparation: Dissolve 10 g of sulfonated polyether ether ketone in 100 mL of dimethylacetamide (DMAc), stir until completely dissolved. Add 0.05 - 0.08 g of carbon quantum dots, and ultrasonically disperse for 30 minutes to make them uniformly dispersed in the solution. Then add 0.5 g of ethylene glycol diglycidyl ether and stir evenly.

[0067] (2) 3D printing: Using an FDM 3D printer, load the above materials into the printing consumable tube. According to the designed membrane structure model, set the printing layer thickness to 20 μm, the nozzle diameter to 0.05 mm, and the printing speed to 30 mm / s for printing.

[0068] (3) Post-treatment: Immerse the printed ion exchange membrane in an ethyl acetate solution of toluene diisocyanate and react at 60 °C for 2 hours for crosslinking. Then wash it repeatedly with deionized water to remove residual solvents and impurities, and finally dry it in vacuum at 40 °C for 24 hours.

[0069] The membrane pore size of the 3D printed ion exchange membrane obtained in this Example 1 is 20 - 40 nm, and the porosity is 50% - 60%.

[0070] Example 2

[0071] A 3D printed ion exchange membrane for acid recovery is prepared as follows:

[0072] (1) Material preparation: Dissolve 8 g of quaternized polysulfone in 80 mL of N-methylpyrrolidone (NMP) and stir to dissolve. Add 0.04 - 0.06 g of carbon quantum dots and ultrasonically disperse for 20 minutes. Add 0.3 g of ethylene glycol diglycidyl ether and stir evenly.

[0073] (2) 3D printing: Using an SLA 3D printer, place the material in the photocuring tank. According to the designed model, set the printing layer thickness to 10 μm, the spot size to 0.1 mm, and the printing speed to 50 mm / s for printing.

[0074] (3) Post-treatment: Immerse the printed ion exchange membrane in an ethyl acetate solution of toluene diisocyanate and react at 50 °C for 3 hours for crosslinking. After washing with deionized water, dry it in vacuum at 35 °C for 18 hours.

[0075] The membrane pore size of the 3D printed ion exchange membrane obtained in this Example 2 is 10 - 40 nm, and the porosity is 40% - 60%.

[0076] Comparative Example 1

[0077] A 3D printed ion exchange membrane is prepared as follows:

[0078] (1) Material preparation: Dissolve 8 g of quaternized polysulfone in 80 mL of N-methylpyrrolidone (NMP) and stir to dissolve. Add 0.3 g of ethylene glycol diglycidyl ether and stir evenly.

[0079] (2) 3D printing: Using an SLA 3D printer, place the material in the photocuring tank. According to the design model, set the printing layer thickness to 10 μm, the spot size to 0.1 mm, and the printing speed to 50 mm / s for printing.

[0080] (3) Post-treatment: Immerse the printed ion exchange membrane in an ethyl acetate solution of toluene diisocyanate and react at 50 °C for 3 hours for crosslinking. After washing with deionized water, vacuum dry at 35 °C for 18 hours.

[0081] The membrane pore size of the 3D printed ion exchange membrane obtained in Example 2 is 10 - 40 nm, and the porosity is 40% - 60%.

[0082] Application Example 1

[0083] Use the 3D printed ion exchange membrane prepared in Example 2 for the waste acid recovery of Shanghai Yueshun. In this application example, the phosphorus-sulfur ratio in the waste acid is 2:1. The treatment data results are shown in Table 1-4.

[0084] Table 1: On-site influent solution data of Shanghai Yueshun Auto Parts Co., Ltd.

[0085]

[0086] Table 2: Data of treated and recovered acid of Shanghai Yueshun Auto Parts Co., Ltd.

[0087]

[0088] Table 3: Data of treated and recovered acid rate of Shanghai Yueshun Auto Parts Co., Ltd.

[0089]

[0090] Table 4: Data of treated aluminum ions of Shanghai Yueshun Auto Parts Co., Ltd.

[0091]

[0092] In summary, the 3D printed ion exchange membrane prepared in Example 2 has a high recovery rate of phosphate and sulfate, as well as a high retention rate of aluminum ions. In this application example, in order to ensure the removal rate of aluminum ions, the pore size selected is about 10 nm. Therefore, the recovery rate of phosphate is much lower than that of sulfate, and the removal rate of phosphate is between 55% - 65%. The recovery rate is relatively low in the initial stage and gradually reaches equilibrium after running for 8 hours.

[0093] Conduct a hardness test on the 3D printed ion exchange membranes prepared in Example 2 and Comparative Example 1.

[0094] - Test method: Use a Vickers Hardness Tester to test the hardness of the membrane sample. - Test conditions:

[0095] - Load: 10 kgf

[0096] - Temperature: 25 °C

[0097] - Humidity: 50%

[0098] - Test results: Comparing Example 2 and Comparative Example 1, that is, the hardness of the membrane before or after modification with carbon quantum dots, the hardness of the membrane modified with carbon quantum dots in Example 2 is significantly stronger than that of the membrane without modification with carbon quantum dots, and the mechanical properties are excellent.

[0099] Perform acid and alkali tolerance tests on the 3D printed ion exchange membranes prepared in Example 2 and Comparative Example 1. - Test method: Immerse the membrane samples in solutions with different pH values (such as pH = 2, pH = 7, pH = 12) respectively, and observe their changes in the acid and alkali environments.

[0100] - Test conditions:

[0101] - Immersion time: 24 hours

[0102] - Temperature: 25 °C

[0103] - Test results: Comparing the changes of the ion exchange membranes in Example 2 and Comparative Example 1 in the acid and alkali environments, it is found that the membrane modified with carbon quantum dots in Example 2 has significantly better chemical resistance and stability.

[0104] In summary, the present invention prepares a 3D printed ion exchange membrane for acid recovery through 3D printing technology, and can regulate the pore size and porosity of the membrane by changing the printing parameters to meet the performance requirements of different acid recovery processes for the ion exchange membrane; at the same time, through modification with carbon quantum dots and crosslinking agents, the mechanical strength and chemical resistance of the membrane can be further improved, and the service life of the membrane can be increased; the finally prepared membrane of the present invention has a high acid recovery rate of phosphate and sulfate and a high aluminum ion interception rate, and can be widely applied to industrial acid recovery processes.

[0105] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of a 3D printed ion exchange membrane for acid recovery, characterized in that, It includes the following steps: S1: Dissolve the ion exchange membrane matrix material and carbon quantum dots in an organic solvent to prepare a casting solution; S2: Add a first crosslinking agent to the casting solution; S3: Prepare an ion exchange membrane by using 3D printing technology; S4: Immerse the printed ion exchange membrane in a second crosslinking agent solution for crosslinking treatment; S5: Clean and dry.

2. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, wherein, In step S1, in the casting solution, the content of the ion exchange membrane matrix material is 0.4 - 0.5 g / mL, and the content of the carbon quantum dots is 0.05 - 0.08 g / mL.

3. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, characterized in that, In step S1, the ion exchange membrane matrix material includes sulfonated polyether ether ketone and quaternized polysulfone, and the organic solvent includes dimethylacetamide and N-methylpyrrolidone.

4. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, characterized in that, In step S2, the addition amount of the first crosslinking agent added to the casting solution is 0.05 - 0.07 g / mL.

5. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, characterized in that, In step S2, the first crosslinking agent is an epoxy resin-based crosslinking agent, and the epoxy resin-based crosslinking agent includes ethylene glycol diglycidyl ether.

6. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, characterized in that, In step S3, the 3D printing technology includes fused deposition modeling or stereolithography technology, the printing speed is 10 - 150 mm / s, the accuracy is between 0.01 mm and 0.2 mm, the wire diameter is 1 - 3 mm, and the layer thickness is 0.05 - 5 mm; When the 3D printing technology uses fused deposition modeling technology, the nozzle diameter is less than 0.5 mm; when the 3D printing technology uses stereolithography technology, the spot size is 0.05 - 0.2 mm.

7. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, characterized in that, In step S4, the concentration of the second crosslinking agent solution is 0.1 - 0.2 g / mL, the solvent includes ethyl acetate, the crosslinking treatment time is 2 - 3 h, and the temperature is 50 - 60 °C.

8. The preparation method of a 3D printed ion exchange membrane for acid recovery according to claim 1, characterized in that, In step S4, the second crosslinking agent is an isocyanate-based crosslinking agent, and the isocyanate-based crosslinking agent includes toluene diisocyanate.

9. A 3D printed ion exchange membrane for acid recovery, prepared by the preparation method according to any one of claims 1-8, characterized in that, The membrane pore size is 10 - 500 nm, and the porosity is 20% - 80%.

10. Application of the 3D printed ion exchange membrane for acid recovery according to claim 9 in acid recovery.

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