Method for preparing separation membrane through interfacial polymerization illumination post-treatment

Abstract

The invention relates to the technical field of separation membrane preparation, in particular to a method for preparing a separation membrane through interfacial polymerization illumination aftertreatment. In order to solve the problems of non-uniform heating, existence of thermal stress and high energy consumption of the existing interfacial polymerization heat treatment, the method comprises the following specific steps: step 1, dissolving a water-phase monomer into a solvent A to obtain a solution A, soaking a porous polymer base membrane in the solution A for 2-15 minutes, and taking out the porous polymer base membrane; 2, dissolving an organic phase monomer in a solvent B to obtain a solution B, soaking the porous polymer base membrane treated in the step 1 in the solution B for 1-15 minutes, and taking out the porous polymer base membrane; and step 3, carrying out light irradiation treatment on the porous polymer base membrane treated in the step 2, and regulating and controlling a further cross-linking reaction process of the polymer separation membrane by utilizing a post-treatment mode of irradiation interface polymerization of light with different wavelengths, so that the cross-linking reaction is effectively promoted to be uniformly and rapidly carried out, and meanwhile, the consumption of energy and time is also reduced. The method can be used in the fields of water treatment, gas separation, biomedicine, food processing, battery diaphragms and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of separation membrane preparation, and more particularly to a method for preparing a separation membrane through post-interfacial polymerization and light irradiation treatment. Background Art

[0002] A separation membrane is a thin film material with selective permeability that can separate different components in a mixture. Separation membrane technology is widely used in chemical, food, pharmaceutical, environmental protection and other fields, such as seawater desalination, sewage treatment, gas separation, protein concentration, etc. Interfacial polymerization is an important method for preparing polymer separation membranes, which has the advantages of fast film formation speed, controllable membrane structure, and excellent membrane performance. In the interfacial polymerization process, two monomers are usually required, one is an aqueous phase monomer and the other is an oil phase monomer. These two monomers undergo polymerization reaction at the interface to form a polymer film. By controlling the conditions of the polymerization reaction, the structure and performance of the membrane can be adjusted. Traditional interfacial polymerization technology promotes the further reaction through oven heating post-treatment, but the uneven heating and thermal stress during the treatment process will affect the membrane structure. Therefore, it is still a huge challenge to prepare separation membranes with excellent structure and performance through interfacial polymerization through green and effective post-treatment methods. Summary of the Invention

[0003] The present invention provides a method for preparing a separation membrane by post-interfacial polymerization light irradiation treatment, aiming to solve the problems of uneven heating, thermal stress and high energy consumption in the existing interfacial polymerization heat treatment.

[0004] The above objectives are achieved through the following technical solutions:

[0005] A method for preparing a separation membrane by interfacial polymerization and light irradiation post-treatment comprises the following steps:

[0006] Step 1: dissolving the aqueous monomer into a strong polar solvent to obtain solution A, and then immersing the porous polymer base membrane in solution A and taking it out;

[0007] Step 2: dissolving the organic phase monomer into a weakly polar solvent to obtain a solution B, and then soaking the porous polymer base membrane obtained after the treatment in step 1 in the solution B and then taking it out;

[0008] Step 3: The porous polymer base film treated in step 2 is subjected to light irradiation treatment.

[0009] The porous polymer base membrane is a polymer ultrafiltration membrane or a microfiltration membrane; the material of the porous polymer base membrane is at least one of polyethersulfone, polysulfone, polyimide, polyacrylonitrile, polyvinyl chloride, polyethylene, polyvinylidene fluoride and cellulose acetate.

[0010] The aqueous phase monomer is at least one of piperazine, m-phenylenediamine, p-phenylenediamine, N-aminoethylpiperazine, polyethyleneimine, glucose, ethylene glycol, glycerol, polyethylene glycol and tris(hydroxymethyl)aminomethane.

[0011] The highly polar solvent is at least one of deionized water, acetonitrile, dimethylformamide, dimethyl sulfoxide, ethanol, isopropanol and ionic liquid.

[0012] The organic phase monomer is at least one of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, 1,3,6-naphthalenetrisulfonyl chloride, toluene diisocyanate and maleic anhydride.

[0013] The weak polar solvent is at least one of n-hexane, n-heptane, n-octane, acetone, cyclohexanone, toluene, xylene, chloroform, carbon tetrachloride and isoparaffin solvents.

[0014] The monomer concentration in solution A is 0.01 to 20 wt %, and the monomer concentration in solution B is 0.01 to 15 wt %.

[0015] The porous polymer-based membrane is immersed in solution A for 0.5 to 60 minutes, and is immersed in solution B for 0.5 to 60 minutes.

[0016] When the porous polymer-based membrane is taken out from liquid A, inert gas blowing or rubber roller squeezing is used to remove residual liquid on the surface.

[0017] After the porous polymer-based membrane is taken out from the infiltration solution B, it is washed with a weak polar solvent.

[0018] The light irradiation is infrared light or ultraviolet light, the wavelength of the light irradiation is 100nm~25μm, the treatment time is 0.5~30min, and the light intensity is 50μW~1000mW / cm 2 .

[0019] The beneficial effects of the method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment of the present invention are:

[0020] Different wavelengths of light irradiation are used to promote further cross-linking reactions between aqueous phase monomers and organic phase monomers in interfacial polymerization.

[0021] High-intensity long-wave light can effectively and evenly heat the reaction system, promote the thermal motion of monomer molecules, and increase the reaction rate and efficiency.

[0022] High-energy light waves of a specific frequency can initiate monomer polymerization, thereby broadening the types of monomers in the interfacial polymerization separation membrane, and improving the ability to modify and modify the separation membrane through the generation of active substances such as free radicals.

[0023] Short-wave light irradiation can also clean the membrane surface, promote the generation of oxygen vacancies, improve the membrane structure, and increase the hydrophilicity of the membrane surface.

[0024] By adjusting the light intensity, illumination time and frequency, the reaction kinetics can be adjusted and the reaction conversion rate and molecular weight distribution of the polymer can be optimized.

[0025] The high-performance nanofiltration membrane prepared by interfacial polymerization through light irradiation post-treatment in the present invention can be widely used in water treatment, gas separation, biomedicine, food processing, battery separators and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a comparison chart of the rejection rates and permeation fluxes of the polyamide nanofiltration membrane post-treated with long-wave infrared light irradiation and the polyamide nanofiltration membrane of the control group heat-treated in an oven for different inorganic salt solutions in Example 1;

[0027] Figure 2 This is a scanning electron microscope photograph of the polyamide nanofiltration membrane after long-wave infrared light irradiation treatment in Example 1;

[0028] Figure 3 This is a scanning electron microscope photograph of the polyamide nanofiltration membrane heat-treated in the control group of Example 1;

[0029] Figure 4 This is a comparison chart of the retention rates and permeation fluxes of the polyamide nanofiltration membrane treated with short-wave ultraviolet light and the polyamide nanofiltration membrane of the control group treated with oven heat for different inorganic salt solutions in Example 3;

[0030] Figure 5 This is a scanning electron microscope photograph of the polyamide nanofiltration membrane after short-wave ultraviolet light irradiation treatment in Example 3. DETAILED DESCRIPTION

[0031] A method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment, in Example 1, comprises the following steps:

[0032] Step 1: soaking a polyethersulfone ultrafiltration membrane (hereinafter referred to as base membrane) in water, and then purging with nitrogen to remove residual solvent on the surface to obtain a wet membrane;

[0033] Step 2: dissolving piperazine in deionized water to obtain an aqueous monomer solution with a concentration of 0.3 wt %, and dissolving trimesoyl chloride in n-hexane to obtain an organic monomer solvent with a concentration of 0.15 wt %;

[0034] Step 3: Soak the base film in the aqueous monomer solution for 3 minutes, then remove the base film and purge with nitrogen to remove the residual solution on the surface;

[0035] Step 4: The base film treated in step 3 is immersed in the organic phase monomer solution mentioned above to carry out interfacial polymerization reaction for 2 minutes, and then the base film is taken out and washed with n-hexane to obtain a polyamide film;

[0036] Step 5: The polyamide membrane was placed in a dark box and irradiated with an infrared light with a light intensity of 300W and a wavelength of 4 μm for 2 minutes to obtain a polyamide nanofiltration membrane with a uniform and dense structure (hereinafter referred to as the filter membrane).

[0037] According to the conventional membrane performance evaluation method, that is, at a pressure of 0.6 MPa and a feed liquid temperature of 25°C:

[0038] The pure water flux of polyamide nanofiltration membrane is 42.3Lm -2 h -1 bar -1 ;

[0039] The rejection rate of 1000ppm sodium sulfate solution is 87.1% and the flux is 29.Lm -2 h -1 bar -1 ;

[0040] The rejection rate of 1000ppm sodium chloride solution is 29.7% and the flux is 30.4Lm -2 h -1 bar -1 ;

[0041] The rejection rate of 1000ppm magnesium sulfate solution is 58.9% and the flux is 33.2Lm -2 h -1 bar -1 ;

[0042] The rejection rate of 1000ppm magnesium chloride solution is 41.4% and the flux is 32.7Lm -2 h -1 bar -1 .

[0043] The treatment time of each of the above solutions is 2 min.

[0044] Comparative example, based on Example 1, the infrared light irradiation scheme in step 5 was replaced by oven heat treatment, and the retention rate and permeation flux of the obtained polyamide nanofiltration membrane for different inorganic salt solutions were compared. Figure 1 As shown:

[0045] The bars in the figure represent flux, and the spheres represent retention. Compared to oven-heat-treated polyamide nanofiltration membranes, the polyamide nanofiltration membranes treated with long-wave infrared light showed no significant difference in retention of inorganic salt solutions, but significantly improved flux. This comparison demonstrates that long-wave infrared light post-treatment can improve nanofiltration membrane flux.

[0046] In Example 1, the scanning electron microscope photograph of the polyamide nanofiltration membrane after long-wave infrared light irradiation treatment is as follows: Figure 2 As shown, the scanning electron microscope photo of the oven heat-treated polyamide nanofiltration membrane of the control example is as shown in FIG. Figure 3 As shown. Figure 2 and Figure 3 By comparison, it is known that long-wave infrared light irradiation treatment can give the nanofiltration membrane a smooth and uniform microstructure.

[0047] Example 2:

[0048] Based on Example 1, the time after infrared light irradiation in step 5 was extended from 2 min to 15 min. The performance of the polyamide nanofiltration membrane was still evaluated according to the above conventional membrane performance evaluation method.

[0049] Treatment of 1000ppm sodium sulfate solution:

[0050] The treatment time was 2 min, the rejection rate was 87.1%, and the flux was 29.8 Lm -2 h -1 bar -1 ;

[0051] The treatment time was 5 min, the rejection rate was 86.6%, and the flux was 26.6 Lm -2 h -1 bar -1 ;

[0052] The treatment time was 10 min, the rejection rate was 77.56%, and the flux was 25.4 Lm -2 h -1 bar -1 ;

[0053] The treatment time was 15 min, the nanofiltration membrane rejection rate was 81.8%, and the flux was 26.5 Lm -2 h -1 bar -1 .

[0054] Example 3:

[0055] Based on Example 1, the infrared light irradiation in step 5 was replaced by ultraviolet light irradiation with a wavelength of 360 nm for 2 minutes. The performance of the polyamide nanofiltration membrane was still evaluated according to the above conventional membrane performance evaluation method.

[0056] Pure water flux is 37.4Lm -2 h -1 bar -1 ;

[0057] The rejection rate of 1000ppm sodium sulfate solution is 86.7% and the flux is 31.8Lm -2 h -1 bar -1 ;

[0058] The rejection rate of 1000ppm sodium chloride solution is 20.7% and the flux is 29.6Lm -2 h -1 bar -1 ;

[0059] The rejection rate of 1000ppm magnesium sulfate solution is 61.4% and the flux is 35.2Lm -2 h -1 bar -1 ;

[0060] The rejection rate of 1000ppm magnesium chloride solution is 25.7% and the flux is 34.9Lm -2 h -1 bar -1 .

[0061] The retention rate and permeation flux of the polyamide nanofiltration membrane treated with light irradiation in this example and the polyamide nanofiltration membrane treated with oven heat in the control group were compared. Figure 4 As shown:

[0062] The bars in the figure represent flux, and the spheres represent retention. Compared to oven-heat-treated polyamide nanofiltration membranes, shortwave UV post-treatment showed no significant change in inorganic salt solution retention, but significantly improved flux. This comparison demonstrates that shortwave UV post-treatment can enhance nanofiltration membrane flux.

[0063] The scanning electron microscope photograph of the polyamide nanofiltration membrane after short-wave ultraviolet irradiation treatment in this example is as follows: Figure 5 As shown in Figure 3, short-wave ultraviolet light irradiation treatment can give the nanofiltration membrane a smooth and uniform microstructure.

[0064] Example 4:

[0065] Based on Example 1, the wavelength of the infrared lamp in step 5 was changed from 4 μm to 360 nm, and the irradiation time was changed from 2 min to 2-10 min;

[0066] Still following the above conventional membrane performance evaluation method, the performance of the polyamide nanofiltration membrane is:

[0067] Treatment of 1000ppm sodium sulfate solution:

[0068] The treatment time was 2 min, the rejection rate was 86.7%, and the flux was 31.8 Lm -2 h -1 bar-1 ;

[0069] The treatment time was 5 min, the rejection rate was 79.4%, and the flux was 29.1 Lm -2 h -1 bar -1 ;

[0070] The treatment time was 10 min, the rejection rate was 68.9%, and the flux was 27.6 Lm -2 h -1 bar -1 ;

[0071] The treatment time was 15 min, the rejection rate was 62.2%, and the flux was 25.3 Lm -2 h -1 bar -1 In summary, the present invention utilizes different wavelength light irradiation interfacial polymerization post-treatment to regulate the further cross-linking reaction process of the polymer separation membrane, which not only effectively promotes the cross-linking reaction to proceed uniformly and rapidly, but also reduces energy and time consumption.

Claims

1. A method for preparing a separation membrane by post-treatment of interfacial polymerization and light irradiation, characterized in that: The following steps are involved: Step 1: dissolving the aqueous monomer into a strong polar solvent to obtain solution A, and then immersing the porous polymer base membrane in solution A and taking it out; Step 2: dissolving the organic phase monomer into a weakly polar solvent to obtain a solution B, and then soaking the porous polymer base membrane obtained after the treatment in step 1 in the solution B and then taking it out; Step 3: The porous polymer base film treated in step 2 is subjected to light irradiation treatment.

2. The method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment according to claim 1, wherein the porous polymer base membrane is a polymer ultrafiltration membrane or a microfiltration membrane; the material of the porous polymer base membrane is at least one of polyethersulfone, polysulfone, polyimide, polyacrylonitrile, polyvinyl chloride, polyethylene, polyvinylidene fluoride and cellulose acetate.

3. The method for preparing a separation membrane by interfacial polymerization and light post-treatment according to claim 1, wherein the aqueous phase monomer is at least one of piperazine, m-phenylenediamine, p-phenylenediamine, N-aminoethylpiperazine, polyethyleneimine, glucose, ethylene glycol, glycerol, polyethylene glycol and tris(hydroxymethylaminomethane).

4. The method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment according to claim 1, wherein the highly polar solvent is at least one of deionized water, acetonitrile, dimethylformamide, dimethyl sulfoxide, ethanol, isopropanol and an ionic liquid.

5. The method for preparing a separation membrane by interfacial polymerization and light post-treatment according to claim 1, wherein the organic phase monomer is at least one of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, 1,3,6-naphthalenetrisulfonyl chloride, toluene diisocyanate and maleic anhydride.

6. The method for preparing a separation membrane by interfacial polymerization and light post-treatment according to claim 1, wherein the weakly polar solvent is at least one of n-hexane, n-heptane, n-octane, acetone, cyclohexanone, toluene, xylene, chloroform, carbon tetrachloride and isoparaffin solvents.

7. The method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment according to claim 1, wherein the monomer concentration in solution A is 0.01 to 20 wt%, and the monomer concentration in solution B is 0.01 to 15 wt%.

8. The method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment according to claim 1, wherein the porous polymer base membrane is immersed in solution A for 0.5 to 60 minutes and in solution B for 0.5 to 60 minutes.

9. The method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment according to claim 1, wherein when the porous polymer base membrane is taken out from liquid A, inert gas purging or roller squeezing is used to remove residual liquid on the surface.

10. The method for preparing a separation membrane by post-interfacial polymerization and light irradiation treatment according to claim 1, wherein the porous polymer base membrane is taken out from the infiltration solution B and then washed with a weak polar solvent.

11. The method for preparing a separation membrane by post-treatment of interfacial polymerization with light according to any one of claims 1 to 10, wherein the light irradiation is infrared light or ultraviolet light, the wavelength of the light irradiation is 100 nm to 25 μm, the treatment time is 0.5 to 30 min, and the light intensity is 50 μW to 1000 mW / cm 2 .

Images