Organic solvent-resistant separation membrane and method for manufacturing the same

Abstract

The application discloses a kind of organic solvent-resistant separation membranes and preparation method thereof, belong to separation membrane processing technical field, for solving the technical problems that separation performance of polymer separation membrane in prior art needs to be further improved and solvent resistance of separation membrane needs to be further improved;The application comprises the following steps: polyimide, reinforcing agent, N-methyl pyrrolidone, pore former and load auxiliary agent are added to beaker, stirring at room temperature until system dissolves, suction filtration, filtrate is placed for 5-8h, to obtain casting solution;The application is prepared by the mutual cooperation of the prepared reinforcing agent, polyimide and polyethylene glycol to prepare casting solution, and is modified after coating the casting solution on pretreated substrate, to prepare support layer, and to prepare separation membrane after modifying plating film outside the support layer, not only effectively improve the permeation flux and retention rate of separation membrane, but also improve the solvent resistance of separation membrane.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of separation membrane processing, in particular to a kind of organic solvent-resistant separation membrane and preparation method thereof. BACKGROUND

[0002] Membrane separation technology refers to the mixture of different particle sizes of molecules at molecular level is selectively separated when passing through semi-permeable membrane, and semi-permeable membrane is also called separation membrane or filter membrane. The membrane wall is covered with small holes, which can be divided into microfiltration membrane (MF), ultrafiltration membrane (UF), nanofiltration membrane (NF) and reverse osmosis membrane (RO) according to the size of the holes. Membrane separation adopts cross-flow filtration or dead-end filtration mode. Membrane separation technology has gradually replaced the heat-based separation process dominated by distillation, and is widely used in wastewater treatment, food processing, seawater desalination and other fields.

[0003] In the fields of biopharmaceuticals, petroleum industry and organic synthesis, a large amount of organic solvents are needed for the separation and purification of chemical products. Therefore, the purification of solutes and the recovery of organic solvents are very important. In addition, heat-sensitive solutes and solvents are easily decomposed during distillation. The separation scale and separation efficiency of nanofiltration separation membrane technology are well matched with such requirements.

[0004] The separation membrane in the prior art mainly includes high molecular membrane and inorganic membrane. The high molecular membrane is usually formed by pouring casting solution on non-woven fabric and then solidifying. It is widely used because of its simple preparation and low cost. The casting solution for preparing high molecular separation membrane is usually composed of polymer, solvent, additive and other components. There are differences in the physicochemical properties between these components, which leads to poor compatibility between the components, easy to cause uneven structure and defects of the membrane, and further affects the separation performance of the membrane. In addition, the weak interface between the components of the separation membrane makes the separation membrane have obvious shortcomings in solvent resistance, especially when it is in contact with organic solvents for a long time. The structure of the membrane is easy to swell, and the solvent resistance of the separation membrane needs to be further improved.

[0005] In view of the technical defects in this regard, a solution is proposed. SUMMARY

[0006] The purpose of the present application is to provide an organic solvent-resistant separation membrane and a preparation method thereof, which solves the technical problems of poor compatibility between the components of the high molecular separation membrane in the prior art, uneven structure and defects of the separation membrane, and further improves the separation performance and solvent resistance of the separation membrane.

[0007] The purpose of the present application can be realized by the following technical scheme: a preparation method of an organic solvent-resistant separation membrane, comprising the following steps:

[0008] S1, polyimide, reinforcing agent, N-methyl pyrrolidone, pore-forming agent and loading aid are added to a beaker, stirred at room temperature until the system is dissolved, filtered, the filtrate is left for 5-8h, to obtain a casting solution;

[0009] S2, the substrate is completely immersed in N-methyl pyrrolidone, soaked at room temperature for 40-60min, the substrate is taken out and laid flat, to obtain a pretreated substrate;

[0010] S3, the casting solution is uniformly coated on the pretreated substrate, a coating layer with a thickness of 50-60μm is formed on the surface of the pretreated substrate, and it is cured at room temperature for 5-10min, to obtain a coated non-woven fabric;

[0011] S4, the coated non-woven fabric is immersed in a modified liquid with a temperature of 70-80℃, and soaked for 10-12h, to obtain a support layer after post-processing;

[0012] S5, the support layer is placed in a mixed solution, soaked at room temperature for 2-3min, immersed in a plating solution, kept completely immersed for 30-60s, taken out of the plating solution, drained, and post-processed to obtain a separation membrane.

[0013] Further, in step S1, the polyimide, reinforcing agent, N-methyl pyrrolidone, pore-forming agent and loading aid are 10g:3g:85mL:0.8g:0.5g, the pore-forming agent is polyethylene glycol 400, and the loading aid is zinc nitrate; in step S2, the substrate is any one of PE non-woven fabric, PP non-woven fabric, nylon non-woven fabric and microporous base film.

[0014] Further, in step S4, the modified liquid is composed of hexamethylene diamine, 2-methyl imidazole and isopropyl alcohol in a ratio of 4g:3g:100mL, and the post-processing operation includes: after the reaction is completed, the immersed coated non-woven fabric is taken out of the modified liquid, washed with isopropyl alcohol three times, and then blown dry with compressed air to obtain a support layer.

[0015] Further, in step S5, the mixed solution is composed of 1,2,4-triaminobenzene hydrochloride, triethylamine and purified water in a ratio of 5g:2g:30mL, the plating solution is composed of trimesoyl chloride and isopropylbenzene in a ratio of 1g:3mL, and the post-processing operation includes: the support layer drained of the plating solution is transferred to a drying box with a temperature of 80-90℃, and dried for 10-15min, the membrane is transferred to a 10wt% sodium hydroxide solution with a temperature of 60-80℃, and treated for 15-30min, the membrane is transferred to deionized water, and ultrasonically dispersed for 40-60min at room temperature, and the membrane is transferred to a drying box with a temperature of 55-65℃, and dried to constant weight under vacuum, to obtain a separation membrane.

[0016] Further, the reinforcing agent is processed by the following steps:

[0017] A1, 4, 4'-dichlorobenzophenone, 4, 4-dihydroxydiphenyl methane, 4, 4'-dihydroxybenzophenone, potassium carbonate and dimethyl sulfoxide are added to a three-necked flask under nitrogen protection, the temperature of the three-necked flask is raised to 120-140℃, stirring until the system is dissolved, the temperature of the three-necked flask is raised to 290-320℃, and the reaction is kept for 2-3h, and then the intermediate I is obtained by post-treatment.

[0018] The synthesis reaction principle of intermediate I is:

[0019]

[0020] In the formula:

[0021] A2, the intermediate I is crushed and concentrated sulfuric acid is added to a three-necked flask, and the reaction is stirred at room temperature for 10-12h, and then the intermediate II is obtained by post-treatment.

[0022] The synthesis reaction principle of intermediate II is:

[0023]

[0024] A3, the intermediate II, 3-amino phthalimide, N-methyl pyrrolidone, toluene, and molecular sieve are added to a three-necked flask under nitrogen protection, and the temperature of the three-necked flask is raised to the refluxing temperature of the system, and the reaction is kept for 10-12h, and then the reinforcing agent is obtained by post-treatment.

[0025] The synthesis reaction principle of the reinforcing agent is:

[0026]

[0027] Further, in step A1, the amount of 4, 4'-dichlorobenzophenone, 4, 4-dihydroxydiphenyl methane, 4, 4'-dihydroxybenzophenone is 1mol: 0.8mol: 0.2mol, the amount of 4, 4'-dichlorobenzophenone, potassium carbonate and dimethyl sulfoxide is 1g: 0.5g: 15mL, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is reduced to room temperature, the reaction solution is slowly added to another three-necked flask containing purified water, and stirred, a large amount of solid is precipitated, and then filtered, the filter cake is mixed with a mixture of acetone and ethanol in a volume ratio of 1:2, and then boiled and kept for 30-50min, the mixture is cooled to room temperature, filtered, and the filter cake is transferred to a drying box with a temperature of 70-80℃, and dried to constant weight to obtain the intermediate I.

[0028] Further, in step A2, the amount of the intermediate I and concentrated sulfuric acid is 1g:10mL, the mass fraction of the concentrated sulfuric acid is 85-90%, and the post-treatment operation comprises: after the reaction is completed, the reaction solution is slowly added to a large amount of ice water, filtered, the filter cake is crushed to a particle size of less than 0.1mm, the filter cake is washed to neutral with deionized water, and then dried, the filter cake is transferred to a drying box with a temperature of 70-80 DEG C, and dried to constant weight to obtain the intermediate II.

[0029] Further, in step A3, the amount of the intermediate II, 3-amino phthalimide, N-methyl pyrrolidone, toluene and molecular sieve is 7g:1g:25mL:20g:3g, and the post-treatment operation comprises: after the reaction is completed, the temperature of the three-necked flask is reduced to room temperature, filtered, the filtrate is transferred to a three-necked flask, the temperature of the three-necked flask is increased to 130-140 DEG C, the solvent is removed by distillation under reduced pressure, the solid after distillation is crushed to a particle size of less than 0.1mm, the solid is soaked in toluene for 10h at room temperature, filtered, the filter cake is washed with toluene for 3 times and then dried, the filter cake is transferred to a drying box with a temperature of 75-85 DEG C, and dried to constant weight to obtain the reinforcing agent.

[0030] The application discloses a kind of organic solvent-resistant separation membranes, and a kind of organic solvent-resistant separation membrane preparation method is prepared.

[0031] The application has the following advantages:

[0032] 1、The organic solvent-resistant separation membrane of the application, by 4,4'-dichlorobenzophenone, 4,4-dihydroxydiphenyl methane, 4,4'-dihydroxybenzophenone as raw material, under the condition of potassium carbonate as catalyst, substitution addition reaction occurs, intermediate I is prepared, intermediate I occurs sulfonation reaction in concentrated sulfuric acid environment, sulfonic acid group is introduced on aromatic ring group, intermediate II is prepared, intermediate II reacts with 3-amino phthalimide, amide bond is generated by amidation reaction between carbonyl group on intermediate II and amino group on 3-amino phthalimide, reinforcing agent is obtained, the amide bond in reinforcing agent has good chemical stability and thermal stability, can enhance the overall performance of membrane material, at the same time, the polarity of amide bond makes reinforcing agent can form hydrogen bond or dipole-dipole interaction with macromolecule in organic solvent, thereby enhancing the adsorption and separation capacity of macromolecule in organic solvent, in addition, sulfonic acid group in reinforcing agent is strong polar group, it can combine with macromolecule in organic solvent through electrostatic interaction, hydrogen bond interaction or dipole-dipole interaction, improve the selective adsorption of separation membrane to macromolecule in organic solvent, thereby improving the separation performance of separation membrane to organic solvent.

[0033] 2、The organic solvent resistant type separation membrane in the application, through taking polyimide, reinforcing agent as support material, taking NMP as solvent, taking polyethylene glycol as pore former, taking zinc nitrate as loading assistant, forming casting solution after dissolving and defoaming, and after coating the casting solution on the substrate, modifying, preparing the support layer, and after modifying and plating the film on the outside of the support layer, preparing the separation membrane; the sulfonic acid groups on the reinforcing agent interact with the polyimide chain to form hydrogen bond or ionic bond, which helps to enhance the compatibility of the reinforcing agent and the polyimide, form more uniform pore structure in the membrane preparation process, improve the separation performance of the separation membrane to macromolecules in the organic solvent and the overall stability of the membrane material, and the polyimide and the reinforcing agent as the main components of the casting solution, the high molecular chain structure of the polyimide and the reinforcing agent makes the separation membrane have stable morphology and good solvent resistance, can withstand the erosion of organic solvents, the polyethylene glycol itself has good flexibility and the performance of promoting the film formation of polyimide, selecting polyethylene glycol as the pore former can not only improve the flexibility and film forming property of the separation membrane, but also cooperate with the sulfonic acid group to adjust the pore size and distribution of the separation membrane, so as to optimize the pore size and distribution of the separation membrane, and further improve the separation performance of the membrane.

[0034] 3、The organic solvent resistant type separation membrane of the application, through the modification liquid composed of hexamethylene diamine, 2-methyl imidazole and isopropyl alcohol to soak the coated non-woven fabric obtained by coating the casting solution on the non-woven fabric, under the catalysis of zinc and 2-methyl imidazole, the amino group on the hexamethylene diamine can react with the compound containing carbonyl group to form addition product, promote the crosslinking degree between the molecules of the separation membrane, in the solvent environment, the close crosslinking structure can reduce the penetration and swelling of the solvent molecules to the membrane material, so as to improve the solvent resistance of the membrane; taking triethylamine as organic base, promoting the dissociation of 1,2,4-triaminobenzene hydrochloride, making the mixed solution more easily soak into the support layer, immersing the support layer after soaking the mixed material into the plating solution obtained by mixing trimesoyl chloride and cumene, trimesoyl chloride as acyl chloride has high reactivity, it reacts with functional groups such as amino or hydroxyl group to form amide bond or ester bond, forming a dense polymer film on the surface of the support layer, the membrane material has undergone a series of drying and heat treatment steps to remove water and solvent in the membrane, promote some chemical reactions in the membrane, make the polymer film structure more close and stable, and then treated by alkaline solution to introduce hydroxyl, carboxyl and other hydrophilic functional groups on the surface of the membrane, enhance the hydrophilicity of the separation membrane, reduce the non-specific interaction between the membrane and the organic solvent, and improve the stability of the membrane in the organic solvent environment. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0036] Embodiment 1

[0037] The present embodiment provides a preparation method of an organic solvent-resistant separation membrane, comprising the following steps:

[0038] S1, preparation of a reinforcing agent

[0039] Take 25.1 g of 4,4'-dichlorobenzophenone, 20.0 g of 4,4-dihydroxydiphenyl methane, 21.2 g of 4,4'-dihydroxybenzophenone, 12.55 g of potassium carbonate and 376.5 mL of dimethyl sulfoxide, and stir them in a three-necked flask under nitrogen protection. Increase the temperature of the three-necked flask to 120 DEG C, and stir until the system is dissolved. Increase the temperature of the three-necked flask to 290 DEG C, and keep the reaction for 2 h. After the reaction is completed, reduce the temperature of the three-necked flask to room temperature, and slowly add the reaction solution into another three-necked flask containing 1500 mL of purified water. Stir, and a large amount of solid is precipitated. Perform suction filtration, mix the filter cake with a mixture of acetone and ethanol (1:2 by volume) after mixing, and boil for 30 min. Reduce the temperature of the mixture to room temperature, perform suction filtration, and transfer the filter cake to a drying box with a temperature of 70 DEG C. Dry until the weight is constant, and obtain intermediate I.

[0040] After the intermediate I is crushed to a particle size of less than 0.1 mm, take 10 g of the crushed intermediate I and 100 mL of 85 wt% sulfuric acid, and stir them in a three-necked flask at room temperature for 10 h. Slowly add the reaction solution into 1000 mL of deionized water with a temperature of 0 DEG C, perform suction filtration, crush the filter cake, wash the filter cake to neutral with deionized water, and then dry. Transfer the filter cake to a drying box with a temperature of 70 DEG C, and dry until the weight is constant. Obtain intermediate II.

[0041] Take 70 g of intermediate II, 10 g of 3-amino phthalimide, 250 mL of N-methyl pyrrolidone, 200 mL of toluene and 30 g of molecular sieves, and stir them in a three-necked flask under nitrogen protection. Increase the temperature of the three-necked flask to the refluxing temperature of the system, and keep the reaction for 10 h. Reduce the temperature of the three-necked flask to room temperature, perform suction filtration, remove the molecular sieves, and transfer the filtrate to a three-necked flask. Increase the temperature of the three-necked flask to 130 DEG C, and remove the solvent under reduced pressure. Crush the solid after distillation to a particle size of less than 0.1 mm, soak the solid in toluene at room temperature for 10 h, perform suction filtration, wash the filter cake with toluene for 3 times, and then dry. Transfer the filter cake to a drying box with a temperature of 75 DEG C, and dry until the weight is constant. Obtain the reinforcing agent.

[0042] S2, preparing casting solution

[0043] Weighing: polyimide 50 g, reinforcing agent 15 g, N-methyl pyrrolidone 425 mL, polyethylene glycol 400 4.0 g, and zinc nitrate 2.5 g are added to a beaker, stirred at room temperature until the system is dissolved, filtered, the filtrate is left to stand for 5 h to remove air bubbles, and a casting solution is obtained.

[0044] S3, preparing coated non-woven fabric

[0045] The PE non-woven fabric is completely immersed in N-methyl pyrrolidone, soaked at room temperature for 40 min, the PE non-woven fabric is taken out and laid flat, and a pretreated substrate is obtained;

[0046] The casting solution is uniformly coated on the pretreated substrate to form a coating layer with a thickness of 50 μm on the surface of the pretreated substrate, and is cured at room temperature for 5 min to obtain a coated non-woven fabric.

[0047] S4, preparing support layer

[0048] Mixing hexamethylene diamine, 2-methyl imidazole and isopropyl alcohol uniformly according to the ratio of 4 g:3 g:100 mL to obtain a modification solution for standby;

[0049] The coated non-woven fabric is immersed in the modification solution at a temperature of 70℃ for 10 h, after the reaction is completed, the immersed coated non-woven fabric is taken out from the modification solution, washed with isopropyl alcohol for three times, and then blown dry with compressed air to obtain a support layer.

[0050] S5, preparing separation membrane

[0051] Mixing 1,2,4-triaminobenzene hydrochloride, triethylamine and purified water uniformly according to the ratio of 5 g:2 g:30 mL to obtain a mixed solution for standby;

[0052] Mixing trimesoyl chloride and isopropylbenzene uniformly according to the ratio of 1 g:3 mL to obtain a plating solution for standby;

[0053] The support layer is placed in the mixed solution and soaked at room temperature for 2 min, the support layer is immersed in the plating solution and kept completely immersed for 30 s, the support layer is taken out from the plating solution and drained, and the support layer drained of the plating solution is transferred to a drying box at a temperature of 80℃ for heat drying for 10 min, the membrane is transferred to a 10 wt% sodium hydroxide solution at a temperature of 60℃ for heat treatment for 2 h, the membrane is transferred to deionized water, ultrasonic dispersed at room temperature for 40 min, and the membrane is transferred to a drying box at a temperature of 55℃ for vacuum drying to constant weight to obtain a separation membrane.

[0054] Example 2

[0055] The present embodiment provides a preparation method of an organic solvent resistant separation membrane, comprising the following steps:

[0056] S1, Preparation of reinforcing agent

[0057] Weigh: 4, 4'-dichlorobenzophenone 25.1 g, 4, 4-dihydroxydiphenyl methane 20.0 g, 4, 4'-dihydroxybenzophenone 21.2 g, potassium carbonate 12.55 g and dimethyl sulfoxide 376.5 mL into a three-necked flask under nitrogen protection, stir, raise the temperature of the three-necked flask to 130 ℃, stir until the system dissolves, raise the temperature of the three-necked flask to 305 ℃, keep the reaction for 2.5 h, after the reaction is completed, reduce the temperature of the three-necked flask to room temperature, slowly add the reaction solution into another three-necked flask containing 1500 mL of purified water, stir, a large amount of solid precipitates, filter, mix the filter cake with a mixture of acetone and ethanol in a volume ratio of 1:2, boil and keep for 40 min, reduce the temperature of the mixture to room temperature, filter, transfer the filter cake into a drying oven with a temperature of 75 ℃, dry to constant weight, to obtain intermediate I.

[0058] After crushing intermediate I to a particle size of less than 0.1 mm, weigh 10 g of the crushed intermediate I and 100 mL of 88 wt% sulfuric acid into a three-necked flask, stir at room temperature for 11 h, slowly add the reaction solution into 1000 mL of deionized water with a temperature of 3 ℃, filter, crush the filter cake, wash the filter cake to neutral with deionized water, dry, transfer the filter cake into a drying oven with a temperature of 75 ℃, dry to constant weight, to obtain intermediate II.

[0059] Weigh: intermediate II 70 g, 3-amino phthalimide 10 g, N-methyl pyrrolidone 250 mL, toluene 200 mL, molecular sieve 30 g into a three-necked flask under nitrogen protection, stir, raise the temperature of the three-necked flask to reflux, keep the reaction for 11 h, reduce the temperature of the three-necked flask to room temperature, filter, remove the molecular sieve, transfer the filtrate into a three-necked flask, raise the temperature of the three-necked flask to 135 ℃, remove the solvent under reduced pressure, crush the distilled solid to a particle size of less than 0.1 mm, soak the solid in toluene at room temperature for 10 h, filter, wash the filter cake with toluene for 3 times, dry, transfer the filter cake into a drying oven with a temperature of 80 ℃, dry to constant weight, to obtain the reinforcing agent.

[0060] S2, Preparation of casting solution

[0061] Weigh: polyimide 50 g, reinforcing agent 15 g, N-methyl pyrrolidone 425 mL, polyethylene glycol 400 4.0 g and zinc nitrate 2.5 g into a beaker, stir at room temperature until the system dissolves, filter, stand the filtrate for 6.5 h to remove bubbles, to obtain the casting solution.

[0062] S3, Preparation of coated non-woven fabric

[0063] The PP non-woven fabric is completely immersed in N-methyl pyrrolidone, soaked at room temperature for 50 min, and the PP non-woven fabric is taken out and laid flat to obtain a pretreated substrate;

[0064] The casting solution is uniformly coated on the pretreated substrate to form a coating layer with a thickness of 55 μm on the surface of the pretreated substrate, and the coating non-woven fabric is obtained by curing at room temperature for 8 min.

[0065] S4, preparation of a support layer

[0066] The hexamethylene diamine, 2-methyl imidazole and isopropyl alcohol are uniformly mixed in a ratio of 4 g:3 g:100 mL to obtain a modification liquid, which is ready for use;

[0067] The coated non-woven fabric is immersed in the modification liquid at a temperature of 75°C for 11 h, and after the reaction is completed, the immersed coated non-woven fabric is taken out of the modification liquid, washed three times with isopropyl alcohol, and then blown dry with compressed air to obtain a support layer.

[0068] S5, preparation of a separation membrane

[0069] The 1,2,4-triaminobenzene hydrochloride, triethylamine and purified water are uniformly mixed in a ratio of 5 g:2 g:30 mL to obtain a mixed solution, which is ready for use;

[0070] The trimesoyl chloride and isopropylbenzene are uniformly mixed in a ratio of 1 g:3 mL to obtain a plating solution, which is ready for use;

[0071] The support layer is placed in the mixed solution and soaked at room temperature for 2.5 min, then the support layer is immersed in the plating solution and kept completely immersed for 45 s, then the support layer is taken out of the plating solution and drained, and the support layer drained of the plating solution is transferred to a drying box at a temperature of 85°C and dried for 13 min, then the membrane is transferred to a 10 wt% sodium hydroxide solution at a temperature of 70°C and treated for 20 min, then the membrane is transferred to deionized water and ultrasonically dispersed at room temperature for 50 min, and then the membrane is transferred to a drying box at a temperature of 60°C and vacuum dried to constant weight to obtain a separation membrane.

[0072] Comparative Example 3

[0073] The present embodiment provides a method for preparing an organic solvent-resistant separation membrane, comprising the following steps:

[0074] S1, preparation of a reinforcing agent

[0075] Weighing: 4,4'-dichlorobenzophenone 25.1 g, 4,4-dihydroxydiphenyl methane 20.0 g, 4,4'-dihydroxybenzophenone 21.2 g, potassium carbonate 12.55 g and dimethyl sulfoxide 376.5 mL into a three-necked flask under nitrogen protection, stirring, increasing the temperature of the three-necked flask to 140℃, stirring until the system is dissolved, increasing the temperature of the three-necked flask to 320℃, keeping the reaction for 3 h, after the reaction is completed, decreasing the temperature of the three-necked flask to room temperature, slowly adding the reaction solution into another three-necked flask containing 1500 mL of purified water, stirring, a large amount of solid precipitates, suction filtration, mixing the filter cake with a mixture of acetone and ethanol in a volume ratio of 1:2, boiling and keeping for 50 min, decreasing the temperature of the mixture to room temperature, suction filtration, transferring the filter cake into a drying oven with a temperature of 80℃, drying to constant weight, to obtain intermediate I.

[0076] After crushing intermediate I to a particle size of less than 0.1 mm, weighing 10 g of the crushed intermediate I and 100 mL of 90 wt% concentrated sulfuric acid into a three-necked flask, stirring at room temperature for 12 h, slowly adding the reaction solution into 1000 mL of deionized water with a temperature of 5℃, suction filtration, crushing the filter cake, washing the filter cake to neutral with deionized water, and then drying, transferring the filter cake into a drying oven with a temperature of 80℃, drying to constant weight, to obtain intermediate II.

[0077] Weighing: 70 g of intermediate II, 10 g of 3-amino phthalimide, 250 mL of N-methyl pyrrolidone, 200 mL of toluene, and 30 g of molecular sieves into a three-necked flask under nitrogen protection, stirring, increasing the temperature of the three-necked flask to the refluxing temperature of the system, keeping the reaction for 12 h, decreasing the temperature of the three-necked flask to room temperature, suction filtration, removing the molecular sieves, transferring the filtrate into a three-necked flask, increasing the temperature of the three-necked flask to 140℃, distilling off the solvent under reduced pressure, crushing the solid after distillation to a particle size of less than 0.1 mm, soaking the solid in toluene at room temperature for 10 h, suction filtration, washing the filter cake with toluene for 3 times, and then drying, transferring the filter cake into a drying oven with a temperature of 85℃, drying to constant weight, to obtain the reinforcing agent.

[0078] S2, preparing a casting solution

[0079] Weighing: 50 g of polyimide, 15 g of the reinforcing agent, 425 mL of N-methyl pyrrolidone, 4.0 g of polyethylene glycol 400, and 2.5 g of zinc nitrate into a beaker, stirring at room temperature until the system is dissolved, suction filtration, and standing the filtrate for 8 h to remove air bubbles, to obtain a casting solution.

[0080] S3, preparing a coated non-woven fabric

[0081] Completely immersing the nylon non-woven fabric into N-methyl pyrrolidone, soaking at room temperature for 60 min, taking out the nylon non-woven fabric and laying it flat, to obtain a pretreated substrate.

[0082] The casting solution was uniformly coated on the pretreated substrate to form a coating layer with a thickness of 60 μm on the surface of the pretreated substrate, and the coating layer was cured at room temperature for 10 min to obtain a coated non-woven fabric.

[0083] S4, preparing a support layer

[0084] Hexamethylene diamine, 2-methyl imidazole and isopropyl alcohol were uniformly mixed in a ratio of 4 g:3 g:100 mL to obtain a modification solution, which was prepared for use;

[0085] The coated non-woven fabric was immersed in the modification solution at a temperature of 80°C for 12 h of soaking, and after the reaction was completed, the immersed coated non-woven fabric was taken out of the modification solution, washed three times with isopropyl alcohol, and then blown dry with compressed air to obtain a support layer.

[0086] S5, preparing a separation membrane

[0087] 1,2,4-triaminobenzene hydrochloride, triethylamine and purified water were uniformly mixed in a ratio of 5 g:2 g:30 mL to obtain a mixed solution, which was prepared for use;

[0088] Trimesoyl chloride and isopropylbenzene were uniformly mixed in a ratio of 1 g:3 mL to obtain a plating solution, which was prepared for use;

[0089] The support layer was placed in the mixed solution and soaked at room temperature for 3 min, then the support layer was immersed in the plating solution and kept fully immersed for 60 s, then the support layer was taken out of the plating solution and drained, and the support layer drained of the plating solution was transferred to a drying box at a temperature of 90°C for 15 min of soaking and drying, then the membrane was transferred to a 10 wt% sodium hydroxide solution at a temperature of 80°C for 30 min of soaking, then the membrane was transferred to deionized water and ultrasonically dispersed at room temperature for 60 min, and then the membrane was transferred to a drying box at a temperature of 65°C and vacuum dried to constant weight to obtain a separation membrane.

[0090] Comparative Example 1

[0091] The difference between this comparative example and Example 3 is that in step S1, the intermediate I is used instead of the intermediate II to prepare the reinforcing agent.

[0092] Comparative Example 2

[0093] The difference between this comparative example and Example 3 is that in step S1, the intermediate II is used instead of the reinforcing agent.

[0094] Comparative Example 3

[0095] The difference between this comparative example and Example 3 is that in step S2, polyethylene glycol 400 is not added.

[0096] Comparative Example 4

[0097] The difference between the present comparative example and Example 3 is that step S5 is cancelled, and the support layer in step S4 is used as the separation membrane.

[0098] Performance test:

[0099] The solvent resistance and separation performance of the separation membranes prepared in Examples 1-3 and Comparative Examples 1-4 were tested. The separation performance was tested by using 30 mL of a 0.02 g / L methanol solution of organic dyes as the feed liquid, using nitrogen to provide pressure, and using the test piece to separate and filter the feed liquid. During the filtration process, the time was started when the first drop of filtrate appeared, and the time was stopped when the filtrate volume reached 15 mL. The permeation flux of the membrane was calculated according to the formula The retention rate of the membrane was determined according to the formula C0-C1 / C0, wherein C0is the concentration of organic dyes in the feed liquid, and C1is the concentration of organic dyes in the filtrate. The solvent resistance was tested by placing the test piece in a N,N-dimethylformamide solvent and soaking it at room temperature for 7 days, and then measuring the separation performance of the test piece. The specific test results are shown in the following table:

[0100]

[0101]

[0102] Data analysis:

[0103] By comparing and analyzing the data in the above table, the permeation flux of the separation membrane prepared in the present application is 20.4 L·m -2 ·h -1 ·bar -1 , the retention rate is 99.6%, after soaking in an organic solvent, the permeation flux of the separation membrane is 19.6 L·m -2 ·h -1 ·bar -1 , the retention rate is 98.6%, the retention rate is 99%, and the retention rate is 99%, all the test data are better than the comparative examples, which shows that the present application is prepared by preparing a reinforcing agent and polyimide, polyethylene glycol, and then modifying the cast film solution after coating the cast film solution on the pretreated substrate to prepare a support layer, and then modifying the film on the outside of the support layer to prepare a separation membrane, which not only effectively improves the permeation flux and retention rate of the separation membrane, but also improves the solvent resistance of the separation membrane.

[0104] ​The above merely illustrates and describes the structure of the present application, and those skilled in the art can make various modifications, additions or substitutions to the specific embodiments described or use similar ways to replace, as long as the modifications, additions or substitutions do not deviate from the structure of the present application or exceed the scope defined by the claims, and should be within the protection scope of the present application.

[0105] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0106] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details and limit the present application to the specific embodiments. Obviously, many modifications and changes can be made according to the contents of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing an organic solvent-resistant separation membrane, characterized by comprising the steps of: Includes the following steps: ​ S1. Add polyimide, reinforcing agent, N-methylpyrrolidone, pore-forming agent and loading agent to a beaker, stir at room temperature until the system is dissolved, filter, and let the filtrate stand for 5-8 hours to obtain casting solution. S2. Completely immerse the substrate in N-methylpyrrolidone for 40-60 minutes at room temperature. Remove the substrate and lay it flat to obtain the pretreated substrate. S3. Apply the casting solution evenly to the pretreated substrate to form a coating layer with a thickness of 50-60μm on the surface of the pretreated substrate. Cure at room temperature for 5-10 minutes to obtain the coated nonwoven fabric. S4. Immerse the coated nonwoven fabric in a modification solution at a temperature of 70-80℃ and keep it warm for 10-12 hours. The post-treatment yields the support layer. The modification solution is composed of hexamethylenediamine, 2-methylimidazole and isopropanol in a ratio of 4g:3g:100mL. S5. Place the support layer in the mixed solution and immerse it at room temperature for 2-3 minutes. Then immerse the support layer in the coating solution and keep it completely submerged for 30-60 seconds. Remove the support layer from the coating solution, drain it, and then perform post-treatment to obtain the separation membrane. The reinforcing agent is obtained through the following steps: A1. Add 4,4'-dichlorobenzophenone, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxybenzophenone, potassium carbonate and dimethyl sulfoxide to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to 120-140℃ and stir until the system is dissolved. Raise the temperature of the three-necked flask to 290-320℃ and keep the reaction at this temperature for 2-3 hours. After post-processing, obtain intermediate I. A2. After crushing intermediate I, add it to a three-necked flask with concentrated sulfuric acid and stir the reaction at room temperature for 10-12 hours. After post-processing, intermediate II is obtained. A3. Add intermediate II, 3-aminophthalimide, N-methylpyrrolidone, toluene, and molecular sieve to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to reflux the system and keep it at this temperature for 10-12 hours. The reinforcing agent is then obtained after post-treatment.

2. The method of claim 1, wherein the organic solvent-resistant separation membrane is prepared by the steps of: In step S1, the ratio of polyimide, reinforcing agent, N-methylpyrrolidone, pore-forming agent, and loading agent is 10g:3g:85mL:0.8g:0.5g, the pore-forming agent is polyethylene glycol 400, and the loading agent is zinc nitrate; in step S2, the substrate is any one of PE nonwoven fabric, PP nonwoven fabric, nylon nonwoven fabric, and microporous base membrane.

3. The method of claim 1, wherein the organic solvent-resistant separation membrane is prepared by the steps of: In step S4, the post-processing operation includes: after the reaction is complete, the immersed coated nonwoven fabric is taken out from the modification solution, washed three times with isopropanol, and then dried with compressed air to obtain the support layer.

4. The method of claim 1, wherein the organic solvent-resistant separation membrane is prepared by the steps of: In step S5, the mixed solution is composed of 1,2,4-triaminobenzene hydrochloride, triethylamine and purified water in a ratio of 5 g:2 g:30 mL, the coating solution is composed of trimesoyl chloride and cumene in a ratio of 1 g:3 mL, and the post-treatment operation includes: transferring the support layer with the coating solution drained to a drying box with a temperature of 80-90℃, keeping warm and drying for 10-15 min, transferring the membrane to a 10 wt% sodium hydroxide solution with a temperature of 60-80℃, keeping warm and treating for 15-30 min, transferring the membrane to deionized water, ultrasonic dispersion for 40-60 min at room temperature, transferring the membrane to a drying box with a temperature of 55-65℃, and vacuum drying to constant weight to obtain the separation membrane.

5. The method of claim 1, wherein the organic solvent-resistant separation membrane is prepared by the steps of: In step A1, the ratio of 4,4'-dichlorobenzophenone, 4,4'-dihydroxydiphenylmethane and 4,4'-dihydroxybenzophenone is 1 mol:0.8 mol:0.2 mol, the ratio of 4,4'-dichlorobenzophenone, potassium carbonate and dimethyl sulfoxide is 1 g:0.5 g:15 mL, and the post-treatment operation includes: after the reaction is completed, reducing the temperature of the three-necked flask to room temperature, slowly adding the reaction solution to another three-necked flask containing purified water, stirring, and filtering under suction, mixing the filter cake with a mixed solution composed of acetone and ethanol in a ratio of 1:2, boiling and keeping warm for 30-50 min, reducing the temperature of the mixed solution to room temperature, filtering under suction, and transferring the filter cake to a drying box with a temperature of 70-80℃, drying to constant weight to obtain the intermediate I.

6. The method of claim 1, wherein the organic solvent-resistant separation membrane is prepared by the steps of: In step A2, the ratio of the intermediate I and concentrated sulfuric acid is 1 g:10 mL, the mass fraction of the concentrated sulfuric acid is 85-90%, and the post-treatment operation includes: after the reaction is completed, slowly adding the reaction solution to a large amount of ice water, filtering under suction, crushing the filter cake to a particle size of less than 0.1 mm, washing the filter cake to neutral with deionized water, filtering under suction, transferring the filter cake to a drying box with a temperature of 70-80℃, and drying to constant weight to obtain the intermediate II.

7. The method for preparing an organic solvent-resistant separation membrane according to claim 1, characterized in that, In step A3, the ratio of the intermediate II, 3-amino phthalimide, N-methyl pyrrolidone, toluene and molecular sieve is 7 g:1 g:25 mL:20 g:3 g, and the post-treatment operation includes: after the reaction is completed, reducing the temperature of the three-necked flask to room temperature, filtering under suction, transferring the filtrate to a three-necked flask, increasing the temperature of the three-necked flask to 130-140℃, distilling off the solvent under reduced pressure, crushing the distilled solid to a particle size of less than 0.1 mm, soaking the solid in toluene for 10 h at room temperature, washing the filter cake with toluene for 3 times, filtering under suction, and transferring the filter cake to a drying box with a temperature of 75-85℃, drying to constant weight to obtain the reinforcing agent.

8. An organic solvent resistant separation membrane, characterized by, A separation membrane resistant to organic solvents is prepared by using the preparation method of the separation membrane resistant to organic solvents according to any one of claims 1-7.

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