Solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane as well as preparation method and application thereof

Abstract

The invention relates to a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane as well as a preparation method and application thereof, and belongs to the technical field of wastewater treatment. The technical problem that a nanofiltration membrane in the prior art is only suitable for a water system and is limited to be used in an organic solvent system or a mixed system of an organic solvent and water is solved. The chemical structural formula of the solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane is as shown in formula I. In the formula I, R1 and R2 are both hydrogen atoms, or R1 and R2 are both methyl, or R1 and R2 are isopropyl and methyl respectively; x, y and z are polymerization degrees, 1 < = x < = 400, 1 < = y < = 400, and 1 < = z < = 400. The solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane has excellent membrane-forming property, mechanical property, thermal stability and chemical stability and high water flux, the retention rate of dye exceeds 90%, and the solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane has excellent application and popularization prospects in the field of treatment of printing and dyeing wastewater containing organic solvents. # imgabs0 # formula I

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and specifically relates to a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane and a preparation method and application thereof, and especially relates to the application of the solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane in treating printing and dyeing wastewater containing organic solvents. Background Art

[0002] Since the beginning of the 21st century, the textile printing and dyeing industry has entered a stage of rapid development and has begun to play an important role in the national economy. The textile printing and dyeing production process consumes a large amount of clean water resources and produces a large amount of printing and dyeing wastewater. According to statistics, at least 200L of printing and dyeing wastewater is discharged for every 1kg of printed and dyed textile products produced. As a typical difficult-to-degrade industrial pollutant, the complexity of textile printing and dyeing wastewater is mainly due to the molecular structure characteristics of the dye and the influence of process additives. Traditional printing and dyeing dyes are based on benzene, naphthalene, and anthraquinone aromatic compounds as the core skeleton, and are often modified with functional groups through aniline and benzidine intermediates. During the production process, dye molecules chelate with metal salts (such as transition metal ions such as chromium, copper, and iron) to form stable complexes, resulting in the presence of high concentrations of organic pollutants and heavy metal ions in the wastewater system, showing the "three highs" characteristics of high salinity, high chroma, and high chemical oxygen demand (COD). In addition, various organic solvents are used in the dyeing, printing and post-processing steps of the printing and dyeing process, such as benzene, toluene, xylene, alcohols and ketones, resulting in a large amount of organic solvents in the wastewater. If the printing and dyeing wastewater is discharged directly without any purification treatment, it will not only cause a waste of resources, but also pose a great threat to human health and the ecological environment. Traditional methods for treating printing and dyeing wastewater include oxidation, coagulation, flocculation, aerobic and anaerobic biological treatment, adsorption, electrochemical oxidation and ozone oxidation, etc. These methods all have certain limitations, resulting in the inability to recycle and reuse dyes and water in printing and dyeing wastewater, resulting in a waste of resources, which is not in line with the concept of energy conservation and green sustainable development.

[0003] Membrane separation technology has the advantages of low energy consumption, low operating pressure, no phase change, no chemical reaction and high separation efficiency, and has been widely developed and applied. Among them, nanofiltration membrane technology is an efficient water purification method that can separate ions and small molecular weight compounds. It can be used for decolorization, water and salt recovery, and COD reduction, meeting the necessary standards for printing and dyeing wastewater treatment. The core of nanofiltration membrane technology is nanofiltration membrane. Currently, the nanofiltration membrane materials commonly used to treat printing and dyeing wastewater include polysulfone (PSF), polyethersulfone (PES), polybenzimidazole (PBI), polyimide (PI), polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF). However, due to the hydrophobicity of its main chain structure, it is easily contaminated by printing and dyeing wastewater, resulting in a decrease in flux and separation efficiency. In addition, the amorphous aggregate structure also makes it susceptible to swelling or dissolution by organic solvents, resulting in the destruction of the integrity of the membrane and the loss of separation performance, so that it can only be used in water systems, and cannot be used in organic solvent systems or organic solvent and water mixed systems. The Chinese patent (publication number 113952846B) uses phenolphthalein and phenolphthalein derivatives to polymerize with fluoroketone to obtain tertiary aminated polyaryletherketone, and then quaternization reaction is performed to prepare zwitterionic polyaryletherketone. The zwitterionic polyaryletherketone loose nanofiltration membrane is obtained by non-solvent induced phase transformation method. The membrane has excellent heat resistance, anti-fouling and permeation selectivity, and can be effectively used to treat high-temperature printing and dyeing wastewater. However, due to the steric hindrance effect of its phenolphthalein side group, the accumulation of polymer chains is hindered, resulting in poor solvent resistance of the zwitterionic polyetheretherketone loose nanofiltration membrane, so that it can only be used for the separation of water systems, and its application range is subject to certain restrictions. Therefore, it is very necessary to develop a zwitterionic polyaryletherketone nanofiltration membrane material with good solvent resistance and anti-fouling properties. Summary of the invention

[0004] The present invention solves the technical problem that the nanofiltration membrane in the prior art is only applicable to water systems and is limited in use in organic solvent systems or organic solvent and water mixed systems, and provides a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane and a preparation method and application thereof. The nanofiltration membrane of the present invention has good solvent resistance, heat resistance, pollution resistance and permeation selectivity.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows.

[0006] In a first aspect, the present invention provides a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane, wherein the chemical structural formula of the material of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane is as shown in Formula I; ; Formula I;

[0007] In the formula I, R1 and R2 are both hydrogen atoms (H), or R1 and R2 are both methyl groups (-CH3), or R1 and R2 are isopropyl groups (-CH(CH3)2) and methyl groups (-CH3), respectively; x, y and z are all polymerization degrees, 1≤x≤400, 1≤y≤400, 1≤z≤400.

[0008] In a second aspect, the present invention provides a method for preparing a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane, the steps of which are as follows:

[0009] S1, subjecting bisphenol monomer, 4,4-difluorobenzophenone and carbonate to a nucleophilic polycondensation reaction at a molar ratio of 1:1:1.2-1.5 to obtain a phenolphthalein polyaryletherketone;

[0010] The bisphenol monomer is phenolphthalein, p-xylenolphthalein or thymolphthalein;

[0011] S2, preparing a casting solution with phenolphthalein polyaryletherketone to form a film on a film-forming substrate, immersing the substrate with the film in deionized water for phase conversion, and obtaining a phenolphthalein polyaryletherketone film;

[0012] S3, soaking the phenolphthalein poly(aryletherketone) membrane in a cross-linking solution containing N,N-bis(3-aminopropyl)methylamine to obtain a cross-linked tertiary aminated poly(aryletherketone) membrane;

[0013] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in a hydrogen peroxide solution with a concentration of 1-5 mol / L, and react at 30-80°C for 2-24 hours. After the reaction, rinse with deionized water to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0014] Preferably, in step S1, the carbonate is anhydrous potassium carbonate, anhydrous sodium carbonate or a mixture of both, and the mass percentage of anhydrous potassium carbonate in the mixture is ≥30%.

[0015] Preferably, the process of step S1 is: firstly add bisphenol monomer, 4,4-difluorobenzophenone, carbonate, water-carrying agent and first organic solvent into a reaction container, dehydrate the obtained mixed solution under the protection of inert atmosphere, heat and react after dehydration, cool after the reaction is completed, then pour the obtained reaction solution into deionized water to precipitate to obtain a white fibrous solid, finally crush the white fibrous solid into powder, wash and dry to obtain phenolphthalein polyaryletherketone.

[0016] More preferably, the solid content of the mixed solution is 10wt%~30wt%.

[0017] More preferably, the first organic solvent is dimethyl sulfoxide, sulfolane, diphenyl sulfone or N-methylpyrrolidone.

[0018] More preferably, the water-carrying agent is toluene.

[0019] More preferably, the volume ratio of the water-carrying agent to the first organic solvent is 1:1-2.

[0020] More preferably, the inert atmosphere is nitrogen.

[0021] More preferably, the dehydration temperature is 120-155° C., and the dehydration time is 2-12 hours.

[0022] More preferably, the reaction temperature is 160-200° C., and the reaction time is 10-20 h.

[0023] More preferably, the cleaning is performed by heating and refluxing with water and ethanol at 80-100° C. for 3-5 times respectively.

[0024] More preferably, the drying is vacuum drying at a temperature of 80-110° C. for a time of 48-72 h.

[0025] In the present invention, the chemical reaction formula of step S1 is (taking toluene as the water-carrying agent):

[0026] ;

[0027] In the formula, R1 and R2 are both hydrogen atoms (H), or R1 and R2 are both methyl groups (-CH3), or R1 and R2 are isopropyl groups (-CH(CH3)2) and methyl groups (-CH3), respectively; n is the degree of polymerization, 1≤n≤400.

[0028] Preferably, the process of step S2 is: first dissolving the phenolphthalein polyaryletherketone in a second organic solvent to obtain a casting liquid, then degassing the casting liquid, pouring it on a film-forming substrate, flattening it to obtain a primary liquid film, and after volatilizing in the air, immersing it in deionized water for phase inversion, so that the second organic solvent and deionized water are fully exchanged to obtain a phenolphthalein polyaryletherketone membrane.

[0029] More preferably, the second organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, N-methylpyrrolidone or tetrahydrofuran.

[0030] More preferably, the concentration of the casting solution is 10wt%~30wt%.

[0031] More preferably, the degassing method is: standing for 24 to 72 hours.

[0032] More preferably, the film-forming substrate is a glass plate.

[0033] More preferably, the paving method is: spreading the casting liquid with a scraper of 150-250 μm at a constant moving speed.

[0034] More preferably, the preparation environment requirements of the primary liquid membrane are: temperature of 10-20° C. and relative humidity of 40%-50%.

[0035] More preferably, the volatilization time is 10 to 120 seconds.

[0036] More preferably, the phase inversion time is 24 to 48 hours.

[0037] Preferably, the process of step S3 is: first dissolving N,N-bis(3-aminopropyl)methylamine in a third organic solvent to obtain a cross-linking solution with a concentration of 0.05-0.5 mol / L; then immersing the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heating to 30-50°C to react for 24-48 hours, cooling to room temperature after the reaction is completed, and rinsing with a third organic solvent and deionized water for 3-5 times respectively to obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0038] More preferably, the third organic solvent is acetonitrile, n-hexane, methanol, ethanol, isopropanol or toluene.

[0039] In the present invention, the chemical reaction formula of step S3 is:

[0040] .

[0041] In a third aspect, the present invention also provides the use of the above-mentioned solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane in treating printing and dyeing wastewater containing organic solvents.

[0042] The organic solvent in the printing and dyeing wastewater of the present invention can be a polar aprotic solvent (N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclopentane, acetonitrile, acetone or N-methylpyrrolidone, etc.), a polar protic solvent (methanol, ethanol, propanol or isopropanol, etc.) and a non-polar solvent (n-hexane, n-heptane, benzene or toluene, etc.).

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane of the invention has excellent film-forming property, mechanical property, thermal stability and chemical stability.

[0045] The method for preparing a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane of the present invention prepares poly(aryletherketone) membranes of various pore sizes by adjusting an immersion precipitation phase conversion method, then immerses the membrane in a cross-linking solution of N,N-bis(3-aminopropyl)methylamine of different concentrations and heats it for cross-linking, and then uses a hydrogen peroxide solution to convert the tertiary amine into a quaternary amine, and finally obtains a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0046] The solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane of the present invention has not only good solvent resistance and stable membrane performance, but also high water flux and a dye retention rate of more than 90%, and has excellent application and promotion prospects in the field of printing and dyeing wastewater treatment containing organic solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 The NMR of the phenolphthalein polyaryletherketone prepared in Example 1 of the present invention is ( 1 H NMR) spectrum.

[0049] Figure 2 This is the infrared absorption (FTIR) spectrum of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane prepared in Example 1 of the present invention.

[0050] Figure 3 This is a relationship diagram between the methanol permeability and sunset yellow rejection rate of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membranes prepared in Examples 1 to 4 of the present invention and the solid content of the casting solution.

[0051] Figure 4 This is a graph showing the relationship between the methanol permeability and sunset yellow rejection of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membranes prepared in Examples 5 to 8 of the present invention and the concentration of the cross-linking solution.

[0052] Figure 5 This is a graph showing the separation performance of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane prepared in Examples 8 to 10 of the present invention for a methanol solution containing 20 ppm sunset yellow.

[0053] Figure 6 The gel contents of the phenolphthalein-based poly(aryletherketone) membrane and the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane prepared in Example 1 of the present invention after being immersed in N,N-dimethylformamide for 168 hours respectively. DETAILED DESCRIPTION

[0054] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0055] In order to make those skilled in the art better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the embodiments. The embodiments described are only specific descriptions of the claims of the present invention, and the claims include but are not limited to the contents of the embodiments described.

[0056] Unless otherwise specified, the reagents and materials described in the following examples can be obtained from commercial sources; the test methods described are conventional methods unless otherwise specified.

[0057] Example 1

[0058] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0059] S1. Add 20mmol phenolphthalein, 20mmol 4,4-difluorobenzophenone, 24mmol potassium carbonate, 18mL toluene and 36mL dimethyl sulfoxide to a three-necked flask equipped with a stirrer, a nitrogen tube, a condenser and a water separator; start mechanical stirring, pass nitrogen into the three-necked flask, and after the reaction monomer is dissolved, heat the reaction system to 140°C and dehydrate for 4h; continue to heat the reaction system to 165°C for 10h; after the system is slightly cooled, add the generated viscous solution dropwise to deionized water for precipitation to obtain a white fibrous solid, crush it, and heat and wash it with water and ethanol for 5 times in turn, and finally place the product in a vacuum oven at 110°C and dry it for 48h to obtain a phenolphthalein-based polyaryletherketone. After testing, the number average molecular weight of the phenolphthalein-based polyaryletherketone is 60000g / mol.

[0060] S2. Dissolve 5 g of phenolphthalein poly(aryletherketone) in 41 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 10 wt%. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 °C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein poly(aryletherketone) membrane, which is stored in deionized water for subsequent use.

[0061] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.05 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0062] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0063] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 17.5 L / m 2. h . bar, and the retention rate of sunset yellow was 90.5%. This indicates that the zwitterionic polyaryletherketone nanofiltration membrane prepared by the present invention has excellent permeation selectivity in an organic solvent system and is very suitable for treating printing and dyeing wastewater containing organic solvents.

[0064] Example 2

[0065] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0066] S1. Same as Example 1.

[0067] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 34 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 12 wt%, and let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0068] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.05 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0069] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0070] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 15.8 L / m 2. h . bar, the retention rate of sunset yellow is 91.6%.

[0071] Example 3

[0072] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0073] S1. Same as Example 1.

[0074] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 28 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 14 wt%. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0075] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.05 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0076] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0077] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 14.3 L / m 2. h . bar, the retention rate of sunset yellow is 92.5%.

[0078] Example 4

[0079] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0080] S1. Same as Example 1.

[0081] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 24 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 16 wt %. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0082] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.05 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0083] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0084] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 13.9 L / m 2. h . bar, the retention rate of sunset yellow is 93.6%.

[0085] Example 5

[0086] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0087] S1. Same as Example 1.

[0088] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 41 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 14 wt%. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0089] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.1 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0090] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0091] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 13.5 L / m 2. h . bar, the retention rate of sunset yellow was 93.0%.

[0092] Example 6

[0093] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0094] S1. Same as Example 1.

[0095] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 41 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 14 wt%. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0096] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.2 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0097] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0098] The zwitterionic poly(aryletherketone) nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic poly(aryletherketone) nanofiltration membrane was 12.0 L / m 2. h . bar, the retention rate of sunset yellow is 94.5%.

[0099] Example 7

[0100] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0101] S1. Same as Example 1.

[0102] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 41 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 14 wt%. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0103] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.3 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0104] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0105] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 11.2 L / m 2. h . bar, the retention rate of sunset yellow was 95.0%.

[0106] Example 8

[0107] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0108] S1. Same as Example 1.

[0109] S2. Dissolve 5 g of the phenolphthalein polyaryletherketone prepared in Example 1 in 41 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 14 wt%. Let it stand for degassing at room temperature or under vacuum for 48 h. Pour the casting solution onto a glass plate at an ambient temperature of 15 ° C and a relative humidity of 40%. Use a 250 μm scraper to spread the casting solution at a constant moving rate to obtain a primary liquid film of uniform thickness. After evaporating in the air for 30 s, immediately transfer it to deionized water for phase transformation into a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein polyaryletherketone membrane, which is stored in deionized water for subsequent use.

[0110] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.4 mol / L cross-linking solution, immerse the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heat to 50°C for 48 hours, cool to room temperature after the reaction, rinse the membrane with acetonitrile and deionized water for 5 times in turn, and obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

[0111] S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in 1 mol / L hydrogen peroxide solution, heat to 50°C for 10 h to fully oxidize the tertiary amine groups into amine-oxy zwitterionic groups. After the reaction, rinse with deionized water for 5 times to obtain a solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane.

[0112] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 10.7 L / m 2. h . bar, the retention rate of sunset yellow was 95.0%.

[0113] Example 9

[0114] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0115] S1. Add 20mmol of p-xylenolphthalein, 20mmol of 4,4-difluorobenzophenone, 24mmol of potassium carbonate, 20mL of toluene and 40mL of cyclopentane into a three-necked flask equipped with a stirrer, a nitrogen tube, a condenser and a water separator; start mechanical stirring, introduce nitrogen into the three-necked flask, and after the reaction monomers are dissolved, heat the reaction system to 140°C and dehydrate for 6h; continue to heat the reaction system to 180°C for 15h; after the system is slightly cooled, add the generated viscous solution dropwise to deionized water for precipitation to obtain a white fibrous solid, which is crushed and washed with water and ethanol for 5 times in turn, and finally the product is placed in a vacuum oven at 110°C and dried for 48h to obtain a phenolphthalein-based polyaryletherketone. After testing, the number average molecular weight of the phenolphthalein-based polyaryletherketone is 110000g / mol.

[0116] S2~S4. Same as Example 8.

[0117] The zwitterionic polyaryletherketone nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane was 11.2 L / m 2. h . bar, the retention rate of sunset yellow is 94.3%.

[0118] Example 10

[0119] The preparation method of solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane comprises the following steps:

[0120] S1. Add 20mmol of thymolphthalein, 20mmol of 4,4-difluorobenzophenone, 24mmol of potassium carbonate, 20mL of toluene and 40mL of diphenyl sulfone to a three-necked flask equipped with a stirrer, a nitrogen tube, a condenser and a water separator; start mechanical stirring, introduce nitrogen into the three-necked flask, and after the reaction monomers are dissolved, heat the reaction system to 140°C and dehydrate for 6h; continue to heat the reaction system to 180°C for 14h; after the system is slightly cooled, add the generated viscous solution dropwise to deionized water for precipitation to obtain a white fibrous solid, which is crushed and washed with water and ethanol for 5 times in turn, and finally the product is placed in a vacuum oven at 110°C and dried for 48h to obtain a phenolphthalein-based polyaryletherketone. After testing, the number average molecular weight of the phenolphthalein-based polyaryletherketone is 120,000 g / mol.

[0121] S2~S4. Same as Example 8.

[0122] The zwitterionic poly(aryletherketone) nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic poly(aryletherketone) nanofiltration membrane was 12.1 L / m 2. h .bar, the retention rate of sunset yellow is 93.2%.

[0123] Figure 1 The phenolphthalein polyaryletherketone prepared in Example 1 of the present invention 1 H NMR spectrum. Figure 1 It can be seen that 1 H NMR (600MHz,CDCl3), hydrogen 2, 4, 5 and 8 are doublets, with chemical shifts of 7.37ppm, 7.78ppm, 7.97ppm, 7.74ppm respectively; hydrogen 1 and 3 are also doublets, with chemical shifts of 7.07-6.99 ppm; hydrogen 6 and 7 are multiplets, with chemical shifts of 7.59ppm. The peak positions, peak numbers and peak splitting of various hydrogens in the spectrum correspond to the chemical structure of polyaryletherketone, indicating that polyaryletherketone was successfully synthesized.

[0124] Figure 2 The FTIR spectra of the phenolphthalein-based poly(aryletherketone) membrane and the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane prepared in Example 1 of the present invention are shown in FIG. Figure 2 It can be seen that compared with the phenolphthalein-based poly(aryletherketone) membrane, the zwitterionized poly(aryletherketone) nanofiltration membrane has a -1 and 2920cm -1 There are obvious absorption peaks, which are caused by the vibration of methyl and methylene groups in the cross-linking agent structure; in addition, the peaks of lactone ring and ether bond are from 1771cm -1 (OC=O) and 1236cm -1 (OCO) shifted to 1761cm -1 (NC=O) and 1230cm -1 (OCO), which is due to the reaction of the lactone ring with the primary amine of the crosslinker (N,N-bis(3-aminopropyl)methylamine); 1650 cm -1 The intensity of the carbonyl peak at 1720 cm -1 The peak of quaternary amine appears at , indicating that the tertiary amine is successfully oxidized to quaternary amine. Therefore, from the above FTIR results analysis, it can be seen that the zwitterionic poly(aryletherketone) nanofiltration membrane is successfully prepared.

[0125] Figure 3 This is a relationship diagram of the methanol permeability and sunset yellow retention rate of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membranes prepared in Examples 1 to 4 of the present invention and the solid content of the casting solution (in Examples 1 to 4, the solid content of the casting solution is 10wt%, 12wt%, 14wt% and 16wt%, respectively).

[0126] Figure 4This is a relationship diagram of the methanol permeability and sunset yellow retention rate of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membranes prepared in Examples 5 to 8 of the present invention and the concentration of the cross-linking solution (in Examples 5 to 8, the concentrations of the cross-linking solution are 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, and 0.4 mol / L, respectively).

[0127] Figure 5 This is a graph showing the separation performance of the solvent-resistant zwitterionic poly(aryletherketone) nanofiltration membrane prepared in Examples 8 to 10 of the present invention for a methanol solution containing 20 ppm sunset yellow.

[0128] Figure 6 The gel content of the phenolphthalein-based polyaryletherketone membrane and the solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane prepared in Example 1 of the present invention after being immersed in N,N-dimethylformamide for 168 hours. Figure 6 It can be seen that the zwitterionic polyaryletherketone nanofiltration membrane has excellent solvent resistance and is suitable for treating printing and dyeing wastewater containing any organic solvent system.

[0129] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A zwitterionized polyaryletherketone nanofiltration membrane, characterized in that: The chemical structural formula of the material of the zwitterionic polyaryletherketone nanofiltration membrane is shown in Formula I; ； Formula I; In the formula I, R1 and R2 are both hydrogen atoms, or R1 and R2 are both methyl groups, or R1 and R2 are isopropyl and methyl groups respectively; x, y and z are all polymerization degrees, 1≤x≤400, 1≤y≤400, 1≤z≤400.

2. The method for preparing the zwitterionic polyaryletherketone nanofiltration membrane according to claim 1, characterized in that: Here are the steps: S1, subjecting bisphenol monomer, 4,4-difluorobenzophenone and carbonate to a nucleophilic polycondensation reaction at a molar ratio of 1:1:1.2-1.5 to obtain a phenolphthalein polyaryletherketone; The bisphenol monomer is phenolphthalein, p-xylenolphthalein or thymolphthalein; S2, preparing a casting solution with phenolphthalein polyaryletherketone to form a film on a film-forming substrate, immersing the film-forming substrate with the film in deionized water for phase conversion, and obtaining a phenolphthalein polyaryletherketone film; S3, soaking the phenolphthalein poly(aryletherketone) membrane in a cross-linking solution containing N,N-bis(3-aminopropyl)methylamine to obtain a cross-linked tertiary aminated poly(aryletherketone) membrane; S4. Soak the cross-linked tertiary aminated poly(aryletherketone) membrane in a hydrogen peroxide solution with a concentration of 1-5 mol / L, and react at 30-80°C for 2-24 hours. After the reaction is completed, rinse with deionized water to obtain a zwitterionized poly(aryletherketone) nanofiltration membrane.

3. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 2, characterized in that: In step S1, the carbonate is anhydrous potassium carbonate, anhydrous sodium carbonate or a mixture of the two, and the mass percentage of anhydrous potassium carbonate in the mixture is ≥30%.

4. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 2, characterized in that: The process of step S1 is as follows: firstly, bisphenol monomer, 4,4-difluorobenzophenone, carbonate, water-carrying agent and first organic solvent are added into a reaction container, the obtained mixed solution is dehydrated under the protection of an inert atmosphere, heated for reaction after dehydration, cooled after the reaction is completed, and then the obtained reaction solution is poured into deionized water for precipitation to obtain a white fibrous solid, and finally the white fibrous solid is crushed into powder, washed and dried to obtain phenolphthalein polyaryletherketone.

5. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 4, characterized in that: The solid content of the mixed solution is 10wt%~30wt%; The first organic solvent is dimethyl sulfoxide, sulfolane, diphenyl sulfone or N-methylpyrrolidone; The water-carrying agent is toluene; The volume ratio of the water-carrying agent to the first organic solvent is 1:1-2; The dehydration temperature is 120-155°C, and the dehydration time is 2-12 hours; The reaction temperature is 160-200°C and the reaction time is 10-20h; The cleaning is performed by heating and refluxing with water and ethanol at 80-100°C for 3-5 times; The drying is vacuum drying at a temperature of 80-110° C. for a time of 48-72 hours.

6. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 2, characterized in that: The process of step S2 is: first dissolving the phenolphthalein polyaryletherketone in a second organic solvent to obtain a casting liquid, then degassing the casting liquid, pouring it on a film-forming substrate, flattening it to obtain a primary liquid film, and after volatilizing in the air, immersing it in deionized water for phase conversion to obtain a phenolphthalein polyaryletherketone film.

7. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 6, characterized in that: The second organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, N-methylpyrrolidone or tetrahydrofuran; The concentration of the casting solution is 10wt%~30wt%; The degassing method is: standing for 24 to 72 hours; The film-forming substrate is a glass plate; The paving method is: using a scraper with a diameter of 150-250 μm to spread the casting liquid at a constant moving speed; The preparation environment requirements of the primary liquid film are: temperature of 10-20°C and relative humidity of 40%-50%; The volatilization time is 10 to 120 seconds; The phase conversion time is 24 to 48 hours.

8. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 2, characterized in that: The process of step S3 is: first dissolving N,N-bis(3-aminopropyl)methylamine in a third organic solvent to obtain a cross-linking solution with a concentration of 0.05-0.5 mol / L; then immersing the phenolphthalein poly(aryletherketone) membrane in the cross-linking solution, heating to 30-50° C. for reaction for 24-48 hours, cooling to room temperature after the reaction is completed, and rinsing with the third organic solvent and deionized water for 3-5 times respectively to obtain a cross-linked tertiary aminated poly(aryletherketone) membrane.

9. The method for preparing the zwitterionized polyaryletherketone nanofiltration membrane according to claim 8, characterized in that: The third organic solvent is acetonitrile, n-hexane, methanol, ethanol, isopropanol or toluene.

10. Use of the zwitterionic polyaryletherketone nanofiltration membrane according to claim 1 in treating printing and dyeing wastewater containing organic solvents.

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