Solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane, preparation method and application thereof

Abstract

The present invention relates to a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane, a preparation method thereof and an application thereof, belonging to the technical field of wastewater treatment. It solves the technical problem that the nanofiltration membranes in the prior art are only applicable to water systems and are limited in use in organic solvent systems or mixed systems of organic solvents and water. The solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane of the present invention has a chemical structural formula as shown in Formula I. In Formula I, both R1 and R2 are hydrogen atoms, or both R1 and R2 are methyl groups, or R1 and R2 are isopropyl group and methyl group respectively; x, y and z are all degrees of polymerization, 1≤x≤400, 1≤y≤400, 1≤z≤400. The solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane has excellent film-forming property, mechanical property, thermal stability and chemical stability, and has a high water flux, and the rejection rate of dyes exceeds 90%, and has excellent application and popularization prospects in the field of printing and dyeing wastewater treatment containing organic solvents. #imgabs0# Formula I.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane, a preparation method thereof and an application thereof, and more particularly 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 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. A large amount of clean water resources are consumed in the production process of textile printing and dyeing, and a large amount of printing and dyeing wastewater is generated. According to statistics, at least 200L of printing and dyeing wastewater is discharged for every 1kg of printed and dyed textile products. As a typical refractory industrial pollutant, the complexity of the components of printing and dyeing wastewater mainly stems from the structural characteristics of dye molecules and the influence of process additives. Traditional printing and dyeing dyes have a core skeleton of benzene series, naphthalene series, anthraquinone-based aromatic compounds, and are often modified with functional groups through aniline and benzidine-based 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 simultaneous presence of high-concentration organic pollutants and heavy metal ions in the wastewater system, showing the "three highs" characteristics of high salinity, high chromaticity, and high chemical oxygen demand (COD). In addition, various organic solvents such as benzene, toluene, xylene, alcohols, and ketones are also used in the steps of dyeing, printing, and post-treatment during the printing and dyeing process, resulting in a large amount of organic solvents in the wastewater. If the printing and dyeing wastewater is directly discharged without any purification treatment, it will not only cause 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 method, coagulation method, flocculation method, aerobic and anaerobic biological treatment methods, adsorption method, electrochemical oxidation, and ozone oxidation. These methods all have certain limitations, resulting in the inability to recycle and reuse dyes and water in printing and dyeing wastewater, causing waste of resources and not meeting the development concepts of energy conservation and green sustainability.

[0003] Membrane separation technology has been widely developed and applied due to its advantages such as low energy consumption, low operating pressure, no phase change, no chemical reaction, and high separation efficiency. Among them, nanofiltration membrane technology is an efficient water purification method that can separate ions and small molecular weight compounds, and can be used for decolorization, water and salt recovery, and reduction of COD, meeting the necessary standards for printing and dyeing wastewater treatment. The core of nanofiltration membrane technology is the nanofiltration membrane. Currently, common nanofiltration membrane materials for treating printing and dyeing wastewater include polysulfone (PSF), polyethersulfone (PES), polybenzimidazole (PBI), polyimide (PI), polyacrylonitrile (PAN), and polyvinylidene fluoride (PVDF), etc. 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 aggregated structure also makes it easily swollen or dissolved by organic solvents, leading to the destruction of the membrane integrity and loss of separation performance, so that it can only be applied in water systems and cannot be used in organic solvent systems or mixed systems of organic solvents and water. Chinese Patent (Publication No. 113952846B) polymerizes phenolphthalein and phenolphthalein derivatives with fluoroketone to obtain tertiary amine-functionalized polyaryletherketone, and then conducts quaternization reaction to prepare zwitterionic polyaryletherketone. A zwitterionic polyaryletherketone loose nanofiltration membrane is obtained by non-solvent induced phase inversion method. This membrane has excellent heat resistance, anti-fouling property, and permeation selectivity, and can be effectively used for treating high-temperature printing and dyeing wastewater. However, due to the steric hindrance effect of its phenolphthalein side group, the polymer chain packing is hindered, resulting in poor solvent resistance of the zwitterionic polyetheretherketone loose nanofiltration membrane, so that it can only be used for separation in water systems, and its application range is limited to a certain extent. Therefore, it is necessary to develop a zwitterionic polyaryletherketone nanofiltration membrane material with good solvent resistance and anti-fouling property. Summary of the Invention

[0004] The present invention provides a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane, its preparation method and application to solve the technical problem that the existing nanofiltration membranes are only applicable to water systems and are limited in use in organic solvent systems or mixed systems of organic solvents and water. The nanofiltration membrane of the present invention has good solvent resistance, heat resistance, anti-fouling property, and permeation selectivity at the same time.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows.

[0006] In the first aspect, the present invention provides a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane, and the chemical structural formula of the material of the solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane is shown in Formula I;

[0007] ;

[0008] Formula I;

[0009] In the said Formula I, R 1 and R 2are all hydrogen atoms (H), or R 1 and R 2 are both methyl groups (-CH 3 ), or R 1 and R 2 are isopropyl (-CH(CH 3 )) 2 and methyl (-CH 3 ), respectively; x, y, and z are all degrees of polymerization, 1 ≤ x ≤ 400, 1 ≤ y ≤ 400, 1 ≤ z ≤ 400.

[0010] In a second aspect, the present invention provides a method for preparing a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane, and the steps are as follows:

[0011] S1. Perform a nucleophilic polycondensation reaction on a bisphenol monomer, 4,4-difluorobenzophenone, and a carbonate in a molar ratio of 1:1:1.2 to 1.5 to obtain a phenolphthalein-based poly(aryl ether ketone);

[0012] The bisphenol monomer is phenolphthalein, p-xylenolphthalein, or thymolphthalein;

[0013] S2. Prepare a casting solution with the phenolphthalein-based poly(aryl ether ketone) and form a membrane on a film-forming substrate. Immerse the substrate with the film in deionized water for phase inversion to obtain a phenolphthalein-based poly(aryl ether ketone) membrane;

[0014] S3. Immerse the phenolphthalein-based poly(aryl ether ketone) membrane in a crosslinking solution containing N,N-bis(3-aminopropyl)methylamine to obtain a crosslinked tertiary amine-functionalized poly(aryl ether ketone) membrane;

[0015] S4. Immerse the crosslinked tertiary amine-functionalized poly(aryl ether ketone) membrane in a hydrogen peroxide solution with a concentration of 1 - 5 mol / L and react at 30 - 80 °C for 2 - 24 h. After the reaction is completed, rinse with deionized water to obtain a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane.

[0016] Preferably, in step S1, the carbonate is one or a mixture of two of potassium carbonate anhydrous and sodium carbonate anhydrous, and in the mixture, the mass percentage of potassium carbonate anhydrous ≥ 30%.

[0017] Preferably, the process of step S1 is as follows: First, add the bisphenol monomer, 4,4-difluorobenzophenone, carbonate, water-carrying agent, and the first organic solvent into a reaction vessel. The obtained mixed solution is dehydrated under an inert atmosphere protection, heated for reaction after dehydration, cooled after the reaction is completed, then pour the obtained reaction solution into deionized water for precipitation to obtain a white fibrous solid, and finally crush the white fibrous solid into powder, wash, and dry to obtain the phenolphthalein-based poly(aryl ether ketone).

[0018] More preferably, the solid content of the mixed solution is 10 wt% - 30 wt%.

[0019] More preferably, the first organic solvent is dimethyl sulfoxide, sulfolane, diphenyl sulfone or N-methylpyrrolidone.

[0020] More preferably, the water-carrying agent is toluene.

[0021] More preferably, the volume ratio of the water-carrying agent to the first organic solvent is 1:1 to 2.

[0022] More preferably, the inert atmosphere is nitrogen.

[0023] More preferably, the temperature for dehydration is 120 to 155 °C, and the time for dehydration is 2 to 12 h.

[0024] More preferably, the temperature for the reaction is 160 to 200 °C, and the time for the reaction is 10 to 20 h.

[0025] More preferably, the cleaning is to heat and reflux with water and ethanol respectively for 3 to 5 times under the condition of 80 to 100 °C.

[0026] More preferably, the drying is vacuum drying, the temperature is 80 to 110 °C, and the time is 48 to 72 h.

[0027] In the present invention, the chemical reaction formula of step S1 (using toluene as the water-carrying agent) is:

[0028] ;

[0029] In the formula, both R 1 and R 2 are hydrogen atoms (H), or both R 1 and R 2 are methyl groups (-CH 3 ), or R 1 and R 2 are isopropyl group (-CH(CH 3 )) 2 and methyl group (-CH 3 ); n is the degree of polymerization, 1 ≤ n ≤ 400.

[0030] Preferably, the process of step S2 is as follows: First, dissolve the phenolphthalein-based polyaryletherketone in a second organic solvent to obtain a casting solution, then defoam the casting solution, pour it on a film-forming substrate, and level it to obtain a primary liquid film. After volatilization in the air, soak it in deionized water for phase inversion to allow sufficient exchange between the second organic solvent and deionized water, thereby obtaining a phenolphthalein-based polyaryletherketone film.

[0031] More preferably, the second organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, N-methylpyrrolidone or tetrahydrofuran.

[0032] More preferably, the concentration of the casting solution is 10 wt% to 30 wt%.

[0033] More preferably, the defoaming method is: standing for 24 to 72 h.

[0034] More preferably, the film-forming substrate is a glass plate.

[0035] More preferably, the paving method is: spreading the casting solution with a 150 - 250 μm doctor blade at a constant moving rate.

[0036] More preferably, the preparation environment requirements for the primary liquid film are: temperature 10 - 20 °C, relative humidity 40% - 50%.

[0037] More preferably, the volatilization time is 10 - 120 s.

[0038] More preferably, the phase inversion time is 24 - 48 h.

[0039] Preferably, the process of step S3 is: first dissolve 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 immerse the phenolphthalein - based polyaryletherketone membrane into the cross - linking solution, heat to 30 - 50 °C and react for 24 - 48 h, after the reaction ends, cool to room temperature, and rinse with the third organic solvent and deionized water 3 - 5 times respectively to obtain a cross - linked tertiary - aminated polyaryletherketone membrane.

[0040] More preferably, the third organic solvent is acetonitrile, n - hexane, methanol, ethanol, isopropanol or toluene.

[0041] In the present invention, the chemical reaction formula of step S3 is:

[0042] .

[0043] Thirdly, the present invention also provides the application of the above solvent - resistant zwitterionic polyaryletherketone nanofiltration membrane in treating printing and dyeing wastewater containing organic solvents.

[0044] The organic solvents in the printing and dyeing wastewater of the present invention can be polar aprotic solvents (such as N,N - dimethylformamide, N,N - dimethylacetamide, dimethyl sulfoxide, sulfolane, acetonitrile, acetone or N - methylpyrrolidone, etc.), polar protic solvents (such as methanol, ethanol, propanol or isopropanol, etc.) and non - polar solvents (such as n - hexane, n - heptane, benzene or toluene, etc.).

[0045] Compared with the prior art, the beneficial effects of the present invention are:

[0046] The solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane of the present invention has excellent film-forming properties, mechanical properties, thermal stability and chemical stability.

[0047] The preparation method of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane of the present invention prepares poly(aryl ether ketone) membranes with various pore sizes by adjusting the immersion precipitation phase inversion method, then immerses the membranes in cross-linking solutions with different concentrations of N,N-bis(3-aminopropyl)methylamine for heating and cross-linking, and then converts tertiary amines into quaternary amines with hydrogen peroxide solution, and finally obtains the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane.

[0048] The solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane of the present invention not only has good solvent resistance and stable membrane performance, but also has high water flux, and the rejection rate of dyes exceeds 90%, and has excellent application and popularization prospects in the field of printing and dyeing wastewater treatment containing organic solvents. Description of the Drawings

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0050] Figure 1 1H NMR spectrum of the phenolphthalein-based poly(aryl ether ketone) prepared in Example 1 of the present invention 1 H NMR

[0051] Figure 2 FTIR spectrum of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in Example 1 of the present invention

[0052] Figure 3 Relationship diagram of methanol permeability and sunset yellow rejection rate of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membranes prepared in Examples 1-4 of the present invention with the solid content of the casting solution

[0053] Figure 4 Relationship diagram of methanol permeability and sunset yellow rejection rate of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membranes prepared in Examples 5-8 of the present invention with the concentration of the cross-linking solution

[0054] Figure 5 Separation performance diagram of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membranes prepared in Examples 8-10 of the present invention for methanol solution containing 20 ppm sunset yellow

[0055] Figure 6The 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 h. Detailed implementation manners

[0056] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0057] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with embodiments. The described embodiments are only specific descriptions of the claims of the present invention, and the claims include but are not limited to the content of the embodiments.

[0058] The reagents and materials described in the following embodiments can be obtained from commercial sources without special instructions; the test methods are conventional methods without special instructions.

[0059] Example 1

[0060] A method for preparing a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane, the steps are as follows:

[0061] S1. Add 20 mmol of phenolphthalein, 20 mmol of 4,4-difluorobenzophenone, 24 mmol of potassium carbonate, 18 mL of toluene and 36 mL of dimethyl sulfoxide into a three-necked flask equipped with a stirrer, a nitrogen tube, a condenser and a water separator; turn on mechanical stirring, introduce nitrogen into the three-necked flask, after the reaction monomers are dissolved, raise the temperature of the reaction system to 140 °C and dehydrate for 4 h; continue to raise the temperature of the reaction system to 165 °C and react for 10 h; after the system is slightly cooled, drop the viscous solution formed into deionized water for precipitation to obtain a white fibrous solid, after pulverization, wash it 5 times successively with water and ethanol by heating, and finally place the product in a vacuum oven at 110 °C and dry it for 48 h to obtain phenolphthalein-based polyaryletherketone. After testing, the number-average molecular weight of this phenolphthalein-based polyaryletherketone is 60000 g / mol.

[0062] S2. Dissolve 5 g of phenolphthalein-based polyaryletherketone in 41 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 10 wt%, let it stand for defoaming for 48 h at room temperature or under vacuum conditions, at an ambient temperature of 15 °C and a relative humidity of 40%, pour the casting solution on a glass plate, and use a 250-μm doctor blade to spread the casting solution at a constant moving rate to obtain a primary liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion to form a film. After 24 h of solvent exchange, take out the film to obtain a phenolphthalein-based polyaryletherketone membrane, and store it in deionized water for subsequent use.

[0063] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a crosslinking solution with a concentration of 0.05 mol / L. Immerse the phenolphthalein-based polyaryletherketone membrane in the crosslinking solution, heat at 50 °C for 48 h, cool to room temperature after the reaction, and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary-amine-functionalized polyaryletherketone membrane.

[0064] S4. Immerse the crosslinked tertiary-amine-functionalized polyaryletherketone membrane in a 1 mol / L hydrogen peroxide solution, heat at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine-oxide zwitterionic groups. After the reaction, rinse 5 times with deionized water to obtain a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane.

[0065] Use the zwitterionic polyaryletherketone nanofiltration membrane prepared in this example to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane is 17.5 L / m 2. h . bar, and the rejection rate of sunset yellow is 90.5%. It shows 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.

[0066] Example 2

[0067] A preparation method of a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane is as follows:

[0068] S1. The same as Example 1.

[0069] S2. Dissolve 5 g of the phenolphthalein-based polyaryletherketone prepared in Example 1 in 34 mL of dimethyl sulfoxide to prepare a casting solution with a concentration of 12 wt%. Let it stand for defoaming for 48 h at room temperature or under vacuum conditions. At an ambient temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate, and use a 250-μm doctor blade to spread the casting solution at a constant moving rate to obtain a primary liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion to form a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein-based polyaryletherketone membrane, and store it in deionized water for subsequent use.

[0070] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a crosslinking solution with a concentration of 0.05 mol / L. Immerse the phenolphthalein-based polyaryletherketone membrane in the crosslinking solution, heat at 50 °C for 48 h, cool to room temperature after the reaction, and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary-amine-functionalized polyaryletherketone membrane.

[0071] S4. Immerse the crosslinked tertiary-aminated poly(aryl ether ketone) membrane in a 1 mol / L hydrogen peroxide solution, heat at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine-oxide zwitterionic groups. After the reaction, rinse with deionized water 5 times to obtain a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane.

[0072] Separate a methanol solution containing 20 ppm sunset yellow using the zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in this example. After testing, the methanol permeation flux of the zwitterionic poly(aryl ether ketone) nanofiltration membrane is 15.8 L / m 2. h . bar, and the rejection rate of sunset yellow is 91.6%.

[0073] Example 3

[0074] A preparation method of a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane is as follows:

[0075] S1. The same as Example 1.

[0076] S2. Dissolve 5 g of the phenolphthalein-based poly(aryl ether ketone) 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 defoaming at room temperature or under vacuum for 48 h. At an ambient temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate, and use a 250-μm doctor blade to spread the casting solution at a constant moving rate to obtain a primary liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion to form a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein-based poly(aryl ether ketone) membrane, and store it in deionized water for subsequent use.

[0077] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.05 mol / L crosslinking solution. Immerse the phenolphthalein-based poly(aryl ether ketone) membrane in the crosslinking solution, heat at 50 °C for 48 h. After the reaction, cool to room temperature, and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary-aminated poly(aryl ether ketone) membrane.

[0078] S4. Immerse the crosslinked tertiary-aminated poly(aryl ether ketone) membrane in a 1 mol / L hydrogen peroxide solution, heat at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine-oxide zwitterionic groups. After the reaction, rinse with deionized water 5 times to obtain a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane.

[0079] Separate a methanol solution containing 20 ppm sunset yellow using the zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in this example. After testing, the methanol permeation flux of the zwitterionic poly(aryl ether ketone) nanofiltration membrane is 14.3 L / m 2. h . bar, and the rejection rate of sunset yellow is 92.5%.

[0080] Example 4

[0081] A preparation method of a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane is as follows:

[0082] S1. The same as Example 1.

[0083] S2. Dissolve 5 g of the phenolphthalein-based poly(aryl ether ketone) 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 defoaming for 48 h at room temperature or under vacuum. At an ambient temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate and spread it out with a 250-μm doctor blade at a constant moving rate to obtain a primary liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion film formation. After 24 h of solvent exchange, take out the film to obtain a phenolphthalein-based poly(aryl ether ketone) membrane, and store it in deionized water for subsequent use.

[0084] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a crosslinking solution with a concentration of 0.05 mol / L. Immerse the phenolphthalein-based poly(aryl ether ketone) membrane in the crosslinking solution and react at 50 °C for 48 h. After the reaction, cool it to room temperature and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary aminated poly(aryl ether ketone) membrane.

[0085] S4. Immerse the crosslinked tertiary aminated poly(aryl ether ketone) membrane in a 1 mol / L hydrogen peroxide solution and react at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine oxide zwitterionic groups. After the reaction, rinse it 5 times with deionized water to obtain a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane.

[0086] Use the zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in this example to separate a methanol solution containing 20 ppm of sunset yellow. After testing, the methanol permeation flux of the zwitterionic poly(aryl ether ketone) nanofiltration membrane is 13.9 L / m 2. h . bar, and the rejection rate of sunset yellow is 93.6%.

[0087] Example 5

[0088] A preparation method of a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane is as follows:

[0089] S1. The same as Example 1.

[0090] S2. Dissolve 5 g of the phenolphthalein-based 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 for 48 h at room temperature or under vacuum. Under the conditions of an ambient temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate and spread it out with a 250-μm doctor blade at a constant moving rate to obtain a nascent liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion film formation. After 24 h of solvent exchange, take out the film to obtain a phenolphthalein-based polyaryletherketone film, and store it in deionized water for subsequent use.

[0091] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a cross-linking solution with a concentration of 0.1 mol / L. Immerse the phenolphthalein-based polyaryletherketone film in the cross-linking solution and react at 50 °C for 48 h. After the reaction, cool it to room temperature and rinse the film 5 times with acetonitrile and deionized water in sequence to obtain a cross-linked tertiary aminated polyaryletherketone film.

[0092] S4. Immerse the cross-linked tertiary aminated polyaryletherketone film in a 1 mol / L hydrogen peroxide solution and react at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine oxide zwitterionic groups. After the reaction, rinse it 5 times with deionized water to obtain a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane.

[0093] Use the zwitterionic polyaryletherketone nanofiltration membrane prepared in this example to separate a methanol solution containing 20 ppm of sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane is 13.5 L / m 2. h . bar, and the rejection rate of sunset yellow is 93.0%.

[0094] Example 6

[0095] A preparation method of a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane, the steps are as follows:

[0096] S1. The same as Example 1.

[0097] S2. Dissolve 5 g of the phenolphthalein-based 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 for 48 h at room temperature or under vacuum. Under the conditions of an ambient temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate and spread it out with a 250-μm doctor blade at a constant moving rate to obtain a nascent liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion film formation. After 24 h of solvent exchange, take out the film to obtain a phenolphthalein-based polyaryletherketone film, and store it in deionized water for subsequent use.

[0098] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.2 mol / L crosslinking solution. Immerse the phenolphthalein-based polyaryletherketone membrane in the crosslinking solution, heat at 50 °C for 48 h, cool to room temperature after the reaction, and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary-aminated polyaryletherketone membrane.

[0099] S4. Immerse the crosslinked tertiary-aminated polyaryletherketone membrane in a 1 mol / L hydrogen peroxide solution, heat at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine-oxide zwitterionic groups. After the reaction, rinse 5 times with deionized water to obtain a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane.

[0100] Use the zwitterionic polyaryletherketone nanofiltration membrane prepared in this example to separate a methanol solution containing 20 ppm sunset yellow. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane is 12.0 L / m 2. h . bar, and the rejection rate of sunset yellow is 94.5%.

[0101] Example 7

[0102] A preparation method of a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane is as follows:

[0103] S1. The same as Example 1.

[0104] S2. Dissolve 5 g of the phenolphthalein-based 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 defoaming for 48 h at room temperature or under vacuum. Under the conditions of an environmental temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate, and use a 250-μm doctor blade to spread the casting solution at a constant moving rate to obtain a primary liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion to form a membrane. After 24 h of solvent exchange, take out the membrane to obtain a phenolphthalein-based polyaryletherketone membrane, and store it in deionized water for subsequent use.

[0105] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a 0.3 mol / L crosslinking solution. Immerse the phenolphthalein-based polyaryletherketone membrane in the crosslinking solution, heat at 50 °C for 48 h, cool to room temperature after the reaction, and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary-aminated polyaryletherketone membrane.

[0106] S4. Immerse the crosslinked tertiary-aminated polyaryletherketone membrane in a 1 mol / L hydrogen peroxide solution, heat at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine-oxide zwitterionic groups. After the reaction, rinse 5 times with deionized water to obtain a solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane.

[0107] The zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm of sunset yellow. After testing, the methanol permeation flux of the zwitterionic poly(aryl ether ketone) nanofiltration membrane was 11.2 L / m 2. h . bar, and the rejection rate of sunset yellow was 95.0%.

[0108] Example 8

[0109] A method for preparing a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane is as follows:

[0110] S1. The same as in Example 1.

[0111] S2. Dissolve 5 g of the phenolphthalein-based poly(aryl ether ketone) 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 defoaming at room temperature or under vacuum for 48 h. Under the conditions of an environmental temperature of 15 °C and a relative humidity of 40%, pour the casting solution onto a glass plate and use a 250-μm doctor blade to spread the casting solution at a constant moving rate to obtain a primary liquid film with a uniform thickness. After volatilizing in air for 30 s, immediately transfer it to deionized water for phase inversion to form a film. After 24 h of solvent exchange, take out the film to obtain a phenolphthalein-based poly(aryl ether ketone) membrane, and store it in deionized water for subsequent use.

[0112] S3. Dissolve N,N-bis(3-aminopropyl)methylamine in acetonitrile to prepare a crosslinking solution with a concentration of 0.4 mol / L. Immerse the phenolphthalein-based poly(aryl ether ketone) membrane in the crosslinking solution and react at 50 °C for 48 h. After the reaction, cool it to room temperature and rinse the membrane 5 times with acetonitrile and deionized water in sequence to obtain a crosslinked tertiary amine-functionalized poly(aryl ether ketone) membrane.

[0113] S4. Immerse the crosslinked tertiary amine-functionalized poly(aryl ether ketone) membrane in a 1 mol / L hydrogen peroxide solution and react at 50 °C for 10 h to fully oxidize the tertiary amine groups into amine oxide zwitterionic groups. After the reaction, rinse it 5 times with deionized water to obtain a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane.

[0114] The zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in this example was used to separate a methanol solution containing 20 ppm of sunset yellow. After testing, the methanol permeation flux of the zwitterionic poly(aryl ether ketone) nanofiltration membrane was 10.7 L / m 2. h . bar, and the rejection rate of sunset yellow was 95.0%.

[0115] Example 9

[0116] A method for preparing a solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane is as follows:

[0117] S1. Add 20 mmol of p - dimethylphenolphthalein, 20 mmol of 4,4 - difluorobenzophenone, 24 mmol of potassium carbonate, 20 mL of toluene and 40 mL of sulfolane 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, after the reaction monomers are dissolved, heat the reaction system to 140 °C and dehydrate for 6 h; continue to heat the reaction system to 180 °C and react for 15 h; after the system cools slightly, drop the resulting viscous solution into deionized water for precipitation to obtain a white fibrous solid. After pulverization, wash it successively with water and ethanol by heating 5 times, and finally dry the product in a vacuum oven at 110 °C for 48 h to obtain phenolphthalein - based polyaryletherketone. After testing, the number - average molecular weight of this phenolphthalein - based polyaryletherketone is 110000 g / mol.

[0118] S2 - S4. The same as Example 8.

[0119] Separate the methanol solution containing 20 ppm of sunset yellow with the zwitterionic polyaryletherketone nanofiltration membrane prepared in this example. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane is 11.2 L / m 2. h . bar, and the rejection rate of sunset yellow is 94.3%.

[0120] Example 10

[0121] A preparation method of a solvent - resistant zwitterionic polyaryletherketone nanofiltration membrane is as follows:

[0122] S1. Add 20 mmol of thymolphthalein, 20 mmol of 4,4 - difluorobenzophenone, 24 mmol of potassium carbonate, 20 mL of toluene and 40 mL of diphenyl sulfone 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, after the reaction monomers are dissolved, heat the reaction system to 140 °C and dehydrate for 6 h; continue to heat the reaction system to 180 °C and react for 14 h; after the system cools slightly, drop the resulting viscous solution into deionized water for precipitation to obtain a white fibrous solid. After pulverization, wash it successively with water and ethanol by heating 5 times, and finally dry the product in a vacuum oven at 110 °C for 48 h to obtain phenolphthalein - based polyaryletherketone. After testing, the number - average molecular weight of this phenolphthalein - based polyaryletherketone is 120000 g / mol.

[0123] S2 - S4. The same as Example 8.

[0124] Separate the methanol solution containing 20 ppm of sunset yellow with the zwitterionic polyaryletherketone nanofiltration membrane prepared in this example. After testing, the methanol permeation flux of the zwitterionic polyaryletherketone nanofiltration membrane is 12.1 L / m 2. h .For bar, the rejection rate of sunset yellow was 93.2%.

[0125] Figure 1 It is the 1 1H NMR spectrum of the phenolphthalein-based polyaryletherketone prepared in Example 1 of the present invention. As can be seen from Figure 1 the figure, 1 1H NMR (600 MHz, CDCl 3 3), the hydrogens at positions 2, 4, 5 and 8 are all doublets, and the chemical shifts are 7.37 ppm, 7.78 ppm, 7.97 ppm and 7.74 ppm respectively; the hydrogens at positions 1 and 3 are also doublets, and the chemical shift is 7.07–6.99 ppm; the hydrogens at positions 6 and 7 are multiplets, and the chemical shift is 7.59 ppm. The peak positions, peak numbers and peak splitting conditions of various hydrogens in the spectrum correspond to the chemical structure of polyaryletherketone, indicating that polyaryletherketone was successfully synthesized.

[0126] Figure 2 It is the FTIR spectra of the phenolphthalein-based polyaryletherketone membrane and the solvent-resistant zwitterionic polyaryletherketone nanofiltration membrane prepared in Example 1 of the present invention. As can be seen from Figure 2 the figure, compared with the phenolphthalein-based polyaryletherketone membrane, the zwitterionic polyaryletherketone nanofiltration membrane shows obvious absorption peaks at 2845 cm -1 and 2920 cm -1 , which are caused by the vibrations of methyl and methylene groups in the crosslinker structure; in addition, the peaks of the lactone ring and ether bond are shifted from 1771 cm -1 (O-C=O) and 1236 cm -1 (O-C-O) to 1761 cm -1 (N-C=O) and 1230 cm -1 (O-C-O) respectively, which is due to the reaction of the lactone ring with the primary amine of the crosslinker (N,N-bis(3-aminopropyl)methylamine); the intensity of the carbonyl peak at 1650 cm -1 also decreases significantly, indicating that the carbonyl group also reacts with the primary amine of the crosslinker (N,N-bis(3-aminopropyl)methylamine); a peak of quaternary amine appears at 1720 cm -1 , indicating that the tertiary amine is successfully oxidized to quaternary amine. Therefore, from the above analysis of the FTIR results, it can be known that the zwitterionic polyaryletherketone nanofiltration membrane was successfully prepared.

[0127] Figure 3 It is the relationship diagram of the methanol permeability and the rejection rate of sunset yellow of the solvent-resistant zwitterionic polyaryletherketone nanofiltration membranes prepared in Examples 1-4 of the present invention with the solid content of the casting solution (in Examples 1-4, the solid contents of the casting solution are 10 wt%, 12 wt%, 14 wt%, 16 wt% respectively).

[0128] Figure 4Relationship diagram of methanol permeability and sunset yellow rejection rate of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membranes prepared in Examples 5-8 of the present invention with the crosslinking solution concentration (in Examples 5-8, the crosslinking solution concentrations are 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, and 0.4 mol / L respectively).

[0129] Figure 5 Separation performance diagram of the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membranes prepared in Examples 8-10 of the present invention for methanol solution containing 20 ppm sunset yellow.

[0130] Figure 6 Gel content of the phenolphthalein-based poly(aryl ether ketone) membrane and the solvent-resistant zwitterionic poly(aryl ether ketone) nanofiltration membrane prepared in Example 1 of the present invention after being immersed in N,N-dimethylformamide for 168 h. From Figure 6 It can be seen that the zwitterionic poly(aryl ether ketone) nanofiltration membrane has excellent solvent resistance and is suitable for treating printing and dyeing wastewater containing any organic solvent system.

[0131] Obviously, the above examples are only for clear illustration and not for limitation of the examples. For those of ordinary skill 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 examples here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present 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 poly(aryletherketone) 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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