A preparation method of a block copolymer / pvdf blended membrane for removing methyl orange in wastewater

Abstract

The application discloses a kind of polymethyl methacrylate macromolecular initiator / polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer / PVDF blend membrane and its preparation method in wastewater treatment application.Belongs to wastewater treatment adsorption material preparation technical field.Raw material includes: laboratory synthesis 3-(((2-cyanopropane-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenyl propionitrile (CPDMN) with methyl methacrylate, methyl methacrylate, methylbenzene, n-butyl acetate, polyvinylidene fluoride, N-N dimethylacetamide.Preparation includes polymethyl methacrylate macromolecular initiator preparation, polymethyl methacrylate-block-polydimethylaminoethyl methacrylate preparation, polymethyl methacrylate-block-polydimethylaminoethyl methacrylate and polyvinylidene fluoride blend preparation membrane.The block copolymer product prepared by nitrogen oxygen free radical stable polymerization has the advantages of pure, no color, reaction process is simple, etc., and the membrane prepared by blending with polyvinylidene fluoride has good performance, and wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of preparation of wastewater treatment adsorption materials, and relates to a poly (methyl methacrylate) macromolecular initiator / poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer / PVDF blended membrane and a preparation method thereof and application of the blended membrane in wastewater treatment. BACKGROUND

[0002] Synthetic dyes are widely used in various industries, including textile processing, food production and pharmaceutical industries.

[0003] Considering the economy, membrane separation technology is usually used as a treatment method for dye wastewater, but the application of traditional membrane direct treatment in dye-containing textile wastewater is limited, and the dye removal rate is insufficient. The membrane after polymer blending effectively removes the dye by complexing the dye with high molecular weight polymers or based on the electrostatic interaction with the dye. SUMMARY

[0004] The application aims to provide a poly (methyl methacrylate) macromolecular initiator / poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer / PVDF blended membrane, a preparation method thereof and application of the blended membrane in wastewater treatment, which has the advantages of simple preparation process, excellent separation performance and good reuse performance, high economic benefit and wide application prospect.

[0005] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0006] A preparation method of a poly (methyl methacrylate) macromolecular initiator / poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer / PVDF blended membrane comprises the following steps:

[0007] (1) Preparation of 3-(((2-cyanopropan-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenylpropanenitrile CPDMN

[0008] A three-necked flask is charged with benzaldehyde, isopropylamine and methanol, a magnet is added, and the reaction is carried out in an oil bath. After the reaction is completed, the temperature is cooled to room temperature. Sodium borohydride is added in batches, and the reaction is monitored by thin layer chromatography. After the raw materials are completely reacted, the solvent is removed by rotary evaporation, dissolved in ethyl acetate, washed with saturated brine, dried over anhydrous magnesium sulfate, and rotary evaporated to obtain compound 1.

[0009] Compound 1 and sodium bicarbonate are dissolved in acetone and water, and potassium monopersulfate is added in batches under ice bath conditions. After stirring, the mixture is filtered with acetone, washed with saturated brine, and the upper organic phase is collected, dried over anhydrous magnesium sulfate, filtered, rotary evaporated, and then separated and purified by a chromatographic column to obtain compound 2.

[0010] Compound 2, azobisisobutyronitrile and toluene were added to a single-necked flask. After the reaction was completed in an oil bath, the solvent was removed by rotary evaporation to obtain a crude product, which was then separated and purified by a chromatography column to obtain the compound CPDMN product.

[0011] (2) Preparation of polymethyl methacrylate macroinitiator

[0012] Methyl methacrylate, alkoxyamine 3-(((2-cyanopropane-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenylpropionitrile CPDMN, and toluene were placed in a reaction vessel, stirred thoroughly to dissolve, and then vacuumed and nitrogen-filled to remove oxygen from the reaction system. The reaction was carried out at 90°C for 4 hours. After the reaction was completed, the solution was diluted with tetrahydrofuran solution, precipitated in cold methanol, filtered, and dried to prepare a polymethyl methacrylate macroinitiator.

[0013] (3) Preparation of polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer

[0014] The polymethyl methacrylate macroinitiator prepared in step (1) is dissolved in n-butyl acetate, and after it is completely dissolved, dimethylaminoethyl methacrylate is added and stirred to mix evenly. After the solution becomes clear and transparent, vacuum-nitrogen is evacuated to remove oxygen in the reaction system, and the reaction is carried out at 90° C. for 4 h. After the reaction is completed, the reaction is cooled to room temperature, diluted with dichloromethane solution, precipitated in n-hexane solution, filtered, and dried to obtain a polymethyl methacrylate-block-poly (dimethylaminoethyl methacrylate) copolymer;

[0015] (4) Preparation of polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane

[0016] The prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer, poly(vinylidene fluoride) and NN dimethylacetamide were mixed and mechanically stirred at 80 °C for 12 h. After the reaction, the mixture was placed in a vacuum oven for degassing for 2 h to obtain a casting solution after the reaction. The solution was cast on a glass plate to prepare a membrane with a thickness of 200 μm. The membrane was immediately immersed in 30 °C deionized water at room temperature. After the membrane was formed, it was transferred to deionized water at room temperature and immersed overnight. After drying for 12-48 h, the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane was obtained.

[0017] In step (2), the molar ratio of 3-(((2-cyanopropane-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenylpropionitrile to methyl methacrylate is 1:100 to 1:150, and the reaction time is 3 h to 5 h;

[0018] The molar ratio of the polymethyl methacrylate macromolecular initiator to dimethylaminoethyl methacrylate in step (3) is 1:50-1:400, and the reaction time is 2 h-6 h.

[0019] The mass ratio of the polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer to polyvinylidene fluoride in step (4) is 1:9-2:3.

[0020] Application of the prepared polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer / PVDF blended membrane in dye wastewater treatment.

[0021] The application has the beneficial effects that the polymethyl methacrylate macromolecular initiator and the polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer are prepared by using the nitroxide radical stable polymerization method, the preparation process is simple, the product is pure, the prepared polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer / polyvinylidene fluoride blended membrane has the hydrophilic function of the block copolymer and high dye adsorption efficiency, and has strong reusability. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The FT-IR graph of the prepared polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer / polyvinylidene fluoride blended membrane of the application.

[0023] Figure 2 The SEM graph of the prepared polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer / polyvinylidene fluoride blended membrane of the application.

[0024] Figure 3 The comparison pictures of the prepared polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer / polyvinylidene fluoride blended membrane with different segment lengths and different adding contents before and after adsorbing methyl orange.

[0025] Figure 4 The preparation reaction mechanism of the polymethyl methacrylate macromolecular initiator of the application.

[0026] Figure 5 The preparation reaction mechanism of the polymethyl methacrylate-block-polydimethylaminoethyl methacrylate copolymer of the application.

[0027] Figures 6-8 The nuclear magnetic resonance characterization graph of the CPDMN. DETAILED DESCRIPTION

[0028] In order to make the content of the present application more convenient to understand, the technical solutions of the present application are further described below in combination with specific embodiments, but the present application is not limited thereto.

[0029] Example 1

[0030] (1) Preparation of CPDMN

[0031] Synthesis of compound 1: 5.0 g (47 mmol) of benzaldehyde, 2.78 g (47 mmol) of isopropylamine, 60 mL of methanol were added into a 250 mL three-necked flask, a magnetic stirrer was added, and the reaction was carried out at 65 ℃ in an oil bath for 8 h. After the reaction was completed, the solution was cooled to room temperature, 2.83 g (75 mmol) of sodium borohydride was added to the solution in several portions, and after stirring for 2 h, the complete reaction of the raw material was monitored by thin layer chromatography. After the solvent of methanol and the unreacted isopropylamine were removed by a rotary evaporator, the crude product was dissolved in ethyl acetate, and the solution was washed with saturated brine 3 times in a separatory funnel, dried with anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation to obtain a yellowish sticky liquid product of 6.56 g.

[0032] Synthesis of compound 2: 6.56 g of compound 1 and 13.12 g of sodium bicarbonate were dissolved in 22 mL of acetone and water, 24.1 g of Oxone was added to the reaction system in batches under ice bath conditions, and stirred for 2 h. After the mixture solution was filtered with acetone and then washed with saturated brine 3 times, the upper organic phase was collected, the organic phase was dried with anhydrous magnesium sulfate, filtered with a sand core funnel, and the obtained solution was subjected to solvent removal by a rotary evaporator to obtain a yellowish sticky liquid. After separation and purification by a chromatographic column (V 石油醚 :V 乙酸乙酯 =7:1), 4.82 g of yellowish liquid compound 2 was obtained.

[0033] Synthesis of CPDMN: 4.82 g of compound 2, 7.76 g of AIBN, and 50 mL of toluene were sequentially added into a 100 mL single-necked flask, and the reaction was carried out at 92 ℃ for 6 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a crude product. After separation and purification by a chromatographic column (V 石油醚 :V 乙酸乙酯 =7:1), 4.7 g of yellowish sticky liquid compound CPDMN was obtained.

[0034] (2) Preparation of poly(methyl methacrylate) macromolecular initiator

[0035] Take 0.1 g of alkoxylamine CPDMN, 3.35 g of methyl methacrylate, 3.45 g of toluene, stir and dissolve thoroughly, then remove oxygen in the reaction system by vacuum-nitrogen, react at 90°C for 3h, after the reaction is completed, dilute with tetrahydrofuran solution, precipitate in cold methanol, filter and dry to prepare poly(methyl methacrylate) macromolecular initiator;

[0036] (3) Preparation of poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer

[0037] Take 2.0 g of poly(methyl methacrylate) macromolecular initiator, 8.64 g of dimethylaminoethyl methacrylate, and 10.64 g of n-butyl acetate, stir and dissolve thoroughly, then remove oxygen in the reaction system by vacuum-nitrogen, react at 90°C for 4h, after the reaction is completed, dilute with dichloromethane solution, precipitate in cold n-hexane, filter and dry to prepare poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer;

[0038] (4) Preparation of poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane

[0039] Take 0.5 g of the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer, 2 g of PVDF, and N-N dimethylacetamide, mechanically stir at 80°C for 12h, after the reaction is completed, degas in a vacuum oven for 2h to obtain the reacted casting solution, cast it on a glass plate to prepare a membrane with a thickness of 200μm, immediately immerse it in 30°C deionized water at room temperature, after the membrane is formed, transfer it to deionized water at room temperature and soak overnight, collect the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane after airing for 12-48h.

[0040] Example 2

[0041] Steps (2) and (3) are the same as in Example 1

[0042] Take 0.5 g of the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer, 2 g of PVDF, and N-N dimethylacetamide, mechanically stir at 80°C for 12h, after the reaction is completed, degas in a vacuum oven for 2h to obtain the reacted casting solution, cast it on a glass plate to prepare a membrane with a thickness of 200μm, immediately immerse it in 30°C deionized water at room temperature, after the membrane is formed, transfer it to deionized water at room temperature and soak overnight, collect the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane after airing for 12-48h.

[0043] Example 3

[0044] Steps (2) and (3) are the same as Example 1

[0045] Take 1 g of the prepared poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer, 1.5 g of PVDF, and N-N dimethylacetamide, and mechanically stir at 80°C for 12 h. After the reaction is completed, degas in a vacuum oven for 2 h to obtain the reacted casting solution. Cast the solution on a glass plate to prepare a film with a thickness of 200 μm. Immediately immerse the film in 30°C deionized water at room temperature. After the film is formed, transfer it to deionized water at room temperature and soak overnight. After air-drying for 12-48 h, collect the prepared poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer / PVDF blend film.

[0046] Example 4

[0047] (1) Preparation of poly (methyl methacrylate) macromolecular initiator

[0048] Take 0.1 g of alkoxyamine CPDMN, 5.02 g of methyl methacrylate, and 5.12 g of toluene. After stirring and dissolving sufficiently, remove oxygen in the reaction system by vacuum-nitrogen degassing. React at 90°C for 4 h. After the reaction is completed, dilute with a tetrahydrofuran solution, precipitate in cold methanol, and filter and dry to prepare poly (methyl methacrylate) macromolecular initiator.

[0049] (2) Preparation of poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer

[0050] Take 2.0 g of poly (methyl methacrylate) macromolecular initiator, 8.98 g of dimethylaminoethyl methacrylate, and 10.64 g of n-butyl acetate. After stirring and dissolving sufficiently, remove oxygen in the reaction system by vacuum-nitrogen degassing. React at 90°C for 4 h. After the reaction is completed, dilute with a dichloromethane solution, precipitate in cold n-hexane, and filter and dry to prepare poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer.

[0051] (3) Preparation of poly (methyl methacrylate)-block-poly (dimethylaminoethyl methacrylate) copolymer / PVDF blend film

[0052] The prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer 0.5 g, PVDF 2 g and N-N dimethylacetamide were weighed, mechanically stirred at 80 °C for 12 h, and after the reaction was completed, were placed in a vacuum oven for 2 h to degas, to obtain the cast solution after the reaction, which was cast on a glass plate to prepare a film with a thickness of 200 μm, immediately immersed in 30 °C deionized water at room temperature, after the film was formed, transferred to the deionized water at room temperature and soaked overnight, and after air-drying for 12-48 h, the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend film was collected.

[0053] Example 5

[0054] Steps (1) and (2) are the same as in Example 4;

[0055] Step (3) Preparation of poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend film

[0056] The prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer 0.75 g, PVDF 1.75 g and N-N dimethylacetamide were weighed, mechanically stirred at 80 °C for 12 h, and after the reaction was completed, were placed in a vacuum oven for 2 h to degas, to obtain the cast solution after the reaction, which was cast on a glass plate to prepare a film with a thickness of 200 μm, immediately immersed in 30 °C deionized water at room temperature, after the film was formed, transferred to the deionized water at room temperature and soaked overnight, and after air-drying for 12-48 h, the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend film was collected.

[0057] Example 6

[0058] Steps (1) and (2) are the same as in Example 4;

[0059] Step (3) Preparation of poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend film

[0060] The prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer 1 g, PVDF 1.5 g and N-N dimethylacetamide were weighed, mechanically stirred at 80 °C for 12 h, and after the reaction was completed, were placed in a vacuum oven for 2 h to degas, to obtain the cast solution after the reaction, which was cast on a glass plate to prepare a film with a thickness of 200 μm, immediately immersed in 30 °C deionized water at room temperature, after the film was formed, transferred to the deionized water at room temperature and soaked overnight, and after air-drying for 12-48 h, the prepared poly(methyl methacrylate)-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend film was collected.

[0061] The physical map and SEM map of the blended membrane are shown in Figure 1 、 Figure 2 As shown in the figures, the pure PVDF membrane has a dense structure, and after adding the copolymer, a porous structure appears on the surface of the membrane, proving the success of the modification.

[0062] Application Example 1

[0063] In the ultrafiltration instrument device, 10 ml of the prepared 10 mg / L methyl orange (MO) dye solution was added to determine the removal rate of the blended membrane in Example 1 to the dye solution, and the concentration of the MO solution before and after interception was measured by a visible spectrophotometer, and the interception rate was 38%.

[0064] Application Example 2

[0065] In the ultrafiltration instrument device, 10 ml of the prepared 10 mg / L methyl orange (MO) dye solution was added to determine the removal rate of the blended membrane in Example 2 to the dye solution, and the concentration of the MO solution before and after interception was measured by a visible spectrophotometer, and the interception rate was 68%.

[0066] Application Example 3

[0067] In the ultrafiltration instrument device, 10 ml of the prepared 10 mg / L methyl orange (MO) dye solution was added to determine the removal rate of the blended membrane in Example 3 to the dye solution, and the concentration of the MO solution before and after interception was measured by a visible spectrophotometer, and the interception rate was 71%.

[0068] Application Example 4

[0069] In the ultrafiltration instrument device, 10 ml of the prepared 10 mg / L methyl orange (MO) dye solution was added to determine the removal rate of the blended membrane in Example 4 to the dye solution, and the concentration of the MO solution before and after interception was measured by a visible spectrophotometer, and the interception rate was 74%.

[0070] Application Example 5

[0071] In the ultrafiltration instrument device, 10 ml of the prepared 10 mg / L methyl orange (MO) dye solution was added to determine the removal rate of the blended membrane in Example 5 to the dye solution, and the concentration of the MO solution before and after interception was measured by a visible spectrophotometer, and the interception rate was 81%.

[0072] Application Example 6

[0073] In the ultrafiltration instrument device, 10 ml of the prepared 10 mg / L methyl orange (MO) dye solution was added to determine the removal rate of the blended membrane in Example 6 to the dye solution, and the concentration of the MO solution before and after interception was measured by a visible spectrophotometer, and the interception rate was 90%.

Claims

1. A method for preparing a polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend film, characterized in that: The following steps are involved: (1) Preparation of 3-(((2-cyanopropane-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenylpropionitrile: Benzaldehyde, isopropylamine, and methanol were placed in a three-necked flask, and magnetite was added. The mixture was reacted in an oil bath. After the reaction was completed, the mixture was cooled to room temperature, and sodium borohydride was added in batches. After stirring for a certain period of time, the reaction of the raw materials was monitored by thin-layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation, the mixture was dissolved in ethyl acetate, washed with saturated brine, dried over anhydrous magnesium sulfate, and rotary evaporated to obtain compound 1. Compound 1 and sodium bicarbonate were dissolved in acetone and water, potassium peroxymonosulfate was added in batches under ice bath, and the mixture was stirred, filtered with acetone, washed with saturated brine, and the upper organic phase was collected, dried over anhydrous magnesium sulfate, filtered, and rotary evaporated. Compound 2 was then separated and purified by column chromatography to obtain compound 2. Compound 2, azobisisobutyronitrile, and toluene were added to a single-necked flask. After the reaction was completed in an oil bath, the solvent was removed by rotary evaporation to obtain a crude product, which was separated and purified by chromatography to obtain the compound 3-(((2-cyanopropan-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenylpropionitrile, which is the CPDMN product. (2) Preparation of polymethyl methacrylate macroinitiator Methyl methacrylate, CPDMN and toluene are placed in a reaction vessel, stirred and dissolved thoroughly, and then vacuumed and nitrogen-filled to remove oxygen from the reaction system, and reacted. After the reaction is completed, the solution is diluted with tetrahydrofuran solution, precipitated in cold methanol, filtered and dried to obtain polymethyl methacrylate macroinitiator. (3) Preparation of polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer: The polymethyl methacrylate macroinitiator prepared in step (2) was dissolved in n-butyl acetate, and dimethylaminoethyl methacrylate was added after complete dissolution, and the mixture was stirred to mix evenly. After the solution became clear and transparent, the reaction system was vacuumed and nitrogen was used to remove oxygen. After the reaction was completed, the mixture was cooled to room temperature, diluted with dichloromethane solution, precipitated in n-hexane solution, filtered, and dried to obtain polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer; (4) Preparation of polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane The prepared polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer, polyvinylidene fluoride and NN dimethylacetamide were mixed and mechanically stirred. After the reaction was completed, the mixture was placed in a vacuum oven for degassing for 2 hours to obtain a casting solution after the reaction. The solution was cast on a glass plate to prepare a film with a thickness of 200 μm. The film was immediately immersed in 30°C deionized water at room temperature. After the film was formed, it was transferred to deionized water at room temperature and immersed overnight. After drying for 12-48 hours, the prepared polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane was collected.

2. The preparation method according to claim 1, wherein : In step (2), the molar ratio of 3-(((2-cyanopropane-2-yl)oxy)(isopropyl)amino)-2,2-dimethyl-3-phenylpropionitrile to methyl methacrylate is 1:100 to 1:

150.

3. The preparation method according to claim 1, wherein : The specific reaction of step (2) is to react at 90°C for 3h to 5h.

4. The preparation method according to claim 1, characterized in that : In step (3), the molar ratio of polymethyl methacrylate macroinitiator to dimethylaminoethyl methacrylate is 1:50 to 1:

400.

5. The preparation method according to claim 1, characterized in that : The reaction conditions in step (3) are 2h to 6h at 90°C.

6. The preparation method according to claim 1, characterized in that : In step (4), the mass ratio of polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer to polyvinylidene fluoride is 1:9 to 2:

3.

7. The preparation method according to claim 1, characterized in that : In step (4), the mechanical stirring is performed at 80° C. for 12 h.

8. A polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane prepared by the method according to any one of claims 1 to 7.

9. Use of the polymethyl methacrylate-block-poly(dimethylaminoethyl methacrylate) copolymer / PVDF blend membrane according to claim 8 in dye wastewater treatment.

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