METHOD FOR PREPARING ANTHRAQUINONE-FUNCTIONALIZED POLY(VINYLIDENE FLUORIDE) MEMBRANE

Abstract

This present disclosure relates to a method for preparation of polyvinylidene fluoride membrane with functional anthraquinones. The method is carried out according, to the following steps: step 1: preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxyl naphthalene; step 2: preparing polyvinylidene fluoride-aromatic ether copolymers: polyvinylidene fluoride was used as the initiator, 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxynaphthalene was the monomer, N,N-dimethylformamide was solvent, cuprous chloride/Me6TREN was the catalytic, polyvinylidene fluoride-aromatic ether copolymer was synthesized by atomic transfer radical polymerization; step 3: reducing the polyvinylidene fluoride-aromatic ether copolymer to quinone by demethoxy oxidation; step 4: using the product of step 3 and N, N-dimethylformamide a film-forming reagents, then scraping into a membrane. Further, the anthraquinone which fixed in the polyvinylidene fluoride membrane would not fall off.

Claims

1. A method for preparation of polyvinylidene fluoride membrane with functional anthraquinones, the method comprising: step 1: preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxyl naphthalene; step 2: preparing polyvinylidene fluoride-aromatic ether copolymers: polyvinylidene fluoride was used as the initiator, 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxynaphthalene was the monomer, N,N-dimethylformamide was solvent, cuprous chloride/Me6TREN was the catalytic, polyvinylidene fluoride-aromatic ether copolymer was synthesized by atomic transfer radical polymerization; step 3: reducing the polyvinylidene fluoride-aromatic ether copolymer to quinone by demethoxy oxidation; step 4: using the product of step 3 and N,N-dimethylformamide as film-forming reagents, then scraping into a membrane.

2. The method of claim 1, wherein the method of preparing 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxyl naphthalene from step 1 comprises steps of: step 1a). preparing 1,4,5,8-tetramethoxynaphthalene: adding naphthazarin, tetramethylammonium bromide and tetrahydrofuran to a round bottom flask, stirring to dissolve, then adding sodium dithionite aqueous solution and dimethyl sulfate solution, stirring evenly; then moving the round bottom flask to ice water bath, reacting for 1 h, then slowly dropping NaOH aqueous solution into the flask. After the drop adding, removing the ice bath, continue to react at room temperature for 30 min, and stirring continuously for 18 h until the reaction was complete. Then extracting the reaction solution with ethyl acetate, washing with saturated brine, drying by anhydrous magnesium sulfate, filtering, and recovering of ethyl acetate under reduced pressure. Finally, separating the solids by column chromatography to obtain the 1,4,5,8-tetramethoxynaphthalene; step 1b). preparing 1,4,5,8-tetramethoxynaphthalene-2-carboxaldehyde: adding N,N-2-methylacetamide to the 2 mouth flask, removing the flask in an ice-water bath, slowly dropping phosphorus oxychloride and 0.063 mol/L 1,4,5,8-tetramethoxynaphthalene in chloroform solution, After the drop adding, removing the ice bath, heating and refluxing reaction for 5 h; then adding ice water to stop the reaction, extracting by chloroform, saturated brine washing, anhydrous magnesium sulfate drying, then filtering, and negative pressure recovery of chloroform, separating by column chromatography; step 1c). preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxynaphthalene: under the protection of argon, adding molecular sieve, anhydrous tetrahydrofuran, anhydrous chromium trichloride and manganese powder in turn in the dry 2 mouth flask, stirring until the color becomes black, then adding allyl bromide, adding 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde and trimethylchlorosilane, reacting for 3 h, adding sodium bicarbonate to stop the reaction, washing with diatomite and ether, extracting by ether, saturated brine washing, anhydrous magnesium sulfate drying, and negative pressure recovery of the concentrated residue, dissolving in tetrahydrofuran, and hydrolyzing with 10% hydrochloric acid, stirring at room temperature for 10 min, extracting with ether, washing with saturated brine, anhydrous magnesium sulfate drying and concentrating under reduced pressure, then separating by column chromatography.

3. The method of claim 2, wherein the mass ratio of naphthazarin, tetrahydrofuran, sodium dithionite, dimethyl sulfate and sodium hydroxide from step 1a) is 1.2-2:70-80:50-60:100-120:100-150.

4. The method of claim 2, wherein the volume ratio of N,N-2-methylacetamide, phosphorus oxychloride, 1,4,5,8-tetramethoxynaphthalene in chloroform from step 1b) is 2-3:2-5:10-25.

5. The method of claim 2, wherein the mass ratio of anhydrous tetrahydrofuran, anhydrous chromium trichloride, 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde, trimethylchlorosilane, allyl bromide, manganese powder in step 1c) is 10-30:10-30:30-60:30-80:30-80:600-800.

6. The method of claim 2, wherein the eluants used in the step (1a), step (1b) and (1c) are the petroleum ether and acetone mixed solvent in volume ratio of 4:1.

7. The method of claim 1, wherein the mass ratio of 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxynaphthalene, polyvinylidene fluoride, N,N-dimethylformamide, the catalytic from step 2 is 30-60:15-12:400-550:0.1-1.

8. The method of claim 1, wherein the method of reducing the polyvinylidene fluoride-aromatic ether copolymer to quinone by demethoxy oxidation from step 3 comprising: adding the polyvinylidene fluoride-aromatic ether copolymer of acetonitrile solution in a 2 mouth flask, adding cerium ammonium nitrate aqueous solution at room temperature with stirring, reacting for 1 hour, negative pressure recovery of acetonitrile, extracting with chloroform, washing with water, and washing with saturated brine, anhydrous magnesium sulfate drying for 1,5 hour, negative pressure recovery of chloroform, separating the solids by column chromatography to obtain the mixture of 2-(1-hydroxy-3-butene)-5,8-dimethoxy-1,4-naphthoquinone and 6(1-hydroxy-3-butene)-5,8-dimethoxy-1,4-naphthoquinone, finally vacuum drying.

9. The method of claim 8, wherein the eluent of silica column chromatography is the mixture of the petroleum ether and acetone with a volume ratio of 3:1.

10. The method of claim 1, wherein the mass ratio of the product of step 3 and N, N-dimethylformamide from step 4 is 80-85:15-20.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings included herein are for the purpose of illustrating the exemplified embodiments and shall not limit the scope of the present invention. Other drawings may be produced by those skilled in the art without creative effort.

[0038] FIG. 1 is the schematic diagram of preparing of 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxynaphthalene;

[0039] FIG. 2 is the schematic diagram of preparing of polyvinylidene fluoride-aromatic ether copolymer.

[0040] FIG. 3 is the sketch of double glass reactor: 1the place of ultraviolet light, 2vacuum orifice, 3water inlet, 4feed inlet, 5water outlet, 6inlert port.

[0041] FIG. 4 is the FTIR spectra of polyvinylidene fluoride membrane modified with anthraquinones.

[0042] FIG. 5 is the graph about the application effect of the polyvinylidene fluoride membrane modified with anthraquinones. The abscissa shows the times of circle application of the polyvinylidene fluoride membrane with functional anthraquinones, the ordinate shows the multiple of removal rate of nitrate. As can be seen from the graph, the ultrafiltration membrane of our invention has stable performance and can be recycled several times.

DETAILED DESCRIPTION OF THE INVENTION

[0043] The present invention is further described in the following exemplified embodiments to illustrate the application of the principles of the invention. It is understood that the invention may be embodied otherwise without departing from such principles. The scope of the claims of the present invention expressly should not be limited to such exemplary or preferred embodiments.

Embodiment 1

[0044] The method for preparation of polyvinylidene fluoride membrane with functional anthraquinones comprises the following steps:

[0045] Step 1: preparing 2-(1-hydroxy-3-butane)-1,4,5,8-tetramethoxyl naphthalene:

[0046] 1a). preparing 1,4,5,8-tetramethoxynaphthalene:

[0047] Adding naphthazarin, tetramethylammonium bromide and tetrahydrofuran to a round bottom flask, stirring to dissolve, then adding sodium dithionite aqueous solution and dimethyl sulfate solution, stirring evenly; then moving the round bottom flask to ice water bath, reacting for 1 h, then slowly dropping NaOH aqueous solution into the flask. After the drop adding, removing the ice bath, continue to react at room temperature for 30 min, and stirring continuously for 18 h until the reaction was complete. Then extracting the reaction solution with ethyl acetate, washing with saturated brine, drying by anhydrous magnesium sulfate, filtering, and recovering of ethyl acetate under reduced pressure. Finally, separating the solids by column chromatography to obtain the 1,4,5,8-tetramethoxynaphthalene; 1 H NMR (400 MHz, DMSO); ?6.44 (d, 4 H), 3.37 (s, 12 H, CH.sub.3).

[0048] The mass ratio of naphthazarin, tetrahydrofuran, sodium dithionite, dimethyl sulfate and sodium hydroxide is 1.5:75:55:110:125;

[0049] 1b). preparing 1,4,5,8-tetramethoxynaphthalene-2-carboxaldehyde:

[0050] Adding N,N-2-methylacetamide to the 2 mouth flask, removing the flask in an ice-water bath, slowly dropping phosphorus oxychloride and 0.063 mol/L 1,4,5,8-tetramethoxynaphthalene in chloroform solution, After the drop adding, removing the ice bath, heating and refluxing reaction for 5 h; then adding ice water to stop the reaction, extracting by chloroform, saturated brine washing, anhydrous magnesium sulfate drying, then filtering, and negative pressure recovery of chloroform, separating by column chromatography; 1 H NMR (400 MHz, DMSO): ?6.49-6.51 (m, 3 H), 3.40 (s, 9 H, CH.sub.3), 3.43 (s, 3 H, CH.sub.3), 10.11 (s, 1H, CHO).

[0051] The volume ratio of N,N-2-methylacetamide, phosphorus oxychloride, 1,4,5,8-tetramethoxynaphthalene in chloroform is 2.5:3:15.

[0052] 1c). preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxynaphthalene:

[0053] Under the protection of argon, adding molecular sieve, anhydrous tetrahydrofuran, anhydrous chromium trichloride and manganese powder in turn in the dry 2 mouth flask, stirring until the color becomes black, then adding allyl bromide, adding 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde and trimethylchlorosilane, reacting for 3 h, adding sodium bicarbonate to stop the reaction, washing with diatomite and ether, extracting by ether, saturated brine washing, anhydrous magnesium sulfate drying, and negative pressure recovery of the concentrated residue, dissolving in tetrahydrofuran, and hydrolyzing with 10% hydrochloric acid, stirring at room temperature for 10 min, extracting with ether, washing with saturated brine, anhydrous magnesium sulfate drying and concentrating under reduced pressure, then separating by column chromatography; 1 H NMR (400 MHz, DMSO): ?6.47-6.51 (m, 3H), 3.37 (s, 9 H, CH.sub.3), 3.43 (s, 3 H, CH.sub.3), 8.45 (s, 1H, OH), 4.83 (t, 1H, CH), 2.39 (m, 2H, CH.sub.2), 4.92 (d, 2H, CH.sub.2) 5.76 (m, 1H, CH).

[0054] The mass ratio of anhydrous tetrahydrofuran, anhydrous chromium trichloride, 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde, trimethylchlorosilane, allyl bromide, manganese powder is 20:20:50:60:50:700.

[0055] Step 2: preparing polyvinylidene fluoride-aromatic ether copolymers:

[0056] adding polyvinylidene fluoride and N,N-dimethylformamide to double glass reactor, stirring evenly, then adding Me.sub.6TREN and 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxynaphthalene, injecting argon to remove oxygen for 30 min, adding cuprous chloride, removing oxygen for 1 hour, then sealing the reactor, removing the reactor to ice-water bath, reacting for 20 s-3 min under the ultraviolet irradiation in the magnetic stirring, filtering with the volume ratio of 1:1 of ethanol and water after the reaction, then extracting with chloroform several times, finally vacuum-drying to obtain the polyfluoroethylene-aromatic ether copolymer.

[0057] The mass ratio of 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxynaphthalene, polyvinylidene fluoride, N,N-dimethylformamide, cuprous chloride/Me6TREN is 45:7:500:0.5.

[0058] Step 3: reducing the polyvinylidene fluoride-aromatic ether copolymer to quinone by demethoxy oxidation:

[0059] More specifically, adding the polyvinylidene fluoride-aromatic ether copolymer of acetonitrile solution in the 2 mouth flask, adding cerium ammonium nitrate aqueous solution at room temperature with stirring, reacting for 1 hour, negative pressure recovery of acetonitrile, extracting with chloroform, washing with water, and washing with saturated brine, anhydrous magnesium sulfate drying for 1.5 hour, negative pressure recovery of chloroform, separating the solids by column chromatography to obtain the mixture of 2-(1-hydroxy-3-butene) -5,8-dimethoxy-1,4-naphthoquinone and 6-(1-hydroxy-3-butene) -5,8-dimethoxy-1,4-naphthoquinone, finally vacuum drying.

[0060] The eluent of silica column chromatography is the mixture of the petroleum ether and acetone with a volume ratio of 3:1.

[0061] Step 4: using the product of step 3 and N,N-dimethylformamide as film-forming reagents, then scraping into a membrane.

[0062] The mass ratio of N,N-dimethylformamide and the product of step 3 is 17:82.

Embodiment 2

[0063] The method for preparation of polyvinylidene fluoride membrane with functional anthraquinones comprises the following steps:

[0064] Step 1: preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxyl naphthalene:

[0065] 1a). preparing 1,4,5,8-tetramethoxynaphthalene:

[0066] Adding naphthazarin, tetramethylammonium bromide and tetrahydrofuran to a round bottom flask, stirring to dissolve, then adding sodium dithionite aqueous solution and dimethyl sulfate solution, stirring evenly; then moving the round bottom flask to ice water bath, reacting for 1 h, then slowly dropping NaOH aqueous solution into the flask. After the drop adding, removing the ice bath, continue to react at room temperature for 30 min, and stirring continuously for 18 h until the reaction was complete. Then extracting the reaction solution with ethyl acetate, washing with saturated brine, diving by anhydrous magnesium sulfate, filtering, and recovering of ethyl acetate under reduced pressure. Finally, separating the solids by column chromatography to obtain the 1,4,5,8-tetramethoxynaphthalene;

[0067] The mass ratio of naphthazarin, tetrahydrofuran, sodium dithionite, dimethyl sulfate and sodium hydroxide is 1.2:80:50:120:150;

[0068] 1b). preparing 1,4,5,8-tetramethoxynaphthalene-2-carboxaldehyde:

[0069] Adding N,N-2-methylacetamide to the 2 mouth flask, removing the flask in an ice-water bath, slowly dropping phosphorus oxychloride and 0.063 mol/L 1,4,5,8-tetramethoxynaphthalene in chloroform solution. After the drop adding, removing the ice bath, heating and refluxing reaction for 5 h; then adding ice water to stop the reaction, extracting by chloroform, saturated brine washing, anhydrous magnesium sulfate drying, then filtering, and negative pressure recovery of chloroform, separating by column chromatography;

[0070] The volume ratio of N,N-2-methylacetamide, phosphorus oxychloride, 1,4,5,8-tetramethoxynaphthalene in chloroform is 2:5:10.

[0071] 1c) preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxynaphthalene:

[0072] Under the protection of argon, adding molecular sieve, anhydrous tetrahydrofuran, anhydrous chromium trichloride and manganese powder in turn in the dry 2 mouth flask, stirring until the color becomes black, then adding allyl bromide, adding 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde and trimethylchlorosilane, reacting for 3 h, adding sodium bicarbonate to stop the reaction, washing with diatomite and ether, extracting by ether, saturated brine washing, anhydrous magnesium sulfate drying, and negative pressure recovery of the concentrated residue, dissolving in tetrahydrofuran, and hydrolyzing with 10% hydrochloric acid, stirring at room temperature for 10 min, extracting with ether, washing with saturated brine, anhydrous magnesium sulfate drying and concentrating under reduced pressure, then separating by column chromatography;

[0073] The mass ratio of anhydrous tetrahydrofuran, anhydrous chromium trichloride, 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde, trimethylchlorosilane, allyl bromide, manganese powder is 10:30:30:80:30:800.

[0074] Step 2: preparing polyvinylidene fluoride-aromatic ether copolymers:

[0075] adding polyvinylidene fluoride and N,N-dimethylformamide to double glass reactor, stirring evenly, then adding Me.sub.6TREN and 2-(1-hydroxy-3-butene) -1,4,5,8-tetramethoxynaphthalene, injecting argon to remove oxygen for 30 min, adding cuprous chloride, removing oxygen for 1 hour, then sealing the reactor, removing the reactor to ice-water bath, reacting for 20 s-3 min under the ultraviolet irradiation in the magnetic stirring, filtering with the volume ratio of 1:1 of ethanol and water after the reaction, then extracting with chloroform several times, finally vacuum-drying to obtain the polyfluoroethylene-aromatic ether copolymer.

[0076] The mass ratio of 2-(1-hydroxy-3-butene-1,4,5,8-tetramethoxynaphthalene, polyvinylidene fluoride, N,N-dimethylformamide, cuprous chloride/Me6TREN is 30:12:4001.

[0077] Step 3: reducing the polyvinylidene fluoride-aromatic ether copolymer to quinone by demethoxy oxidation:

[0078] More specifically, adding the polyvinylidene fluoride-aromatic ether copolymer of acetonitrile solution in the 2 mouth flask, adding cerium ammonium nitrate aqueous solution at room temperature with stirring, reacting for 1 hour, negative pressure recovery of acetonitrile, extracting with chloroform, washing with water, and washing with saturated brine, anhydrous magnesium sulfate drying for 1.5 hour, negative pressure recovery of chloroform, separating the solids by column chromatography to obtain the mixture of 2-(1-hydroxy-3-butene) -5,8-dimethoxy-1,4-naphthoquinone and 6-(1-hydroxy-3-butene) -5,8-dimethoxy-1,4-naphthoquinone, finally vacuum drying.

[0079] The eluent of silica column chromatography is the mixture of the petroleum ether and acetone with a volume ratio of 3:1.

[0080] Step 4: using the product of step 3 and N,N-dimethylformamide film-forming reagents, then scraping into a membrane.

[0081] The mass ratio of N,N-dimethylformamide and the product of step 3 is 15:85.

Embodiment 3

[0082] The method for preparation of polyvinylidene fluoride membrane with functional anthraquinones comprises the following steps:

[0083] Step 1: preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxyl naphthalene:

[0084] 1a). preparing 1,4,5,8-tetramethoxynaphthalene:

[0085] Adding naphthazarin, tetramethylammonium bromide and tetrahydrofuran to a round bottom flask, stirring to dissolve, then adding sodium dithionite aqueous solution and dimethyl sulfate solution, stirring evenly; then moving the round bottom flask to ice water bath, reacting for 1 h, then slowly dropping NaOH aqueous solution into the flask. After the drop adding, removing the ice bath, continue to react at room temperature for 30 min, and stirring continuously for 18 h until the reaction was complete. Then extracting the reaction solution with ethyl acetate, washing with saturated brine, drying by anhydrous magnesium sulfate, filtering, and recovering of ethyl acetate under reduced pressure. Finally, separating the solids by column chromatography to obtain the 1,4,5,8-tetramethoxynaphthalene;

[0086] The mass ratio of naphthazarin, tetrahydrofuran, sodium dithionite, dimethyl sulfate and sodium hydroxide is 2:70:60:100:100;

[0087] 1b). preparing 1,4,5,8-tetramethoxynaphthalene-2-carboxaldehyde:

[0088] Adding N,N-2-methylacetamide to the 2 mouth flask, removing the flask in an ice-water bath, slowly dropping phosphorus oxychloride and 0.063 mol/L 1,4,5,8-tetramethoxynaphthalene in chloroform solution, After the drop adding, removing the ice bath, heating and refluxing reaction for 5 h; then adding ice water to stop the reaction, extracting by chloroform, saturated brine washing, anhydrous magnesium sulfate drying, then filtering, and negative pressure recovery of chloroform, separating by column chromatography;

[0089] The volume ratio of N,N-2-methylacetamide, phosphorus oxychloride, 1,4,5,8-tetramethoxynaphthalene in chloroform is 3:2:25.

[0090] 1c). preparing 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxynaphthalene:

[0091] Under the protection of argon, adding molecular sieve, anhydrous tetrahydrofuran, anhydrous chromium trichloride and manganese powder in turn in the dry 2 mouth flask, stirring until the color becomes black, then adding allyl bromide, adding 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde and trimethylchlorosilane, reacting for 3 h, adding sodium bicarbonate to stop the reaction, washing with diatomite and ether, extracting by ether, saturated brine washing, anhydrous magnesium sulfate drying, and negative pressure recovery of the concentrated residue, dissolving in tetrahydrofuran, and hydrolyzing with 10% hydrochloric acid, stirring at room temperature for 10 min, extracting with ether, washing with saturated brine, anhydrous magnesium sulfate drying and concentrating under reduced pressure, then separating by column chromatography;

[0092] The mass ratio of anhydrous tetrahydrofuran, anhydrous chromium trichloride, 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde, trimethylchlorosilane, allyl bromide, manganese powder is 30:10:60:30:80:800.

[0093] Step 2: preparing: polyvinylidene fluoride-aromatic ether copolymers:

[0094] adding polyvinylidene fluoride and N,N-dimethylformamide to double glass reactor, stirring evenly, then adding Me.sub.6TREN and 2-(1-hydroxyl-3-butene) -1,4,5,8-tetramethoxynaphthalene, injecting argon to remove oxygen for 30 min, adding cuprous chloride, removing oxygen for 1 hour, then sealing the reactor, removing the reactor to ice-water bath reacting for 20 s-3 min under the ultraviolet irradiation in the magnetic stirring, filtering with the volume ratio of 1:1 of ethanol and water after the reaction, then extracting with chloroform several times, finally vacuum-drying to obtain the polyfluoroethylene-aromatic ether copolymer.

[0095] The mass ratio of 2-(1-hydroxy-3-butene)-1,4,5,8-tetramethoxynaphthalene, polyvinylidene fluoride, N,N-dimethylformamide, cuprous chloride/Me6TREN is 60:5:550:0.1.

[0096] Step 3: reducing the polyvinylidene fluoride-aromatic ether copolymer to quinone by demethoxy oxidation:

[0097] More specifically, adding the polyvinylidene fluoride-aromatic ether copolymer of acetonitrile solution in the 2 mouth flask, adding cerium ammonium nitrate aqueous solution at room temperature with stirring, reacting for 1 hour, negative pressure recovery of acetonitrile, extracting with chloroform, washing with water, and washing with saturated brine, anhydrous magnesium sulfate drying for 1.5 hour, negative pressure recovery of chloroform, separating the solids by column chromatography to obtain the mixture of 2-(1-hydroxy-3-butene) -5,8-dimethoxy-1,4-naphthoquinone and 6-(1-hydroxy-3-butene) -5,8-dimethoxy-1,4-naphthoquinone, finally vacuum drying.

[0098] The eluent of silica column chromatography is the mixture of the petroleum ether and acetone with a volume ratio of 3:1.

[0099] Step 4: using the product of step 3 and N,N-dimethylformamide as film-forming reagents, then scraping into a membrane.

[0100] The mass ratio of N,N-dimethylformamide and the product of step 3 is 20:80.

[0101] The application data of polyvinylidene fluoride membrane with functional anthraquinones in the degradation of nitrogen-containing wastewater are shown in

TABLE-US-00001 TABLE 1 The The The nitrogen- The nitrogen- nitrogen- nitrogen- containing containing containing containing wastewater wastewater wastewater wastewater treated by the treated by the without treated by product of product of Test items treatment PVDF embodiment 1 embodiment 2 Nitrogen 200 mg/L 56 mg/L 16 mg/L 20 mg/L content Removal 72% 92% 90% rate