Filter material for sewage treatment and preparation method thereof

Abstract

The invention discloses a filter material for sewage treatment and a preparation method thereof, and relates to the field of filter materials. When preparing the filter material for sewage treatment, the present invention loads ferrous ions on porous mullite, and then polymerizes pyromellitic anhydride and 2-butene-1,4-diamine on the surface to obtain modified nano mullite; polyvinylidene fluoride powder is sequentially treated with sodium hydroxide and potassium permanganate, sulfuric acid and sodium bisulfite, and then reacted with 2-mercaptobenzoxazole-5-carboxylic acid to obtain modified polyvinylidene fluoride; modified polyvinylidene fluoride, modified nano mullite, 3-[[2-(acryloyloxy)ethyl] dimethylammonium] propane-1-sulfonate and polyvinylpyrrolidone are mixed and then electrostatically spun to obtain a filter material for sewage treatment. The filter material for sewage treatment prepared by the present invention has excellent mechanical properties, antibacterial properties, dehydration properties and filtration properties.

Description

Technical Field

[0001] The invention relates to the field of filter materials, in particular to a filter material for sewage treatment and a preparation method thereof. Background Art

[0002] With the development of my country's social economy and the improvement of people's environmental awareness, the daily output and treatment volume of urban sewage are increasing, the construction scale of urban sewage treatment plants is also growing, and the production of residual sludge, a byproduct of sewage treatment, is also showing a clear upward trend. How to properly and safely dispose of sewage has become a problem that needs to be solved urgently. Sludge is complex in nature and contains toxic and harmful elements and a large amount of water. If it is randomly piled up and transferred, toxic and harmful substances will erode the food production chain on which we depend for survival, which will not only affect our health, but also waste available resources. Therefore, the present invention prepares a filter material for sewage treatment with dehydration performance. Summary of the invention

[0003] The purpose of the present invention is to provide a filter material for sewage treatment and a preparation method thereof, so as to solve the problems existing in the prior art.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] The invention discloses a filter material for sewage treatment, which is prepared by electrostatic spinning after uniformly mixing modified polyvinylidene fluoride, modified nano mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate and polyvinyl pyrrolidone.

[0006] As an optimization, the polyvinyl pyrrolidone model is PVPK30, which comes from Chiping County Jinshun Chemical Co., Ltd.

[0007] As an optimization, the modified polyvinylidene fluoride is obtained by treating polyvinylidene fluoride powder with sodium hydroxide and potassium permanganate, sulfuric acid and sodium bisulfite in sequence, and then reacting with 2-mercaptobenzoxazole-5-carboxylic acid.

[0008] As an optimization, the polyvinylidene fluoride powder model is W#9200, which comes from Shanghai Xinjihua Plastic Co., Ltd.

[0009] As an optimization, the modified nano mullite is obtained by loading ferrous ions on porous mullite and then polymerizing pyromellitic anhydride and 2-butene-1,4-diamine on the surface.

[0010] As an optimization, the porous mullite model is 200 mesh and comes from Gongyi Hengxinda Environmental Protection Technology Co., Ltd.

[0011] A method for preparing a filter material for sewage treatment, comprising the following preparation steps:

[0012] (1) Mix porous mullite, ferrous sulfate heptahydrate and deionized water in a mass ratio of 1:(1.1-1.3):(9-11), soak at 105-115°C for 23-25 ​​hours, filter, wash with methanol for 3-5 times, and dry at 80-90°C for 5-7 hours to obtain ferrous nano-mullite; mix ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide in a mass ratio of 1:(1.4-1.6):(0.67-0.69):(11-13), stir at 65-75°C and 200-300 rpm for 2-4 hours, cool naturally to room temperature and centrifuge, wash with deionized water for 3-5 times, dry at 75-85°C for 8-10 hours, grind and sieve 200-300 mesh to obtain modified nano-mullite;

[0013] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water, ultrasonicate at 57-59°C for 25-35 min, filter, wash with deionized water for 3-5 times, and dry at 50-60°C for 5-7 h to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water, ultrasonicate at 20-30°C for 25-35 min, filter, and wash with deionized water for 3-5 times. The mixture was washed 3 to 5 times, dried at 50 to 60°C for 5 to 7 hours to obtain hydroxylated polyvinylidene fluoride; hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane were mixed in a mass ratio of 1:(2 to 3):(16 to 18), stirred at 45 to 55°C and 300 to 500 rpm for 1 to 3 hours, filtered, washed with deionized water for 3 to 5 times, and dried at 35 to 45°C for 1 to 3 hours to obtain modified polyvinylidene fluoride;

[0014] (3) The modified polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide were mixed in a mass ratio of 1:(0.04-0.06):(0.07-0.09):(0.1-0.3):(3-4), and dissolved by stirring at 85-95°C and 350-450 r / min for 11-13 h. The mixture was cooled to 20-30°C, and 0.01-0.02 times the mass of azobisisobutyronitrile of the modified polyvinylidene fluoride was added. The mixture was stirred for 10-20 min, and electrospinning was performed using a 4-6 mL syringe to form a film. The film was allowed to stand at 125-135°C for 6-8 h, and washed with deionized water for 3-5 times. The film was dried at 60-70°C for 5-7 h to obtain a filter material for sewage treatment.

[0015] As an optimization, the reaction equation of the ferrous nano-mullite in step (1) is:

[0016] .

[0017] As an optimization, the reaction equation for modifying the nano-mullite in step (1) is:

[0018] .

[0019] As an optimization, the step (2) of mixing the polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water is performed in a mass ratio of 1:(0.5-0.7):(0.9-1.1):(17-18).

[0020] As an optimization, in step (2), the dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water are mixed in a mass ratio of 1:(0.9~1.1):(0.5~0.7):(17~18).

[0021] As an optimization, the reaction equation of the hydroxylated polyvinylidene fluoride in step (2) is:

[0022] .

[0023] As an optimization, the reaction equation for the modified polyvinylidene fluoride in step (2) is:

[0024] .

[0025] As an optimization, the process parameters of the electrospinning in step (3) are: spinning temperature 20~30℃, humidity 40%~60%, electrospinning needle model 15~25G, electric field distance 14~16cm, applied voltage 11~13kV, roller receiving speed 25~35r / min, translation speed 350~450mm / min, spinning solution injection speed 0.6~0.8mL / min, and electrospinning time 15~25min.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0027] When preparing the filter material for sewage treatment, the present invention comprises the following steps: after porous mullite is loaded with ferrous ions, pyromellitic anhydride and 2-butene-1,4-diamine are polymerized on the surface to obtain modified nano mullite; polyvinylidene fluoride powder is treated with sodium hydroxide and potassium permanganate, sulfuric acid and sodium bisulfite in sequence, and then reacted with 2-mercaptobenzoxazole-5-carboxylic acid to obtain modified polyvinylidene fluoride; and modified polyvinylidene fluoride, modified nano mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate and polyvinyl pyrrolidone are uniformly mixed and then electrostatically spun to obtain the filter material for sewage treatment.

[0028] Firstly, porous mullite is loaded with ferrous ions, and then pyromellitic anhydride and 2-butene-1,4-diamine are polymerized on the surface to obtain modified nano-mullite; porous mullite with high specific surface area and rich pore structure is used as filler to adsorb heavy metal ions, organic pollutants, dyes, oil pollution and other harmful substances in sewage through physical adsorption, chemical adsorption or electrostatic action, thereby improving the filterability of the filter material for sewage treatment; ferrous ions are loaded in porous mullite by liquid phase infiltration method, and used as catalyst, and calcium peroxide is dissolved in water to release H2O2 for Fenton reaction, thereby generating a high redox potential. ·OH, degrades microorganisms and extracellular polymers in sludge, releases bound water, and improves the antibacterial and dehydration properties of filter materials for sewage treatment; by polymerizing pyromellitic anhydride and 2-butene-1,4-diamine to encapsulate ferrous nano-mullite, carbon-carbon double bonds are introduced on the surface, forming a cross-linked network with thiol groups under high temperature conditions, thereby improving the mechanical properties of filter materials for sewage treatment; the anhydride reacts with the amino group to form a carboxyl group, which reacts with Fe2+ to form a complex, reducing the redox potential of Fe2+ and Fe3+, accelerating the recycling of Fe2+, and further improving the dehydration performance of filter materials for sewage treatment.

[0029] Secondly, polyvinylidene fluoride powder is treated with sodium hydroxide and potassium permanganate, sulfuric acid and sodium bisulfite in sequence, and then reacted with 2-mercaptobenzoxazole-5-carboxylic acid to obtain modified polyvinylidene fluoride; modified polyvinylidene fluoride, modified nano mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate and polyvinyl pyrrolidone are mixed and then electrospun to obtain a filter material for sewage treatment; through strong oxidizing, strong alkali and strong acid treatment, polyvinylidene fluoride is defluorinated and hydroxylated, and active groups are introduced to graft 2-mercaptobenzoxazole-5-carboxylic acid, and the benzoxazole ring can inhibit cell wall synthesis, destroy cell membrane, and improve the antibacterial property of the filter material for sewage treatment; at the same time, the aromatic ring in benzoxazole can adsorb organic pollutants containing aromatic rings or other π electron structures through π-π stacking. The lone pair of electrons in nitrogen atoms can form coordination bonds to complex heavy metal ions, thereby improving the filtration performance of the filter material for sewage treatment. The thiol group and carbon-carbon double bonds are click-reacted under thermal initiation conditions to form a cross-linked network, thereby improving the mechanical properties of the filter material for sewage treatment. By doping polyvinyl pyrrolidone as a porogen, electrospinning and then washing are performed to form a pore structure, thereby improving the filtration performance of the filter material for sewage treatment. The thiol group is used to cross-link 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate to introduce positive and negative ions with stronger ability to bind water molecules, thereby enhancing hydrophilicity and reducing surface pollution. The zwitterionic tail can also be embedded in the bacterial cell membrane to destroy the integrity of the cell membrane, thereby further improving the dehydration performance, filtration performance and antibacterial properties of the filter material for sewage treatment. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Embodiment 1:

[0032] A method for preparing a filter material for sewage treatment, the method comprising the following steps:

[0033] (1) Porous mullite, ferrous sulfate heptahydrate and deionized water were mixed in a mass ratio of 1:1.1:9, infiltrated at 105°C for 25 hours, filtered, washed with methanol three times, and dried at 80°C for 7 hours to obtain ferrous nano-mullite; ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide were mixed in a mass ratio of 1:1.4:0.67:11, stirred at 65°C and 200 rpm for 4 hours, cooled naturally to room temperature and centrifuged, washed with deionized water three times, dried at 75°C for 10 hours, ground and sieved with 200 mesh to obtain modified nano-mullite;

[0034] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water in a mass ratio of 1:0.5:0.9:17, ultrasonicate at 57°C for 35 minutes, filter, wash with deionized water for 3 times, and dry at 50°C for 7 hours to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water in a mass ratio of 1:0.9:0.5:17, ultrasonicate at 20°C for 35 minutes, filter, wash with deionized water for 3 times, and dry at 50°C for 7 hours to obtain hydroxylated polyvinylidene fluoride; mix hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane in a mass ratio of 1:2:16, stir at 45°C and 300 rpm for 3 hours, filter, wash with deionized water for 3 times, and dry at 35°C for 3 hours to obtain modified polyvinylidene fluoride;

[0035] (3) Modified polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide were mixed in a mass ratio of 1:0.04:0.07:0.1:3, stirred and dissolved at 85°C and 350 r / min for 13 h, cooled to 20°C, and 0.01 times the mass of azobisisobutyronitrile of modified polyvinylidene fluoride was added, and stirring was continued for 20 min. 4 mL of The syringe was used for electrospinning deposition into a film under the conditions of spinning temperature 20°C, humidity 40%, electrospinning needle model 15G, electric field distance 14cm, external voltage 11kV, roller receiving speed 25r / min, translation speed 350mm / min, spinning solution push speed 0.6mL / min, and electrospinning time 15min. The film was allowed to stand at 125°C for 8h, washed with deionized water 3 times, and dried at 60°C for 7h to obtain a filter material for sewage treatment.

[0036] Embodiment 2:

[0037] A method for preparing a filter material for sewage treatment, the method comprising the following steps:

[0038] (1) Porous mullite, ferrous sulfate heptahydrate and deionized water were mixed in a mass ratio of 1:1.2:10, infiltrated at 110°C for 24 hours, filtered, washed with methanol for 4 times, and dried at 85°C for 6 hours to obtain ferrous nano-mullite; ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide were mixed in a mass ratio of 1:1.5:0.68:12, stirred at 70°C and 250 rpm for 3 hours, cooled naturally to room temperature and centrifuged, washed with deionized water for 4 times, dried at 80°C for 9 hours, ground and sieved with 250 mesh to obtain modified nano-mullite;

[0039] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water in a mass ratio of 1:0.6:1:17.5, ultrasonicate at 58°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water in a mass ratio of 1:1:0.6:17.5, ultrasonicate at 25°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain hydroxylated polyvinylidene fluoride; mix hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane in a mass ratio of 1:2.5:17, stir at 50°C and 400 rpm for 2 hours, filter, wash with deionized water 4 times, and dry at 40°C for 2 hours to obtain modified polyvinylidene fluoride;

[0040] (3) Modified polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide were mixed in a mass ratio of 1:0.05:0.08:0.2:3.5, stirred and dissolved at 90°C and 400 r / min for 12 h, cooled to 25°C, and 0.015 times the mass of azobisisobutyronitrile of modified polyvinylidene fluoride was added, and stirring was continued for 15 min. 5 mL of The electrospinning was carried out by using a syringe, and the electrospinning was deposited into a film under the conditions of spinning temperature 25°C, humidity 50%, electrospinning needle model 20G, electric field distance 15cm, external voltage 12kV, roller receiving speed 30r / min, translation speed 400mm / min, spinning solution push speed 0.7mL / min, and electrospinning time 20min. The film was allowed to stand at 130°C for 7h, washed with deionized water 4 times, and dried at 65°C for 6h to obtain a filter material for sewage treatment.

[0041] Embodiment 3:

[0042] A method for preparing a filter material for sewage treatment, the method comprising the following steps:

[0043] (1) Porous mullite, ferrous sulfate heptahydrate and deionized water were mixed in a mass ratio of 1:1.3:11, infiltrated at 115°C for 23 hours, filtered, washed with methanol for 5 times, and dried at 90°C for 5 hours to obtain ferrous nano-mullite; ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide were mixed in a mass ratio of 1:1.6:0.69:13, stirred at 75°C and 300 rpm for 2 hours, cooled naturally to room temperature and centrifuged, washed with deionized water for 5 times, dried at 85°C for 8 hours, ground and sieved to obtain modified nano-mullite;

[0044] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water in a mass ratio of 1:0.7:1.1:18, ultrasonicate at 59°C for 25 min, filter, wash with deionized water for 5 times, and dry at 60°C for 5 h to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water in a mass ratio of 1:1.1:0.7:18, ultrasonicate at 30°C for 25 min, filter, wash with deionized water for 5 times, and dry at 60°C for 5 h to obtain hydroxylated polyvinylidene fluoride; mix hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane in a mass ratio of 1:3:18, stir at 55°C and 500 rpm for 1 h, filter, wash with deionized water for 5 times, and dry at 45°C for 1 h to obtain modified polyvinylidene fluoride;

[0045] (3) Modified polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide were mixed in a mass ratio of 1:0.06:0.09:0.3:4, stirred and dissolved at 95°C and 450 r / min for 11 h, cooled to 30°C, and 0.02 times the mass of azobisisobutyronitrile of modified polyvinylidene fluoride was added, and stirring was continued for 10 min. 6 mL of The syringe was used for electrospinning deposition into a film under the conditions of spinning temperature 30°C, humidity 60%, electrospinning needle model 25G, electric field distance 16cm, external voltage 13kV, roller receiving speed 35r / min, translation speed 450mm / min, spinning solution push speed 0.8mL / min, and electrospinning time 25min. The film was allowed to stand at 135°C for 6h, washed with deionized water 5 times, and dried at 70°C for 5h to obtain a filter material for sewage treatment.

[0046] Comparative Example 1:

[0047] A method for preparing a filter material for sewage treatment, the method comprising the following steps:

[0048] (1) Porous mullite, ferrous sulfate heptahydrate and deionized water were mixed in a mass ratio of 1:1.2:10, infiltrated at 110°C for 24 hours, filtered, washed with methanol for 4 times, and dried at 85°C for 6 hours to obtain ferrous nano-mullite; ferrous nano-mullite, terephthalic acid, 2-butene-1,4-diamine and N,N-dimethylformamide were mixed in a mass ratio of 1:1.5:0.68:12, stirred at 70°C and 250 rpm for 3 hours, cooled naturally to room temperature and centrifuged, washed with deionized water for 4 times, dried at 80°C for 9 hours, ground and sieved with 250 mesh to obtain modified nano-mullite;

[0049] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water in a mass ratio of 1:0.6:1:17.5, ultrasonicate at 58°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water in a mass ratio of 1:1:0.6:17.5, ultrasonicate at 25°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain hydroxylated polyvinylidene fluoride; mix hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane in a mass ratio of 1:2.5:17, stir at 50°C and 400 rpm for 2 hours, filter, wash with deionized water 4 times, and dry at 40°C for 2 hours to obtain modified polyvinylidene fluoride;

[0050] (3) Mix modified polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide in a mass ratio of 1:0.05:0.08:0.2:3.5, stir and dissolve at 90°C and 400 r / min for 12 h, cool to 25°C, add 0.015 times the mass of azobisisobutyronitrile of modified polyvinylidene fluoride, continue stirring for 15 min, and add 5 mL The electrospinning was carried out by using a syringe, and the electrospinning was deposited into a film under the conditions of spinning temperature 25°C, humidity 50%, electrospinning needle model 20G, electric field distance 15cm, external voltage 12kV, roller receiving speed 30r / min, translation speed 400mm / min, spinning solution push speed 0.7mL / min, and electrospinning time 20min. The film was allowed to stand at 130°C for 7h, washed with deionized water 4 times, and dried at 65°C for 6h to obtain a filter material for sewage treatment.

[0051] Comparative Example 2:

[0052] A method for preparing a filter material for sewage treatment, the method comprising the following steps:

[0053] (1) Porous mullite, ferrous sulfate heptahydrate and deionized water were mixed in a mass ratio of 1:1.2:10, infiltrated at 110°C for 24 hours, filtered, washed with methanol for 4 times, and dried at 85°C for 6 hours to obtain ferrous nano-mullite; ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide were mixed in a mass ratio of 1:1.5:0.68:12, stirred at 70°C and 250 rpm for 3 hours, cooled naturally to room temperature and centrifuged, washed with deionized water for 4 times, dried at 80°C for 9 hours, ground and sieved with 250 mesh to obtain modified nano-mullite;

[0054] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water in a mass ratio of 1:0.6:1:17.5, ultrasonicate at 58°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water in a mass ratio of 1:1:0.6:17.5, ultrasonicate at 25°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain hydroxylated polyvinylidene fluoride;

[0055] (3) Mix hydroxylated polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide in a mass ratio of 1:0.05:0.08:0.2:3.5, stir and dissolve at 90°C and 400 r / min for 12 h, cool to 25°C, add 0.015 times the mass of azobisisobutyronitrile of hydroxylated polyvinylidene fluoride, continue stirring for 15 min, and heat for 5 min. The electrospinning was carried out by using a syringe L, and the electrospinning was deposited into a film under the conditions of spinning temperature 25°C, humidity 50%, electrospinning needle model 20G, electric field distance 15cm, external voltage 12kV, roller receiving speed 30r / min, translation speed 400mm / min, spinning solution push speed 0.7mL / min, and electrospinning time 20min. The film was allowed to stand at 130°C for 7h, washed with deionized water 4 times, and dried at 65°C for 6h to obtain a filter material for sewage treatment.

[0056] Comparative Example 3:

[0057] A method for preparing a filter material for sewage treatment, the method comprising the following steps:

[0058] (1) Porous mullite, ferrous sulfate heptahydrate and deionized water were mixed in a mass ratio of 1:1.2:10, infiltrated at 110°C for 24 hours, filtered, washed with methanol for 4 times, and dried at 85°C for 6 hours to obtain ferrous nano-mullite; ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide were mixed in a mass ratio of 1:1.5:0.68:12, stirred at 70°C and 250 rpm for 3 hours, cooled naturally to room temperature and centrifuged, washed with deionized water for 4 times, dried at 80°C for 9 hours, ground and sieved with 250 mesh to obtain modified nano-mullite;

[0059] (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water in a mass ratio of 1:0.6:1:17.5, ultrasonicate at 58°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water in a mass ratio of 1:1:0.6:17.5, ultrasonicate at 25°C for 30 minutes, filter, wash with deionized water for 4 times, and dry at 55°C for 6 hours to obtain hydroxylated polyvinylidene fluoride; mix hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane in a mass ratio of 1:2.5:17, stir at 50°C and 400 rpm for 2 hours, filter, wash with deionized water 4 times, and dry at 40°C for 2 hours to obtain modified polyvinylidene fluoride;

[0060] (3) The modified polyvinylidene fluoride, modified nano-mullite, polyvinyl pyrrolidone and N,N-dimethylformamide were mixed in a mass ratio of 1:0.05:0.2:3.5, stirred and dissolved at 90°C and 400 r / min for 12 h, cooled to 25°C, and 0.015 times the mass of azobisisobutyronitrile of the modified polyvinylidene fluoride was added. The stirring was continued for 15 min. The electrospinning was carried out using a 5 mL syringe at a spinning temperature of 25°C, a humidity of 50%, an electrospinning needle model of 20G, an electric field distance of 15 cm, an applied voltage of 12 kV, a roller receiving speed of 30 r / min, a translation speed of 400 mm / min, a spinning solution injection speed of 0.7 mL / min, and an electrospinning time of 20 min to form an electrospinning film. The film was allowed to stand at 130°C for 7 h, washed with deionized water 4 times, and dried at 65°C for 6 h to obtain a filter material for sewage treatment.

[0061] Test Case

[0062] 1. Mechanical properties

[0063] Test method: Take samples of 30 mm×5 mm in size from the filter materials for sewage treatment obtained in each embodiment and the comparative example, and test the breaking strength using a universal material testing machine produced by Instron Corporation of the United States.

[0064] 2. Dehydration performance

[0065] Test method: The filter material for sewage treatment obtained in each embodiment and the comparative example are placed tightly in a Buchner funnel, and a volume of 100 mL of sludge mixed liquid (sewage from a municipal sewage purification plant and calcium peroxide are mixed at a mass ratio of 1:0.001) is taken and filtered at a pressure of 0.04 MPa, so that the liquid is discharged from the bottom of the funnel through the filter material for sewage treatment, and the remaining wet mud cake after filtration is placed in an evaporating dish (evaporating dish weight m0) and weighed m1, and dried at 105°C to a constant weight and weighed again m2 to calculate the moisture content. ; Take 100 mL of the sludge mixture and place it in an evaporating dish (evaporating dish weight m0) and weigh M1. Dry it at 105°C until constant weight and weigh M2 again to calculate the moisture content. ; .

[0066] 3. Filtration performance

[0067] Test method: The filter material for sewage treatment obtained in each embodiment and the comparative example are placed tightly in a Buchner funnel, and a 100 mL volume of sludge mixed liquid (sewage from a municipal sewage purification plant and calcium peroxide are mixed at a mass ratio of 1:0.001) is taken and the copper ion concentration P0 is detected by ICP-MS. The mixture is filtered at a pressure of 0.04 MPa, and the liquid is discharged from the bottom of the funnel through the filter material for sewage treatment, and the copper ion concentration P1 is measured again. .

[0068] 3. Filtration performance

[0069] Test method: Take 2×2 cm test samples of the filter materials for sewage treatment obtained in each embodiment and the comparative example according to GB / T37206, sterilize by high pressure, place in 10 mL of 106 CFU / mL Escherichia coli solution, shake and culture at 37°C for 12 h, dilute the solution by 105 and evenly spread it on the surface of the solid culture medium with an "L"-shaped stick, and record the number of colonies in the culture medium after 12 h (the blank group N0 is without sample);

[0070] .

[0071] Table 1 below shows the analysis results of the mechanical properties, antibacterial properties, dehydration properties and filtration properties of the filter materials for sewage treatment using Examples 1 to 3 of the present invention and Comparative Examples 1 to 3.

[0072] Table 1

[0073]

[0074] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the filter material for sewage treatment prepared by the present invention has good mechanical properties, antibacterial properties, dehydration properties and filtration properties.

[0075] By comparison, the dehydration rates of Examples 1, 2, and 3 are higher than those of Comparative Example 1, which illustrates that the ferrous ions are loaded in the porous mullite by the liquid phase infiltration method, and used as a catalyst, and calcium peroxide is dissolved in water to release H2O2 for Fenton reaction, generating ·OH with a high redox potential, degrading microorganisms and extracellular polymers in the sludge, releasing bound water, and improving the dehydration performance of the filter material for sewage treatment; the ferrous nano-mullite is wrapped by polymerization of pyromellitic anhydride and 2-butene-1,4-diamine to form a carboxyl group, which reacts with Fe2+ to form a complex, thereby reducing the redox potential of Fe2+ and Fe3+, accelerating the recycling regeneration of Fe2+, and further improving the dehydration performance of the filter material for sewage treatment.

[0076] By comparison, the breaking strength, removal rate and antibacterial rate of Examples 1, 2 and 3 are higher than those of Comparative Example 2, which indicates that the polyvinylidene fluoride is defluorinated and hydroxylated by strong oxidizing, strong alkali and strong acid treatment, and active groups are introduced to graft 2-mercaptobenzoxazole-5-carboxylic acid, and the benzoxazole ring can inhibit cell wall synthesis, destroy cell membrane, and improve the antibacterial property of the filter material for sewage treatment; at the same time, the aromatic ring in benzoxazole can adsorb organic pollutant molecules containing aromatic rings or other π electron structures through π-π stacking, and the lone pair of electrons contained in nitrogen atoms can form coordination bonds to complex heavy metal ions, thereby improving the filtration performance of the filter material for sewage treatment; the thiol group and the carbon-carbon double bond are subjected to a click reaction under thermal initiation conditions to form a cross-linked network, thereby further improving the mechanical properties of the filter material for sewage treatment.

[0077] By comparison, the dehydration rate, removal rate and antibacterial rate of Examples 1, 2 and 3 are higher than that of Comparative Example 3, which illustrates that the use of thiol-crosslinked 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate can introduce positive and negative ions with stronger ability to bind water molecules, enhance hydrophilicity and reduce surface contamination. The zwitterionic tail can also be embedded in the bacterial cell membrane to destroy the integrity of the cell membrane, thereby further improving the dehydration performance, filtration performance and antibacterial properties of the filter material for sewage treatment.

[0078] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A filter material for sewage treatment, characterized in that: The filter material for sewage treatment is prepared by electrostatic spinning after mixing modified polyvinylidene fluoride, modified nano mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate and polyvinyl pyrrolidone; The modified polyvinylidene fluoride is obtained by treating polyvinylidene fluoride powder with sodium hydroxide and potassium permanganate, sulfuric acid and sodium bisulfite in sequence, and then reacting with 2-mercaptobenzoxazole-5-carboxylic acid; The modified nano mullite is obtained by loading ferrous ions on porous mullite and then polymerizing pyromellitic anhydride and 2-butene-1,4-diamine on the surface.

2. A method for preparing a filter material for sewage treatment, characterized in that: The method comprises the following preparation steps: (1) Mix porous mullite, ferrous sulfate heptahydrate and deionized water in a mass ratio of 1:(1.1-1.3):(9-11), soak at 105-115°C for 23-25 ​​hours, filter, wash with methanol for 3-5 times, and dry at 80-90°C for 5-7 hours to obtain ferrous nano-mullite; mix ferrous nano-mullite, pyromellitic anhydride, 2-butene-1,4-diamine and N,N-dimethylformamide in a mass ratio of 1:(1.4-1.6):(0.67-0.69):(11-13), stir at 65-75°C and 200-300 rpm for 2-4 hours, cool naturally to room temperature and centrifuge, wash with deionized water for 3-5 times, dry at 75-85°C for 8-10 hours, grind and sieve 200-300 mesh to obtain modified nano-mullite; (2) Mix polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water, ultrasonicate at 57-59°C for 25-35 min, filter, wash with deionized water for 3-5 times, and dry at 50-60°C for 5-7 h to obtain dehydrofluorinated polyvinylidene fluoride; mix dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water, ultrasonicate at 20-30°C for 25-35 min, filter, and wash with deionized water for 3-5 times. The mixture was washed 3 to 5 times, dried at 50 to 60°C for 5 to 7 hours to obtain hydroxylated polyvinylidene fluoride; hydroxylated polyvinylidene fluoride, 2-mercaptobenzoxazole-5-carboxylic acid and dichloromethane were mixed in a mass ratio of 1:(2 to 3):(16 to 18), stirred at 45 to 55°C and 300 to 500 rpm for 1 to 3 hours, filtered, washed with deionized water for 3 to 5 times, and dried at 35 to 45°C for 1 to 3 hours to obtain modified polyvinylidene fluoride; (3) The modified polyvinylidene fluoride, modified nano-mullite, 3-[[2-(acryloyloxy)ethyl]dimethylammonium]propane-1-sulfonate, polyvinyl pyrrolidone and N,N-dimethylformamide were mixed in a mass ratio of 1:(0.04-0.06):(0.07-0.09):(0.1-0.3):(3-4), and dissolved by stirring at 85-95°C and 350-450 r / min for 11-13 h. The mixture was cooled to 20-30°C, and 0.01-0.02 times the mass of azobisisobutyronitrile of the modified polyvinylidene fluoride was added. The mixture was stirred for 10-20 min, and electrospinning was performed using a 4-6 mL syringe to form a film. The film was allowed to stand at 125-135°C for 6-8 h, and washed with deionized water for 3-5 times. The film was dried at 60-70°C for 5-7 h to obtain a filter material for sewage treatment.

3. The method for preparing a filter material for sewage treatment according to claim 2, characterized in that: In step (2), the polyvinylidene fluoride powder, sodium hydroxide, potassium permanganate and deionized water are mixed in a mass ratio of 1:(0.5-0.7):(0.9-1.1):(17-18).

4. The method for preparing a filter material for sewage treatment according to claim 2, characterized in that: In step (2), the dehydrofluorinated polyvinylidene fluoride, sulfuric acid, sodium bisulfite and deionized water are mixed in a mass ratio of 1:(0.9-1.1):(0.5-0.7):(17-18).

5. The method for preparing a filter material for sewage treatment according to claim 2, characterized in that: The process parameters of the electrospinning in step (3) are: spinning temperature 20~30°C, humidity 40%~60%, electrospinning needle model 15~25G, electric field distance 14~16cm, applied voltage 11~13kV, roller receiving speed 25~35r / min, translation speed 350~450mm / min, spinning solution injection speed 0.6~0.8mL / min, and electrospinning time 15~25min.

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