Plant-based sewage filtration membrane and method of making same

Abstract

The application discloses a plant-based sewage filtering membrane and a preparation method thereof, and relates to the technical field of membrane materials. In the preparation of the plant-based sewage filtering membrane, tetraethyl orthosilicate, zinc acetate, an acetic acid solution and a polyvinyl alcohol solution are mixed, and then electrostatic spinning and calcination are performed to obtain a flexible base film. After the flexible base film is treated with trimethoxysilane, one side of the flexible base film is grafted with diethyl allyl malate, and the other side of the flexible base film is grafted with allyl trimethyl ammonium chloride. After treatment with hydrochloric acid, the plant-based sewage filtering membrane is obtained. The plant-based sewage filtering membrane prepared by the application has good flexibility, sewage filtering effect and antibacterial performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of membrane materials, in particular to a plant-based sewage filtration membrane and a preparation method thereof. BACKGROUND

[0002] Industrial production and daily life will produce a large amount of wastewater, which will cause serious threat to the ecological environment and human health if directly discharged without treatment. Therefore, wastewater treatment has become an important part of environmental protection. Membrane separation technology has shown broad application prospects in the field of wastewater treatment due to its small land occupation, low operation energy consumption, and low investment cost. This technology is economical and sustainable, and only a small amount of chemical agents is needed, which is environmentally friendly, and has become an ideal choice for wastewater treatment.

[0003] According to the composition of the material, the membrane material can be divided into three types: organic membrane, inorganic membrane and organic / inorganic composite membrane. Although the organic membrane has high mechanical strength, good flexibility and easy processing, its chemical stability is poor and it is difficult to adapt to extreme environmental conditions. Inorganic membranes can adapt to complex water quality and harsh environments, and have obvious advantages in wastewater treatment. However, the brittleness, poor vibration resistance and easy breakage of inorganic membranes restrict their wider application. Therefore, it is necessary to develop a flexible sewage filtration membrane that can adapt to complex water quality. SUMMARY

[0004] The purpose of the present application is to provide a plant-based sewage filtration membrane and a preparation method thereof to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions:

[0006] A plant-based sewage filtration membrane is prepared by treating a flexible base film with trimethoxysilane, grafting allyl diethyl malate on one side, grafting allyl trimethyl ammonium chloride on the other side, and then treating with hydrochloric acid.

[0007] As an optimization, the flexible base film is prepared by mixing tetraethyl orthosilicate, zinc acetate, acetic acid solution and polyvinyl alcohol solution, and then electrospinning and calcining.

[0008] As an optimization, the allyl diethyl malate is prepared by reacting DL-diethyl malate and 3-isocyanate propylene.

[0009] A preparation method of a plant-based sewage filtration membrane includes the following preparation steps:

[0010] (1) the spinning solution is collected by a metal needle of a syringe at a negative electrode, an injection speed is set to be constant at 1-1.2 mL / h, a high-voltage power supply of 20-22 kV is added to form an electric field, a collection distance is 12-15 cm, a receiving roller speed is 220-240 rpm, a drying chamber humidity is 40%-50%, a temperature is 20-25 °C, the electrospun membrane is prepared by placing the electrospun membrane in a muffle furnace for high-temperature calcination, a temperature rising rate is set to be 2 °C / min, and the flexible base membrane is obtained by calcining at 600-700 °C for 2-3 h;

[0011] (2) the trimethoxysilane, anhydrous ethanol and pure water are uniformly mixed according to a mass ratio of 1:2-3:8-10, the pH is adjusted to 9-10 by using sodium hydroxide, the mixture is stirred at 60-70 °C for 30-40 min, the silane treatment solution is prepared, the flexible base membrane is protected by oiling on one side surface, the one side surface of the flexible base membrane is placed downward in a container, the flexible base membrane is completely immersed in the silane treatment solution, and the one side silane treatment membrane is obtained by placing the flexible base membrane at 60-70 °C for 8-10 h, washing the one side silane treatment membrane with anhydrous ethanol and pure water for 3-5 times in sequence, and drying the one side silane treatment membrane at 60-70 °C for 8-10 h;

[0012] (3) the diethyl allyl malate, chloroplatinic acid and n-hexane are uniformly mixed according to a mass ratio of 1:0.01-0.02:6-8 to prepare the malic acid treatment solution, the one side silane treatment membrane is immersed in the malic acid treatment solution, and the malic acid treatment membrane is obtained by placing the one side silane treatment membrane at 70-80 °C for 8-10 h, washing the one side silane treatment membrane with pure water and anhydrous ethanol for 3-5 times in sequence, and drying the one side silane treatment membrane at 60-70 °C for 8-10 h;

[0013] (4) the quaternary ammonium treatment solution is prepared by uniformly mixing the allyl trimethyl ammonium chloride, chloroplatinic acid and n-hexane according to a mass ratio of 1:0.01-0.02:6-8, the untreated surface of the malic acid treatment membrane is upward, the malic acid treatment membrane is immersed in the silane treatment solution, and the double side treatment membrane is obtained by placing the malic acid treatment membrane at 60-70 °C for 8-10 h, washing the malic acid treatment membrane with anhydrous ethanol and pure water for 3-5 times in sequence, drying the malic acid treatment membrane at 60-70 °C for 8-10 h, re-immersing the malic acid treatment membrane in the quaternary ammonium treatment solution, placing the malic acid treatment membrane at 70-80 °C for 8-10 h, taking out the malic acid treatment membrane, and washing the malic acid treatment membrane with pure water and anhydrous ethanol for 3-5 times in sequence, and drying the malic acid treatment membrane at 60-70 °C for 8-10 h;

[0014] (5) the double side treatment membrane is immersed in a hydrochloric acid solution with a mass fraction of 9-10% at room temperature, and the plant-based sewage filtration membrane is prepared by placing the double side treatment membrane for 6-8 h, adjusting the pH to neutral by using sodium hydroxide, continuing to place the double side treatment membrane for 20-24 h, taking out the double side treatment membrane, and washing the double side treatment membrane with pure water for 3-5 times.

[0015] As optimization, the preparation method of the spinning solution in step (1) is as follows: polyvinyl alcohol and pure water are uniformly mixed at a mass ratio of 1:8-10, heated and stirred in a water bath at 75-85 DEG C for 4-6 h to obtain a polyvinyl alcohol solution; acetic acid and pure water are uniformly mixed at a mass ratio of 1:2-3 to prepare an acetic acid solution; 1 part of tetraethyl orthosilicate, 2-3 parts of the acetic acid solution and 3-4 parts of the polyvinyl alcohol solution are weighed, zinc acetate is weighed at a molar ratio of 1:3-5 of zinc acetate to tetraethyl orthosilicate, the zinc acetate and the acetic acid solution are uniformly mixed, the tetraethyl orthosilicate is added at a uniform speed under stirring within 10 min, after the addition is completed, the stirring is continued for 2-3 h, the polyvinyl alcohol solution is added, and the stirring is continued for 60-80 min to prepare the spinning solution.

[0016] As optimization, the alcoholysis degree of the polyvinyl alcohol is 98.0-99.0 mol%, and the viscosity is 20.0-30.0 mPa.s, and the manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd.

[0017] As optimization, the oiling protection in step (2) is that plant oil or animal oil is uniformly applied on the surface.

[0018] As optimization, the preparation method of the allyl malate diethyl ester in step (3) is as follows: under a nitrogen atmosphere, DL-malic acid diethyl ester and 3-isocyanate propylene are added to ethyl acetate at a molar ratio of 1:1, the amount of DL-malic acid diethyl ester is 6-8 times, dibutyl tin dilaurate is added, the amount of DL-malic acid diethyl ester is 0.005-0.008 times, stirring is carried out at 65-70 DEG C for 2-3 h, anhydrous ethanol is added, the amount of DL-malic acid diethyl ester is 2-3 times, the reaction is continued for 20-30 min, drying is carried out at 80-85 DEG C for 8-10 h to prepare the allyl malate diethyl ester.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] In the preparation of the plant-based sewage filtration membrane, the tetraethyl orthosilicate, zinc acetate, acetic acid solution and polyvinyl alcohol solution are mixed, electrospinning is carried out, and calcination is carried out to prepare a flexible base film, one side of the flexible base film is subjected to oiling protection, one side is treated with trimethoxysilane, the oiling protection is washed away, allyl malate diethyl ester is grafted, trimethoxysilane is used for treatment again, allyl trimethyl ammonium chloride is grafted, and hydrochloric acid is used for treatment to prepare the plant-based sewage filtration membrane.

[0021] Firstly, the doping of zinc ions can change the crystal structure of the silicon dioxide, making it more dense and uniform, and the zinc ions dispersed in the silicon dioxide matrix or the formed nanoparticles can effectively hinder the initiation and expansion path of microcracks. When the fiber is bent or stretched by external force, these heterogeneous interfaces can consume energy and prevent cracks from developing through, thereby improving flexibility, and the obtained flexible base film structure is amorphous or has small grain size and almost no defects, thereby showing good flexibility.

[0022] Secondly, one side of the grafting allyl malate diethyl ester is an anionic surface after hydrolysis, and the other side is a cationic surface; the anionic surface and the cationic surface can repel the same charge ion pollutants through the same charge electrostatic repulsion, and the untrapped ions will be adsorbed and complexed by the other side, thereby having good filtering effect.

[0023] Finally, the anionic surface and the cationic surface both have good contact sterilization effect, the malate diethyl ester used in the application is a plant-based element, and the release of zinc ions into water also has a certain sterilization effect, and is also an element needed by the human body, safe and harmless. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be described below in conjunction with the embodiments of the application, obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0025] In order to more clearly illustrate the method provided by the application, the following embodiments are described in detail.

[0026] Embodiment 1

[0027] A preparation method of a plant-based sewage filtration membrane mainly includes the following preparation steps:

[0028] (1) polyvinyl alcohol and pure water were mixed uniformly according to a mass ratio of 1:8, heated and stirred in a 75℃ water bath for 6h to obtain a polyvinyl alcohol solution; acetic acid and pure water were mixed uniformly according to a mass ratio of 1:2 to prepare an acetic acid solution; 1 part of tetraethyl orthosilicate, 2 parts of the acetic acid solution, and 3 parts of the polyvinyl alcohol solution were weighed according to mass fraction; zinc acetate was weighed according to a molar ratio of 1:5 between zinc acetate and tetraethyl orthosilicate; the zinc acetate and the acetic acid solution were mixed uniformly, and under stirring, tetraethyl orthosilicate was added at a uniform speed within 10 minutes; after the addition was completed, stirring was continued for 2h; then the polyvinyl alcohol solution was added, and stirring was continued for 60min to prepare a spinning solution; the spinning solution was collected on a negative electrode using a metal needle of a syringe; a constant injection speed of 1mL / h was set; a high-voltage power supply of 20kV was applied to form an electric field; the collection distance was 12cm; the receiving roller rotated at a speed of 220rpm; the humidity in the drying chamber was 40%; and the temperature was 20℃; then the electrospun membrane was placed in a muffle furnace for high-temperature calcination; a temperature rising rate of 2℃ / min was set; and the calcination was carried out at 650℃ for 3h to obtain a flexible base film;

[0029] (2) trimethoxysilane, anhydrous ethanol, and pure water were mixed uniformly according to a mass ratio of 1:2:8; the pH was adjusted to 9 using sodium hydroxide; stirring was carried out at 60℃ for 40min to prepare a silane treatment solution; one side surface of the flexible base film was protected by applying castor oil; the protected side surface was placed downward in a container; the flexible base film was completely immersed in the silane treatment solution; the container was placed at 60℃ for 10h; the flexible base film was taken out and washed with anhydrous ethanol and pure water for 3 times respectively; and the flexible base film was dried at 60℃ for 10h to obtain a single-sided silane treated film;

[0030] (3) under a nitrogen atmosphere, DL-malic acid diethyl ester and 3-isocyanate propylene were added to ethyl acetate in a mass ratio of 1:1, 6 times the mass of DL-malic acid diethyl ester; DL-malic acid diethyl ester was added to the mixture in a mass ratio of 0.005 times the mass of DL-malic acid diethyl ester; dibutyltin dilaurate was added at 65℃ and stirred for 3h; anhydrous ethanol was added in a mass ratio of 2 times the mass of DL-malic acid diethyl ester; the reaction was continued for 30min; and the mixture was dried at 82℃ for 9h to obtain allyl malic acid diethyl ester; allyl malic acid diethyl ester, chloroplatinic acid, and n-hexane were mixed uniformly according to a mass ratio of 1:0.01:6 to prepare a malic acid treatment solution; the single-sided silane treated film was immersed in the malic acid treatment solution; the container was placed at 70℃ for 10h; the film was taken out and washed with pure water and anhydrous ethanol for 3 times respectively; and the film was dried at 60℃ for 10h to obtain a malic acid treated film;

[0031] (4) mixing allyl trimethyl ammonium chloride, chloroplatinic acid and n-hexane in a mass ratio of 1:0.01:6 to prepare a quaternary ammonium treatment solution; immersing the untreated surface of the malic acid treatment film in the silane treatment solution with the untreated surface facing upward, and standing at 60℃ for 10h; taking out and washing with anhydrous ethanol and pure water for 3 times respectively; drying at 60℃ for 10h; immersing in the quaternary ammonium treatment solution again, and standing at 70℃ for 10h; taking out and washing with pure water and anhydrous ethanol for 3 times respectively; drying at 60℃ for 10h to obtain a double-sided treatment film;

[0032] (5) immersing the double-sided treatment film in a 9% hydrochloric acid solution at room temperature, standing for 8h, adjusting the pH to neutral with sodium hydroxide, continuing to stand for 20h, taking out and washing with pure water for 3 times to obtain a plant-based sewage filtration membrane.

[0033] Example 2

[0034] A preparation method of a plant-based sewage filtration membrane mainly comprises the following preparation steps:

[0035] (1) mixing polyvinyl alcohol and pure water in a mass ratio of 1:9 to obtain a polyvinyl alcohol solution; mixing acetic acid and pure water in a mass ratio of 1:2.5 to prepare an acetic acid solution; taking 1 part of tetraethyl orthosilicate, 2.5 parts of the acetic acid solution and 3.5 parts of the polyvinyl alcohol solution by mass fraction; taking zinc acetate according to a molar ratio of 1:4 between the molar amount of zinc acetate and the molar amount of tetraethyl orthosilicate; mixing the zinc acetate and the acetic acid solution uniformly; adding the tetraethyl orthosilicate at a constant speed within 10 minutes under stirring; continuing to stir for 2.5h after the addition is completed; adding the polyvinyl alcohol solution and continuing to stir for 70min to prepare a spinning solution; collecting the spinning solution on a negative electrode with a metal needle of a syringe; setting the injection speed to be constant at 1.1mL / h; forming an electric field with an external high-voltage power supply of 21kV; setting the collection distance to be 13cm; setting the receiving roller speed to be 230rpm; setting the drying room humidity to be 45%; setting the temperature to be 22℃; and placing it in a drying oven at 75℃ for 2.5h to prepare an electrospun membrane; placing the electrospun membrane in a muffle furnace for high-temperature calcination; setting the heating rate to be 2℃ / min; and calcining at 650℃ for 2.5h to obtain a flexible base film;

[0036] (2) mixing trimethoxysilane, anhydrous ethanol and pure water in a mass ratio of 1:2.5:9 to prepare a silane treatment solution; adjusting the pH to 9.5 with sodium hydroxide; stirring at 65℃ for 35min; using castor oil to protect one side surface of the flexible base film; placing the protected side surface downward in a container; immersing the flexible base film in the silane treatment solution completely; standing at 65℃ for 9h; taking out and washing with anhydrous ethanol and pure water for 4 times respectively; and drying at 65℃ for 9h to obtain a single-sided silane treatment film;

[0037] (3) under the atmosphere of nitrogen, DL-malic acid diethyl ester and 3-isocyanate propylene were added into ethyl acetate with the mass of DL-malic acid diethyl ester 7 times, then DL-malic acid diethyl ester with the mass of 0.006 times of dibutyltin dilaurate was added, and the reaction was stirred at 68℃ for 2.5h, then DL-malic acid diethyl ester with the mass of 2.5 times of anhydrous ethanol was added and the reaction was continued for 25min, and then drying was carried out at 82℃ for 9h to prepare allyl malate diethyl ester; allyl malate diethyl ester, chloroplatinic acid and n-hexane were mixed uniformly at the mass ratio of 1:0.015:7 to prepare a malic acid treatment solution, and the single-sided silane treatment film was immersed in the malic acid treatment solution and placed at 75℃ for 9h, then taken out and washed with pure water and anhydrous ethanol for 4 times respectively, and dried at 65℃ for 9h to obtain a malic acid treatment film;

[0038] (4) allyl trimethyl ammonium chloride, chloroplatinic acid and n-hexane were mixed uniformly at the mass ratio of 1:0.015:7 to prepare a quaternary ammonium treatment solution; the untreated surface of the malic acid treatment film was immersed in the silane treatment solution, and placed at 65℃ for 9h, then taken out and washed with anhydrous ethanol and pure water for 4 times respectively, and dried at 65℃ for 9h, then immersed in the quaternary ammonium treatment solution and placed at 75℃ for 9h, then taken out and washed with pure water and anhydrous ethanol for 4 times respectively, and dried at 65℃ for 9h to obtain a double-sided treatment film;

[0039] (5) the double-sided treatment film was immersed in a hydrochloric acid solution with a mass fraction of 9.5% at room temperature, and placed for 7h, then the pH was adjusted to neutral with sodium hydroxide, and continued to be placed for 22h, then taken out and washed with pure water for 4 times to prepare a plant-based sewage filtration membrane.

[0040] Example 3

[0041] A preparation method of a plant-based sewage filtration membrane mainly includes the following preparation steps:

[0042] (1) polyvinyl alcohol and pure water were mixed uniformly according to a mass ratio of 1:10, heated and stirred in a 85℃ water bath for 4h to obtain a polyvinyl alcohol solution; acetic acid and pure water were mixed uniformly according to a mass ratio of 1:3 to prepare an acetic acid solution; 1 part of tetraethyl orthosilicate, 3 parts of the acetic acid solution and 4 parts of the polyvinyl alcohol solution were weighed according to the mass fraction, zinc acetate was weighed according to a molar ratio of 1:5 between zinc acetate and tetraethyl orthosilicate, and the zinc acetate was mixed uniformly with the acetic acid solution; under stirring, the tetraethyl orthosilicate was added at a constant speed within 10 minutes, after the addition was completed, the stirring was continued for 3h, and then the polyvinyl alcohol solution was added and the stirring was continued for 80min to prepare a spinning solution; the spinning solution was collected on a negative electrode by a metal needle of a syringe, a constant injection speed of 1.2mL / h was set, a high-voltage power supply of 22kV was applied to form an electric field, the collection distance was 15cm, the receiving roller rotated at a speed of 240rpm, the humidity in the drying chamber was 50%, and the temperature was 25℃, and then the electrospun membrane was prepared by placing it in a drying oven at 80℃ for 3h; the electrospun membrane was calcined in a muffle furnace, the heating rate was set to 2℃ / min, and the calcination was carried out at 650℃ for 2h to obtain a flexible base film;

[0043] (2) trimethoxysilane, anhydrous ethanol and pure water were mixed uniformly according to a mass ratio of 1:3:10, the pH was adjusted to 10 with sodium hydroxide, and the stirring was carried out at 70℃ for 30min to prepare a silane treatment solution; the flexible base film was protected by applying castor oil to one side of the surface, the side surface protected by the oil was placed downward in a container, the flexible base film was completely immersed in the silane treatment solution, and the container was placed at 70℃ for 8h, then the flexible base film was taken out and washed with anhydrous ethanol and pure water for 5 times respectively, and dried at 70℃ for 8h to obtain a single-sided silane treated film;

[0044] (3) under a nitrogen atmosphere, DL-malic acid diethyl ester and 3-isocyanate propylene were added to ethyl acetate with a mass of 8 times that of DL-malic acid diethyl ester according to a molar ratio of 1:1, then dibutyltin dilaurate with a mass of 0.008 times that of DL-malic acid diethyl ester was added, the stirring was carried out at 70℃ for 2h, anhydrous ethanol with a mass of 3 times that of DL-malic acid diethyl ester was added and the reaction was continued for 20min, and the drying was carried out at 85℃ for 8h to prepare allyl malic acid diethyl ester; the allyl malic acid diethyl ester, chloroplatinic acid and n-hexane were mixed uniformly according to a mass ratio of 1:0.02:8 to prepare a malic acid treatment solution, the single-sided silane treated film was immersed in the malic acid treatment solution, and the container was placed at 80℃ for 8h, then the single-sided silane treated film was taken out and washed with pure water and anhydrous ethanol for 5 times respectively, and dried at 70℃ for 8h to obtain a malic acid treated film;

[0045] (4) mixing allyl trimethyl ammonium chloride, chloroplatinic acid and n-hexane in a mass ratio of 1:0.02:8 to prepare a quaternary ammonium treatment solution; immersing the untreated surface of the malic acid treated membrane in the silane treatment solution, standing at 70°C for 8h, taking out and washing with absolute ethanol and pure water for 5 times respectively, drying at 70°C for 8h, immersing in the quaternary ammonium treatment solution, standing at 80°C for 8h, taking out and washing with pure water and absolute ethanol for 5 times respectively, drying at 70°C for 8h to obtain a double-sided treated membrane;

[0046] (5) immersing the double-sided treated membrane in a 10% hydrochloric acid solution at room temperature, standing for 8h, adjusting the pH to neutral with sodium hydroxide, continuing to stand for 24h, taking out and washing with pure water for 5 times to obtain a plant-based sewage filtration membrane.

[0047] Example 4

[0048] Example 4 is different from Example 2 only in that the "constant temperature calcination at 650°C" in step (1) is adjusted to "constant temperature calcination at 600°C", and the rest of the steps are the same as Example 2.

[0049] Example 5

[0050] Example 5 is different from Example 2 only in that the "constant temperature calcination at 650°C" in step (1) is adjusted to "constant temperature calcination at 700°C", and the rest of the steps are the same as Example 2.

[0051] Comparative Example 1

[0052] Comparative Example 1 is different from Example 2 only in that no zinc acetate is added in step (1), and the rest of the steps are the same as Example 2.

[0053] Comparative Example 2

[0054] Comparative Example 2 is different from Example 2 only in that the "zinc acetate and tetraethyl orthosilicate are weighed in a molar ratio of 1:4" in step (1) is modified to "zinc acetate and tetraethyl orthosilicate are weighed in a molar ratio of 1:2", and the rest of the steps are the same as Example 2.

[0055] Comparative Example 3

[0056] Comparative Example 3 is different from Example 2 only in that the "zinc acetate and tetraethyl orthosilicate are weighed in a molar ratio of 1:4" in step (1) is modified to "zinc acetate and tetraethyl orthosilicate are weighed in a molar ratio of 1:1", and the rest of the steps are the same as Example 2.

[0057] Comparative Example 4

[0058] Comparative Example 4 is different from Example 2 only in that the tetraethyl orthosilicate in step (1) is replaced by an equal molar amount of zinc acetate, and the rest of the steps are the same as Example 2.

[0059] Comparative Example 5

[0060] Comparative Example 5 differs from Example 2 only in that the "isothermally calcined at 650℃" in Step (1) is changed to "isothermally calcined at 800℃", and the other steps are the same as Example 2.

[0061] Comparative Example 6

[0062] Comparative Example 6 differs from Example 2 only in that the "isothermally calcined at 650℃" in Step (1) is changed to "isothermally calcined at 900℃", and the other steps are the same as Example 2.

[0063] Comparative Example 7

[0064] A preparation method of a plant-based sewage filtration membrane mainly includes the following preparation steps:

[0065] (1) Polyvinyl alcohol and pure water are mixed uniformly according to a mass ratio of 1:9, heated and stirred in a water bath at 80℃ for 5h to obtain a polyvinyl alcohol solution; acetic acid and pure water are mixed uniformly according to a mass ratio of 1:2.5 to prepare an acetic acid solution; 1 part of tetraethyl orthosilicate, 2.5 parts of the acetic acid solution, and 3.5 parts of the polyvinyl alcohol solution are weighed, zinc acetate is weighed according to a molar ratio of 1:4 of zinc acetate and tetraethyl orthosilicate, and the zinc acetate and the acetic acid solution are mixed uniformly, under stirring, the tetraethyl orthosilicate is added at a uniform speed within 10 minutes, after the addition is completed, the stirring is continued for 2.5h, the polyvinyl alcohol solution is added, and the stirring is continued for 70min to prepare a spinning solution; the spinning solution is collected on a negative electrode by a metal needle of a syringe, an injection speed is set to be constant at 1.1mL / h, a high-voltage power supply of 21kV is applied to form an electric field, a collection distance is 13cm, a receiving roller rotates at a speed of 230rpm, a drying room humidity is 45%, and a temperature is 22℃, and then the electrostatic spinning membrane is prepared by placing it in a drying oven at 75℃ for 2.5h;

[0066] (2) Trimethoxysilane, anhydrous ethanol, and pure water are mixed uniformly according to a mass ratio of 1:2.5:9, the pH is adjusted to 9.5 by sodium hydroxide, and stirring is performed at 65℃ for 35min to prepare a silane treatment solution; the flexible base membrane is completely immersed in the silane treatment solution and kept at a distance of more than 2cm from the container wall, and is placed at 65℃ for 9h, and then taken out and washed with anhydrous ethanol and pure water for 4 times respectively, and dried at 65℃ for 9h to obtain a silane treated membrane; one side surface of the silane treated membrane is protected by rubbing with castor oil, and the side surface protected by rubbing is placed in a container with the side surface down,

[0067] (3) under nitrogen atmosphere, diethyl DL-malate and 3-isocyanate propylene were added into ethyl acetate with 7 times of diethyl DL-malate, then dibutyl tin dilaurate with 0.006 times of diethyl DL-malate was added, and the mixture was stirred at 68℃ for 2.5h, then anhydrous ethanol with 2.5 times of diethyl DL-malate was added and the mixture was reacted for 25min, and the mixture was dried at 82℃ for 9h to obtain diethyl allyl malate; diethyl allyl malate, chloroplatinic acid and n-hexane were mixed at a mass ratio of 1:0.015:7 to prepare a malic acid treatment solution, and the silane treated film was placed in a container with the side of the silane treated film treated by oil protection facing down, the malic acid treatment solution was added and the silane treated film was completely immersed, and the mixture was placed at 75℃ for 9h, and then the silane treated film was taken out and washed with pure water and anhydrous ethanol for 4 times respectively, and the mixture was dried at 65℃ for 9h to obtain a malic acid treated film;

[0068] (4) allyl trimethyl ammonium chloride, chloroplatinic acid and n-hexane were mixed at a mass ratio of 1:0.015:7 to prepare a quaternary ammonium treatment solution; the untreated surface of the malic acid treated film was upwardly immersed in the silane treatment solution, and the mixture was placed at 65℃ for 9h, and then the mixture was taken out and washed with anhydrous ethanol and pure water for 4 times respectively, and the mixture was dried at 65℃ for 9h, and then the mixture was immersed in the quaternary ammonium treatment solution, and the mixture was placed at 75℃ for 9h, and then the mixture was taken out and washed with pure water and anhydrous ethanol for 4 times respectively, and the mixture was dried at 65℃ for 9h to obtain a double-sided treated film;

[0069] (5) the double-sided treated film was immersed in a hydrochloric acid solution with a mass fraction of 9.5% at room temperature, and the mixture was placed for 7h, and then the pH was adjusted to neutral by sodium hydroxide, and the mixture was placed for 22h, and then the mixture was taken out and washed with pure water for 4 times to obtain a plant-based sewage filtration membrane.

[0070] Comparative Example 8

[0071] Comparative Example 8 is different from Example 2 in that the quaternary ammonium treatment solution is not used for treatment, and both sides are treated by the malic acid treatment solution. The remaining steps are the same as those of Example 2.

[0072] Comparative Example 9

[0073] Comparative Example 9 is different from Example 2 in that the malic acid treatment solution is not used for treatment, and both sides are treated by the quaternary ammonium treatment solution. The remaining steps are the same as those of Example 2.

[0074] Comparative Example 10

[0075] The difference between Comparative Example 10 and Example 2 is in step (5), which is modified as follows: the double-sided treated membrane is immersed in a sodium chloride solution with a mass fraction of 9.5% at room temperature for 22 h, taken out and washed with pure water for 4 times to obtain a plant-based sewage filtration membrane. The double-sided treated membrane is immersed in a hydrochloric acid solution with a mass fraction of 9.5% at room temperature for 7 h, and then the pH is adjusted to neutral with sodium hydroxide, and the membrane is continuously immersed for 22 h, taken out and washed with pure water for 4 times to obtain a plant-based sewage filtration membrane.

[0076] Comparative Example 11

[0077] Polyvinyl alcohol and pure water are mixed in a mass ratio of 1:9, heated and stirred in a water bath at 80°C for 5 h to obtain a polyvinyl alcohol solution; acetic acid and pure water are mixed in a mass ratio of 1:2.5 to prepare an acetic acid solution; 1 part of tetraethyl orthosilicate, 2.5 parts of the acetic acid solution and 3.5 parts of the polyvinyl alcohol solution are weighed; zinc acetate is weighed according to a molar ratio of 1:4 between zinc acetate and tetraethyl orthosilicate; the zinc acetate and the acetic acid solution are mixed uniformly, and under stirring, the tetraethyl orthosilicate is added at a constant speed within 10 minutes; after the addition is completed, the stirring is continued for 2.5 h; then the polyvinyl alcohol solution is added and the stirring is continued for 70 min to obtain a spinning solution; the spinning solution is collected on a negative electrode using a metal needle of a syringe, the injection speed is set to be constant at 1.1 mL / h, a high-voltage power supply of 21 kV is applied to form an electric field, the collection distance is 13 cm, the receiving roller rotates at a speed of 230 rpm, the humidity in the drying chamber is 45%, and the temperature is 22°C; then the electrospun membrane is placed in a muffle furnace for high-temperature calcination, the temperature rising rate is set to be 2°C / min, and the calcination is carried out at 650°C for 2.5 h to obtain a flexible base membrane.

[0078] Test Example 1

[0079] Test of flexibility

[0080] The flexible base membranes obtained in Examples and Comparative Examples 1-6 are cut into test samples with a size of 3 cm*10 cm, 3 cm of the edge of each test sample is clamped, and the test sample is rotated by 180 degrees to observe the state of the test sample.

[0081] Table 1

[0082]

[0083]

[0084] As can be seen from the experimental data of Examples 1-5 and Comparative Examples 1-6 in Table 1, the plant-based sewage filtration membrane prepared by the present application has good flexibility.

[0085] The results of Comparative Examples 1-3 and Comparative Examples 1-4 show that doping zinc ions can change the crystal structure of the silicon dioxide, making it more dense and uniform, and the metal ions dispersed in the silicon dioxide matrix or the nanoparticles formed can effectively hinder the initiation and propagation path of microcracks. When the fiber is bent or stretched by external force, these heterogeneous interfaces can consume energy and prevent cracks from developing through, thereby improving the flexibility of the material. When the ratio of zinc ions to tetraethyl orthosilicate is 1:3-5, the effect is better, but too much doping will cause the grain size in the flexible base film to increase, thereby making the overall brittle.

[0086] The results of Comparative Examples 1-5 and Comparative Examples 5-6 show that when calcined at 600-700°C, the resulting flexible base film is amorphous or has small grain size, and almost no defects, thereby exhibiting good flexibility, but as the temperature increases, the grain size increases, thereby making the overall brittle.

[0087] Therefore, by selecting the ratio of zinc ions to tetraethyl orthosilicate as 1:3-5 and the calcination temperature as 600-700°C, a flexible base film with good flexibility can be obtained.

[0088] Test Example 2

[0089] Test of filtration effect

[0090] Test method of filtration effect: The materials obtained in Examples 1-3 and Comparative Examples 7-11 were used for filtration, with the membrane thickness controlled at 200 um, 100 mL of 0.1 moL / L rhodamine B solution, and 100 mL of 0.1 moL / L copper sulfate solution. The surface treated with the quaternary ammonium treatment solution was used as the filtration surface. The retention rate was calculated according to the residual molar amount in the filtrate after filtration, and the retention rate = 1-initial molar amount / filtrate molar amount after filtration. The results are shown in Table 2.

[0091] Table 2

[0092] Rhodamine B rejection Copper ion rejection Example 1 99.3％ 95.7％ Example 2 98.8％ 95.5％ Example 3 98.6％ 95.0％ Comparative Example 7 95.4％ 93.7％ Comparative Example 8 69.6％ 87.5％ Comparative Example 9 97.1％ 90.2％ Comparative Example 10 97.5％ 90.5％ Comparative Example 11 42.9％ 23.5％

[0093] As can be seen from the experimental data of Examples 1-3 and Comparative Examples 7-11 in Table 2, the plant-based sewage filtration membrane prepared by the present application has good filtration effect.

[0094] As can be seen from the data comparison of Examples 1-3 and Comparative Example 7, the oil protection is performed before the treatment with the silane treatment solution, and the main solvent is water, which can protect the other side from being modified, but the subsequent reaction main solvent will dissolve the oil, thereby affecting the protection effect, and thus reducing the cation filtration effect.

[0095] From the data comparison of Examples 1-3 and Comparative Example 8, it can be found that the cationic surface treated by quaternary ammonium salt can repel the cationic pollutants through electrostatic repulsion, thereby improving the retention rate of cationic pollutants.

[0096] From the data comparison of Examples 1-3 and Comparative Example 9, it can be found that the anionic surface treated by malic acid can adsorb the unretained cations through electrostatic adsorption complexation, and the adsorption complexation effect on copper ions is better.

[0097] From the data comparison of Examples 1-3 and Comparative Example 10, it can be found that the final treatment with hydrochloric acid can fully hydrolyze the diethyl malate groups on the surface of the membrane into carboxylate groups, thereby playing a better electrostatic adsorption complexation effect.

[0098] From the data comparison of Comparative Example 10, it can be found that the flexible base film has a certain retention effect, and the retention rate of rhodamine B is higher than that of copper ions, which may be due to the size barrier effect, because the rhodamine B molecule is larger than the copper ion.

[0099] Test Example 3

[0100] Test of antibacterial performance

[0101] Test method of antibacterial performance: The materials obtained in Examples 1-3 and Comparative Examples 7-11 were ground and sieved through a 200-mesh sieve as test samples, and Escherichia coli was activated to prepare a bacterial suspension with a concentration of 10 7 CFU / mL. Then 0.1 g of each test sample was placed in 10 mL of the bacterial suspension diluted 100 times (10 5 CFU / mL), and the bacterial suspension added with pure silicon dioxide powder was used as a blank group and placed at room temperature for 48 h. Finally, each group of bacterial suspensions was diluted 100 times, and 100 μL was uniformly coated on the surface of TSA culture medium. After incubation at 37℃ for 24 h, the bacterial colony growth was counted, and the antibacterial rate was calculated. The antibacterial rate = (A-B) / A, where A is the bacterial count of the silicon dioxide powder, and B is the bacterial count of each test sample. The results are shown in Table 2

[0102] Table 2

[0103]

[0104]

[0105] From the experimental data comparison of Examples 1-3 and Comparative Examples 7-11 in Table 3, it can be found that the plant-based sewage filtration membrane prepared by the present application has good antibacterial performance. Because the zinc ions, grafted malic acid and quaternary ammonium salt structure doped in the plant-based sewage filtration membrane all have bactericidal effects, the multiple synergies make the bactericidal effect better.

[0106] The above detailed description of the specific embodiments of the present application is provided for the purpose of further explaining the objects, technical solutions and advantages of the present application, and it should be understood that the above description is merely specific embodiments of the present application and is not intended to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A plant-based wastewater filtration membrane, characterized in that, The plant-based wastewater filtration membrane is prepared by treating a flexible base membrane with trimethoxysilane, grafting allyl malate onto one side and allyl trimethylammonium chloride onto the other side, and then treating it with hydrochloric acid. The flexible base film is prepared by electrospinning and calcining a mixture of tetraethyl orthosilicate, zinc acetate, acetic acid solution and polyvinyl alcohol solution. The allyl malate diethyl ester is prepared by reacting DL-malate diethyl ester and propylene 3-isocyanate.

2. A method for preparing a plant-based wastewater filtration membrane, characterized in that, The preparation steps include the following: (1) The spinning solution is collected at the negative electrode using a syringe metal needle. The injection speed is set to be constant at 1~1.2 mL / h. A high voltage power supply of 20~22 kV is applied to form an electric field. The collection distance is 12~15 cm, the receiving roller speed is 220~240 rpm, the humidity of the drying chamber is 40%~50%, the temperature is 20~25℃, and then it is dried at 70~80℃ for 2~3 h to obtain an electrospun film. The electrospun membrane was placed in a muffle furnace for high-temperature calcination. The heating rate was set to 2℃ / min, and the membrane was calcined at a constant temperature of 600~700℃ for 2~3 hours to obtain a flexible base membrane. The spinning solution is prepared as follows: polyvinyl alcohol and pure water are mixed evenly at a mass ratio of 1:8~10, and heated and stirred in a water bath at 75~85℃ for 4~6 hours to obtain a polyvinyl alcohol solution; acetic acid and pure water are mixed evenly at a mass ratio of 1:2~3 to prepare an acetic acid solution; 1 part of tetraethyl orthosilicate, 2~3 parts of acetic acid solution, and 3~4 parts of polyvinyl alcohol solution are weighed according to the mass ratio; zinc acetate is weighed according to the molar ratio of zinc acetate to tetraethyl orthosilicate of 1:3~5; zinc acetate and acetic acid solution are mixed evenly; under stirring conditions, tetraethyl orthosilicate is added at a uniform rate within 10 minutes; after the addition is completed, stirring is continued for 2~3 hours; then polyvinyl alcohol solution is added, and stirring is continued for 60~80 minutes to obtain the spinning solution; (2) Mix trimethoxysilane, anhydrous ethanol and pure water in a mass ratio of 1:2~3:8~10, adjust the pH to 9~10 with sodium hydroxide, stir at 60~70℃ for 30~40 min to obtain silane treatment solution; apply oil protection to one side of the flexible base film, place the oil-protected side down in a container, add silane treatment solution to completely immerse the flexible base film, let it stand at 60~70℃ for 8~10 h, take it out and wash it with anhydrous ethanol and pure water 3~5 times each, dry it at 60~70℃ for 8~10 h to obtain a single-sided silane-treated film; (3) Allyl malic acid diethyl ester, chloroplatinic acid and n-hexane are mixed evenly in a mass ratio of 1:0.01~0.02:6~8 to prepare malic acid treatment solution. The single-sided silane treatment membrane is immersed in the malic acid treatment solution and left to stand at 70~80℃ for 8~10h. It is then taken out and washed with pure water and anhydrous ethanol 3~5 times each. It is then dried at 60~70℃ for 8~10h to obtain malic acid treatment membrane. (4) Allyltrimethylammonium chloride, chloroplatinic acid, and n-hexane are mixed evenly in a mass ratio of 1:0.01~0.02:6~8 to prepare a quaternary ammonium treatment solution; the untreated surface of the malic acid treated membrane is placed upward and immersed in the silane treatment solution, and left to stand at 60~70℃ for 8~10h. The membrane is then removed and washed with anhydrous ethanol and pure water 3~5 times each, dried at 60~70℃ for 8~10h, and then immersed in the quaternary ammonium treatment solution again, left to stand at 70~80℃ for 8~10h, removed and washed with pure water and anhydrous ethanol 3~5 times each, and dried at 60~70℃ for 8~10h to obtain a double-sided treated membrane; (5) Immerse the double-sided treated membrane in a 9-10% hydrochloric acid solution at room temperature, let it stand for 6-8 hours, then adjust the pH to neutral with sodium hydroxide, and let it stand for another 20-24 hours. Take it out and wash it with pure water 3-5 times to obtain a plant-based wastewater filter membrane.

3. The method for preparing a plant-based wastewater filtration membrane according to claim 2, characterized in that, The degree of alcoholysis of the polyvinyl alcohol is 98.0~99.0 mol%, and the viscosity is 20.0~30.0 mPa.s.

4. The method for preparing a plant-based wastewater filtration membrane according to claim 2, characterized in that, The oiling protection in step (2) involves evenly applying vegetable or animal oil to the surface.

5. The method for preparing a plant-based wastewater filtration membrane according to claim 2, characterized in that, The preparation method of allyl malate diethyl ester in step (3) is as follows: Under a nitrogen atmosphere, DL-malic acid diethyl ester and propylene 3-isocyanate are added to ethyl acetate in a molar ratio of 1:1, which is 6 to 8 times the mass of DL-malic acid diethyl ester. Then, dibutyltin dilaurate is added in a molar ratio of 0.005 to 0.008 times the mass of DL-malic acid diethyl ester. The mixture is stirred and reacted at 65 to 70°C for 2 to 3 hours. Then, anhydrous ethanol in a molar ratio of 2 to 3 times the mass of DL-malic acid diethyl ester is added and the reaction is continued for 20 to 30 minutes. The mixture is then dried at 80 to 85°C for 8 to 10 hours to obtain allyl malate diethyl ester.

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