Preparation method and application of copper powder sintered filter with antibacterial hydrogel grafted on surface

Abstract

The invention discloses a preparation method and application of a copper powder sintered filter with the surface grafted with antibacterial hydrogel. Firstly, dopamine is used for carrying out surface treatment on the copper powder sintered filter to form a layer of protective film, so that corrosion is prevented, and the protective film can be tightly combined with later hydrogel. The preparation method comprises the following steps: soaking a filter sheet treated by dopamine into an aqueous solution of acrylamide, water-soluble polymer, N, N-methylene bisacrylamide and ammonium persulfate, then adding a mixed aqueous solution of silver nitrate and sodium hydrogen sulfite, uniformly mixing the solution under stirring, and rapidly catalyzing ammonium persulfate by silver ions to generate free radicals to initiate polymerization of acrylamide, so as to obtain the water-soluble polymer filter sheet. Sodium hydrogen sulfite and ammonium persulfate continue to initiate polymerization of acrylamide, the copper powder sintered filter is taken out and cross-linked through calcium nitrate, and the copper powder sintered filter with the antibacterial hydrogel grafted on the surface is obtained and applied to removal of emulsified oil and algae. Part of silver ions in the hydrogel react with copper to obtain nano-silver, and the hydrogel is endowed with good antibacterial performance.

Description

Technical Field

[0001] The invention discloses a preparation method and application of a copper powder sintered filter sheet with antibacterial hydrogel grafted on the surface, and belongs to the field of wastewater, sewage treatment and functional materials. Background Art

[0002] With the acceleration of industrialization, oily wastewater generated by industries such as petrochemicals, machinery manufacturing, and food processing has become a global environmental problem. This type of wastewater usually contains various forms of oil pollutants such as floating oil, dispersed oil, emulsified oil, and dissolved oil. Its chemical oxygen demand is high and its toxicity is high. Direct discharge will destroy the ecological balance of water bodies and threaten human health. According to statistics, more than 1 billion tons of oily wastewater are generated by industrial activities worldwide each year. With increasingly stringent environmental regulations, the development of efficient, energy-saving, and environmentally friendly oil-water separation technology has become a scientific and technological proposition that urgently needs to be broken through.

[0003] Among the many separation technologies, traditional treatment methods such as gravity sedimentation, flotation separation and chemical demulsification have obvious limitations: gravity sedimentation is only applicable to floating oil with a particle size greater than 150μm; flotation has high energy consumption and low efficiency in treating emulsified oil; chemical demulsification is easy to introduce secondary pollution and increase treatment costs. Membrane separation has attracted much attention due to its high efficiency, low energy consumption and modular design. Its core mechanism is based on the physicochemical properties of membrane materials: intercepting oil droplets through pore size screening effect, or achieving selective permeation by using surface wettability differences. For example, hydrophobic modified polyvinylidene fluoride membrane can separate emulsified oil through the "oil preferential adsorption-membrane pore penetration" mechanism, while hydrophilic modified ceramic membrane relies on the "water phase preferential passage" principle to block the oil phase. Compared with traditional technologies, membrane separation can achieve a retention rate of more than 99% for emulsified oil with a particle size <20μm, and no chemical agents need to be added, avoiding secondary pollution. However, single material membranes face bottlenecks such as fast flux decay, poor anti-pollution, and insufficient mechanical strength. For example, pure organic membranes (such as polypropylene and polysulfone) are easily clogged by oil, resulting in reduced flux, while inorganic ceramic membranes have excellent stability but are brittle and expensive. These defects have led to innovative research on composite membranes, aiming to synergize the advantages of the two types of materials.

[0004] As the core material of membrane separation technology, polymer membranes play an important role in the treatment of oily wastewater due to their adjustable pore structure, good film-forming properties and cost advantages. However, traditional polymer membranes such as polyvinylidene fluoride (PVDF), polyethersulfone (PES) and polyacrylonitrile (PAN) have defects such as strong surface hydrophobicity, easy adhesion of oil stains, poor anti-pollution performance, and significant flux attenuation during long-term operation. To this end, researchers have functionalized polymer membranes through various strategies such as surface modification, chemical grafting, and co-mixing and doping, aiming to optimize their wettability, anti-pollution and separation efficiency. Related research has become a hot topic in the field of membrane science. Although polymer membrane modification technology has made significant progress, its large-scale application still faces multiple challenges: ① The long-term stability of the surface coating is insufficient and it is easy to fall off during strong shear force or chemical cleaning; ② The dispersion uniformity of nanofillers in co-mixing modification is difficult to control, which can easily cause membrane structural defects; ③ The complex modification process leads to an increase in membrane production costs, which restricts industrial promotion. Future research needs to focus on: developing high-durability modification methods (such as covalently fixed functional layers), exploring green and low-cost modification processes (such as bio-based coatings), and developing in-situ monitoring and self-repairing technologies to extend membrane life. At the same time, combining artificial intelligence to screen modified material formulas is expected to accelerate the customized development of high-performance polymer membranes and promote oily wastewater treatment technology towards high efficiency and intelligence.

[0005] Porous metal materials are composed of a rigid framework and internal voids, which give them excellent physical properties and good mechanical properties. Even compared with inorganic ceramic membranes, porous metal materials have a wider range of application prospects due to their porosity, controllable pore size, high filtration accuracy, good recyclability, easy modification, high strength and good toughness. As a porous metal material, copper powder sintered filter discs are increasingly used in filtration and separation, chemical reaction engineering, airflow control devices, power equipment, heat pipes, acoustic control, biomedical implants and environmental protection. By adjusting copper powders of different sizes and proportions, the powder particles are subjected to "point contact" plastic deformation through bidirectional pressing of the mold, followed by step-by-step sintering, and polishing treatment by electrochemical methods after sintering. Combining powder metallurgy with surface engineering, the cross-scale construction of pore structure from macro to micro is achieved through the coordinated control of physical pressing parameters and sintering dynamics. Due to the hydrophobicity of copper, the preparation of super-hydrophobic copper-based filter membranes also has application prospects in the field of water / oil separation. At the same time, the pore geometry and wettability control the separation efficiency and flux of the membrane filtration device. Since oil-in-water and water-in-oil emulsions have different droplet size distributions, a single membrane geometry is not suitable for all applications. In this regard, copper powder sintered filters can be customized with different pore sizes and porosities through different powder particle types, different pressures, etc. This membrane strategy may achieve high-efficiency or high-flux separation for different separation scenarios. By controlling the surface of the sintered material, different surface modifications can further enhance the hydrophilicity of the porous metal material and its repulsion to specific substances.

[0006] Porous metal materials have been studied in depth as filter membranes with special wettability to achieve oil-water separation. This special wettability can be achieved by coating metal mesh and porous metal on the membrane by physical and chemical methods [Nanoscale Research Letters, 2018, 13: 284]. Porous metal materials used in the separation field have a high dependence on porosity and pore size. Higher pore size and porosity mean higher permeability and separation efficiency. Copper powder sintered filter discs are a kind of metal porous material. They are made of copper powder and pressed at high temperature. They are composed of a metal skeleton and internal voids. In the powder metallurgy process, copper powder sintered filter discs are prepared by regulating the pressing pressure, sintering temperature and sintering time, as well as the powder particle size, to achieve strict control of porosity and pore size. However, copper powder sintered filter discs are easily corroded during water treatment. Through the study of various modifications of copper powder sintered filter discs, it is believed that it can open up a wider application prospect in the field of separation membrane technology.

[0007] Hydrogels have attracted widespread attention due to their unique three-dimensional network structure, high hydrophilicity, biocompatibility and environmental friendliness [JJ Membr. Sci., 2023, 679: 11]. Due to their unique properties, the use of hydrogels in membrane materials has significant advantages and provides new possibilities for the development of membrane separation technology. In order to achieve environmentally friendly, efficient, and long-term stable treatment of oily wastewater, hydrogel nanofiber filtration membranes prepared using electrospinning technology are considered to be a suitable choice. Sodium alginate is a natural polysaccharide derived from brown algae, rich in hydroxyl and carboxyl groups, and can react with cations (such as Ca 2+ ) cross-linked to form a hydrogel. Mixing polyethylene oxide with sodium alginate solution can not only improve the rheological properties of the spinning solution and stabilize the electrospinning process, but also significantly enhance the hydrophilicity of the membrane.

[0008] In view of the problems that traditional filter membranes are easily contaminated, resulting in decreased separation efficiency, hydrogel membranes have good hydrophilicity but low strength, are easy to breed bacteria, and copper powder sintered filter discs are easily corroded, the present invention reports a preparation method and application of a copper powder sintered filter disc with surface grafted antibacterial hydrogel. First, the copper powder sintered filter disc is surface treated with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel behind. The filter disc treated with dopamine is immersed in an aqueous solution of acrylamide, water-soluble polymer, N, N-methylenebisacrylamide and ammonium persulfate, and then a mixed aqueous solution of silver nitrate and sodium bisulfite is added. The solution is mixed evenly under stirring, and silver ions quickly catalyze ammonium persulfate to produce free radicals to initiate the polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate the polymerization of acrylamide. The copper powder sintered filter disc is taken out, and after calcium nitrate cross-linking, a copper powder sintered filter disc with surface grafted antibacterial hydrogel is obtained, which is applied to the removal of emulsified oil and algae. Some silver ions in the hydrogel react with copper to obtain nanosilver, which gives the hydrogel good antibacterial properties. Summary of the invention

[0009] The present invention aims to solve the problems that traditional filter membranes are easily contaminated, resulting in reduced separation efficiency, hydrogel membranes are hydrophilic but low in strength, easy to breed bacteria, and copper powder sintered filter discs are easily corroded. The technical solution to the above problems is to provide a preparation method and application of a copper powder sintered filter disc with antibacterial hydrogel grafted on the surface.

[0010] The present invention discloses a method for preparing a copper powder sintered filter sheet with an antibacterial hydrogel grafted on the surface and its application, which is characterized by comprising the following steps:

[0011] a) ultrasonically cleaning the copper powder sintered filter disc with anhydrous ethanol and acetone respectively, drying and setting aside, dissolving dopamine in a tris(hydroxymethyl)aminomethane-acid buffer solution, soaking the cleaned and dried copper powder sintered filter disc in the tris(hydroxymethyl)aminomethane-acid buffer solution of dopamine for 5 to 24 hours, then taking out the copper powder sintered filter disc, repeatedly rinsing it with deionized water to remove the residue on its surface, and drying it for setting aside; treating the copper powder sintered filter disc with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel prepared in the subsequent steps;

[0012] b) the copper powder sintered filter disc treated with dopamine obtained in step a) is immersed in a mixed aqueous solution of 1% to 15% acrylamide, 0.1% to 2% water-soluble polymer, 0.1% to 1% N,N-methylenebisacrylamide and 0.01% to 0.5% ammonium persulfate, and then an aqueous solution of 0.01% to 0.1% silver nitrate and 0.01% to 0.5% sodium bisulfite is added, and the solution is quickly mixed under stirring, silver ions catalyze ammonium persulfate to produce free radicals to initiate polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate polymerization of acrylamide, thereby grafting a layer of chemically cross-linked hydrogel on the porous interior and surface of the copper powder sintered filter disc; the semi-interpenetrating network structure formed by the water-soluble polymer and polyacrylamide improves the strength of the hydrogel;

[0013] c) immersing the copper powder sintered filter sheet grafted with a layer of chemically cross-linked hydrogel obtained in step b) in a calcium nitrate aqueous solution with a mass percentage concentration of 0.5% to 5% for cross-linking for 1 to 8 hours to obtain a copper powder sintered filter sheet with an antibacterial hydrogel grafted on the surface, the surface of which has good hydrophilicity and a water contact angle of 1 to 12 degrees;

[0014] d) During the reaction, part of the silver ions react with the copper on the surface of the copper powder sintered filter to obtain nanosilver, which together with the silver ions in the hydrogel give the hydrogel good antibacterial properties, and its antibacterial rate against Escherichia coli is 75% to 100%;

[0015] e) preparing an emulsified oil containing 0.1% to 5% by mass percentage concentration; assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the modified copper powder sintered filter disc has a retention rate of 80% to 99.9% for the emulsified oil and a flux of 200 to 3000 L m -2 h -1 bar -1 , thus efficiently removing emulsified oil from sewage;

[0016] f) preparing an algae aqueous solution with an algae density of 10 million / L to 100 million / L, assembling the copper powder sintered filter disc with antibacterial hydrogel grafted on the surface obtained in step c) into a cross-flow filtration device, wherein the copper powder sintered filter disc has an algae retention rate of 85% to 99% and a flux of 300 to 4200 L m -2 h -1 bar -1 , thereby efficiently removing algae in the water and avoiding the formation of algal blooms.

[0017] The membrane pore size of the copper powder sintered filter sheet described in the present invention is 1 to 100 microns, the water-soluble polymer is any one of sodium alginate, water-soluble starch, carboxymethyl chitosan, and polyvinyl alcohol, and the algae is any one of cyanobacteria, green algae, diatoms, and chlorella, or a mixture of two or more thereof. DETAILED DESCRIPTION

[0018] Specific embodiments of the present invention are described below, but the present invention is not limited to the embodiments.

[0019] Example 1.

[0020] a) ultrasonically cleaning a copper powder sintered filter disc with a membrane pore size of 1 micron with anhydrous ethanol and acetone respectively, drying and setting aside; dissolving dopamine in a tris(hydroxymethyl)aminomethane-acid buffer solution, soaking the cleaned and dried copper powder sintered filter disc in the tris(hydroxymethyl)aminomethane-acid buffer solution of dopamine for 24 hours, then taking out the copper powder sintered filter disc, repeatedly rinsing it with deionized water to remove the residue on its surface, and drying it for setting aside; treating the copper powder sintered filter disc with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel prepared in the subsequent steps;

[0021] b) the copper powder sintered filter disc treated with dopamine obtained in step a) is immersed in a mixed aqueous solution of 1% by mass concentration of acrylamide, 0.1% by mass concentration of sodium alginate, 0.1% by mass concentration of N,N-methylenebisacrylamide and 0.01% by mass concentration of ammonium persulfate, and then an aqueous solution of 0.01% by mass concentration of silver nitrate and 0.01% by mass concentration of sodium bisulfite is added, and the solution is quickly mixed and uniformly stirred, silver ions catalyze ammonium persulfate to produce free radicals to initiate polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate polymerization of acrylamide, thereby grafting a layer of chemically cross-linked hydrogel on the porous interior and surface of the copper powder sintered filter disc; the semi-interpenetrating network structure formed by sodium alginate and polyacrylamide improves the strength of the hydrogel;

[0022] c) immersing the copper powder sintered filter disc grafted with a layer of chemically cross-linked hydrogel obtained in step b) in a calcium nitrate aqueous solution with a mass percentage concentration of 0.5% for cross-linking for 1 hour to obtain a copper powder sintered filter disc with an antibacterial hydrogel grafted on the surface, the surface of which has good hydrophilicity and a water contact angle of 12 degrees;

[0023] d) During the reaction, part of the silver ions reacted with the copper on the surface of the copper powder sintered filter to obtain nanosilver, which together with the silver ions in the hydrogel gave the hydrogel good antibacterial properties, and its antibacterial rate against Escherichia coli was 75%;

[0024] e) preparing an emulsified oil containing 0.1% by mass percentage; assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the retention rate of the modified copper powder sintered filter disc for the emulsified oil reaches 99.9% and the flux reaches 200 L m -2 h -1 bar -1 , thus efficiently removing emulsified oil from sewage;

[0025] f) preparing a blue algae aqueous solution with a blue algae density of 10 million / L, assembling the copper powder sintered filter disc with antibacterial hydrogel grafted on the surface obtained in step c) into a cross-flow filtration device, wherein the retention rate of the modified copper powder sintered filter disc for blue algae reaches 99%, and the flux reaches 300L m -2 h -1 bar -1 , thereby efficiently removing blue algae in the water and avoiding the occurrence of algal blooms.

[0026] Example 2.

[0027] a) ultrasonically cleaning a copper powder sintered filter disc with a membrane pore size of 100 microns with anhydrous ethanol and acetone respectively, and drying for later use; dissolving dopamine in a tris(hydroxymethyl)aminomethane-acid buffer solution, and soaking the cleaned and dried copper powder sintered filter disc in the tris(hydroxymethyl)aminomethane-acid buffer solution of dopamine for 5 hours; then taking out the copper powder sintered filter disc, repeatedly rinsing it with deionized water to remove the residue on its surface, and drying it for later use; treating the copper powder sintered filter disc with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel prepared in the subsequent steps;

[0028] b) soaking the copper powder sintered filter disc treated with dopamine obtained in step a) in a mixed aqueous solution of 15% by mass concentration of acrylamide, 2% by mass concentration of water-soluble starch, 1% by mass concentration of N,N-methylenebisacrylamide and 0.5% by mass concentration of ammonium persulfate, and then adding an aqueous solution of 0.1% by mass concentration of silver nitrate and 0.5% by mass concentration of sodium bisulfite, and mixing the solution quickly and uniformly under stirring, wherein silver ions catalyze ammonium persulfate to produce free radicals to initiate polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate polymerization of acrylamide, thereby grafting a layer of chemically cross-linked hydrogel on the porous interior and surface of the copper powder sintered filter disc; the semi-interpenetrating network structure formed by the water-soluble starch and polyacrylamide improves the strength of the hydrogel;

[0029] c) immersing the copper powder sintered filter disc grafted with a layer of chemically cross-linked hydrogel obtained in step b) in a 5% by mass calcium nitrate aqueous solution for cross-linking for 8 hours to obtain a copper powder sintered filter disc with an antibacterial hydrogel grafted on the surface, the surface of which has good hydrophilicity and a water contact angle of 1 degree;

[0030] d) During the reaction, part of the silver ions reacted with the copper on the surface of the copper powder sintered filter to obtain nanosilver, which together with the silver ions in the hydrogel gave the hydrogel good antibacterial properties, and its antibacterial rate against Escherichia coli was 100%;

[0031] e) preparing an emulsified oil with a mass percentage concentration of 5%; assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the modified copper powder sintered filter disc has an interception rate of 80% for the emulsified oil and a flux of 3000 L m -2 h -1 bar -1 , thus efficiently removing emulsified oil from sewage;

[0032] f) preparing a green algae aqueous solution with a green algae density of 100 million per liter, assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the modified copper powder sintered filter disc has a green algae retention rate of 85% and a flux of 4200 L m -2 h -1 bar -1 , thereby efficiently removing green algae in the water and avoiding the formation of algal blooms.

[0033] Example 3.

[0034] a) ultrasonically cleaning a copper powder sintered filter disc with a membrane pore size of 40 microns with anhydrous ethanol and acetone respectively, drying and setting aside, dissolving dopamine in a tris(hydroxymethyl)aminomethane-acid buffer solution, soaking the cleaned and dried copper powder sintered filter disc in the tris(hydroxymethyl)aminomethane-acid buffer solution of dopamine for 8 hours, then taking out the copper powder sintered filter disc, repeatedly rinsing it with deionized water to remove the residue on its surface, and drying it for setting aside; treating the copper powder sintered filter disc with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel prepared in the subsequent steps;

[0035] b) the copper powder sintered filter disc treated with dopamine obtained in step a) is immersed in a mixed aqueous solution of 5% by mass concentration of acrylamide, 1% by mass concentration of carboxymethyl chitosan, 0.2% by mass concentration of N,N-methylenebisacrylamide and 0.15% by mass concentration of ammonium persulfate, and then an aqueous solution of 0.05% by mass concentration of silver nitrate and 0.05% by mass concentration of sodium bisulfite is added, and the solution is quickly mixed and uniformly stirred, silver ions catalyze ammonium persulfate to produce free radicals to initiate polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate polymerization of acrylamide, thereby grafting a layer of chemically cross-linked hydrogel on the porous interior and surface of the copper powder sintered filter disc; the semi-interpenetrating network structure formed by carboxymethyl chitosan and polyacrylamide improves the strength of the hydrogel;

[0036] c) immersing the copper powder sintered filter disc grafted with a layer of chemically cross-linked hydrogel obtained in step b) in a calcium nitrate aqueous solution with a mass percentage concentration of 2.5% for cross-linking for 5 hours to obtain a copper powder sintered filter disc with an antibacterial hydrogel grafted on the surface, the surface of which has good hydrophilicity and a water contact angle of 10 degrees;

[0037] d) During the reaction, part of the silver ions react with the copper on the surface of the copper powder sintered filter to obtain nanosilver, which together with the silver ions in the hydrogel give the hydrogel good antibacterial properties, and its antibacterial rate against Escherichia coli is 90%;

[0038] e) preparing an emulsified oil containing 0.5% by mass percentage; assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the modified copper powder sintered filter disc has a retention rate of 98% for the emulsified oil and a flux of 2600 L m -2 h -1 bar -1 , thus efficiently removing emulsified oil from sewage;

[0039] f) preparing a diatom solution with a diatom density of 50 million / L, assembling the copper powder sintered filter disc with antibacterial hydrogel grafted on the surface obtained in step c) into a cross-flow filtration device, wherein the diatom retention rate of the modified copper powder sintered filter disc reaches 98%, and the flux reaches 3600 L m -2 h -1 bar -1 , thereby efficiently removing diatoms in the water and avoiding the occurrence of algal blooms.

[0040] Example 4.

[0041] a) ultrasonically cleaning a copper powder sintered filter disc with a membrane pore size of 60 microns with anhydrous ethanol and acetone respectively, drying and setting aside; dissolving dopamine in a tris(hydroxymethyl)aminomethane-acid buffer solution, soaking the cleaned and dried copper powder sintered filter disc in the tris(hydroxymethyl)aminomethane-acid buffer solution of dopamine for 12 hours, then taking out the copper powder sintered filter disc, repeatedly rinsing it with deionized water to remove the residue on its surface, and drying it for setting aside; treating the copper powder sintered filter disc with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel prepared in the subsequent steps;

[0042] b) the copper powder sintered filter disc treated with dopamine obtained in step a) is immersed in a mixed aqueous solution of 5% by mass concentration of acrylamide, 1% by mass concentration of polyvinyl alcohol, 0.6% by mass concentration of N,N-methylenebisacrylamide and 0.08% by mass concentration of ammonium persulfate, and then an aqueous solution of 0.06% by mass concentration of silver nitrate and 0.06% by mass concentration of sodium bisulfite is added, and the solution is quickly mixed and uniformly stirred, silver ions catalyze ammonium persulfate to produce free radicals to initiate polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate polymerization of acrylamide, thereby grafting a layer of chemically cross-linked hydrogel on the porous interior and surface of the copper powder sintered filter disc; the semi-interpenetrating network structure formed by polyvinyl alcohol and polyacrylamide improves the strength of the hydrogel;

[0043] c) immersing the copper powder sintered filter disc grafted with a layer of chemically cross-linked hydrogel obtained in step b) in a 4% by mass calcium nitrate aqueous solution for cross-linking for 5 hours to obtain a copper powder sintered filter disc with an antibacterial hydrogel grafted on the surface, the surface of which has good hydrophilicity and a water contact angle of 4 degrees;

[0044] d) During the reaction, part of the silver ions react with the copper on the surface of the copper powder sintered filter to obtain nanosilver, which together with the silver ions in the hydrogel give the hydrogel good antibacterial properties, and its antibacterial rate against Escherichia coli is 90%;

[0045] e) preparing an emulsified oil with a mass percentage concentration of 2%; assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the modified copper powder sintered filter disc has a retention rate of 92% for the emulsified oil and a flux of 2400 L m -2 h -1 bar -1 , thus efficiently removing emulsified oil from sewage;

[0046] f) preparing a mixed algae aqueous solution with a density of 50 million / L for both blue algae and green algae, assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the retention rates of the modified copper powder sintered filter disc for blue algae and green algae are 93% and 92% respectively, and the flux is 2800 L m -2 h -1 bar -1 , thereby efficiently removing blue algae and green algae in the water and avoiding the occurrence of algal blooms.

Claims

1. A preparation method and application of a copper powder sintered filter sheet with antibacterial hydrogel grafted on the surface, characterized in that The following steps are involved: a) ultrasonically cleaning the copper powder sintered filter disc with anhydrous ethanol and acetone respectively, drying and setting aside, dissolving dopamine in a tris(hydroxymethyl)aminomethane-acid buffer solution, soaking the cleaned and dried copper powder sintered filter disc in the tris(hydroxymethyl)aminomethane-acid buffer solution of dopamine for 5 to 24 hours, then taking out the copper powder sintered filter disc, repeatedly rinsing it with deionized water to remove the residue on its surface, and drying it for setting aside; treating the copper powder sintered filter disc with dopamine to form a protective film, which not only prevents corrosion but also can be tightly combined with the hydrogel prepared in the subsequent steps; b) the copper powder sintered filter disc treated with dopamine obtained in step a) is immersed in a mixed aqueous solution of 1% to 15% acrylamide, 0.1% to 2% water-soluble polymer, 0.1% to 1% N,N-methylenebisacrylamide and 0.01% to 0.5% ammonium persulfate, and then an aqueous solution of 0.01% to 0.1% silver nitrate and 0.01% to 0.5% sodium bisulfite is added, and the solution is quickly mixed under stirring, silver ions catalyze ammonium persulfate to produce free radicals to initiate polymerization of acrylamide, and sodium bisulfite and ammonium persulfate continue to initiate polymerization of acrylamide, thereby grafting a layer of chemically cross-linked hydrogel on the porous interior and surface of the copper powder sintered filter disc; the semi-interpenetrating network structure formed by the water-soluble polymer and polyacrylamide improves the strength of the hydrogel; c) immersing the copper powder sintered filter sheet grafted with a layer of chemically cross-linked hydrogel obtained in step b) in a calcium nitrate aqueous solution with a mass percentage concentration of 0.5% to 5% for cross-linking for 1 to 8 hours to obtain a copper powder sintered filter sheet with an antibacterial hydrogel grafted on the surface, the surface of which has good hydrophilicity and a water contact angle of 1 to 12 degrees; d) During the reaction, part of the silver ions react with the copper on the surface of the copper powder sintered filter to obtain nanosilver, which together with the silver ions in the hydrogel give the hydrogel good antibacterial properties, and its antibacterial rate against Escherichia coli is 75% to 100%; e) preparing an emulsified oil containing 0.1% to 5% by mass percentage concentration; assembling a copper powder sintered filter disc with a surface grafted antibacterial hydrogel obtained in step c) into a cross-flow filtration device, wherein the modified copper powder sintered filter disc has a retention rate of 80% to 99.9% for the emulsified oil and a flux of 200 to 3000 L m -2 h -1 bar -1 , thus efficiently removing emulsified oil from sewage; f) preparing an algae aqueous solution with an algae density of 10 million / L to 100 million / L, assembling the copper powder sintered filter disc with antibacterial hydrogel grafted on the surface obtained in step c) into a cross-flow filtration device, wherein the copper powder sintered filter disc has an algae retention rate of 85% to 99% and a flux of 300 to 4200 L m -2 h -1 bar -1 , thereby efficiently removing algae in the water and avoiding the formation of algal blooms.

2. The preparation method and application of a copper powder sintered filter sheet with antibacterial hydrogel grafted on the surface as claimed in claim 1, characterized in that The membrane pore size of the copper powder sintered filter sheet is 1 to 100 microns.

3. The preparation method and application of a copper powder sintered filter sheet with antibacterial hydrogel grafted on the surface as claimed in claim 1, characterized in that The water-soluble polymer is any one of sodium alginate, water-soluble starch, carboxymethyl chitosan and polyvinyl alcohol.

4. The preparation method and application of a copper powder sintered filter sheet with antibacterial hydrogel grafted on the surface as claimed in claim 1, characterized in that The algae is any one of blue algae, green algae, diatom and chlorella, or a mixture of two or more thereof.