Composite mineralized filter element for filtering and separating drinking water and preparation method of composite mineralized filter element

Abstract

The invention relates to the technical field of mineralization filter element preparation, in particular to a composite mineralization filter element for filtering and separating drinking water and a preparation method of the composite mineralization filter element. The filter element is composed of a pretreatment layer, a mineralization layer, an antibacterial layer and a composite reaction layer; efficient interception and hydrophilic diversion are realized; the mineralization layer adopts a nano-hydroxyapatite / diatomite complex and is added with a polycarboxylic acid vinyl ester derivative; the antibacterial layer is combined with silver-loaded zeolite, zinc oxide nanoparticles and a benzoxazole sulfonate derivative; according to the composite reaction layer, the degradation rate of organic pollutants under visible light is larger than or equal to 95% / h by reducing graphene oxide / TiO-NH / boron nitride quantum dot heterojunctions. The water purifier has efficient mineralization, long-acting antibacterial and deep catalytic properties, and is suitable for deep purification of drinking water with high turbidity and high organic matter content.

Description

Technical Field

[0001] The present invention relates to the technical field of mineralized filter element preparation, and particularly to a composite mineralized filter element for drinking water filtration and separation and a preparation method thereof. Background Art

[0002] Currently, the mineralized layers of filter elements mostly use natural ores or single hydroxyapatite, which have limited ion exchange capacity and uneven pore structures. After long-term use, they are easily blocked by suspended substances, resulting in a flux decline of more than 50%. In addition, traditional mineralizing agents have weak selective adsorption ability for heavy metals and are prone to ion desorption when the pH fluctuates, causing secondary pollution.

[0003] The mainstream antibacterial layer uses silver-loaded zeolite or silver nanoparticles. Although it can provide broad-spectrum antibacterial properties, the dissolution amount of silver ions in acidic or high-temperature water can reach 0.5 - 2.0 ppb. Long-term intake may cause argyria in the human body. At the same time, silver-based antibacterial agents have poor inhibitory effects on stubborn bacteria in biofilms, the diameter of the antibacterial circle is usually < 10 mm, and silver nanoparticles are prone to agglomeration and inactivation, with a service life of less than 6 months.

[0004] As a commonly used photocatalytic material, titanium dioxide has a band gap width of 3.2 eV and can only utilize ultraviolet light. The degradation efficiency of organic pollutants under natural light is < 30%. Although the light response range can be extended through nitrogen doping or noble metal modification, the quantum efficiency of the modified TiO 2 is still lower than 10%, and the cost is high. In addition, the recombination rate of photo-generated electron-hole pairs is high, resulting in insufficient generation of free radicals and difficulty in completely mineralizing pesticide residues and endocrine disruptors.

[0005] Existing composite filter elements are mostly assembled by simple lamination or gluing. The bonding strength at the layer interface is low, and interlayer peeling is likely to occur under water pressure impact or temperature change, resulting in short circuit or functional failure. At the same time, the material compatibility of each functional layer is poor. For example, direct contact between activated carbon and metal antibacterial agents may trigger redox reactions, leading to inactivation of the antibacterial agent or corrosion of the carbon skeleton.

[0006] Nanomaterials are prone to agglomeration in traditional processes, with a particle size distribution D90 > 500 nm and a specific surface area loss > 60%, severely limiting their adsorption and catalytic activities. In addition, the continuous forming technology of multi-layer filter elements is not mature. It often requires step-by-step processing and then assembly, with a production cycle of up to 48 hours and a good product rate < 70%, making it difficult to meet the large-scale application requirements.

[0007] In summary, there are significant bottlenecks in the material properties, structural design, and preparation processes of existing drinking water filter elements. There is an urgent need to develop an integrated filter element solution with high-efficiency mineralization, long-term antibacterial, deep catalysis, and stable structure to cope with complex water quality challenges and meet increasingly strict drinking water safety standards. Summary of the Invention

[0008] (1) Technical problems to be solved In view of the deficiencies of the prior art, the present invention provides a composite mineralization filter element for drinking water filtration and separation and a preparation method thereof.

[0009] (2) Technical solutions A composite mineralization filter element for drinking water filtration and separation comprises, from outside to inside, a pretreatment layer, a mineralization layer, an antibacterial layer and a composite reaction layer. Each layer is bonded by a hot-melt interface agent to form an integral structure; The pretreatment layer is made of polypropylene fiber C with an average diameter of 20-30 μm 3 H 6 and coconut shell activated carbon with a particle size of 100-200 mesh in a mass ratio of 1:2 by a twin-screw melt spinning machine. The melting temperature is 270°C ± 5°C, the pore diameter of the spinneret is 0.3 mm, and a polydopamine hydrophilic coating with a thickness of 250 ± 50 nm is coated on the surface of the fiber substrate 9 H 11 NO 2 , and the chemical structural formula is:

[0010] The coating solution is formed by oxidative polymerization of 10 mg / mL dopamine hydrochloride 8 H 11 NO 2 ·HCl in a Tris-HCl buffer solution with pH = 8.5 ± 0.2. After curing, the water contact angle ≤ 15°; The mineralization layer is composed of nano-hydroxyapatite Ca with a particle size of 50-100 nm 5 (PO 4 ) 3 OH and porous diatomite SiO 2 ·nH 2 O mixed in a mass ratio of 1:3-1:5, and uniformly doped with 5%-8% by mass of a polycarboxylic acid vinyl ester derivative as an ion exchange enhancer. The derivative is copolymerized from acrylic acid and sodium vinyl sulfonate under the initiation of ammonium persulfate, and the weight average molecular weight of the copolymer is 20,000-30,000 Da; the reaction formula is:

[0011] The antibacterial layer is composed of silver-loaded zeolite with a silver loading of 3%-5%, zinc oxide nanoparticles and a benzoxazole sulfonate derivative compounded in a mass ratio of 2:1:0.05. The MIC value of the benzoxazole sulfonate derivative against Escherichia coli is 4.2 μg / mL, and the decomposition rate in 80°C hot water for 24 hours < 1%. Its structural formula is:

[0012] The composite reaction layer is composed of reduced graphene oxide with a thickness of 0.5 - 1.0 nm and amino-modified titanium dioxide nanotubes with a tube diameter of 10 - 15 nm and a length of 300 - 600 nm, TiO 2 -NH 2 which are covalently connected through C-N bonds to form a heterojunction, and doped with hexagonal boron nitride quantum dots with a particle size of 2 - 5 nm. The pretreatment layer realizes the interception of large-particle impurities and hydrophilic diversion, with a water contact angle ≤ 15° and a 40% increase in flux; the mineralization layer synergistically adsorbs through carboxylic acid and sulfonic acid bifunctional groups, with a Ca²⁺ / Mg²⁺ exchange capacity of 2.8 mmol / g, a 50% increase compared to the traditional mineralization layer; the antibacterial layer combines inorganic-organic antibacterial mechanisms, with an antibacterial rate against Escherichia coli ≥ 99.9% and a dissolved silver ion content < 0.1 ppb, meeting the GB 5749-2022 standard; the composite reaction layer generates ·OH and ·O 2 ⁻ free radicals under visible light, with an organic pollutant degradation efficiency ≥ 98% / h and a lifespan 3 times longer than that of pure TiO 2 .

[0013] Preferably, the synthesis of the polycarboxylate vinyl ester derivative is carried out by dissolving acrylic acid C 3 H 4 O 2 and sodium vinyl sulfonate C 2 H 3 O 3 in deionized water at a molar ratio of 1:1, adding 1.0 wt% ammonium persulfate as an initiator, stirring and reacting at 85°C ± 2°C under nitrogen protection for 8 hours, dialyzing the reaction solution to remove unreacted monomers, and freeze-drying to obtain a white porous solid; the carboxylic acid group density of the derivative is 3.2 mmol / g, the sulfonic acid group density is 1.8 mmol / g, and the adsorption capacity for Ca²⁺ is ≥ 2.5 mmol / g in the pH range of 6 - 8.

[0014] Preferably, the preparation method of the benzoxazole sulfonate derivative is specifically to first dissolve benzoxazole C 7 H 5 NO in dichloromethane, cool it to 0 - 5°C in an ice bath, and slowly dropwise add chlorosulfonic acid HSO 3 Cl at a molar ratio of 1:1.2, stir and react for 2 hours to generate a sulfonyl chloride intermediate C 7 H 4 NO 3 SCl, and the reaction by-product HCl is removed by nitrogen purging. The specific reaction formula is as follows:

[0015] Then, an excessive amount of methanol is added to the intermediate, and the reaction is stirred at room temperature for 4 hours. The specific reaction formula is as follows:

[0016] The product was washed three times with deionized water and vacuum dried at 60 °C for 12 hours to obtain a white crystalline solid. The purity was ≥99.5% by HPLC detection; the thermal decomposition temperature of the derivative was 225 °C ± 5 °C, the solubility in water at 25 °C was 0.75 mg / mL, and the dissolution amount of the antibacterial agent in simulated drinking water in 30 days was <0.05 ppb.

[0017] Preferably, the amino-modified titanium dioxide nanotubes are synthesized by a sol-gel-hydrothermal method: tetrabutyl titanate and ethylenediamine are dissolved in absolute ethanol at a molar ratio of 1:0.5, stirred and hydrolyzed for 24 hours, then transferred to a polytetrafluoroethylene autoclave, and hydrothermally reacted at 180 °C for 12 hours. The product is centrifuged and washed and then dispersed in dilute nitric acid with pH = 4, and aged at 60 °C for 6 hours to enhance crystallinity; the specific surface area of the nanotubes is 280 ± 20 m² / g, and the pore size distribution is 2 - 10 nm.

[0018] Preferably, the preparation method of the composite mineralized filter element for drinking water filtration and separation comprises the following steps: S1: Preparation of the pretreatment layer: Polypropylene particles with a melt index of 25 g / 10 min and coconut shell activated carbon powder are melt-blended at 270 °C ± 5 °C, and spun into fibers through a melt-blown machine. The fiber substrate is sprayed with a polydopamine coating under a pressure of 0.4 MPa, then pre-dried at 60 °C for 30 min, and then cured by ultraviolet light with a wavelength of 365 nm and an intensity of 100 mW / cm² for 40 min; S2: Sintering of the mineralized layer: Nano-hydroxyapatite, diatomite and polyvinyl carboxylate derivatives are added to a planetary ball mill according to a mass ratio of 1:3:0.08, zirconia balls are used as the grinding medium, the ball-to-material ratio is 5:1, and ball milling is carried out at a rotation speed of 400 rpm for 5 h. The mixed powder is filled into a graphite mold, placed in a tube furnace, and heated to 900 °C ± 10 °C at a rate of 10 °C / min in a mixed atmosphere of nitrogen and CO 2 and kept at this temperature for 3 h, and then cooled to room temperature with the furnace to obtain a porous mineralized layer with a porosity of 65% ± 3% and a compressive strength of 18 MPa ± 2 MPa; S3: Molding of the antibacterial layer: Silver-loaded zeolite, zinc oxide nanoparticles and benzoxazole sulfonate derivatives are added to a supercritical CO 2 dispersion device, dispersed at 40 °C and 15 MPa for 30 min, and the dispersed slurry is made into a fiber membrane by an electrospinning machine; S4: Composite reaction layer assembly: Mix reduced graphene oxide and amino-modified titanium dioxide nanotubes at a volume ratio of 1:4, add boron nitride quantum dots with a mass fraction of 3%, ultrasonically disperse for 30 min, then transfer to a high-pressure reactor, react at 120°C ± 5°C under argon protection for 6 h, filter the reaction product by vacuum filtration to make a film with a thickness of 50 - 80 μm, and dry it in vacuum at 60°C for 12 h; S5: Overall composite: After each functional layer is activated by an oxygen / argon mixed gas plasma, hot press and composite at 200°C ± 10°C and 8 MPa for 20 min. A SiO 2 transition layer with a thickness of 15 ± 5 nm is formed at the interlayer interface by chemical vapor deposition. The deposition source is tetraethoxysilane, the deposition temperature is 400°C ± 20°C, and the deposition rate is 2 nm / min.

[0019] Preferably, in the supercritical CO 2 dispersion process, the critical parameters of CO 2 are a temperature of 31.1°C and a pressure of 7.38 MPa. The actual operating conditions are a temperature of 40°C ± 2°C and a pressure of 15 MPa ± 0.5 MPa. The particle size distribution of the dispersed mixture is D50 = 80 nm ± 10 nm, and D90 = 150 nm ± 20 nm.

[0020] Preferably, the tensile strength of the electrospun fiber membrane is 8.5 MPa ± 0.5 MPa, the elongation at break is 25% ± 3%, the water flux ≥ 2000 L / m²·h, and the inhibition zone diameter against Staphylococcus aureus ≥ 15 mm.

[0021] Preferably, the test conditions for the photocatalytic performance of the composite reaction layer film are: using a 10 mg / L methylene blue solution as the simulated pollutant, the light intensity is 50 mW / cm², and after 1 hour of reaction, the decolorization rate of the solution ≥ 95%, and the chemical oxygen demand removal rate ≥ 90%.

[0022] Preferably, in the hot press composite process, the interlayer bonding strength is tested by 180° peel force ≥ 15 N / cm. The elemental distribution of the silica transition layer shows that Si and O elements are distributed in a gradient at the interface, and the thickness coefficient of variation ≤ 10%.

[0023] (III) Beneficial technical effects Compared with the existing technology, the beneficial effects of the present invention are: 1. Four - layer collaborative purification system: The pretreatment layer intercepts large - particle impurities and realizes hydrophilic diversion. The water contact angle ≤ 15°, and the flux is increased by 40%; The mineralization layer synergistically adsorbs through carboxylic acid and sulfonic acid bifunctional groups. The Ca²⁺ / Mg²⁺ exchange capacity reaches 2.8 mmol / g, which is 50% higher than that of the traditional mineralization layer; The antibacterial layer combines inorganic - organic antibacterial mechanisms. The antibacterial rate against Escherichia coli ≥ 99.9%, and the dissolved silver ions < 0.1 ppb, meeting the GB 5749 - 2022 standard; The composite reaction layer generates ·OH and ·O 2 ⁻ free radicals under visible light. The degradation efficiency of organic pollutants ≥ 98% / h, and the lifespan is 3 times longer than that of pure TiO 2 .

[0024] 2. Innovative material design: Polyvinyl carboxylate derivatives are copolymerized by acrylic acid and sodium vinyl sulfonate to form a porous network structure. The specific surface area ≥ 200 m² / g, and form a chemical bond with diatomite during the sintering process. The compressive strength reaches 18 MPa; The sulfonic acid methyl ester group of benzoxazole sulfonate derivatives enhances the hydrogen - bond interaction with silver - loaded zeolite, and the amino group (-NH 2 ) provides targeted bactericidal activity. The MIC value is as low as 4.2 μg / mL, and the stability in 80 °C hot water is increased by 90%; TiO 2 -NH 2 / graphene / BN heterojunction improves the photogenerated electron mobility through amino modification. BN quantum dots inhibit electron - hole recombination, and the quantum efficiency reaches 35% (λ = 420 nm).

[0025] 3. High - efficiency preparation process: Supercritical CO 2 dispersion makes the particle size D90 of antibacterial components ≤ 150 nm, and combined with electrospinning to make a fiber membrane with a porosity ≥ 85%. The flux is maintained ≥ 2000 L / m²·h; Plasma activation and SiO 2 transition layer deposition makes the interlayer bonding strength ≥ 15 N / cm, and the peeling force is 80% higher than that of the traditional hot - pressing process; There is no toxic solvent residue in the whole process, and the material utilization rate ≥ 95%, which is suitable for large - scale production. Description of the Drawings

[0026] Figure 1 is the production flow chart of the composite mineralization filter element for drinking water filtration and separation; Figure 2 is the test results of the antibacterial rate and photocatalytic efficiency of the comparative example and the examples. Detailed Embodiments

[0027] Example 1 Raw materials and equipment: Mineralization layer: The mass fraction of polyvinyl carboxylate derivative is 5%, the sintering temperature is 900 °C, and the mass ratio of diatomite to hydroxyapatite is 1:3; Antibacterial layer: Loading amount of benzoxazole sulfonate derivative is 3%, mass ratio of silver-loaded zeolite to ZnO is 2:1; Composite reaction layer: Doping amount of boron nitride quantum dots (BN) is 2%; Equipment: Planetary ball mill, supercritical CO 2 Reactor, electrospinning machine.

[0028] Preparation steps: Mineralization layer: Hydroxyapatite, diatomite and polycarboxyvinyl ester derivative are mixed and ball milled for 5 hours, and sintered at 900 °C for 3 hours in N 2 / CO 2 Atmosphere, porosity is 65%; Antibacterial layer: Silver-loaded zeolite, ZnO and C 9 H 8 N 2 O 5 S are dispersed by supercritical CO 2 (40 °C, 15 MPa) and then electrospun, fiber diameter is 120 nm; Composite reaction layer: Graphene and TiO 2 -NH 2 Are mixed at a volume ratio of 1:4, doped with 2% BN quantum dots, and reacted in a high-pressure reactor at 120 °C for 6 hours.

[0029] Performance test: Mineralization ability: Ca²⁺ adsorption capacity is 2.5 mmol / g; Antibacterial rate: Bacteriostatic rate against Escherichia coli is 99.2%; Photocatalytic efficiency: Methylene blue degradation rate is 92% / h; Example 2 Raw materials and equipment: Mineralization layer: Mass fraction of polycarboxyvinyl ester derivative is 8%, sintering temperature is 920 °C, mass ratio of diatomite to hydroxyapatite is 1:5; Antibacterial layer: Loading amount of benzoxazole sulfonate derivative is 5%, mass ratio of silver-loaded zeolite to ZnO is 2:1; Composite reaction layer: Doping amount of BN quantum dots is 4%; Equipment: The same as in Example 1.

[0030] Preparation steps: Mineralization layer: Sintering temperature is increased to 920 °C, content of polycarboxyvinyl ester derivative is increased to 8%, porosity is 70%; Antibacterial layer: Loading amount of C 9 H 8 N 2 O 5 S is increased to 5%, fiber diameter is 100 nm; Composite reaction layer: The doping amount of BN is increased to 4%, and the reaction time is extended to 7 hours.

[0031] Performance test: Mineralization ability: The Ca²⁺ adsorption capacity is 3.1 mmol / g; Antibacterial rate: The antibacterial rate against Staphylococcus aureus is 99.9%; Photocatalytic efficiency: The degradation rate of methylene blue is 98% / h.

[0032] Example 3 Raw materials and equipment: Mineralization layer: The mass fraction of polyvinyl carboxylate derivative is 6%, the sintering temperature is 880 °C, and the mass ratio of diatomite to hydroxyapatite is 1:4; Antibacterial layer: The loading amount of benzoxazole sulfonate derivative is 4%, and the mass ratio of silver-loaded zeolite to ZnO is 2:1; Composite reaction layer: The doping amount of BN quantum dots is 3%; Equipment: The same as in Example 1.

[0033] Preparation steps: Mineralization layer: The sintering temperature is reduced to 880 °C, the content of polyvinyl carboxylate derivative is 6%, and the porosity is 60%; Antibacterial layer: C 9 H 8 N 2 O 5 The loading amount of S is 4%, and the fiber diameter is 150 nm; Composite reaction layer: The doping amount of BN is 3%, and the reaction time is 5 hours.

[0034] Performance test: Mineralization ability: The Ca²⁺ adsorption capacity is 2.8 mmol / g; Antibacterial rate: The antibacterial rate against Pseudomonas aeruginosa is 99.6%; Photocatalytic efficiency: The degradation rate of methylene blue is 95% / h.

[0035] Comparative example Raw materials and equipment: Mineralization layer: Polyvinyl carboxylate derivative is not added, only diatomite and hydroxyapatite (mass ratio 1:3), and the sintering temperature is 900 °C; Antibacterial layer: Only silver-loaded zeolite and ZnO (mass ratio 2:1), without C 9 H 8 N 2 O 5 S; Composite reaction layer: BN quantum dots are not doped, only graphene and TiO 2 -NH 2 ; Equipment: The same as in Example 1.

[0036] Preparation steps: Mineralized layer: Directly sinter diatomaceous earth and hydroxyapatite, without polyvinyl carboxylate derivatives; Antibacterial layer: Only mix silver-loaded zeolite and ZnO, without using supercritical CO 2 Dispersion; Composite reaction layer: Do not add BN, reaction time is 6 hours.

[0037] Performance test: Mineralization ability: Ca²⁺ adsorption capacity is 1.2 mmol / g; Antibacterial rate: The antibacterial rate against Escherichia coli is 85%; Photocatalytic efficiency: The degradation rate of methylene blue is 30% / h.

[0038] Performance comparison chart:

[0039] Conclusion: Polyvinyl carboxylate derivatives significantly improve the ion exchange capacity, and Example 2 is 158% higher than the comparative example; Benzoxazole sulfonate derivatives increase the antibacterial rate to over 99%, and Example 2 is 14.9% higher than the comparative example; Doping with BN quantum dots increases the degradation efficiency to over 95%, and Example 3 is 217% higher than the comparative example.

Claims

1. A composite mineralized filter element for drinking water filtration and separation, characterized in that: From the outside to the inside, it includes a pretreatment layer, a mineralization layer, an antibacterial layer and a composite reaction layer, and each layer is bonded by a hot-melt interface agent to form an integral structure; The pretreatment layer is prepared by a twin-screw melt-blown machine with a mass ratio of 1:2 of polypropylene fiber C3H6 with an average diameter of 20-30 μm and coconut shell activated carbon with a particle size of 100-200 mesh, the melting temperature is 270°C ± 5°C, the spinneret hole diameter is 0.3 mm, and the surface of the fiber substrate is coated with a polydopamine hydrophilic coating C9H with a thickness of 250 ± 50 nm. 11 NO2, chemical structure is: The coating solution consisted of 10 mg / mL dopamine hydrochloride C8H 11 NO2·HCl is formed by oxidative polymerization in Tris-HCl buffer at pH=8.5±0.2, and the water contact angle after solidification is ≤15°; The mineralized layer is a mixture of nano-hydroxyapatite Ca5(PO4)3OH with a particle size of 50-100nm and porous diatomaceous earth SiO2·nH2O in a mass ratio of 1:3-1:5, and is uniformly doped with a polyvinyl carboxylate derivative with a mass fraction of 5%-8% as an ion exchange enhancer. The derivative is copolymerized by acrylic acid and sodium vinyl sulfonate under the initiation of ammonium persulfate, and the weight average molecular weight of the copolymer is 20,000-30,000 Da; the reaction formula is: The antibacterial layer is composed of silver-loaded zeolite with a silver loading of 3%-5%, zinc oxide nanoparticles and benzoxazole sulfonate derivatives in a mass ratio of 2:1:0.

05. The MIC value of the benzoxazole sulfonate derivative against Escherichia coli is 4.2 μg / mL, and the decomposition rate in 80°C hot water for 24 hours is less than 1%. The structural formula is: The composite reaction layer is formed by covalently connecting reduced graphene oxide with a thickness of 0.5-1.0 nm and amino-modified titanium dioxide nanotubes TiO2-NH2 with a tube diameter of 10-15 nm and a length of 300-600 nm through CN bonds to form a heterojunction, and is doped with hexagonal boron nitride quantum dots with a particle size of 2-5 nm. The photogenerated electron-hole pair lifetime of the heterojunction is ≥50 ns, and the degradation efficiency of organic pollutants under visible light is ≥98% / h.

2. The composite mineralized filter element for drinking water filtration and separation according to claim 1, characterized in that: The synthesis of the polyvinyl carboxylate derivative is carried out by dissolving acrylic acid C3H4O2 and sodium vinyl sulfonate C2H3O3SNa in deionized water at a molar ratio of 1:1, adding 1.0wt% ammonium persulfate as an initiator, stirring and reacting at 85°C±2°C for 8 hours under nitrogen protection, dialyzing the reaction solution to remove unreacted monomers, and freeze-drying to obtain a white porous solid; the carboxylic acid group density of the derivative is 3.2mmol / g, the sulfonic acid group density is 1.8mmol / g, and the adsorption capacity for Ca²⁺ in the pH range of 6-8 is ≥2.5mmol / g.

3. The composite mineralized filter element for drinking water filtration and separation according to claim 1, characterized in that: The preparation method of the benzoxazole sulfonate derivative is specifically as follows: firstly dissolve benzoxazole C7H5NO in dichloromethane, cool to 0-5°C in an ice bath, slowly drop chlorosulfonic acid HSO3Cl at a molar ratio of 1:1.2, stir and react for 2 hours to generate a sulfonyl chloride intermediate C7H4NO3SCl, and remove the reaction byproduct HCl by purging with nitrogen. The specific reaction formula is as follows: Then, excess methanol was added to the intermediate and stirred at room temperature for 4 hours. The specific reaction formula is as follows: The product was washed three times with deionized water and vacuum dried at 60°C for 12 hours to obtain a white crystalline solid with a purity of ≥99.5% as determined by HPLC; the thermal decomposition temperature of the derivative was 225°C±5°C, the water solubility was 0.75 mg / mL at 25°C, and the antimicrobial agent dissolution amount in simulated drinking water for 30 days was <0.05 ppb.

4. The composite mineralized filter element for drinking water filtration and separation according to claim 1, characterized in that: The amino-modified titanium dioxide nanotubes are synthesized by a sol-gel-hydrothermal method: tetrabutyl titanate and ethylenediamine are dissolved in anhydrous ethanol in a molar ratio of 1:0.5, stirred and hydrolyzed for 24 hours, then transferred to a polytetrafluoroethylene high-pressure reactor, hydrothermally reacted at 180°C for 12 hours, the product is dispersed in dilute nitric acid with a pH of 4 after centrifugal washing, and aged at 60°C for 6 hours to enhance crystallinity; the specific surface area of ​​the nanotubes is 280±20m² / g, and the pore size distribution is 2-10nm.

5. A method for preparing a composite mineralized filter element for drinking water filtration and separation as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Preparation of pretreatment layer: melt blend polypropylene particles with a melt index of 25g / 10min and coconut shell activated carbon powder at 270℃±5℃, and form the fibers by melt-blowing machine. Spray the polydopamine coating on the fiber substrate at a pressure of 0.4MPa, and then pre-dry at 60℃ for 30min, and then cure with ultraviolet light with a wavelength of 365nm and an intensity of 100mW / cm² for 40min. S2: Sintering of mineralized layer: Nano-hydroxyapatite, diatomaceous earth and polyvinyl carboxylate derivatives were added into a planetary ball mill in a mass ratio of 1:3:0.08, with zirconium oxide balls as grinding media and a ball-to-material ratio of 5:

1. The mixture was ball-milled at 400 rpm for 5 h. The mixed powder was filled into a graphite mold, placed in a tubular furnace, heated to 900°C±10°C at a rate of 10°C / min in a nitrogen and CO2 mixed atmosphere, sintered at this temperature for 3 h, and cooled to room temperature with the furnace to obtain a porous mineralized layer with a porosity of 65%±3% and a compressive strength of 18MPa±2MPa. S3: Antibacterial layer forming: silver-loaded zeolite, zinc oxide nanoparticles and benzoxazole sulfonate derivatives were added into a supercritical CO2 dispersion device at a mass ratio of 2:1:0.05, dispersed at 40°C and 15MPa for 30 minutes, and the dispersed slurry was formed into a fiber membrane by an electrospinning machine; S4: Composite reaction layer assembly: Reduced graphene oxide and amino-modified titanium dioxide nanotubes were mixed in a volume ratio of 1:4, and 3% by mass of boron nitride quantum dots were added. After ultrasonic dispersion for 30 minutes, the mixture was transferred to a high-pressure reactor and reacted at 120℃±5℃ under argon protection for 6 hours. The reaction product was vacuum filtered to form a film with a thickness of 50-80μm, and then vacuum dried at 60℃ for 12 hours. S5: Overall composite: After each functional layer is activated by oxygen / argon mixed gas plasma, it is hot-pressed and composited at 200℃±10℃ and 8MPa pressure for 20min. A SiO2 transition layer with a thickness of 15±5nm is generated at the interface between the layers by chemical vapor deposition. The deposition source is tetraethoxysilane, the deposition temperature is 400℃±20℃, and the deposition rate is 2nm / min.

6. The method for preparing a composite mineralized filter element for drinking water filtration and separation according to claim 5, characterized in that: In the supercritical CO2 dispersion process, the critical parameters of CO2 are temperature 31.1°C and pressure 7.38MPa. The actual operating conditions are temperature 40°C±2°C and pressure 15MPa±0.5MPa. The particle size distribution of the dispersed mixture is D50=80nm±10nm and D90=150nm±20nm.

7. The method for preparing a composite mineralized filter element for drinking water filtration and separation according to claim 5, characterized in that: The tensile strength of the electrospun fiber membrane is 8.5MPa±0.5MPa, the elongation at break is 25%±3%, the water flux is ≥2000L / m²·h, and the diameter of the inhibition zone against Staphylococcus aureus is ≥15mm.

8. The method for preparing a composite mineralized filter element for drinking water filtration and separation according to claim 5, characterized in that: The photocatalytic performance test conditions of the composite reaction layer film are: using 10 mg / L methylene blue solution as a simulated pollutant, the light intensity is 50 mW / cm², and after one hour of reaction, the solution decolorization rate is ≥95%, and the chemical oxygen demand removal rate is ≥90%.

9. The method for preparing a composite mineralized filter element for drinking water filtration and separation according to claim 5, characterized in that: In the hot pressing composite process, the interlayer bonding strength is ≥15N / cm through a 180° peeling force test, and the element distribution of the silicon dioxide transition layer shows that Si and O elements are distributed in a gradient at the interface, and the thickness variation coefficient is ≤10%.

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