A silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens, its preparation method and application.

Abstract

This invention belongs to the field of catalysts and water treatment, and discloses a silver phosphate-based composite photocatalytic microreaction material for dual-targeted enrichment of antibiotics and pathogens, as well as its preparation and application. The material uses a conductive carbon-based framework as a carrier, on which silver phosphate photocatalytic active components are grown in situ. A dual-targeted enrichment shell is constructed using carboxymethyl-β-cyclodextrin and quaternized chitosan, thus forming an integrated composite structure of "conductive framework - silver phosphate photocatalytic active layer - antibiotic enrichment component - pathogen adsorption component". Carboxymethyl-β-cyclodextrin on the material surface enriches antibiotic molecules, while quaternized chitosan adsorbs pathogen cells. Ag3PO4 generates photogenerated holes, electrons, and reactive oxygen species under visible light excitation. The conductive carbon-based framework promotes the transfer of photogenerated electrons, enabling reactive oxygen species to be generated in situ near antibiotic molecules and pathogen cells and exert their oxidizing effect. This achieves antibiotic degradation, pathogen inactivation, and reduction of the risk of combined pollution.

Description

Technical Field

[0001] This invention belongs to the field of catalysts and water treatment, and specifically relates to a silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens, its preparation method, and its application. Background Technology

[0002] Antibiotics are widely used in medical treatment, livestock and poultry farming, aquaculture, and agricultural production. Some antibiotics, once in the aquatic environment, are difficult to completely remove and may enter natural water bodies through hospital wastewater, aquaculture tailwater, domestic sewage, and surface runoff. Simultaneously, pathogenic bacteria or opportunistic pathogens such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa may coexist in water bodies, gradually transforming water pollution from a simple chemical pollution problem into a complex pollution issue involving antibiotics, pathogens, and potential drug resistance risks. Therefore, developing water treatment materials capable of simultaneously degrading antibiotics and inactivating pathogens is of great significance.

[0003] Currently, common technologies for treating antibiotic-contaminated water bodies include adsorption, membrane separation, biological treatment, ozone oxidation, persulfate oxidation, and photocatalytic oxidation. Among these, adsorption utilizes activated carbon, resins, carbon materials, and cyclodextrin materials to enrich and remove antibiotics; membrane separation reduces the concentration of some pollutants through retention; and advanced oxidation technologies generate reactive oxygen species to oxidize and degrade antibiotic molecules. Cyclodextrin materials, with their hydrophobic interior and hydrophilic exterior, can capture some organic molecules through inclusion bonding, and are therefore frequently used for pollutant adsorption or enrichment.

[0004] To combat pathogen contamination, current technologies commonly employ methods such as chlorine disinfection, ultraviolet disinfection, ozone disinfection, silver-based antibacterial materials, chitosan-based antibacterial materials, and photocatalytic antibacterial materials. Chitosan and its quaternized derivatives, possessing cationic groups, can interact with negatively charged bacterial cell membranes, thus exhibiting certain antibacterial properties. Among these, quaternized chitosan, due to its more stable positive charge, typically exhibits better water solubility and antibacterial activity than ordinary chitosan.

[0005] Photocatalysis is a common advanced oxidation treatment method. Silver phosphate (Ag3PO4) is a typical visible-light-responsive photocatalytic material that can generate photogenerated electrons, holes, and related reactive oxygen species under visible light irradiation, and can be used for the degradation of organic pollutants and the inactivation of microorganisms. In existing technologies, to improve the photocatalytic performance of Ag3PO4 alone, it is usually combined with materials such as graphene, reduced graphene oxide, carbon nanotubes, g-C3N4, metal oxides, and metal sulfides to promote the separation of photogenerated carriers, improve visible light utilization efficiency, or improve material stability.

[0006] In addition, some technologies combine Ag3PO4 with oxidants such as persulfate and hydrogen peroxide to construct a photocatalytic-advanced oxidation synergistic system to enhance the generation of reactive oxygen species; or load photocatalytic materials onto membranes, particles, gels, or supports to improve material recyclability and ease of application. These technologies provide a foundation for antibiotic degradation or pathogen inactivation, but most still focus on the degradation of single pollutants, single antibacterial functions, or single photocatalytic performance enhancement.

[0007] In summary, the existing technology still has the following drawbacks:

[0008] First, existing technologies are mostly designed for treating single pollutants, making it difficult to simultaneously achieve antibiotic degradation and pathogen inactivation. Adsorption methods mainly achieve the enrichment and transfer of antibiotics, but cannot completely destroy their molecular structure; conventional disinfection technologies can inactivate some pathogens, but their ability to deeply degrade antibiotic molecules is limited; single photocatalytic systems also tend to focus on one aspect of antibiotic degradation or antibacterial activity, lacking a simultaneous purification design for water bodies with combined antibiotic and pathogen pollution.

[0009] Second, existing silver phosphate-based photocatalytic materials lack synergistic interface structures for antibiotic-pathogen co-contamination. Although the photocatalytic, molecular inclusion, or bacterial adsorption effects of Ag3PO4, cyclodextrin, and quaternized chitosan have been reported, simply using these components in parallel cannot guarantee that antibiotic molecules and pathogen cells with significantly different sizes and migration behaviors will simultaneously accumulate at the same photocatalytically active interface. Ordinary Ag3PO4 materials still mainly rely on the free diffusion of the target analyte to the catalyst surface, which easily leads to spatial separation of enrichment sites, electron transport channels, and reactive oxygen generation sites, making it difficult to form a stable "simultaneous enrichment-near-distance oxidation" microreaction interface.

[0010] Third, existing Ag3PO4 materials still suffer from problems such as rapid recombination of photogenerated carriers, insufficient stability, and inadequate component synergy. Single Ag3PO4 is prone to particle agglomeration and photocorrosion, affecting sustained catalytic performance. In some Ag3PO4-carbon composite systems, simple physical mixing results in insufficient interfacial bonding and limited electron transport efficiency. Furthermore, simple mixing of functional components such as cyclodextrin, chitosan, and Ag3PO4 fails to form a stable integrated microreaction interface encompassing "pollutant enrichment-interfacial contact-photocatalytic oxidation," thus limiting overall purification efficiency. Summary of the Invention

[0011] To overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a method for preparing a silver phosphate-based composite photocatalytic microreaction material with dual-targeted enrichment of antibiotics and pathogens. This material uses a conductive carbon-based framework as a carrier, on which a silver phosphate Ag3PO4 photocatalytic active component is grown in situ. Furthermore, a dual-targeted enrichment shell is constructed using carboxymethyl-β-cyclodextrin and quaternized chitosan, thereby forming an integrated composite structure of "conductive framework - silver phosphate photocatalytic active layer - antibiotic enrichment component - pathogen adsorption component".

[0012] Another objective of this invention is to provide a silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens prepared by the above method.

[0013] Another objective of this invention is to provide the application of the above-mentioned silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens in wastewater treatment.

[0014] The objective of this invention is achieved through the following solution:

[0015] A method for preparing a silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens includes the following steps:

[0016] (1) Disperse the conductive carbon-based framework in water or a water-ethanol mixed solvent to obtain a uniform dispersion;

[0017] (2) Add silver source to dispersion and stir for 30-120 min under light-protected conditions to allow Ag to react. + The Ag3PO4 is adsorbed or complexed onto the surface of the conductive carbon-based framework; then a phosphate solution is added and the mixture is reacted under light-protected conditions for 1-6 h to allow Ag3PO4 to be deposited in situ onto the surface of the conductive carbon-based framework, thus obtaining an Ag3PO4 / conductive carbon-based framework composite material.

[0018] (3) Dissolve carboxymethyl-β-cyclodextrin and quaternized chitosan in an aqueous system, add the Ag3PO4 / conductive carbon-based skeleton composite material from step (2), and add EDC and NHS as crosslinking agents to conduct a crosslinking reaction, so that carboxymethyl-β-cyclodextrin and quaternized chitosan form a crosslinked composite shell and coat and fix it on the surface of the material; finally, after centrifugation, washing and drying, the silver phosphate-based composite photocatalytic material with dual-target enrichment of antibiotics and pathogens is obtained.

[0019] The conductive carbon-based framework mentioned in step (1) is at least one of nitrogen-sulfur co-doped porous carbon, nitrogen-sulfur co-doped reduced graphene oxide, reduced graphene oxide, graphene oxide, carbon nanotubes, and porous carbon aerogel, preferably nitrogen-sulfur co-doped porous carbon. This conductive carbon-based framework serves as a dispersion carrier for Ag3PO4, inhibiting Ag3PO4 particle aggregation; and as an interfacial electron transport channel, it promotes the transfer of photogenerated electrons from Ag3PO4 under visible light irradiation, reduces the electron-hole recombination probability, and improves the photostability of Ag3PO4.

[0020] The nitrogen-sulfur co-doped porous carbon described in step (1) is prepared by the following steps: graphene oxide, dopamine hydrochloride, and thiourea are dispersed in water, the pH is adjusted to 8.0-9.0 using Tris-HCl buffer, and the mixture is stirred continuously at 20-25 °C for 12 h to allow dopamine to self-polymerize on the surface of graphene oxide and introduce nitrogen and sulfur precursors; subsequently, the mixture is washed, freeze-dried, and calcined under a nitrogen atmosphere to obtain the nitrogen-sulfur co-doped porous carbon framework. This framework has a large specific surface area, porous structure, and electrical conductivity, which can enhance the dispersibility of Ag3PO4 and the interfacial electron transfer capability.

[0021] In the preparation step of the nitrogen-sulfur co-doped porous carbon, the mass ratio of graphene oxide, dopamine hydrochloride and thiourea is 1:2:3; the calcination temperature is 600-900 ℃, preferably 700-800 ℃, more preferably 750 ℃; and the calcination time is 1-4 h, preferably 2 h.

[0022] The preferred dispersion medium in step (1) is deionized water; the preferred dispersion method is ultrasonic dispersion for 30-60 min; the concentration of the conductive carbon-based skeleton in the resulting uniform dispersion is 1.0-1.25 g / L.

[0023] The Ag3PO4 photocatalytic active component described in step (2) is formed through an in-situ precipitation reaction of a silver source and a phosphate on the surface of a conductive carbon-based framework. The silver source is silver nitrate, silver acetate, or other soluble silver salts, preferably silver nitrate; the phosphate is at least one of Na2HPO4, NaH2PO4, K2HPO4, and KH2PO4, preferably Na2HPO4. During the preparation process, silver ions first adsorb or complex with oxygen-, nitrogen-, or sulfur-containing functional groups on the surface of the conductive carbon-based framework, and then react with phosphate to generate Ag3PO4, causing Ag3PO4 to be deposited in situ on the surface of the conductive carbon-based framework, rather than through simple physical mixing. The Ag⁺ and PO4... 3- The molar ratio is 2.5:1-3.5:1, preferably 3:1; the mass percentage of Ag3PO4 in the Ag3PO4 / conductive carbon-based skeleton composite material is 20%-80%, preferably 30%-70%.

[0024] In step (3), a dual-targeted enrichment shell is further constructed on the surface of the Ag3PO4 / conductive carbon-based framework composite material. The dual-targeted enrichment shell is composed of carboxymethyl-β-cyclodextrin and quaternized chitosan. Carboxymethyl-β-cyclodextrin contains hydrophobic cavities, carboxyl groups, and hydroxyl groups, and can enrich tetracycline, quinolone, sulfonamide, and β-lactam antibiotic molecules through host-guest interactions, hydrophobic interactions, hydrogen bonding, and electrostatic interactions. Quaternized chitosan contains cationic quaternary ammonium salt groups, which can interfacially bind to negatively charged pathogen cell membranes through electrostatic adsorption, enhancing the contact between the material and bacterial cells. Together, they constitute the antibiotic-pathogen dual-targeted enrichment interface, enabling antibiotic molecules and pathogen cells to accumulate near the Ag3PO4 photocatalytic active site, thereby shortening the reactive oxygen species interaction distance and improving the in-situ oxidation efficiency at the interface.

[0025] The aqueous phase system described in step (3) is deionized water; carboxymethyl-β-cyclodextrin and quaternized chitosan are dissolved and then mixed.

[0026] The mass ratio of carboxymethyl-β-cyclodextrin to quaternized chitosan in step (3) is 1:5-5:1, preferably 1:2-2:1, and more preferably 1:1. 0.1-0.5 g of carboxymethyl-β-cyclodextrin is added per 1 g of Ag3PO4 / conductive carbon-based skeleton composite material, preferably 0.25 g of carboxymethyl-β-cyclodextrin.

[0027] The dual-targeted enrichment shell was constructed using an EDC / NHS crosslinking method. EDC activated the carboxyl groups of carboxymethyl-β-cyclodextrin and, in the presence of NHS, promoted the formation of a crosslinking network between carboxymethyl-β-cyclodextrin and the amino groups in quaternized chitosan. This crosslinking network was formed and coated on the surface of the Ag3PO4 / conductive carbon-based framework composite material to improve shell stability and resistance to leaching during water treatment. The amount of EDC used was 20%-100% of the mass of carboxymethyl-β-cyclodextrin, and the amount of NHS used was 12%-60% of the mass of carboxymethyl-β-cyclodextrin.

[0028] The crosslinking reaction in step (3) has a pH of 4.5-6.5, a reaction temperature of 20-25 ℃, and a reaction time of 1-8 h; preferably, the reaction is carried out at pH 5.5 and 20-25 ℃ for 4 h.

[0029] In another preferred embodiment, the antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material can be further immobilized into microspheres, membranes, coatings, or fillers.

[0030] Preferably, the antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material microspheres are prepared by the following steps: the obtained antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material is added to a sodium alginate solution with a mass fraction of 1%-4% to form a uniform slurry, and then dropped into a CaCl2 solution with a mass fraction of 1%-5% for cross-linking to obtain immobilized photocatalytic microspheres. The microspheres have a particle size of 0.5-5.0 mm, preferably 1.0-2.0 mm. Each 1 g of antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material corresponds to 2 g of sodium alginate and 6 g of CaCl2, and cross-linking is performed at 20-25 °C for 3 h. After immobilization, the material is easier to separate from water and reuse, reducing the risk of powder material loss and secondary release of silver components.

[0031] This invention also provides the use of the aforementioned silver phosphate-based composite photocatalyst material with dual-targeted enrichment of antibiotics and pathogens in the purification of water bodies contaminated with antibiotics and / or pathogens. In use, the silver phosphate-based composite photocatalyst material with dual-targeted enrichment of antibiotics and pathogens is added to water containing antibiotics and / or pathogens, and treated under visible light irradiation. Carboxymethyl-β-cyclodextrin on the material surface preferentially enriches antibiotic molecules, quaternized chitosan adsorbs pathogen cells, and Ag3PO4 generates photogenerated holes, electrons, and reactive oxygen species under visible light excitation. The conductive carbon-based framework promotes the transfer of photogenerated electrons, causing reactive oxygen species to be generated in situ near antibiotic molecules and pathogen cells and exert their oxidizing effect. This achieves antibiotic degradation, pathogen inactivation, and reduction of the risk of combined pollution.

[0032] Furthermore, the silver phosphate-based composite photocatalyst material for dual-target enrichment of antibiotics and pathogens of the present invention can be used synergistically with persulfate to construct a synergistic purification system of silver phosphate-based composite photocatalyst material / persulfate / visible light. The persulfate is perdisulfate (PDS), permonosulfate (PMS), or a combination thereof, preferably PDS. Under visible light irradiation, the Ag3PO4 / conductive carbon-based framework can promote the activation of persulfate, generating substances including ·OH and SO42-. ⁻ O2 ⁻ and 1 Active species, including O2, work synergistically with the dual-target enrichment interface to improve the simultaneous purification efficiency of antibiotics and pathogens in water bodies with complex pollution.

[0033] Through the above technical solution, this invention forms a composite microreaction structure that differs from traditional silver phosphate-based photocatalytic materials. Traditional methods mainly rely on the random diffusion of antibiotic molecules or pathogens to the surface of the photocatalytic material. In contrast, this invention constructs antibiotic enrichment sites and pathogen adsorption sites using carboxymethyl-β-cyclodextrin and quaternized chitosan, respectively, allowing target pollutants to actively approach the Ag3PO4 photocatalytic active interface. Simultaneously, a conductive carbon-based framework promotes the separation of photogenerated carriers and the stabilization of Ag3PO4, enabling the reactive oxygen species generated by photocatalysis to function in situ near the target pollutants. This achieves a synergistic technical effect of "pollutant enrichment—interfacial electron transfer—in-situ generation of reactive oxygen species—simultaneous purification of composite pollutants."

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] First, this invention improves the contact efficiency between antibiotics and pathogens and photocatalytically active sites. Existing Ag3PO4 photocatalytic materials mainly rely on the free diffusion of pollutants into the catalyst surface in water, resulting in limited contact efficiency. This invention constructs a carboxymethyl-β-cyclodextrin / quaternized chitosan dual-targeting shell on the Ag3PO4 / conductive carbon framework surface. Carboxymethyl-β-cyclodextrin is used to enrich antibiotic molecules, while quaternized chitosan is used to adsorb negatively charged pathogen cells, thereby enabling both antibiotics and pathogens to accumulate near the photocatalytically active interface.

[0036] Second, this invention improves the interfacial utilization efficiency of reactive oxygen species (ROS). In existing photocatalytic systems, ROS easily diffuses in water and is consumed by non-target components, leading to a decrease in actual utilization. This invention enriches target pollutants near the Ag3PO4 active site through a dual-targeting shell, enabling ROS generated by visible light excitation to function in situ near antibiotic molecules and pathogen cells, thereby reducing ineffective diffusion and improving the efficiency of antibiotic degradation and pathogen inactivation.

[0037] Third, this invention improves the dispersibility, electron transport capability, and stability of Ag3PO4. Existing single Ag3PO4 is prone to aggregation, and photogenerated electron-hole recombination is rapid, resulting in insufficient photostability. This invention uses a conductive carbon framework to support Ag3PO4, and through Ag⁺ adsorption / complexation followed by in-situ reaction with phosphate ions, Ag3PO4 is generated in situ on the surface of the conductive framework, forming a tighter interfacial contact. This facilitates photogenerated electron transfer, reduces carrier recombination, and improves the structural stability of Ag3PO4.

[0038] Fourth, this invention exhibits better structural stability and application adaptability. In existing technologies, cyclodextrin or chitosan components are often introduced through physical adsorption or simple mixing, which easily detach during water treatment. This invention uses an EDC / NHS crosslinking method to stably fix carboxymethyl-β-cyclodextrin and quaternized chitosan onto the material surface, and can be further stabilized using sodium alginate-Ca... 2+ Cross-linking to prepare immobilized microspheres facilitates material recycling and reuse, reducing the risk of powder material loss.

[0039] In summary, the technical contribution of this invention is not a simple superposition of the known functions of Ag3PO4, cyclodextrin, and quaternized chitosan, but rather lies in the continuous interface construction of "Ag3PO4 in situ loaded onto a conductive carbon skeleton—EDC / NHS crosslinking to construct a dual-targeting shell," which couples pollutant accumulation sites, electron transport channels, and reactive oxygen species generation sites on the same composite interface. Compared with Comparative Example 9, which contained all the main raw materials but was only physically mixed, Example 1 showed that the degradation rate of tetracycline hydrochloride increased from 45.3% to 96.4%, and the log reduction values ​​of Escherichia coli and Staphylococcus aureus increased from 2.5 and 2.2 to 6.2 and 5.8, respectively; the performance of Comparative Example 8 without the addition of EDC / NHS was also significantly reduced. The above results indicate that the spatial synergistic structure formed by in-situ loading and a stable crosslinked shell produces technical effects that differ from the independent effects of each component. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0041] Unless otherwise stated, the room temperature referred to in this specification is 20-25 ℃, and all steps in the examples where the temperature is not explicitly stated are performed within this temperature range.

[0042] Example 1

[0043] (1) Weigh 100 mg of graphene oxide and add it to 100 mL of deionized water. Disperse the mixture by sonication for 60 min to obtain a uniform dispersion. Add 200 mg of dopamine hydrochloride and 300 mg of thiourea to the dispersion. Adjust the pH to 8.5 using Tris-HCl buffer. Stir at room temperature for 12 h to allow dopamine to self-polymerize on the surface of graphene oxide and introduce nitrogen and sulfur precursors. After the reaction is complete, centrifuge the product and wash it three times with deionized water and ethanol, respectively. Freeze-dry the product for 24 h. Then place it in a tube furnace and heat it to 750 °C at 5 °C / min under a nitrogen atmosphere. Hold the temperature for 2 h to obtain nitrogen-sulfur co-doped porous carbon framework NSPC.

[0044] (2) Weigh 100 mg of NSPC and disperse it in 80 mL of deionized water. Add 0.255 g of AgNO3 and stir in the dark for 60 min. Then dissolve 0.071 g of Na2HPO4 in 20 mL of deionized water and add it dropwise to the above system at 1 mL / min. React in the dark for 2 h to allow Ag3PO4 to be deposited in situ on the surface of NSPC. After centrifugation, washing, and vacuum drying at 60 °C for 12 h, the Ag3PO4 / NSPC composite material is obtained.

[0045] (3) Subsequently, 50 mg of carboxymethyl-β-cyclodextrin and 50 mg of quaternized chitosan were weighed and dissolved in deionized water. After mixing, 200 mg of Ag3PO4 / NSPC was added, the pH was adjusted to 5.5, 20 mg of EDC and 12 mg of NHS were added, and the mixture was stirred at room temperature in the dark for 4 h. After centrifugation, washing and drying, the dual-target enrichment silver phosphate-based composite photocatalyst material was obtained, which was named CD-QCS@Ag3PO4 / NSPC-1.

[0046] Example 2

[0047] The main preparation process of this embodiment is the same as that of Example 1, except that the proportion of quaternized chitosan in the dual-target enrichment shell is higher, that is, the difference lies in step (3). Specifically, after preparing the Ag3PO4 / NSPC composite material according to the method of Example 1, 20 mg of carboxymethyl-β-cyclodextrin and 100 mg of quaternized chitosan were weighed and dissolved in deionized water, mixed evenly, and then 200 mg of Ag3PO4 / NSPC was added. The pH of the system was adjusted to 5.5, and 20 mg of EDC and 12 mg of NHS were added. The mixture was stirred for 4 h at room temperature in the dark to form a composite shell of carboxymethyl-β-cyclodextrin and quaternized chitosan on the surface of Ag3PO4 / NSPC. After the reaction was completed, the product was centrifuged, washed and dried to obtain a dual-target enrichment silver phosphate-based composite photocatalytic material with a high proportion of quaternized chitosan, denoted as CD-QCS@Ag3PO4 / NSPC-2.

[0048] Example 3

[0049] The main preparation process in this embodiment is the same as that in Example 1, except that the proportion of carboxymethyl-β-cyclodextrin in the dual-target enrichment shell is higher, i.e., the difference lies in step (3). Specifically, after preparing the Ag3PO4 / NSPC composite material according to the method in Example 1, 100 mg of carboxymethyl-β-cyclodextrin and 20 mg of quaternized chitosan were weighed and dissolved in deionized water, mixed evenly, and then 200 mg of Ag3PO4 / NSPC was added. The pH of the system was adjusted to 5.5, and 20 mg of EDC and 12 mg of NHS were added. The mixture was stirred for 4 h at room temperature in the dark. After the reaction was completed, the product was centrifuged, washed three times with deionized water, and vacuum dried at 40 °C for 12 h to obtain a dual-target enrichment silver phosphate-based composite photocatalyst material with a high proportion of carboxymethyl-β-cyclodextrin, denoted as CD-QCS@Ag3PO4 / NSPC-3.

[0050] Example 4

[0051] The main preparation process of this embodiment is the same as that of Example 1, except that the Ag3PO4 loading is lower, that is, the difference lies in step (2). Specifically, 100 mg of NSPC is weighed and added to 80 mL of deionized water, ultrasonically dispersed for 30 min, and then 0.128 g of AgNO3 is added and stirred in the dark for 60 min; then 0.0355 g of Na2HPO4 is dissolved in 20 mL of deionized water and slowly added dropwise to the above AgNO3 / NSPC dispersion system, and stirred in the dark for 2 h to allow Ag3PO4 to be generated in situ on the surface of NSPC. After centrifugation, washing, and drying, the obtained product was added to a mixed solution consisting of 50 mg of carboxymethyl-β-cyclodextrin and 50 mg of quaternized chitosan. The pH was adjusted to 5.5, and 20 mg of EDC and 12 mg of NHS were added. The mixture was stirred at room temperature in the dark for 4 h. After centrifugation, washing, and drying, a dual-targeted enrichment silver phosphate-based composite photocatalyst with low Ag3PO loading was obtained, denoted as CD-QCS@Ag3PO4 / NSPC-4.

[0052] Example 5

[0053] The main preparation process of this embodiment is the same as that of Example 1, except that the Ag3PO4 loading is higher, that is, the difference lies in step (2). Specifically, 100 mg of NSPC was weighed and added to 80 mL of deionized water, ultrasonically dispersed for 30 min, and then 0.382 g of AgNO3 was added and stirred in the dark for 60 min; then 0.1065 g of Na2HPO4 was dissolved in 20 mL of deionized water and slowly added dropwise to the AgNO3 / NSPC dispersion system, and stirred in the dark for 2 h, so that a higher content of Ag3PO4 was deposited in situ on the surface of NSPC. After centrifugation, washing and drying, the product was added to a mixed solution composed of 50 mg of carboxymethyl-β-cyclodextrin and 50 mg of quaternized chitosan, the pH was adjusted to 5.5, 20 mg of EDC and 12 mg of NHS were added, and stirred at room temperature in the dark for 4 h, finally obtaining a dual-targeted enrichment silver phosphate-based composite photocatalyst material with high Ag3PO4 loading, denoted as CD-QCS@Ag3PO4 / NSPC-5.

[0054] Example 6

[0055] This embodiment mainly focuses on the preparation of silver phosphate-based composite photocatalytic material microspheres for dual-target enrichment of antibiotics and pathogens.

[0056] 0.5 g of the CD-QCS@Ag3PO4 / NSPC-1 powder material obtained in Example 1 was weighed and added to 50 mL of a 2.0% sodium alginate solution. The mixture was magnetically stirred for 2 h to form a homogeneous slurry. Then, the slurry was added dropwise to 100 mL of a 3.0% CaCl2 solution using a syringe, with gentle stirring maintained during the addition. After crosslinking for 3 h, immobilized photocatalytic microspheres were formed. The obtained microspheres were removed, washed three times with deionized water, and dried at room temperature to obtain immobilized dual-targeted enrichment silver phosphate-based composite photocatalytic microspheres, denoted as CD-QCS@Ag3PO4 / NSPC / SA-Ca.

[0057] Example 7

[0058] The main difference between this embodiment and Example 1 lies in step (1). In this embodiment, reduced graphene oxide is used instead of nitrogen-sulfur co-doped porous carbon framework NSPC in Example 1 as the conductive carbon framework. 100 mg of reduced graphene oxide was weighed and dispersed in 80 mL of deionized water. After ultrasonic dispersion for 60 min, 0.255 g of AgNO3 was added and stirred for 60 min under light-protected conditions. Subsequently, 0.071 g of Na2HPO4 was dissolved in 20 mL of deionized water and slowly added dropwise to the above system. The reaction was carried out in the dark for 2 h, so that Ag3PO4 was deposited in situ on the surface of reduced graphene oxide. After centrifugation, washing, and drying, the product was added to a mixed solution of 50 mg carboxymethyl-β-cyclodextrin and 50 mg quaternized chitosan. The pH was adjusted to 5.5, and 20 mg EDC and 12 mg NHS were added. The mixture was stirred at room temperature in the dark for 4 h to obtain a dual-targeted enrichment silver phosphate-based composite photocatalyst with reduced graphene oxide as the conductive framework, denoted as CD-QCS@Ag3PO4 / rGO.

[0059] Example 8

[0060] The main difference between this embodiment and Example 1 lies in step (1). In this embodiment, nitrogen-sulfur co-doped porous carbon aerogel is used as the conductive confinement framework. 100 mg of nitrogen-sulfur co-doped porous carbon aerogel was weighed and added to 80 mL of deionized water for ultrasonic dispersion for 30 min. 0.255 g of AgNO3 was added and stirred in the dark for 60 min. Subsequently, 0.071 g of Na2HPO4 was dissolved in 20 mL of deionized water and slowly added dropwise to the above dispersion system. The reaction was carried out in the dark for 2 h. After the reaction was completed, the product was centrifuged, washed, and dried to obtain Ag3PO4-loaded nitrogen-sulfur co-doped porous carbon aerogel composite material. Subsequently, the surface was modified according to the construction method of carboxymethyl-β-cyclodextrin and quaternized chitosan composite shell in Example 1 to obtain an aerogel-type dual-targeted enrichment silver phosphate-based composite photocatalyst material, denoted as CD-QCS@Ag3PO4 / NSCA.

[0061] Comparative Example 1

[0062] 0.255 g of AgNO3 was dissolved in 80 mL of deionized water and stirred for 30 min in the dark. 0.071 g of Na2HPO4 was dissolved in 20 mL of deionized water and slowly added dropwise to the AgNO3 solution, stirred in the dark for 2 h. After the reaction was complete, the resulting precipitate was centrifuged, washed three times each with deionized water and ethanol, and dried under vacuum at 60 °C for 12 h to obtain pure Ag3PO4 material. This comparative example lacks a conductive carbon framework and a carboxymethyl-β-cyclodextrin / quaternized chitosan dual-targeted enrichment shell.

[0063] Comparative Example 2

[0064] The Ag3PO4 / NSPC composite material was prepared according to the method of Example 1, but without the construction of the carboxymethyl-β-cyclodextrin and quaternized chitosan shell, i.e., step (3) of Example 1 was omitted. Specifically, 100 mg of NSPC was weighed and dispersed in 80 mL of deionized water, and 0.255 g of AgNO3 was added. The mixture was stirred in the dark for 60 min. Subsequently, 0.071 g of Na2HPO4 dissolved in 20 mL of deionized water was added dropwise, and the mixture was reacted in the dark for 2 h. The product was centrifuged, washed, and dried to obtain the Ag3PO4 / NSPC composite material. This comparative example contains Ag3PO4 and NSPC, but lacks the antibiotic-pathogen dual-target enrichment shell.

[0065] Comparative Example 3

[0066] Ag3PO4 / NSPC composite materials were prepared according to the method in Example 1. Then, only 100 mg of carboxymethyl-β-cyclodextrin was added, without the addition of quaternized chitosan. Other crosslinking and coating conditions were the same as in Example 1. After the reaction, the product was centrifuged, washed, and dried to obtain Ag3PO4 / NSPC material containing only a carboxymethyl-β-cyclodextrin shell, denoted as CD@Ag3PO4 / NSPC. This comparative example lacks the quaternized chitosan pathogen adsorption component.

[0067] Comparative Example 4

[0068] Ag3PO4 / NSPC composite materials were prepared according to the method in Example 1. Then, only 100 mg of quaternized chitosan was added, without the addition of carboxymethyl-β-cyclodextrin. Other crosslinking and coating conditions were the same as in Example 1. After the reaction, the product was centrifuged, washed, and dried to obtain Ag3PO4 / NSPC material containing only a quaternized chitosan shell, denoted as QCS@Ag3PO4 / NSPC. This comparative example lacks the carboxymethyl-β-cyclodextrin antibiotic enrichment component.

[0069] Comparative Example 5

[0070] 200 mg of pure Ag3PO4, 50 mg of carboxymethyl-β-cyclodextrin (CD), and 50 mg of quaternized chitosan (QCS) were weighed, directly mixed, and ground for 10 min to obtain a physical mixture of Ag3PO4+CD+QCS. Although this comparative example contains Ag3PO4, carboxymethyl-β-cyclodextrin, and quaternized chitosan, the three components did not form a stable composite structure through in-situ deposition, cross-linking, or interfacial coupling, nor did it contain an NSPC conductive framework.

[0071] Comparative Example 6

[0072] NSPC was prepared according to the method in Example 1. Then, 200 mg of NSPC was weighed and added to a mixed solution of 50 mg of carboxymethyl-β-cyclodextrin and 50 mg of quaternized chitosan. The pH was adjusted to 5.5, and 20 mg of EDC and 12 mg of NHS were added. The mixture was stirred at room temperature in the dark for 4 h. After centrifugation, washing, and drying, the CD-QCS / NSPC material was obtained. This comparative example contains NSPC and a dual-targeting shell, but lacks the Ag3PO4 photocatalytic active component.

[0073] Comparative Example 7

[0074] Pure Ag3PO4 was prepared according to the method of Comparative Example 1. Then, 200 mg of Ag3PO4 was weighed and added to a mixed solution of 50 mg of carboxymethyl-β-cyclodextrin and 50 mg of quaternized chitosan. The pH was adjusted to 5.5, and 20 mg of EDC and 12 mg of NHS were added. The mixture was stirred at room temperature in the dark for 4 h. After centrifugation, washing, and drying, the CD-QCS@Ag3PO4 material was obtained. This comparative example contains Ag3PO4 and a dual-targeted enrichment shell, but lacks the NSPC conductive framework.

[0075] Comparative Example 8

[0076] Ag3PO4 / NSPC composite materials were prepared according to the method in Example 1. Ag3PO4 / NSPC was then added to a mixed solution of 50 mg carboxymethyl-β-cyclodextrin and 50 mg quaternized chitosan, and the pH was adjusted to 5.5. EDC and NHS were not added, and the mixture was stirred for 4 h at room temperature in the dark. After the reaction was complete, the product was centrifuged, washed, and dried to obtain non-crosslinked CD-QCS / Ag3PO4 / NSPC material. This comparative example contains the main functional components but lacks the step of constructing a stable crosslinked shell.

[0077] Comparative Example 9

[0078] NSPC was prepared according to the method of Example 1, and pure Ag3PO4 was prepared according to the method of Comparative Example 1. Then, NSPC, Ag3PO4, carboxymethyl-β-cyclodextrin, and quaternized chitosan were directly mixed and ground according to the mass ratios in Example 1 to obtain a physical mixture of NSPC + Ag3PO4 + CD + QCS. After this physical mixture was added to water, each component dispersed independently. There was no tight electron transport interface formed in situ between Ag3PO4 and NSPC, and CD and QCS did not form a stable cross-linked shell coating around the photocatalytic active sites. Therefore, this comparative example is used to distinguish the impact of "coexistence of known components" versus "integrated microreaction interface formed by in-situ loading and cross-linking" on the technical effect.

[0079] Comparative Example 10

[0080] Ag3PO4 / NSPC composite materials were prepared according to the method in Example 1. Subsequently, unquaternized chitosan was used to replace quaternized chitosan, and a shell layer was constructed together with carboxymethyl-β-cyclodextrin. Specifically, 50 mg of carboxymethyl-β-cyclodextrin and 50 mg of chitosan were weighed and dissolved in a weakly acidic aqueous solution. Then, 200 mg of Ag3PO4 / NSPC was added, the pH was adjusted to 5.5, 20 mg of EDC and 12 mg of NHS were added, and the mixture was stirred at room temperature in the dark for 4 h to obtain CD-CS@Ag3PO4 / NSPC material. In this comparative example, quaternized chitosan was replaced with ordinary chitosan to illustrate the role of quaternized modified cationic groups in the construction of a dual-target interface.

[0081] Tetracycline hydrochloride was used as a typical antibiotic pollutant with an initial concentration of 10 mg / L. The dosage of the composite photocatalyst was 0.2 g / L, the system volume was 100 mL, and the pH was 7.0. Each group of materials underwent dark adsorption for 30 min, followed by reaction under visible light (λ > 420 nm) for 60 min. The concentration of tetracycline hydrochloride was determined by high-performance liquid chromatography (HPLC). The concentration of tetracycline hydrochloride at the start of light exposure was denoted as C0, and the concentration after t min of light exposure was denoted as C. The degradation rate η of tetracycline hydrochloride was calculated as η = (C0 - C) / C0 × 100%. The apparent rate constant k was calculated using the pseudo-first-order kinetic model ln(C0 / C) = kt; the k values ​​in Table 1 were obtained from C0 and C at t = 60 min.

[0082] Table 1. Degradation results of tetracycline hydrochloride by different materials

[0083]

[0084] As shown in Table 1, after 60 min of visible light reaction, the degradation rates of tetracycline hydrochloride in Examples 1-8 were all above 90%, indicating that different embodiments of the present invention can effectively achieve antibiotic degradation. Among them, Example 3, due to its high proportion of carboxymethyl-β-cyclodextrin, had an enhanced ability to enrich tetracycline hydrochloride molecules, achieving a degradation rate of 98.1%; Example 5, due to its high Ag3PO4 loading, had an increased number of photocatalytic active sites, achieving a degradation rate of 97.3%; and Example 6, although in the form of immobilized microspheres, still achieved a degradation rate of 92.6%, indicating that the immobilization treatment did not damage the core photocatalytic function of the material.

[0085] In contrast, the degradation rates of tetracycline hydrochloride in Comparative Examples 1-10 were significantly lower than those in the Example Group. Comparative Example 1, consisting of pure Ag3PO4, had a degradation rate of only 48.6%, indicating that Ag3PO4 alone is insufficient for efficient interfacial degradation. Comparative Example 2, lacking the β-CD / QCS dual-targeting shell, had a degradation rate of only 57.4%, demonstrating that a conductive framework and Ag3PO4 alone are insufficient for efficient pollutant enrichment. Comparative Example 6, lacking the Ag3PO4 photocatalytically active component, had a degradation rate of only 22.7%, indicating that adsorption cannot replace photocatalytic degradation. Although Comparative Example 9 contained all the main raw materials, it was merely a physical mixture, resulting in a degradation rate of only 45.3%, demonstrating that the key to this invention is not simple mixing, but rather the integrated micro-reaction interface formed by in-situ deposition and the construction of a stable shell.

[0086] Using *Escherichia coli* (strain preservation number: ATCC 25922) and *Staphylococcus aureus* (strain preservation number: ATCC6538) as typical pathogens, initial concentrations of 1×10⁻⁶ were prepared respectively. 6 CFU / mL bacterial suspension. The composite photocatalyst material was added at a concentration of 0.2 g / L, the system volume was 50 mL, and the pH was 7.0. Each group of materials was first contacted with the bacterial suspension in the dark for 30 min, followed by reaction under visible light (λ > 420 nm) for 60 min. After the reaction, the number of surviving bacteria was determined using a tenfold serial dilution and plate count method. The decrease in the log value of pathogens was calculated as log... 10 The (N0 / N) calculation is used, where N0 is the viable bacterial concentration at the start of light exposure and N is the viable bacterial concentration after t min of light exposure; t in the results listed in Table 2 is 60 min.

[0087] Table 2. Inactivation results of different materials on pathogens

[0088]

[0089] Table 2 shows that Examples 1-8 all exhibited significant inactivation effects against *Escherichia coli* and *Staphylococcus aureus*. Example 1 showed a log reduction of 6.2 for *Escherichia coli* and 5.8 for *Staphylococcus aureus*, indicating that the material can effectively inactivate both Gram-negative and Gram-positive bacteria simultaneously. Example 2, due to its higher proportion of quaternized chitosan and increased density of cationic groups on the material surface, enhanced the electrostatic adsorption between the material and bacterial cell membranes, resulting in a log reduction of 6.8 for *Escherichia coli* and 6.3 for *Staphylococcus aureus*. Example 5, with its higher Ag3PO4 loading, generated more reactive oxygen species under visible light irradiation, thus demonstrating strong sterilization ability.

[0090] In contrast, the pathogen inactivation effects of Comparative Examples 1-10 were significantly lower than those of the Example Group. Comparative Example 1, consisting of pure Ag3PO4, showed log reduction values ​​of only 2.1 and 1.8 against Escherichia coli and Staphylococcus aureus, respectively, indicating that the sterilization ability of Ag3PO4 alone is limited. Comparative Example 3, lacking quaternized chitosan, showed log reduction values ​​of only 2.3 and 2.0 against Escherichia coli and Staphylococcus aureus, respectively, indicating that without QCS, the material is difficult to effectively capture bacteria and form a close-range inactivation interface. Comparative Example 6, lacking Ag3PO4 photocatalytic active centers, showed log reduction values ​​of only 1.2 and 1.0, indicating that relying solely on the adsorption or contact effect of CD-QCS / NSPC cannot achieve efficient sterilization. Although Comparative Example 9 contained all the main raw materials, its sterilization effect was significantly lower than that of Example 1 due to the lack of in-situ loading and cross-linked shell structure, indicating that a stable composite interface construction is key to achieving efficient sterilization.

[0091] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens, characterized in that... Includes the following steps: (1) Disperse the conductive carbon-based framework in water or a water-ethanol mixed solvent to obtain a uniform dispersion; (2) Add silver source to dispersion and stir for 30-120 min under light-protected conditions to allow Ag to react. + The Ag3PO4 is adsorbed or complexed onto the surface of the conductive carbon-based framework; then a phosphate solution is added and the mixture is reacted under light-protected conditions for 1-6 h to allow Ag3PO4 to be deposited in situ onto the surface of the conductive carbon-based framework, thus obtaining an Ag3PO4 / conductive carbon-based framework composite material. (3) Dissolve carboxymethyl-β-cyclodextrin and quaternized chitosan in an aqueous system, add the Ag3PO4 / conductive carbon-based skeleton composite material from step (2), and add EDC and NHS as crosslinking agents to conduct a crosslinking reaction, so that carboxymethyl-β-cyclodextrin and quaternized chitosan form a crosslinked composite shell and coat and fix it on the surface of the material; finally, after centrifugation, washing and drying, the silver phosphate-based composite photocatalytic material with dual-target enrichment of antibiotics and pathogens is obtained.

2. The preparation method of the silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens according to claim 1, characterized in that: The conductive carbon-based framework mentioned in step (1) is at least one of nitrogen-sulfur co-doped porous carbon, nitrogen-sulfur co-doped reduced graphene oxide, reduced graphene oxide, graphene oxide, carbon nanotubes, and porous carbon aerogel, preferably nitrogen-sulfur co-doped porous carbon; the concentration of the conductive carbon-based framework in the obtained uniform dispersion is 1.0-1.25 g / L.

3. The preparation method of the silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens according to claim 2, characterized in that: The nitrogen-sulfur co-doped porous carbon described in step (1) is prepared by the following steps: graphene oxide, dopamine hydrochloride and thiourea are dispersed in water, the pH is adjusted to 8.0-9.0 using Tris-HCl buffer, and the mixture is stirred continuously at 20-25 °C for 12 h to allow dopamine to self-polymerize on the surface of graphene oxide and introduce nitrogen and sulfur precursors; then, after washing, freeze drying and calcination under a nitrogen atmosphere, a nitrogen-sulfur co-doped porous carbon framework is obtained. In the preparation step of the nitrogen-sulfur co-doped porous carbon, the mass ratio of graphene oxide, dopamine hydrochloride and thiourea is 1:2:3; the calcination temperature is 600-900 ℃ and the calcination time is 1-4 h.

4. The preparation method of the silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens according to claim 1, characterized in that: The silver source is silver nitrate, silver acetate, or other soluble silver salts, preferably silver nitrate; the phosphate is at least one of Na2HPO4, NaH2PO4, K2HPO4, and KH2PO4, preferably Na2HPO4; The Ag + With PO4 3- The molar ratio is 2.5:1-3.5:1, preferably 3:1; the mass percentage of Ag3PO4 in the Ag3PO4 / conductive carbon-based skeleton composite material is 20%-80%, preferably 30%-70%.

5. The preparation method of the silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens according to claim 1, characterized in that: The aqueous phase system described in step (3) is water; The mass ratio of carboxymethyl-β-cyclodextrin to quaternized chitosan in step (3) is 1:5-5:1; 0.1-0.5 g of carboxymethyl-β-cyclodextrin is added for every 1 g of Ag3PO4 / conductive carbon-based skeleton composite material; the amount of EDC is 20%-100% of the mass of carboxymethyl-β-cyclodextrin, and the amount of NHS is 12%-60% of the mass of carboxymethyl-β-cyclodextrin. The pH of the crosslinking reaction in step (3) is 4.5-6.5, the reaction temperature is 20-25 °C, and the reaction time is 1-8 h.

6. The preparation method of the silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens according to claim 1, characterized in that: The antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material is further immobilized into microspheres, membranes, coatings, or fillers. The antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material microspheres are prepared by the following steps: the obtained antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material is added to a sodium alginate solution with a mass fraction of 1%-4% to form a uniform slurry, and then dropped into a CaCl2 solution with a mass fraction of 1%-5% for cross-linking to obtain immobilized photocatalytic microspheres. The immobilized photocatalytic microspheres have a particle size of 0.5-5.0 mm; each 1 g of antibiotic-pathogen dual-target enrichment silver phosphate-based composite photocatalytic material corresponds to the use of 2 g sodium alginate and 6 g CaCl2, and is cross-linked at 20-25 ℃ for 3 h.

7. A silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens, prepared by the method according to any one of claims 1-6.

8. The use of the silver phosphate-based composite photocatalytic microreaction material for dual-target enrichment of antibiotics and pathogens as described in claim 7 in the purification of water bodies contaminated by antibiotics and / or pathogens.

9. The use according to claim 8, characterized in that: When in use, the silver phosphate-based composite photocatalytic material, which targets and enriches both antibiotics and pathogens, is added to water containing antibiotics and / or pathogens and treated under visible light irradiation.

10. The application according to claim 9, characterized in that: The silver phosphate-based composite photocatalytic material for dual-target enrichment of antibiotics and pathogens is combined with persulfate, wherein the persulfate is at least one of perdisulfate (PDS) and permonsulfate (PMS).

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