Cofe-ldo@moo3 / pvdf catalyst and preparation method and application thereof

Abstract

The application discloses a preparation method of a CoFe-LDO@MoO3 / PVDF catalyst, and specifically comprises the following steps: taking urea and ammonium fluoride as an adjusting agent, taking a cobalt source and an iron source as a metal source, and synthesizing CoFe-LDH through a first hydrothermal reaction; then mixing the CoFe-LDH with CH3CSNH2 and a molybdenum source, and then sequentially performing a second hydrothermal reaction, cooling, washing, drying and calcining to obtain CoFe-LDO@MoO3; finally taking dimethyl sulfoxide as a solvent, taking polyvinylidene fluoride as a carrier, pouring the CoFe-LDO@MoO3 on the PVDF to obtain the CoFe-LDO@MoO3 / PVDF catalyst. The CoFe-LDO@MoO3 / PVDF catalyst synthesized by the application still has a high removal efficiency of more than 87% after 5 cycles, and has a great development prospect in the field of removing organic wastewater in practical application.

Description

Technical Field

[0001] This invention belongs to the field of organic wastewater pollutant removal catalyst technology, specifically involving CoFe-LDO@MoO3 / PVDF catalyst, preparation method of CoFe-LDO@MoO3 / PVDF catalyst, and application of CoFe-LDO@MoO3 / PVDF catalyst. Background Technology

[0002] With the large-scale development of the medical industry and the continuous upgrading of environmental monitoring technologies, antibiotics are widely used in clinical diagnosis and treatment. A large amount of new antibiotic pollutants are continuously discharged into the aquatic environment, posing a significant threat to aquatic ecological security and human health. Antibiotic pollutants have stable chemical structures and poor biodegradability, making it difficult for traditional water treatment technologies such as activated sludge processes and conventional adsorption methods to achieve efficient and deep removal. These technologies suffer from poor removal efficiency, easy generation of toxic intermediate products, and insufficient treatment stability, representing a pressing technical challenge in the field of water pollution remediation.

[0003] Currently, advanced oxidation technologies (AOPs) are the mainstream technology for treating recalcitrant organic pollutants in water. Among them, persulfate-based advanced oxidation technologies (PS-AOPs) have become a research hotspot for the degradation of antibiotic pollutants due to their advantages such as strong oxidation capacity, wide applicability, and mild reaction conditions. Layered bimetallic oxides (LDOs) are widely used in PS-AOPs water treatment due to their large specific surface area, abundant active sites, tunable metal composition, low metal ion leaching rate, and excellent structural stability. CoFe-LDO combines the catalytic advantages of both Co and Fe bimetals. Co metal has excellent PMS activation performance and can efficiently trigger the PMS activation reaction, while Fe metal is inexpensive and environmentally friendly. The synergistic effect of the two can significantly enrich the catalytic active sites and promote PMS decomposition and pollutant degradation. However, CoFe-LDO alone has drawbacks such as slow metal redox cycle rate, high HVMO formation energy barrier, and weak dominance of non-radical pathways, which greatly limit its catalytic degradation efficiency and practical application effect. Molybdenum trioxide (MoO3), as a non-toxic and economical layered semiconductor material, possesses a multivalent electronic structure, excellent chemical stability, and electronic conductivity. It can serve as a highly efficient co-catalyst to modulate the electronic structure of metal active sites and accelerate the production of Co³⁺. + / Co² + The redox cycle lowers the energy barrier for HVMO formation, promotes the formation and stabilization of highly active Co(IV)=O intermediates, and effectively compensates for the catalytic shortcomings of single CoFe-LDO.

[0004] Currently, powdered LDO-based catalysts generally suffer from engineering application problems such as easy agglomeration, low mass transfer efficiency, difficulty in recovery and separation, and poor cycle stability, significantly increasing the operating costs of actual wastewater treatment. Polyvinylidene fluoride (PVDF) is a high-molecular membrane material with excellent chemical stability, high mechanical strength, and low cost. It possesses characteristics such as porous structure, large specific surface area, and strong adhesion, making it an ideal carrier for immobilizing powdered catalytic materials and preparing composite membrane-based catalysts. Loading CoFe-LDO@MoO3 composite catalytic material onto a PVDF membrane substrate can effectively solve the technical problems of difficult recovery, easy loss, and secondary pollution of powdered catalysts, while optimizing interfacial mass transfer efficiency and improving the overall stability and recyclability of the catalyst. In summary, the industry currently lacks an integrated catalytic material that can precisely control the interfacial electronic structure, efficiently generate stable HVMO non-radical active species, has strong anti-interference ability, is recyclable, and is easy to separate and recover. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing CoFe-LDO@MoO3 / PVDF catalyst, which can effectively degrade antibiotic pollutants in water.

[0006] A second objective of this invention is to provide a CoFe-LDO@MoO3 / PVDF catalyst.

[0007] A third objective of this invention is to provide the application of the CoFe-LDO@MoO3 / PVDF catalyst in the degradation of organic pollutants in wastewater.

[0008] The first technical solution adopted in this invention is a method for preparing CoFe-LDO@MoO3 / PVDF catalyst, specifically as follows: CoFe-LDH is synthesized through a first hydrothermal reaction using urea and ammonium fluoride as regulators and cobalt and iron sources as metal sources; then, CoFe-LDH is mixed with CH3CSNH2 and a molybdenum source, and then subjected to a second hydrothermal reaction, cooling, washing, drying, and calcination to obtain CoFe-LDO@MoO3; finally, CoFe-LDO@MoO3 is cast onto PVDF using dimethyl sulfoxide as solvent and polyvinylidene fluoride as carrier.

[0009] The invention is further characterized by: The cobalt source is (CH3COO)2Co, the iron source is Fe(NO3)3·9H2O, and the molybdenum source is Na2MoO4.

[0010] The molar ratio of urea to ammonium fluoride is 6:5, and the molar ratio of cobalt to iron in the cobalt source and iron source is (0.5~3):1.

[0011] The conditions for the first hydrothermal reaction are: hydrothermal reaction at 100-140℃ for 8-24 h; the conditions for the second hydrothermal reaction are: hydrothermal reaction at 180-200℃ for 24-36 h.

[0012] The drying temperature was 60℃ and the time was 12 h; the calcination conditions were: calcination at 350-550℃ for 3 h.

[0013] The mass ratio of CH3CSNH2 to Na2MoO4 is 2:1; the mass ratio of CoFe-LDH to Na2MoO4 is (1-2.5):1.

[0014] The mass ratio of CoFe-LDO@MoO3 to PVDF is (2.5-0.625):1.

[0015] The second technical solution adopted in this invention is a CoFe-LDO@MoO3 / PVDF catalyst prepared by a method for preparing CoFe-LDO@MoO3 / PVDF catalyst.

[0016] The third technical solution adopted in this invention is the application of CoFe-LDO@MoO3 / PVDF catalyst in the degradation of organic pollutants in wastewater.

[0017] The third technical solution adopted in this invention is further characterized by, Organic pollutants include endocrine disruptors and antibiotics. Antibiotics include tetracycline, oxytetracycline, ofloxacin, sulfadiazine, and sulfamethoxazole. Endocrine disruptors include bisphenol A and 4-chlorophenol.

[0018] The beneficial effects of this invention are: This invention utilizes PVDF as the immobilization substrate and (CH3COO)2Co, Fe(NO3)3·9H2O, and Na2MoO4 as metal sources to successfully prepare CoFe-LDO@MoO3 / PVDF nanomaterials via a two-step hydrothermal-calcination method. This material not only effectively degrades SMZ but also rapidly degrades tetracycline, oxytetracycline, ofloxacin, sulfamethoxazole, bisphenol A, and 4-chlorophenol. Using the catalyst obtained in this invention combined with a PMS system, 100% removal efficiency of TC, OTC, and OFX in solution at 10 mg / L can be achieved within 30 min. Furthermore, the degradation efficiency of SMZ remains above 87% after five cycles of the same catalyst, demonstrating high reusability. In addition, compared to other activation methods, the catalyst provided by this invention does not require additional energy or chemicals to generate active species; it only requires Co in the catalyst. Ⅳ =O species activation PMS has the advantages of being more economical and simpler, and can be widely used. Attached Figure Description

[0019] Figure 1 This is a flow chart of the preparation process of the catalyst of the present invention; Figure 2 This is a SEM scan image of the catalyst obtained in Example 1 of the present invention; Figure 3 The removal performance of SMZ in different reaction systems; Figure 4a This is a graph showing the free radical capture experiment results of the catalyst obtained in Example 1 of this invention; Figure 4b This is a graph showing the free radical capture experiment results of the catalyst obtained in Comparative Example 3 of this invention; Figure 4c This is the EPR characterization diagram (DMPO) of the catalyst obtained in Example 1 of the present invention. Figure 4d This is the EPR characterization diagram (TEMP) of the catalyst obtained in Example 1 of the present invention. Figure 5a This describes the effect of different PMS concentrations of the catalyst obtained in Example 1 of this invention on SMZ degradation; Figure 5b This illustrates the effect of different initial SMZ concentrations of the catalyst obtained in Example 1 of this invention on SMZ degradation. Figure 5c This illustrates the effect of different pH values ​​on SMZ degradation of the catalyst obtained in Example 1 of this invention. Figure 5d This is a Zeta potential test of the catalyst obtained in Example 1 of the present invention; Figure 6 This is a graph showing the degradation effect of CoFe-LDO@MoO3 / PVDF on different pollutants obtained in Example 1 of this invention; Figure 7a This is the electrochemical characterization (linear sweep voltammetry) of the CoFe-LDO@MoO3 / PVDF catalyst obtained in Example 1 of this invention. Figure 7b This is the electrochemical characterization diagram (open circuit potential) of the CoFe-LDO@MoO3 / PVDF catalyst obtained in Example 1 of this invention. Detailed Implementation

[0020] The following detailed description is provided in conjunction with specific implementation methods and accompanying drawings.

[0021] The preparation method of the CoFe-LDO@MoO3 / PVDF catalyst of the present invention is as follows: CoFe-LDH is synthesized through a first hydrothermal reaction using urea (CO(NH2)2) and ammonium fluoride (NH4F) as regulators and cobalt source and iron source as metal source; then CoFe-LDH is mixed with CH3CSNH2 and molybdenum source and subjected to a second hydrothermal reaction, followed by cooling, washing, drying and calcination to obtain CoFe-LDO@MoO3; finally, CoFe-LDO@MoO3 is cast onto PVDF using dimethyl sulfoxide (DMSO) as solvent and polyvinylidene fluoride (PVDF) as support to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0022] The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve CO(NH2)2 and NH4F in ultrapure water to obtain solution 1; Solution 2 was obtained by dissolving (CH3COO)2Co and Fe(NO3)3·9H2O in ultrapure water; (2) Mix solution 1 and solution 2 to obtain a mixed solution, and transfer it to a reaction vessel for hydrothermal reaction. After the reaction is completed, cool the mixture, wash the obtained product three times with ultrapure water and anhydrous ethanol respectively, and then dry it to obtain CoFe-LDH.

[0023] (3) CoFe-LDH was mixed with CH3CSNH2 and Na2MoO4 and then transferred to a reactor for hydrothermal reaction. After the reaction was completed, the mixture was cooled, and the resulting product was washed three times with ultrapure water and anhydrous ethanol, respectively, and then dried. Subsequently, the precursor obtained from the above reaction was placed in a tube furnace for pyrolysis and calcination to obtain the CoFe-LDO@MoO3 catalyst.

[0024] (4) Finally, using dimethyl sulfoxide (DMSO) as solvent and polyvinylidene fluoride (PVDF) as support, CoFe-LDO@MoO3 was cast onto PVDF to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0025] The cobalt source is (CH3COO)2Co, the iron source is Fe(NO3)3·9H2O, and the molybdenum source is Na2MoO4.

[0026] The molar ratio of urea to ammonium fluoride is 6:5, and the molar ratio of cobalt to iron in the cobalt source and iron source is (0.5~3):1.

[0027] The conditions for the first hydrothermal reaction are: hydrothermal reaction at 100-140℃ for 8-24 h; the conditions for the second hydrothermal reaction are: hydrothermal reaction at 180-200℃ for 24-36 h.

[0028] The drying temperature was 60℃ and the time was 12 h; the calcination conditions were: calcination at 350-550℃ for 3 h.

[0029] The mass ratio of CH3CSNH2 to Na2MoO4 is 2:1; the mass ratio of CoFe-LDH to Na2MoO4 is (1-2.5):1.

[0030] The mass ratio of CoFe-LDO@MoO3 to PVDF is (2.5-0.625):1.

[0031] The application of the CoFe-LDO@MoO3 / PVDF catalyst prepared in this invention in the degradation of organic pollutants in wastewater, including endocrine disruptors and antibiotics, wherein the antibiotics include tetracycline (TC), oxytetracycline (OTC), ofloxacin (OFX), sulfadiazine (SMZ), and sulfamethoxazole (SMX), and the endocrine disruptors include bisphenol A (BPA) and 4-chlorophenol (4-CP).

[0032] This invention successfully prepared CoFe-LDO@MoO3 / PVDF nanomaterials through a two-step hydrothermal and calcination process, using urea and ammonium fluoride as regulators and cobalt, iron, and molybdenum sources as metal sources. NH4F acts as both a structural mediator and a crystal-forming agent during the growth process. The effective chelation of NH4F with transition metal cations controls their hydrolysis release rate, promotes the formation and directional assembly of LDH crystal nuclei in solution, and also acts as a precipitant, providing an alkaline environment for the synthesis solution, which facilitates the precipitation of metal ions and the formation of well-structured layered hydroxides.

[0033] To address the secondary pollution caused by metal leaching when using powdered heterogeneous catalysts in organic wastewater removal, this invention modifies layered bimetallic hydroxides (LDHs) through high-temperature calcination. This improves the material's stability and catalytic activity, constructs more active sites, and enhances the catalyst's selective degradation of pollutants. The CoFe-LDO@MoO3 / PVDF catalyst synthesized in this invention maintains a high removal efficiency of over 87% after five cycles, demonstrating significant potential for practical applications in organic wastewater removal. EPR and free radical capture experiments show that the CoFe-LDO@MoO3 / PVDF catalyst activates PMS to generate both non-radical and free radicals to degrade various new pollutants, with these two pathways synergistically promoting the removal of target pollutants.

[0034] Example 1 Preparation methods of CoFe-LDO@MoO3 / PVDF catalysts, such as Figure 1 As shown, please follow these steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reaction vessel for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH; (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0035] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0036] Example 2 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 0.5 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0037] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0038] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0039] Example 3 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 2 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0040] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0041] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0042] Example 4 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 3 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0043] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0044] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0045] Example 5 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 110 °C for 12 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0046] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0047] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0048] Example 6 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0049] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 180 °C for 36 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0050] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0051] Example 7 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0052] (2) Dissolve 90 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0053] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0054] Example 8 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0055] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 450 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0056] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0057] Example 9 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0058] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0059] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.015 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0060] Example 10 The preparation method of CoFe-LDO@MoO3 / PVDF catalyst is carried out according to the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash and dry to obtain CoFe-LDH.

[0061] (2) Dissolve 200 mg CoFe-LDH in 30 mL of deionized water and stir for 30 min. Then add 180 mg CH3CSNH2 and 90 mg Na2MoO4 to the above solution and stir for 30 min. Transfer the mixed reaction solution to a 50 mL reactor and hydrothermally react at 200 °C for 24 h. After the reaction is complete, cool, wash, and dry. Finally, place the dried catalyst precursor in a muffle furnace and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO@MoO3.

[0062] (3) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.0075 g of CoFe-LDO@MoO3 was added and stirred continuously for 12 h. The above solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO@MoO3 / PVDF catalyst.

[0063] Comparative Example 1 The preparation method of Fe-LDO@MoO3 / PVDF catalyst differs from that in Example 1 in that (CH3COO)2Co is not added, and step (1) specifically includes the following steps: 6 mmol CO(NH2)2 and 5 mmol NH4F were dissolved in 15 mL of ultrapure water to obtain solution 1; 1 mmol Fe(NO3)3·9H2O was dissolved in 15 mL of ultrapure water to obtain solution 2; solution 1 and solution 2 were mixed and transferred to a 50 mL reactor and hydrothermally reacted at 120 °C for 8 h. After the reaction was completed, the mixture was cooled, washed and dried to obtain Fe-LDH.

[0064] All other raw materials, process parameters and steps are the same as in Example 1, and the resulting product is denoted as Fe-LDO@MoO3 / PVDF catalyst.

[0065] Comparative Example 2 The preparation method of the Co-LDO@MoO3 / PVDF catalyst differs from that in Example 1 in that Fe(NO3)3·9H2O is not added, and step (1) specifically includes the following steps: 6 mmol CO(NH2)2 and 5 mmol NH4F were dissolved in 15 mL of ultrapure water to obtain solution 1; 1 mmol (CH3COO)2Co was dissolved in 15 mL of ultrapure water to obtain solution 2; solution 1 and solution 2 were mixed and transferred to a 50 mL reactor and hydrothermally reacted at 120 °C for 8 h. After the reaction was completed, the mixture was cooled, washed and dried to obtain Co-LDH.

[0066] All other raw materials, process parameters and steps are the same as in Example 1, and the resulting product is denoted as Co-LDO@MoO3 / PVDF catalyst.

[0067] Comparative Example 3 The preparation method of CoFe-LDO / PVDF catalyst includes the following steps: (1) Dissolve 6 mmol CO(NH2)2 and 5 mmol NH4F in 15 mL of ultrapure water to obtain solution 1; dissolve 1 mmol (CH3COO)2Co and 1 mmol Fe(NO3)3·9H2O in 15 mL of ultrapure water to obtain solution 2 of (CH3COO)2Co and Fe(NO3)3·9H2O; mix the above solution 1 and solution 2 and transfer them to a 50 mL reactor for hydrothermal reaction at 120 °C for 8 h. After the reaction is completed, cool, wash, dry and calcine at 550 °C for 3 h in air atmosphere. After cooling to room temperature, obtain CoFe-LDO.

[0068] (2) 0.6 g of PVDF powder was dissolved in DMSO solution at 90 °C and stirred for 12 h. Then 0.03 g of CoFe-LDO was added and stirred continuously for 12 h. The solution was transferred to a petri dish and dried at 80 °C to obtain the CoFe-LDO / PVDF catalyst.

[0069] Effect verification 1. Characterization Test like Figure 1 The preparation process flow diagram shown illustrates the synthesis of layered metal oxide catalysts CoFe-LDO@MoO3 / PVDF supported on PVDF using a hydrothermal-calcination-casting method.

[0070] Figure 2 The image shows a SEM scan of the catalyst obtained in Example 1 of this invention; where ad is a SEM image at different magnifications; fi is the corresponding EDS image; it can be seen that the catalyst obtained in Example 1 exhibits a petal-shaped microstructure and the elements are evenly distributed.

[0071] In this invention, EDS and SEM analyses confirm the successful preparation of the CoFe-LDO@MoO3 / PVDF catalyst. The three-dimensional structure, large specific surface area, and high mechanical strength of PVDF provide a favorable environment for the formation of CoFe-LDO@MoO3 / PVDF nanomaterials. The uniform and stable loading of the nanomaterials effectively solves the problems of nanoparticle aggregation and recycling difficulties.

[0072] 2. Degradation experiment This experiment used SMZ (10 mg / L) as the target pollutant and conducted a room temperature degradation experiment in 50 mL of solution to simulate antibiotic pollution in the environment. The catalyst materials obtained in Example 1 and Comparative Examples 1-3 were fixed on the clamps using plastic clips and immersed in three identical system solutions. PMS (1 mM) was added to trigger the experiment. At set time intervals, 1.0 mL of the suspension was extracted by filtration through a 0.22 μm polytetrafluoroethylene membrane. Potential free radicals were immediately inhibited with methanol quencher. A blank experiment was also set up, i.e., without the catalysts obtained in Example 1 or Comparative Examples 1-3, only PMS was used to degrade SMZ. After the reaction, the catalyst was recovered, washed 2-3 times with deionized water and anhydrous ethanol, and dried in an oven overnight (60 °C, 12 h). The collected catalyst was used for reuse experiments. All experiments were performed at least two to three times, and the average data and their error values ​​are given.

[0073] Figure 3 The figure shows the effect of different catalysts (corresponding to Example 1 and Comparative Examples 1-3) on the degradation of SMX. The effects of different catalyst components on PMS activation and SXZ degradation were further investigated. It was found that the degradation effect of SMZ was the best when the catalyst contained Co, Fe and Mo at the same time.

[0074] 3. Assay for bioactive species The experimental steps for free radical capture are as follows: To confirm and quantify the ROS generated during the catalytic degradation reaction using the catalyst system of this invention, free radical quenching experiments were conducted using methanol (MeOH), tert-butanol (TBA), p-benzoquinone (p-BQ), furfuryl alcohol (FFA), and dimethyl sulfoxide (DMSO) as ROS scavengers. The quenchers were added before the catalyst and PMS, i.e., before the catalytic degradation reaction started. This experiment also employed a single-factor controlled variable method and was compared with a blank experiment without quenchers.

[0075] The experimental procedure for EPR electron paramagnetic resonance is as follows: Electron paramagnetic resonance (EPR) spectroscopy was used to further verify the presence of ROS in the reaction system. 5,5-Dimethyl-1-pyrrolline-N-oxide (DMPO) was used as SO4. - 4-Amino-2,2,6,6-Tetramethylpiperidine (TEMP) is used as a spin trapping agent for OH·. 1 O2 spin trapping agent. The preparatory procedures before the test are as follows: First, replace the target pollutant with an equal volume of deionized water, then add a certain amount of catalyst and PMS to start the experiment. At the set time point, take out a certain volume of the reaction solution and mix it with the spin trapping agent. Use a clean capillary tube to draw up the above mixture, and finally, place it at the bottom of a narrow-mouthed quartz tube to begin the test.

[0076] Figure 4 shows the free radical capture experiment results (a) and EPR characterization diagram (cd) of the catalyst obtained in Example 1 of the present invention. Figure 4b The results of the free radical capture experiment for the catalyst obtained in Comparative Example 3 are shown. From the quenching test and EPR analysis, the following conclusions can be drawn: singlet oxygen may exist in the system. 1 MoO3 contains O2 and high-valence metal oxygen species, which play an important role in this system. A comparison of quenching tests between the catalysts obtained in the examples and those obtained in Comparative Example 3 revealed that the addition of MoO3 may have modulated the electronic structure of the catalyst surface, thereby promoting the generation of non-radical pathways.

[0077] 4. Stability and anti-interference test Figures 5a-5d This paper describes the effect of the CoFe-LDO@MoO3 / PVDF / PMS system obtained in Example 1 of this invention on SMZ degradation under different PMS concentrations, different initial SMZ concentrations, and different pH values. The results show that the optimal PMS dosage is 0.25 mM, the optimal initial SMZ concentration is 10 mg / L, and CoFe-LDO@MoO3 / PVDF exhibits significant degradation effects over a wide pH range. Zeta potential results further indicate that as pH increases, the catalyst surface gradually transitions from a strongly positive charge to a weakly positive charge, reflecting a continuous deprotonation process of surface hydroxyl groups, and the degradation performance is relatively unaffected by pH.

[0078] Figure 6 This image shows the degradation effect of the CoFe-LDO@MoO3 / PVDF catalyst obtained in Example 1 of this invention on various novel pollutants. This invention targets emerging pollutants such as common tetracycline antibiotics (tetracycline, oxytetracycline), sulfonamide antibiotics (sulfamethoxazole, sulfadiazine), and phenolic endocrine disruptors (bisphenol A, tetrachlorophenol), examining the relationship between the structure of different pollutants and their removal rates. It can be seen that the presence of substituents in pollutants usually affects removal efficiency, because some reactive oxygen species are more likely to attack certain specific structures or groups on the pollutants. From... Figure 6 The study found that the CoFe-LDO@MoO3 / PVDF catalyst pair achieved a 100% removal efficiency for pollutants such as tetracycline (TC), oxytetracycline (OTC), ofloxacin (OFX), and sulfadiazine (SMZ) within 30 min. The removal rates for bisphenol A (BPA), sulfamethoxazole (SMX), and tetrachlorophenol (4-CP) were 76.5%, 80%, and 38%, respectively. This indicates that the CoFe-LDO@MoO3 / PVDF / PMS catalytic system can selectively remove most electron-rich pollutants.

[0079] 5. Electrochemical testing To investigate the electron transfer mechanism between the catalyst and the catalytic reaction system, electrochemical performance was characterized using a CHI-660E electrochemical workstation from Shanghai Chenhua Co., Ltd., including linear sweep voltammetry and open-circuit potential analysis. Electrochemical tests were performed in a standard three-electrode system. The catalyst, platinum electrode, and saturated calomel electrode were used as the working electrode, counter electrode, and reference electrode, respectively, with a 0.05 mol / L saturated Na₂SO₄ solution as the electrolyte buffer.

[0080] Figure 7 shows the electrochemical characterization of the CoFe-LDO@MoO3 / PVDF catalyst obtained in Example 1 of this invention. To determine the electron transfer mechanism in the CoFe-LDO@MoO3 / PVDF / PMS system, the electrochemical performance of the reaction system under different conditions was tested. (a) is the LSV diagram; (b) is the open-circuit potential. As shown in Figure 7(a), the current density in the reaction system decreased after the introduction of PMS and SMZ, indicating that a stable complex (CoFe-LDO@MoO3 / PVDF / PMS*) was formed on the surface of CoFe-LDO@MoO3 / PVDF after PMS adsorption. SMZ, as an electron-rich pollutant, transfers electrons to the catalyst surface through this complex to complete further oxidation. As shown in Figure 7(b), the OCP curve further determines the direction of electron transfer. After injecting PMS into the system, the voltage rose rapidly, with the CoFe-LDO@MoO3 / PVDF catalyst showing the fastest upward trend. This is because CoFe-LDO@MoO3 / PVDF has the strongest ability to transfer electrons to PMS. With the addition of SMZ, the open-circuit potential of different catalyst systems gradually decreased, indicating that the oxidized CoFe-LDO@MoO3 / PVDF gained electrons from SMZ and transferred them to PMS. The above electrochemical experiments show that an electron transfer mechanism exists in the CoFe-LDO@MoO3 / PVDF / PMS system and promotes the degradation of SMZ. SMZ acts as an electron donor, PMS as an electron acceptor, and CoFe-LDO@MoO3 / PVDF / PMS plays an intermediate mediating role.

[0081] Because polyvinylidene fluoride (PVDF) has a three-dimensional interconnected porous membrane structure with a large specific surface area and excellent pore connectivity, it can uniformly load the CoFe-LDO@MoO3 active component, effectively exposing abundant catalytic active sites and providing sufficient reaction interfaces for the degradation reaction of antibiotic pollutants in solution. Since the recovery of powdered catalysts is difficult and their residues in the environment can cause serious water pollution problems, PVDF, as a catalyst immobilization support, can effectively solve the problem of powder material recovery in advanced oxidation processes, improve the material recycling rate, and inhibit the dissolution of metal ions. At the same time, PVDF does not contain toxic or harmful components or radioactive elements at room temperature, making it a pollution-free and environmentally friendly material. Therefore, this invention uses PVDF as an immobilization support to synthesize this catalyst.

Claims

1. A method for preparing a CoFe-LDO@MoO3 / PVDF catalyst, characterized in that, Specifically, CoFe-LDH is synthesized through a first hydrothermal reaction using urea and ammonium fluoride as regulators and cobalt, iron, and molybdenum sources as metal sources. Subsequently, CoFe-LDH is mixed with CH3CSNH2 and Na2MoO4 and then subjected to a second hydrothermal reaction, followed by cooling, washing, drying, and calcination to obtain CoFe-LDO@MoO3. Finally, CoFe-LDO@MoO3 is cast onto PVDF using dimethyl sulfoxide as solvent and polyvinylidene fluoride as carrier.

2. The preparation method of the CoFe-LDO@MoO3 / PVDF catalyst according to claim 1, characterized in that, The cobalt source is (CH3COO)2Co, the iron source is Fe(NO3)3·9H2O, and the molybdenum source is Na2MoO4.

3. The preparation method of the CoFe-LDO@MoO3 / PVDF catalyst according to claim 1, characterized in that, The molar ratio of urea to ammonium fluoride is 6:5, and the molar ratio of cobalt to iron in the cobalt source and iron source is (0.5~3):

1.

4. The preparation method of the CoFe-LDO@MoO3 / PVDF catalyst according to claim 1, characterized in that, The conditions for the first hydrothermal reaction are: hydrothermal reaction at 100-140℃ for 8-24 h; the conditions for the second hydrothermal reaction are: hydrothermal reaction at 180-200℃ for 24-36 h.

5. The method for preparing the CoFe-LDO@MoO3 / PVDF catalyst according to claim 1, characterized in that, The drying temperature is 60℃ and the time is 12 h; the calcination conditions are: calcination at 350-550℃ for 3 h.

6. The method for preparing the CoFe-LDO@MoO3 / PVDF catalyst according to claim 1, characterized in that, The mass ratio of CH3CSNH2 to Na2MoO4 is 2:1; the mass ratio of CoFe-LDH to Na2MoO4 is (1-2.5):

1.

7. The method for preparing the CoFe-LDO@MoO3 / PVDF catalyst according to claim 1, characterized in that, The mass ratio of CoFe-LDO@MoO3 to PVDF is (2.5-0.625):

1.

8. The CoFe-LDO@MoO3 / PVDF catalyst prepared by the method according to any one of claims 1-7.

9. The application of the CoFe-LDO@MoO3 / PVDF catalyst according to any one of claims 1-8 in the degradation of organic pollutants in wastewater.

10. The application of the CoFe-LDO@MoO3 / PVDF catalyst according to claim 9 in the degradation of organic pollutants in wastewater, characterized in that, The organic pollutants include endocrine disruptors and antibiotics, including tetracycline, oxytetracycline, ofloxacin, sulfadiazine, and sulfamethoxazole, and the endocrine disruptors include bisphenol A and 4-chlorophenol.

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