Preparation Of Silver Phosphate-Based Nanomaterials And Study On The Photocatalytic Degradation Of Tetracycline Hydrochloride

Antibiotic pollution has become an environmental problem with global concern,which threatens human health and the ecosystem seriously.Photocatalytic technology is widely used in the environmental and energy fields with the advantages of high efficiency,and environmentally friendly,which is considered one of the most promising technologies in wastewater treatment.However,the rapid combination of photogenerated electron-hole pairs,low sunlight utilization and the difficulty of recycling photocatalytic materials limit the practical application of photocatalytic technology seriously.The above problems can be solved by constructing visible light response heterojunction structure and doping easily recyclable materials.In this study,silver phosphate/molybdenum disulfide（Ag₃PO₄/MoS₂）nanomaterial was prepared by constructing a Z-scheme heterojunction structure,which was successfully applied to the photocatalytic treatment of antibiotic wastewater under visible light conditions.The results showed that Ag₃PO₄/MoS₂ had excellent photocatalytic degradation properties,due to the separation of photogenerated electron-hole pairs being promoted effectively by the Z-scheme heterojunction structure.On this basis,the magnetic Ag₃PO₄/MoS₂/Fe₃O₄ photocatalyst was successfully prepared,which was beneficial to the recycling of the photocatalyst.The main research contents and results of this paper are as follows:（1）The high 1T phase oxygen-containing MoS₂ was prepared by hydrothermal synthesis method,which was used as the co-catalyst.Then the Ag₃PO₄/MoS₂nanomaterial was successfully prepared by the ion exchange method and systematically characterized.Under visible light diffraction,the photocatalytic degradation of tetracycline hydrochloride（TCH）by the as-prepared Ag₃PO₄/MoS₂ nanomaterial was investigated.The photocatalytic degradation mechanism and toxicity variety were analyzed.The experimental results showed that under the optimal conditions（0.2 g/L Ag₃PO₄/MoS₂,25℃,10 mg/L TCH,p H=5）,the degradation efficiency of TCH could reach up to 98.9%within 10 min.After 4 recycling times of photocatalytic degradation reaction,the degradation efficiency still achieved 91.3%,indicating that the Ag₃PO₄/MoS₂ nanomaterial was prepared with excellent photocatalytic properties and chemical stability.Combing the results of the scavenger experiment and electron spin resonance（ESR）spectroscopy,h⁺,e^-,and·OH played a major role during the photocatalytic degradation of TCH.According to the experimental and theoretical calculation,the photocatalytic degradation mechanism of TCH by the Ag₃PO₄/MoS₂nanomaterial was investigated.The results showed that the Z-scheme heterojunction structure was formed between MoS₂ and Ag₃PO₄,which effectively promoted the separation of photogenerated electron-hole pairs.Based on the toxicity prediction and cytotoxicity assay,it was found that the ecotoxicity of the reaction system decreased gradually with the photocatalytic reaction.In addition,under solar irradiation,the Ag₃PO₄/MoS₂ nanomaterial showed excellent photocatalytic degradation properties on the mixed antibiotic wastewater（TCH:95.0%,Norfloxacin（NOR）:77.5%,Sulfamethazine（SMZ）:74.4%,60 min）,indicating that Ag₃PO₄/MoS₂ photocatalyst has an excellent application potential.（2）In practical applications,it is difficult for the powdered photocatalyst to recycle.In this work,based on the as-prepared Ag₃PO₄/MoS₂ nanomaterial,the magnetic Ag₃PO₄/MoS₂/Fe₃O₄ photocatalyst was prepared and characterized systematically.Under visible light irradiation,the photocatalytic degradation of TCH by Ag₃PO₄/MoS₂/Fe₃O₄ nanomaterial was investigated.The effect of different parameters on the degradation efficiency was investigated and optimized.Then the photocatalytic reaction mechanism and toxicity variety were analyzed.Under the optimal conditions（0.2 g/L Ag₃PO₄/MoS₂/Fe₃O₄,25℃,10 mg/L TCH,p H=5）,the degradation efficiency of TCH could reach up to 99.0%after 7.5 min photocatalytic degradation reaction.After4 recycling times,the photocatalytic degradation efficiency could still achieve more than 99.0%.The characterization results showed that the Ag₃PO₄/MoS₂/Fe₃O₄photocatalyst with excellent recyclability and chemical stability was prepared.·O₂^-and h⁺played a major role in the photocatalytic degradation of TCH through scavenger experiments and ESR spectroscopy.Combing with the experimental analysis and theoretical calculations,Z-scheme heterojunction was formed among Ag₃PO₄,MoS_2,and Fe₃O₄,which was beneficial to improve the photocatalytic property of Ag₃PO₄/MoS₂.According to the toxicity prediction and cytotoxicity assay,the ecotoxicity was significantly reduced during the photocatalytic degradation of TCH by the Ag₃PO₄/MoS₂/Fe₃O₄ nanomaterials;In addition,the Ag₃PO₄/MoS₂/Fe₃O₄photocatalyst also showed excellent photocatalytic degradation property for mixed antibiotic wastewater（TCH:93.6%,NOR:73.0%,SMZ:71.7%,30 min）in the effluent.In summary,the photocatalytic degradation property of Ag₃PO₄-based nanomaterials for TCH was investigated.The photocatalytic reaction pathways and influence mechanisms under different photocatalytic systems were elucidated.During the photocatalytic degradation of TCH,the toxicity variety of the reaction system was explored.This study not only provides a method for the effective removal of antibiotics from the water environment,but also provides a reference for the modification of Ag₃PO₄-based photocatalytic materials,which broadens the practical application of photocatalytic technology in the actual wastewater treatment.