Construction Of Bismuth Based Z-scheme Bi₃O₄Cl/Bi₂MoO₆ Composite Photocatalyst And Study On Photocatalytic Activity

As a typical organic pollutant,antibiotic wastewater has caused more and more environmental pollution in recent years,and it is very difficult to treat it.Norfloxacin is a typical quinolone antibiotic,which is widely used in clinical medicine and animal husbandry.After entering the environment,it causes soil acidification,water pollution and other environmental problems.Traditional physical and chemical methods and biological methods have many shortcomings and deficiencies in the treatment of norfloxacin,so they cannot be applied well.As a kind of advanced oxidation technology,photocatalytic oxidation method has attracted wide attention due to its advantages such as low pollution or no pollution,can effectively use sunlight,easy availability and low cost,and has gradually become a current research hotspot.Since a single photocatalyst has a narrow response range to visible light,and the electrons and holes are easy to recombine,so the photocatalytic efficiency is limited.The construction of a Z-scheme composite photocatalytic system can well improve the photocatalytic performance.After the two single catalysts are successfully combined,the redox ability of the system is improved,and the active free radicals（such as h⁺,·O₂^-and·OH）can degrade organic pollutants in wastewater more effectively.Therefore,in order to expand the visible light response range,reduce the electron-hole recombination rate and improve the photocatalytic efficiency,this study tried to synthesize a new binary Z-scheme composite photocatalytic material to efficiently degrade norfloxacin and other organic pollutants.Aiming at the above problems,this article takes bismuth-based semiconductors as the research object,and synthesizes the Z-scheme Bi₃O₄Cl/Bi₂MoO₆composite photocatalyst by hydrothermal and in-situ synthesis methods,and applies it to the study of photocatalytic degradation of norfloxacin under visible light irradiation.The catalytic activities of the Bi₃O₄Cl/Bi₂MoO₆composite catalyst,Bi₃O₄Cl and Bi₂MoO₆catalysts were compared,and the effects of the initial concentration of norfloxacin,the dose of the composite catalyst,the particle ratio of the composite catalyst and the visible light irradiation time on the degradation efficiency were also studied.In addition,the stability and reusability of the composite photocatalyst were also investigated,and the mechanism of the composite Z-scheme Bi₃O₄Cl/Bi₂MoO₆photocatalytic system for catalytic degradation of pollutants was proposed.The main research results are as follows:1.Compared with Bi₃O₄Cl and Bi₂MoO₆monomer,the Z-scheme Bi₃O₄Cl/Bi₂MoO₆composite photocatalyst has expanded the visible light response range and has more excellent photocatalytic activity.2.The successful construction of Z-scheme composite photocatalytic system reduces the recombination rate of electrons and holes,and significantly improves the redox capacity of the whole system.3.Z-scheme composite photocatalyst has better degradation efficiency for NFX.The degradation rate can reach 93.4%when the dosage of catalyst is 1.0 g/L and the initial concentration of norfloxacin is 5.0 mg/L under visible light irradiation for 150min.4.Through the capture experiment of active species,it was proved that the active free radicals such as h⁺,·OH and·O₂^-produced in the reaction process played a key role in the degradation of norfloxacin.5.The composite photocatalyst has a good degradation ability for different kinds of pollutants,the order from large to small is:Norfloxacin>acridine orange>tetracycline>methylene blue>crystal violet.In addition,Z-scheme Bi₃O₄Cl/Bi₂MoO₆composite photocatalyst still has a good degradation efficiency after five cycle experiments.Therefore,this research technology has a good application prospect in the treatment of antibiotic wastewater and has a certain guiding significance in the field of sewage treatment and environmental governance.