Preparation Of Bi₂WO₆ Ternary Composite Photocatalyst And Its Performance For Degradation Of Tetracycline

In recent years,antibiotics have been widely used in various industries of human beings.People are facing the threat of increasing antibiotic pollution.Removing antibiotics from the environment has become an urgent problem to be solved.Photocatalytic oxidation technology is a new type of treatment technology using sustainable light energy as an energy source with the properties of non-selectivity,strong oxidizing ability,no secondary pollution,low economic cost and easy operation.It is considered to be one of the most promising ways to deal with environmental issues and is favored in areas such as wastewater treatment.Bismuth tungstate?Bi₂WO₆,BWO?is one of the lanthanide photocatalysts with visible-near-infrared light effect discovered in recent years,and has strong visible light capturing ability.Compared with titanium dioxide photocatalyst,Bismuth tungstate greatly improves the utilization efficiency of light energy,so it is widely used in the research of antibiotic wastewater.Although bismuth tungstate has good photocatalytic properties for antibiotic degradation,its photocatalytic activity is still limited.In order to more effectively remove antibiotics from environmental wastewater,we need to further improve the photocatalytic performance of bismuth tungstate.In this study,we first combined BWO,TCPP and rGO to construct a new and more efficient Z-type TCPP/rGO/BWO heterojunction photocatalyst.The crystal structure,morphology,microstructure,chemical composition,elemental state,optical and photoelectrochemical properties of the TCPP/rGO/BWO heterojunction are characterized.This Z-scheme TCPP/rGO/Bi₂WO₆ photocatalyst has significantly enhanced photocatalytic activity for the tetracycline?TC?degradation under the irradiation of visible light?k>420 nm?within 60 min,as compared to pure Bi₂WO₆,rGO/Bi₂WO₆ and TCPP/Bi₂ WO₆composites.The effects of the photocatalyst dosages,pollutant concentrations,coexisting ions and illumination conditions on the photodegradation were investigated.A moderate amount of photocatalyst?0.3 g/L?and a low initial TC concentration?15mg/L?are the best conditions for photocatalytic degradation of TC.NO₃^-,Cl^-and CO₃^2-have a certain inhibitory effect on photocatalytic degradation of TC.Because CO₃^2-can act as a capture agent for h+,so its inhibition is very significant.The shorter the wavelength of the light,the more energy the photocatalyst can absorb,and the better the photocatalytic degradation of TC.According to the trapping experiments and electron spin resonance analyses,the hole?h⁺?and superoxide radical?·O₂^-?mainly contribute to the TC decomposition in the TCPP/rGO/Bi₂WO₆ photocatalytic system.The photodegradation process in the TCPP/rGO/Bi₂WO₆ ternary composites can be well described by the proposed Z-scheme mechanism.The results indicate that more efficient charge separation,better light absorption,and larger surface area from the developed photocatalyst collectively contribute to the excellent photocatalytic performances.Besides,the photocatalyst has great stability and recyclability with a removal efficiency of 79.27%even after five times of repeated treatment.This work reports a new strategy for the preparation of Z-type heterojunction photocatalysts with high photocatalytic activity and provides a new solution for efficient removal of antibiotic wastewater by photocatalysis.