Fabrication Of Z-scheme CdWO₄/ZnFe₂O₄ System With Double-response Activity For Light-microwave Catalytic Degradation Of Tetracycline

Tetracycline?TC?,as an effective antibiotic,has been extensively used in the treatment of bacterial infections in humans and animals on account of its broad-spectrum antibacterial activity,low toxicity,and low cost.However,TC is poorly metabolized or absorbed in biological bodies,which can cause 90%of the dosage to be discharged into the environment through excreta.The TC detected(at ng?L^-11 or?g?L^-1)in the aquatic system is deemed to be potential hazard for human health and the ecosystem because of the ecotoxicity and the formation of antibiotic resistance genes.In recent years,the elimination of TC in water mainly adopts adsorption,biodegradation,and chemical oxidation methods including advanced oxidation precesses.Among them,photocatalysis technology has been regarded as a well-established and ideal technique to deal with organics in water owing to the easy operation,high efficiency and no secondary pollution.Also,microwave-induced catalytic oxidation technology can expedite the reaction and shorten the treatment time due to its strong penetration and high energy efficiency.Therefore,this study combines photocatalysis with MW catalytic oxidation technology,and constructs a catalytic system that can utilize both light energy and MW energy to achieve rapid and complete degradation of organic pollutants at different concentrations in water.In this work,a novel Z-scheme CdWO4/ZnFe2O4 catalytic system with ultraviolet-microwave?UV-MW?double-response activity was constructed using isoelectric point and high-temperature calcination methods for the degradation of tetracycline in water.The effects of several parameters including particle ratio?CdWO4:ZnFe2O4?,irradiation time,MW power,initial concentration,catalyst dose,and catalyst reuse cycles on the catalytic activity of CdWO₄/ZnFe₂O₄ under UV-MW were also investigated.The degradation mechanism on the Z-scheme CdWO4/ZnFe2O4/UV-MW catalytic system was proposed.The results reveal that the combination of photocatalytic and MW-induced catalytic oxidation technology achieves superior CdWO₄/ZnFe₂O₄ catalytic performance.Z-scheme CdWO4/ZnFe2O4 system displays high catalytic activity under UV-MW.Particularly,the generated MW plasma accelerates electron transfer and production of active species,which promotes the enhancement of redox capacity and the degradation of organic pollutants.At 1:8 particle ratio,CdWO₄/ZnFe₂O₄ has higher catalytic activity,and when the initial concentration was 25.0 mg/L and the catalyst dosage was 1.0 g/L,the degradation rate of tetracycline solution was up to 87.3%under UV?200 W?-MW?400 W?irradiation within 35.0 min.Moreover,the catalytic activity of CdWO4/ZnFe2O4 remains high after five reuse cycles.During the degradation,the·OH plays a major role,while the·O₂^-and h⁺play relatively minor roles.Therefore,the CdWO₄/ZnFe₂O₄/UV-MW technology demonstrates to be promising in the treatment of antibiotics at different concentrations in water and wastewater.