Construction of novel microwave-photo dual responsive Z-scheme CdWO4/ZnFe2O4 system using isoelectric point method for antibiotic degradation and mechanism perspective

A novel Z-scheme CdWO4/ZnFe2O4 photocatalyst is successfully constructed adopting isoelectric point method, and is introduced into integrated microwave-ultraviolet (MW-UV) system for the degradation of tetracycline antibiotics in aqueous solution. The influences of particle ratio (CdWO4: ZnFe2O4), irradiation time, MW power, initial concentration, catalyst dosage and reuse times on the degradation in the CdWO4/ZnFe2O4/MW-UV system are examined. The possible mechanism of Z-scheme CdWO4/ZnFe2O4 microwave-photo catalytic degradation is proposed. The results indicate the Z-scheme CdWO4/ZnFe2O4 photocatalyst possesses superior dual responsive catalytic activity in integrated MW-UV system. In particular, the production of MW plasma promotes the isolation of the photogenerated carriers, improving the redox capability of the catalytic system. The Z-scheme CdWO4/ZnFe2O4 at 1.0:8.0 particle ratios displays optimal dual responsive catalytic activity. Magnetic Z-scheme CdWO4/ZnFe2O4 retains high dual responsive catalytic activity after 5 cycles. Besides, •OH plays a dominant role in the degradation of CdWO4/ZnFe2O4/MW-UV catalytic system. Hence, the dual responsive Z-scheme CdWO4/ZnFe2O4/MW-UV approach has great potential in treating those water and wastewater with various concentrations of antibiotic.