Heterostructure coal-bearing strata kaolinite/MnFe2O4 composite for activation of peroxydisulfate to efficiently degrade chlortetracycline hydrochloride

The excessive discharge of the antibiotic chlortetracycline hydrochloride (CTC·HCl) directly threatens human life and health. Different from previous studies on MnFe2O4 (MFO) combined with bulk BT or disc-shaped DE in the treatment of antibiotic wastewater, in this study, layered coal-bearing strata kaolinite (CK) was used as a carrier to prepare MnFe2O4/coal-bearing strata kaolinite (MFO/CK) catalyst, and used to evaluate the effect of activated peroxodisulfate (PDS) in the removal of CTC·HCl in wastewater under visible light. Compared with MFO and CK, the specific surface area of MnFe2O4/coal-bearing strata kaolinite-40% (MFO/CK-40%) was significantly increased, the reactive sites increased, and the PDS activation and CTC·HCl degradation were better. After 60 min of reaction under visible light, the removal rate of CTC·HCl can reach 85.1%. In addition, the influence of various factors on the degradation of CTC·HCl was investigated. It is concluded that the most effective removal of CTC·HCl occurs when there is an additional 25 mg of MFO/CK-40%, the concentration of CTC·HCl is 50 mg/L, pH= 4, and PDS is 1.5 mL. Then, through electron spin resonance and radical trapping experiments, it was determined that h+ and ·O2− were the main active species for removing CTC·HCl. The mechanism of CTC·HCl degradation by the MFO/CK-40%/PDS/Vis system was discussed. Finally, the stability and reusability of the MFO/CK-40% composite material were tested. After 3 cycles of experiments, the removal rate of CTC·HCl is still more than 70%, indicating that the MFO/CK-40% composite material has good stability and catalytic activity. Therefore, the MFO/CK catalyst can be used as a new and efficient PDS activator, which is widely used in the photocatalytic degradation of organic matter in wastewater. Not applicable.