Degradation of cephalexin by persulfate activated with magnetic loofah biochar: Performance and mechanism

Abstract

Antibiotic contamination has become a serious environmental problem and much attention has been paid to its purification. The sulfate radical (SO4−) based advanced oxidation processes (AOPs) exhibited significant potential in the treatment of antibiotics. In this study, the magnetic biochar (Fe2O3@LBC) derived from loofah was prepared to activate persulfate (PS) for cephalexin (CEX) degradation. Under the optimal conditions, 73.9% of CEX was removed in the Fe2O3@LBC/PS system. Free radicals quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that HO and SO4− were responsible for the degradation of CEX. The C-OH of the catalyst played a crucial role in the degradation process. In addition, the conversion between Fe3+ and Fe2+ enhanced the degradation of CEX by producing SO4−. The degradation performance of other antibiotics and CEX in different water matrices indicated the broad adaptability and applications of Fe2O3@LBC. The main intermediates and the possible transformation pathways were proposed. These results provided a potential insight into biochar based catalysts for the degradation of antibiotics by activation of persulfate.