Degradation of sulfamethazine by biochar-supported bimetallic oxide/persulfate system in natural water: Performance and reaction mechanism

[Display omitted] •The removal rate of SMT was up to 99 % under the synergistic action of FeMgO/BC and persulfate.•Highly efficient removal of TOC was achieved by PS + FeMgO/BC system in SMT polluted water.•SO4•− played the dominated role in the degradation of SMT.•Fe2+ and O-containing groups were key active sites for the activation of persulfate.•FeMgO/BC had high stability with low metal leaching. The rapid development of aquaculture results in the increased concentrations and kinds of antibiotics in water environment, and the sharply growing antibiotic contamination has caused increasing concerns. Herein, an innovative sulfamethazine (SMT) removal approach was developed by activation of persulfate (PS) using biochar-based materials prepared by co-precipitation and pyrolysis: Fe-Mg oxide/biochar (FeMgO/BC). Experiments on the activation of PS by FeMgO/BC under different factors were carried out. The involved mechanism and degradation pathway were also studied. Notably, the SMT removal rate reached 99 % under the optimum reaction condition, while the TOC removal efficiency reached 77.9 %. PS was activated by FeMgO/BC and the dominated active radical was SO4•−. Fe2+ from FeMgO and the hydroxyl and carboxyl groups on the surface of biochar contributed to the production of SO4•−. The dehydrogenation, bond cracking and unsaturated bond addition process occurred in the degradation of SMT. Furthermore, FeMgO/BC exhibits excellent reusability and stability. Considering the outstanding actual water application performances and the weak biotoxicity, FeMgO/BC shows a promising potential in the removal of antibiotics under actual water conditions.