Efficient peroxymonosulfate activation by magnetic CoFe2O4 nanoparticle immobilized on biochar toward sulfamethoxazole degradation: Performance, mechanism and pathway

Utilizing biomass waste to create highly efficient biochar-based catalysts has drawn intensively interest since it adheres to the idea of waste recycling in environmental conservation. Herein, CoFe2O4 nanoparticles immobilized on biochar (BC) derived from rape straw were synthesized and applied in degrading sulfamethoxazole (SMX) by activating peroxymonosulfate (PMS). Experimental results indicated that the 30 wt% CoFe2O4/BC composite catalyst had the best catalytic activity with the SMX degradation efficiency of 93% within 20 min, which was probably the fact that BC as a carrier not only effectively inhibited the agglomeration of CoFe2O4 nanoparticles and increased the active sites, but also could simultaneously participate in the catalytic degradation reaction as an activator of PMS. In addition, cycle experiments illustrated that the as-prepared catalyst possessed the excellent stability, and the magnetic property measurements implied that they were convenient for separation and recovery. According to quenching experiments, electron paramagnetic resonance (EPR) and electrochemical studies, both radical and non-radical process participated into degrading SMX, where the generated SO4·-, ·OH and O2·- as the major radical active species while 1O2 and direct electron transfer were responsible for the non-radical route. Besides, using high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, a potential SMX degradation pathway was suggested. The present CoFe2O4/BC composite would be a promising PMS activation catalyst for environmental remediation.