Enhanced activation of persulfate by AC@CoFe2O4 nanocomposites for effective removal of lomefloxacin

Abstract Magnetic AC@CoFe2O4 nanocomposites (decoration of activated carbon with CoFe2O4 nanoparticles) as an efficient persulfate (PS) activator were successfully prepared through a facile co-precipitation method. The crystalline, morphology and textural properties of the composites were characterized. Then the catalytic performances of as-synthesized AC@CoFe2O4 were investigated towards PS activation for the degradation of lomefloxacin (LMF). Results demonstrated that the sample prepared at a 1:1 mass ratio of AC (activated carbon) to CoFe2O4 possessed higher catalytic activity owing to the synergistic interactions between these two components. The maximum LMF degradation of 98.4% and the pseudo first-order kinetic constant of 0.03796 min−1 were achieved after 60 min reaction at the optimized operation conditions: 0.2 g∙L−1 of AC@ CoFe2O4 and 1 g∙L−1 of PS, pH of 5.0 and reaction temperature of 25 °C. The free radical quenching experiments and XPS analysis were undertaken to illustrate the proposed mechanism, which indicated that the SO4 − and HO were the predominant radicals involved in LMF degradation. Moreover, the Co(II), Fe(II) and oxygenated functional groups participated in the PS activation process. Subsequently, several oxidation intermediates were identified and five suggested pathways were proposed to reveal the reaction mechanism, indicating a comprehensive route of LMF decomposition via the activation of PS. AC@CoFe2O4 also displayed good reusability and magnetic property, which would hold great potential in the persulfate-based treatment of antibiotic contaminated wastewater.