Readily separable and stable CoFe2O4 beads for activating peroxymonosulfate to degrade lomefloxacin hydrochloride: Optimization, performance and degradation mechanism

Abstract

CoFe2O4 is regarded as a star material because of its high catalytic activity and excellent separation performance. However, metal-ion dissolution and collection difficulty of powdery CoFe2O4 in practical applications are still critical scientific issues, which will not only cause new environmental risks but also may result in partial loss of catalysts. In this work, buoyant CoFe2O4-loaded hollow glass microspheres embedded in sodium alginate beads (CHS) for activating peroxymonosulfate (PMS) to degrade lomefloxacin hydrochloride (LMH) were successfully prepared by an impregnation-precipitation-gel method. The experimental results showed that the heterogeneous catalytic system (CHS + PMS) displayed 9.5-, 7.7- and 6.6-times degradation rates (kobs) towards LMH than that of leached Fe + PMS, Co + PMS, and Fe + Co + PMS homogeneous systems, respectively. More importantly, CHS could effectively alleviate the dissolution of metal ions due to the coordination of the carboxylate group on the alginate to the Co and Fe sites on the surface of CoFe2O4, ultimately the leached concentration of Co (0.089 mg/L) and Fe (0.014 mg/L) ions from CHS were only about 11.1% and 16.5% of the powdery CoFe2O4, respectively. Primary radicals involved in the LMH degradation process were ·OH and SO4·- through EPR characterization and quenching experiments. This study offers the possibility to design practical potential heterogeneous catalyst for stable activation of PMS.