Peroxymonosulfate activation over NiCo2O4/MnOOH for enhancing Ciprofloxacin degradation in water

Abstract

In this study, the catalyst NiCo 2O4/MnOOH was effectively synthesized by coating MnOOH nanorods with 1, 5, 10, and 20% NiCo 2O4 to activate peroxymonosulfate (PMS) and enhance the catalytic performance in breaking down the antibiotic ciprofloxacin (CIP). The result demonstrated that the 20% NiCo 2O4/MnOOH + PMS system had the highest performance of CIP degradation. The CIP (20 μM) was degraded by 97.8% during 30-min reaction at 100 mg L−1 of 20% NiCo 2O4/MnOOH, and 200 μM PMS. The observed kinetic rate constants of prepared catalysts with PMS were in the order: 20% NiCo 2O4/MnOOH (1.78 x10 −1 min −1) > 10% NiCo 2O4/MnOOH (1.19 x10 −1 min −1) > 5% NiCo 2O4/MnOOH (0.91 x10 −1 min −1) > 1% NiCo 2O4/MnOOH (0.38 x10 −1 min −1) > MnOOH (0.27 x10 −1 min −1). Different operating parameters (solution pH, PMS concentration, catalyst amount, organic matter, and inorganic ions) were investigated to determine their impact on the degradation of CIP. Durability and reusability of catalyst for CIP degradation were examined. In addition, electron paramagnetic resonance (EPR) and scavenger test revealed the existence of sulfate radical (SO4•-), hydroxyl radical (•OH), superoxide radical (O2•-), and singlet oxygen (1O2) that were involved in the degradation of CIP under NiCo 2O4/MnOOH + PMS system.