Efficient degradation of ciprofloxacin by activated peroxymonosulfate using OV-rich NiCo4-LDH: Insights into radical production pathway and catalytic mechanism

In this study, the NiCo4-LDH with abundant surface oxygen vacancies (SOVs) was synthesized by a simple solvent thermal method, and was used to activate peroxymonosulfate (PMS) through heterogenous catalysis for ciprofloxacin (CIP) degradation. The OV-rich NiCo4-LDH/PMS system exhibited excellent CIP removal efficiency and rapid kinetics, as 95.0 % of the CIP was degraded within 10 min and the COD removal rate was 71.2 %. SO4•−, •OH, O2•− and 1O2 were involved in the degradation of CIP, with O2•− contributing the most, followed by SO4•−, •OH and 1O2. Ethanol, as solvent, could modulate the intrinsic electron properties and produce abundant OVs on the surface of NiCo4-LDH, which enhanced the generation of O2•−. This study shed new light on the skillful design and application of heterogeneous catalysts for environmental remediation.