Levofloxacin degradation by porous Cox/CN activated peroxymonosulfate: Investigation of efficiency, mechanism, and degradation pathways

Abstract

Co is a transition metal with a promising catalytic effect. Catalytic activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) using cobalt-based catalysts has received increasing attention as a promising technology that can remove difficult-to-degrade pollutants from water. Herein, a porous Co-doped g-C3N4 catalyst Cox/CN with non-uniform pores was synthesized to investigate the degradation of levofloxacin (LEV) by its activated peroxymonosulfate (PMS). The results showed that Co was uniformly distributed in g-C3N4 in the form of CoN bonds, which provided more active sites for the activation of PMS. The catalytic performance of Cox/CN was investigated by factors such as Co doping, catalyst dosing, PMS dosing, initial pH of the solution, and reaction temperature, and it was found that Cox/CN could maintain good catalytic activity in the pH range of 5–9. The cyclic catalytic degradation experiments showed that Cox/CN has good stability and reusability. The degradation mechanisms and pathways of LEV were also revealed such that SO4− was the main reactive oxidizing species (ROS), and LEV was degraded to organic compounds of smaller molecular mass through six pathways. This study offered a new strategy for synthesizing structurally diverse non-homogeneous Co-based catalysts and for the degradation of antibiotics.