Construction of Active Sites within Hematite Via S and Cu Co-Doping for Boosting Peroxymonosulfate Activation Toward Ciprofloxacin Degradation

Abstract

Advanced oxidation processes (AOPs) have come to the fore as a prospective way to ciprofloxacin (CIP) decontamination in aquatic environments. The key to promote CIP degradation via peroxymonosulfate (PMS) activation by iron-based catalysts lies in the exploitation of the catalysts with efficient active catalytic and redox sites. Here, S and Cu co-doped hematite nanoplates (SCH) were synthesized via a two-step solvothermal method, exhibiting superior catalytic performance compared to pristine hematite. The hexagonal nanoplates SCH contained abundant oxygen vacancies and highly reactive Fe0 and Fe(II) species on the surface. Under optimized conditions (pH = 6.8, PMS = 0.2 g/L, catalyst = 0.2 g/L), the SCH-0.07 sample achieved 99.99% CIP degradation within 60 minutes and maintained 60% efficiency over five cycles. The enhanced catalytic activity was attributed to the presence of abundant oxygen vacancies and highly reactive Fe0 and Fe(II) species on the surface after S and Cu co-doping. Furthermore, S and Cu co-doping reduced energy barriers, enhancing electron transfer efficiency in PMS activation. Reactive oxygen species (ROS) analysis identified superoxide radicals (O2•−) and singlet oxygen (1O2) as the primary contributors to CIP degradation. These findings provide insights into improving the efficiency of iron-based catalyst for environmental remediation via AOPs.

Keywords: Co-doping, Hematite, PMS activation, CIP degradation