Self-Fenton Cu-Mn catalysts for efficient ciprofloxacin removal: in-situ H2O2 generation and activation

Abstract

The Fenton oxidation system is a widely employed advanced oxidation processes (AOPs) in wastewater treatment. However, the traditional Fenton oxidation system suffers from low oxidant utilization efficiency, leading to significant resource wastage. This study presents a novel self-Fenton Cu-Mn bimetallic catalyst (with a Cu:Mn ratio of 10:1), which is capable of simultaneously activating O₂ to generate H₂O₂ in situ and further catalyzing the decomposition of H₂O₂ to produce reactive oxygen species (ROS). Notably, this self-Fenton system demonstrate high removal efficiency for ciprofloxacin (CIP) across a broad pH range (2−9), achieving up to 92.55 % removal in water. Quenching experiments, electron paramagnetic resonance (EPR) analysis, steady-state concentration measurements, and Galvanic oxidation reactor (GOR) experiments collectively confirmed the generation of multiple ROS species (·OH, ·O₂⁻, and ¹O₂) and indicated that electron transfer plays a significant role in pollutant degradation. X-ray photoelectron spectroscopy (XPS) analysis revealed that Cu⁰ exhibited high catalytic activity, enabling simultaneous generation and activation of H₂O₂. Liquid chromatography-mass spectrometry (LC-MS) and toxicity assessments demonstrated a significant reduction in the toxicity of CIP degradation products. This work elucidates a novel Cu-Mn synergistic mechanism wherein Mn facilitates the generation of H₂O₂, while Cu effectively activates it into ROS. This synergism effect enables the removal of pollutants through both radical and non-radical pathways, thereby offering an innovative strategy for environmental remediation and AOPs.