Ciprofloxacin Degradation in Electro-Fenton System with S-nZVI@BC/NF composite electrode

Abstract

In this study, biochar-supported sulfurized nano-zero-valent iron (S-nZVI@BC)-modified nickel foam (NF) composite electrode materials (S-nZVI@BC/NF) were prepared by chemical reduction and hydrothermal methods. This material was employed as the cathode in an electro-Fenton (EF) system, which enabled in-situ generation and activation of hydrogen peroxide (H₂O₂) to achieve efficient removal of the antibiotic ciprofloxacin (CIP) from aqueous solutions. Structural and electrochemical properties of the electrode were thoroughly investigated by means of scanning electron microscopy (for morphological characterization), X-ray diffraction (for crystal structure analysis), X-ray photoelectron spectroscopy (for surface chemical composition detection), and electrochemical testing (for activity assessment). Catalytic activities of different electrodes were evaluated via comparative experiments, and the effects of parameters such as Fe/C ratio, voltage, aeration rate, pH, and Na₂SO₄ concentration on degradation efficiency were systematically investigated. Results showed that the S-nZVI@BC/NF composite electrode exhibits excellent morphology, structure, and electrochemical performance. Specifically, when the initial CIP concentration was 10 mg·L⁻¹, Na₂SO₄ concentration was 30 mM, applied voltage was 2.5 V, initial pH was 3, reaction time was 120 min, and aeration rate was 1.2 L·min⁻¹, the degradation efficiency reached 99.4%. Additionally, the stability and applicability of the system under varying pollutant concentrations, types, water matrices, and anion types were evaluated. The degradation mechanism and pathway were further explored via quenching experiments combined with LC-MS analysis. This composite electrode material can stably and efficiently degrade CIP as well as other common antibiotics, thus providing a feasible approach for the rapid removal of pollutants from wastewater.