Elimination of miconazole nitrate from water by electro-Fenton: effect of operating parameters and degradation pathway†

This study investigates the removal of miconazole, a widely used pharmaceutical, from water using the electro-Fenton process. By systematically evaluating key parameters such as applied current intensity (10–500 mA), catalyst concentration (0.1–1.0 mM Fe²⁺), and water matrix composition, optimal conditions for maximizing pollutant removal efficiency were identified. The highest first-order oxidation rate constant of 36.4 × 10⁻² min⁻¹ was achieved under optimal conditions, demonstrating the efficiency of the electro-Fenton process. Total organic carbon (TOC) removal reached a maximum of 90% after 180 min of treatment, indicating significant mineralization of the pollutant. Ten major aromatic oxidation intermediates were identified using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS), providing valuable insight into the degradation pathways. This study stands out for its comprehensive optimization of key parameters, ensuring robust and practical application of the electro-Fenton process for pharmaceutical removal. Achieving 90% TOC removal and a high oxidation rate constant (36.4 × 10⁻² min⁻¹) demonstrates superior mineralization efficiency. The identification of ten major degradation intermediates via UHPLC-HRMS provides valuable insight into pollutant breakdown pathways. Additionally, by considering real water matrix effects, this work enhances the practical applicability of electro-Fenton in sustainable wastewater treatment. The obtained results highlight the electro-Fenton process as an effective and promising technology for the removal and mineralization of pharmaceutical contaminants from water, contributing to the advancement of sustainable wastewater treatment solutions.