Construction of Novel Electro-Fenton Systems by Magnetically Decorating Zero-Valent Iron onto RuO2-IrO2/Ti Electrode for Highly Efficient Pharmaceutical Wastewater Treatment

Abstract

The Electro-Fenton (E-Fenton) technique has shown great potential in wastewater treatment, while the sustainable and continuing supply of Fe2+ remains challenging. Herein, we demonstrate the construction of a novel E-Fenton system by magnetically decorating zero-valent iron (ZVI) onto a RuO2-IrO2/Ti (ZVI-RuO2-IrO2/Ti) electrode for high-efficient treatment of pharmaceutical wastewater, which is considerably refractory and harmful to conventional biological processes. By using ZVI as a durable source of Fe(II) irons, 78.69% of COD and 76.40% of TOC may be rapidly removed by the developed ZVI-RuO2-IrO2/Ti electrode, while the ZVI-RuO2-IrO2/Ti electrode using ZVI only reduces 35.64% of COD under optimized conditions at initial COD and TOC values of 5500 mg/L and 4300 mg/L, respectively. Moreover, the increase in BOD5/COD from 0.21 to 0.52 highlights the enhanced biodegradability of the treated effluent. The analysis of a simultaneously formed precipitation on electrodes suggests that the coagulation process dominated by Fe3+/Fe2+ also plays a non-negligible role in pharmaceutical wastewater treatment. In addition, the monitoring of the evolution of nitrogen elements and the formation of by-products in the E-Fenton process verifies its great capacity toward those organic pollutants found in pharmaceutical wastewater. Our study offers a practical solution for enhancing the performance of E-Fenton systems, and effectively treating refractory pharmaceutical wastewater.