Efficient degradation and mineralization of ornidazole in aqueous solutions via electro-fenton process using stainless steel electrode as sources of ferrous ions (Fe2+): Experimental and DFT calculations

Ornidazole (ORD) is a persistent pharmaceutical contaminant commonly used to treat infections caused by anaerobic bacteria and protozoa. This study presents a cost-effective and environmentally friendly approach for the removal of ORD from contaminated environments. Carbon felt was used as the cathode, and stainless steel was used as the sacrificial anode, which also serves as an insitu source of Fenton's catalyst (Fe²⁺) through auto-generation, eliminating the need for external catalyst addition. Different operational parameters were investigated to enhance degradation efficiency. The degradation experiment demonstrated the highest ORD removal efficiency of 90.95 % and a mineralization efficiency of 84.5 % within 120 min under optimal conditions i.e., an applied current of 75 mA, an applied voltage of 2,5 V, an initial solution pH of 5, and an electrode spacing of 1.5 cm. Additionally, quenching experiments confirmed the crucial role of •OH in the degradation process of ORD. Furthermore, the proposed EF process exhibited better effectiveness of ORD degradation even in real water matrices (river water 91.32 % and tap water 94,32 %). Density functional theory (DFT) calculations were conducted to determine the reaction sites of ORD involved in the degradation mechanism.