Oestrone removal by anodic oxidation using different mixed metal oxide anodes and graphite cathode

Abstract

In this study, the removal of oestrone (E1), one of the endocrine disrupting compounds (EDCs) that strongly affects the life activities of organisms in the receiving water environment and is naturally secreted by many organisms and enters water resources, was investigated by the anodic oxidation (AO) process using titanium (Ti) anode and different metal oxide (MMO) anodes (Ti/Pt, Ti/IrO2, Ti/RuO2, Ti/IrO2-Ta2O5 and Ti/IrO2-RuO2-SnO2) and graphite cathode. Batch experiments showed removal efficiencies between 86.1 and 92.3%. The highest removal efficiency was obtained at the Ti/Pt anode using an applied current of 1.5 A (28 mA/cm2 current density), an initial pH of 8.3, an initial E1 concentration of 20 mg/L, an oxidation time of 160 min and an electrolyte concentration of 0.1 M Na2SO4. Different E1 concentrations (5 mg/L, 10 mg/L, 20 mg/L) were investigated. After 160 min, the removals were 97.9%, 95.5% and 92.4%, with degradation rates (k) of 0.0235, 0.0186 and 0.0158 min-1 and high R2 values. The specific energy consumption was also calculated to be in the range of 396-412 kWh/m3 and the lowest SEC value was obtained at an initial E1 concentration of 20 mg/L. The focus of the study was, for the first time, the efficient removal of oestrone (E1) by anodic oxidation.Six different mixed metal oxide anodes were investigated with a graphite cathode.A Ti/Pt anode achieved 92.3% efficiency at pH 8.3, 28 mA/cm2 and 160 min.E1 removal: 97.9%, 95.5% and 92.4% for 5 mg/L, 10 mg/L and 20 mg/L at 160 min.E1 degradation rates: 0.0235, 0.0186 and 0.0158 min-1 for 5, 10 and 20 mg/L.The specific energy consumption was calculated to be between 396 and 412 kWh/m3.