Cr(III)-induced electrochemical advanced oxidation processes for the V2O3 dissolution in alkaline media

Oxidative dissolution is a critical step for the environmental remediation of heavy metal oxides in industrial solid wastes. In order to overcome the drawbacks of high energy consumption and severe environmental pollution in conventional treatments, a novel electrochemical advanced oxidation process was first reported for the V2O3 oxidative extraction in alkaline media. Multi-walled carbon nanotubes modified electrode was employed to produce hydrogen peroxide via two-electron-pathway oxygen reduction reaction, following by the Cr(III)-induced activation process to generate highly oxidative (OH)-O-center dot radical. The oxidative dissolution ratio was affected by the alkaline concentration, and the V(III) was completely transferred within 160 min treatment at the pH of 13. Subsequently, the vanadium and chromium were selectively recovered by a solvent extraction method. Electron spin resonance spectroscopy and quenching reagents were performed to probe the reaction mechanism and main reactive species, indicating that the heterogeneous electro-catalytic oxidative dissolution process was mainly attributed to the in-situ generated (OH)-O-center dot. Furthermore, the long-term stability test illustrates the excellent durability of the MWCNTs modified electrode. Therefore, this novel method offers a promising solid waste treatment approach, and new insight on the electrochemical advanced oxidation process in alkaline media. (C) 2016 Elsevier B.V. All rights reserved.