Insight into in-situ radical and non-radical oxidative degradation of organic compounds in complex real matrix during electrooxidation with boron doped diamond electrode: A case study of oil sands process water treatment

Abstract

Radical and non-radical oxidants identification and transformation mechanisms in electrooxidation using boron doped diamond electrode (EO-BDD) have been limited to synthetic solutions with little attention given to real complex matrix. In this study, electron paramagnetic resonance spectrometry (EPR) and spectrophotometry were used to identify/quantify the radical and non-radical oxidants generated during the EO treatment of oil sands process water (OSPW). The EPR spectra confirmed the direct electrogeneration of BDD(OH), SO4− and CO3− as radical oxidants from H2O, SO42‒ and CO32‒ oxidation, respectively, in both OSPW and ultra-pure water containing either SO42‒ or CO32‒. There was also accumulation of S2O82‒, C2O62‒ and active chlorine as non-radical oxidants from the oxidation of SO42‒, CO32‒ and Cl‒, respectively. The degradation of organic contents of the OSPW was by both radical and non-radical oxidation pathways, achieving complete degradation and mineralization of dissolved organic contents at current density ≥ 5 mA cm‒2.