Three-dimensional photoelectrocatalytic degradation of ethyl xanthate catalyzed by activated bentonite-based bismuth ferrites particle electrodes: Influencing factors, kinetics, and mechanism

Abstract

In the present study, activated bentonite-based bismuth ferrites (A-BiFe/Bent) as particle electrodes were employed to degrade ethyl xanthate (EX) in a 3-dimensional Electro-Fenton system under visible light (Vis-3D/EF). The various operation conditions, including electrolyte types, electrolyte concentration, particle electrode dosage, applied voltage, aeration rate and initial pH, were investigated in detail. The degradation product of EX in the Vis-3D/EF system catalyzed by A-BiFe/Bent particle electrodes was comprehensively explored by UV-Visible spectrophotometer (UV–visible), proton nuclear magnetic resonance (1H NMR), liquid chromatograph-mass spectrometer (LC-MS) and fourier transform infrared (FTIR) techniques. It was found that EX was directly degraded into CO2, H2O and SO42- during the photoelectrocatalytic degradation. Based on the analysis results of X-ray photoelectron spectroscopy (XPS), quenching experiment and Electron Spin Resonance (ESR), the possible mechanism for the photoelectrocatalytic degradation of EX in the Vis-3D/EF system catalyzed by A-BiFe/Bent particle electrodes was proposed. The reasons for the highly oxidative capacity of Vis-3D/EF reaction system catalyzed by A-BiFe/Bent were mainly attributed to the high-efficient generation of H2O2, multiple generation sources for active species, and participation by all active species (·OH, h+ and ·O2-). The result of comparative experiment and kinetics indicate that a significant coupling effect between photocatalytic action and 2-dimensional electrode existed in the Vis-3D/EF system. A-BiFe/Bent presented good recycling efficiency and high stability during the photoelectrocatalytic degradation of EX. The Vis-3D/EF system catalyzed by A-BiFe/Bent particle electrodes holds great potential to treat EX in mineral flotation wastewater.