Degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in real-field soil by an integrated visible-light photocatalysis and solvent migration system with p-n heterojunction BiVO4/Bi2O3

Abstract

Degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in real-field soil was conducted using an integrated photocatalysis-solvent migration system of BiVO4/Bi2O3 and n-hexane. The photocatalyst BiVO4/Bi2O3 was synthesized, and its performance was found to be affected by the BiVO4 content, with 20 wt% BiVO4 showing the best performance owing to its p-n heterojunction being well formed. Migration was affected by the amount of n-hexane, with 15% n-hexane giving the most effective transportation of PCDD/Fs. 37.2% of 17 PCDD/Fs was removed in 60h by the integrated photocatalysis-solvent migration system, although the reaction zone covered 8.5% of the volume of the soil. The result showed that migration via n-hexane fulfilled the aim of carrying contaminants from inside of the soil to the surface. Electron-scavenging experiments with BiVO4/Bi2O3 showed an 18.4% of performance in removal compared to no-scavenging condition, which showed that the main reactions driving BiVO4/Bi2O3 visible light photocatalysis for aryl-chloride were found to be reduction-based. Owing to the hindering effect of Cl atoms, degradation by hydroxyl radical could proceed after initial dechlorination. This study establishes the applicability of integrated photocatalysis-solvent migration systems in real-field settings, and is the first report of a visible-light photocatalyst, BiVO4/Bi2O3, for the degradation of PCDD/Fs in soil. (C) 2017 Elsevier B.V. All rights reserved.