Photopromoted oxidative dissolution of stibnite

Light irradiation plays an important role in the oxidative dissolution of Sb2S3. A qualitative mechanism was proposed through simulated experiments to describe the dissolution reaction under various ambient conditions, specifically darkness/light and aerobic/anaerobic conditions. The pH-dependent solubility of Sb2S3(s) and photo-induced oxidative dissolution are two types of reaction mechanisms. The oxidation of Sb(III) and its sulfides by light irradiation induce the prompt dissolution of Sb2S3. Photo-oxidants in the form of hydroxyl radicals ((OH)-O-center dot), superoxide anion free radicals (O-center dot(2)-) and photo-generated holes (h(vb)(+)) were produced in the photo-induced oxidative dissolution reaction of Sb2S3. Among these, O-2 and O-center dot(2)- are the most significant oxidants. The main oxidation products of Sb2S3 are Sb(V), S-0 and S2O32-. This study may help elucidate the geochemistry and fate of antimony in the environment. (C) 2015 Elsevier Ltd. All rights reserved.