Sulfate radicals generation and refractory pollutants removal on defective facet-tailored TiO2 with reduced matrix effects

Abstract

Abstract Sulfate radical (SO4 −) based oxidation is an efficient and selective strategy for environmental decontamination. Herein, we confirmed, for the first time, that the fine modulation on semiconducting TiO2 was able to improve the redox-cycling capability for heterogeneous peroxydisulfate (PDS, S2O82−) activation and radicals generation. PDS activation by defective TiO2−x exposed by high-energy {0\u202f0\u202f1} polar facets was a superior Fenton-like catalytic system for rhodamine B (RhB) and bisphenol A (BPA) degradation, with good activity and selectivity under neutral pH. By radical inhibiting tests with two different scavengers, fluorescence measurements with terephthalic acid and electron paramagnetic resonance (EPR) technique, only the SO4 − was identified to be the main reactive species from PDS activation on defective TiO2−x for pollutants degradation. Compared to the reported TiO2−x/H2O2 system, the proposed TiO2−x/PDS system exhibited much lower water matrix effects in the presence of four typical anions, natural organic matters and real surface water for target pollutants degradation. The selective SO4 −-mediated TiO2−x/PDS catalytic system in natural water matrix and the no toxicity of catalytic material were of considerable interest for practical environmental applications with highly complex chemistry. Our findings elucidated a new strategy for efficient and selective PDS activation based on the defect-related chemistry, which can degrade environmental contaminants and remedy contaminated soil based on sulfate components with much reduced matrix effects.