Photoactivation of sulfite by FeTiO3 for organic pollutant degradation: Performance and mechanism

In recent years, the exploration of sulfite (S(IV))-based advanced oxidation processes has attracted increasing attention due to its high performance in the degradation of aqueous organic contaminants. In this study, we investigated the activation of S(IV) by ilmenite (FeTiO 3 ) under photo irradiation using phenol as a substrate. The FeTiO 3 /S(IV)/photo system demonstrated a remarkable phenol removal rate, achieving 81.4 % degradation within 30 min under optimal conditions. The photocatalytic mechanism involves the generation of electron-hole pairs in FeTiO 3 , with photogenerated holes activating the adsorbed S(IV) on the catalyst’s surface to produce various free radicals, among which SO 4 − is identified as the primary active species. Density functional theory calculations further suggest that electron transfer between ilmenite and S(IV) may occur via a Fe-O-S bridge. Additionally, the approach demonstrates satisfactory reusability of the photocatalyst and consistent effectiveness in real-water matrices. This study contributes to the development of more efficient, cost-effective, and environmentally friendly water treatment strategies by providing a deeper understanding of the proposed FeTiO 3 /S(IV)/photo system.