Cobalt-doped molybdenum disulfide for efficient sulfite activation to remove As(III): Preparation, efficacy, and mechanisms

The sulfite(S(IV))-based advanced oxidation process has attracted significant attention in removing As(III) in the water matrix for its low-cost and environmental-friendly. In this study, a cobalt-doped molybdenum disulfide (Co–MoS₂) nanocatalyst was first applied to activate S(IV) for As(III) oxidation. Some parameters including initial pH, S(IV) dosage, catalyst dosage, and dissolved oxygen were investigated. The experiment results show that >Co(II) and >Mo(VI) on the catalyst surface promptly activated S(IV) in the Co–MoS₂/S(IV) system, and the electron transfer between Mo, S, and Co atoms accelerated the activation. SO₄^•− was identified as the main active species for As(III) oxidation. Furthermore, DFT calculations confirmed that Co doping improved the MoS₂ catalytic capacity. This study has proven that the material has broad application prospects through reutilization test and actual water experiments. It also provides a new idea for developing bimetallic catalysts for S(IV) activation.