Enhanced catalytic activities of natural iron ore in peroxymonosulfate activation assisted by WS2 for rapid degradation of pollutants

The seek for efficient and low-cost heterogeneous catalysts for peroxymonosulfate (PMS) activation holds great promise in the treatment of organic contaminants. Natural iron ore (IO) has been identified as a potential catalyst due to its low environmental risk and cost-savings. Herein, the commercial tungsten sulfide (WS 2 ) was employed to significantly enhance the performance of IO towards PMS activation (WS 2 /IO/PMS) for the removal of pollutants. This system demonstrated remarkable performance, with >98.2% removal of organic pollutants in 60 min, including dyes and antibiotics, under the optimized conditions of 0.50 g/L IO, 0.10 g/L WS 2 , 2.0 mM PMS, and initial pH 6.0. The apparent degradation rate constant ( k ) of Acid Orange 7 (AO7) in WS 2 /IO/PMS system (0.073 min −1 ) was about 30.4-fold and 104.3-fold higher than that of in WS 2 /PMS system (0.0024 min −1 ) and IO/PMS system (0.0007 min −1 ), respectively. Mechanism insights revealed the crucial role of WS 2 in boosting the degradation kinetics in the WS 2 /IO/PMS system. The exposed W 4+ or S 2− species on WS 2 surface were the dominant reactive sites responsible for the promotion of Fe 3+ /Fe 2+ redox cycles and subsequently the PMS activation. Importantly, the electrochemical analysis demonstrates that the iron ions released from IO were prone to adsorb onto the WS 2 surface, forming active Fe species with high oxidative potential, which remarkably accelerated the electron transfer for Fe 2+ regeneration, thereby enhancing PMS activation to generate reactive oxygen species like hydroxyl radicals ( OH), sulfate radicals (SO 4 − ) and superoxide radicals (O 2 − ). Furthermore, the practicability of WS 2 /IO/PMS system was validated by treating various pollutants and investigating the interference of coexisting anions in water. Overall, this study provides a green and advanced strategy to enhance the PMS activation by natural iron ore for efficient water decontamination.