Synergistic activation of peroxymonosulfate and persulfate by ferrous ion and molybdenum disulfide for pollutant degradation: Theoretical and experimental studies

Activation of peroxymonosulfate (PMS) and persulfate (PS) by Fe 2+ is widely used for oxidizing organic pollutants. However, their application is limited by the slow conversion rate of Fe 3+ to Fe 2+ and the accumulation of Fe 3+ . Here, we introduce commercial molybdenum disulfide (MoS 2 ) to promote the activation of PMS and PS by Fe 2+ , and explore the mechanism of this promotion using experimental and theoretical methods. The Fe 2+ /PMS/MoS 2 and Fe 2+ /PS/MoS 2 systems achieved faster rate of PMS and PS conversion and also higher degradation efficiency toward pollutants. About 94.7% and 87.6% of rhodamine B (RhB) could be degraded in Fe 2+ /PMS/MoS 2 (54 μM Fe 2+ , 1 mM PMS) and Fe 2+ /PS/MoS 2 (54 μM Fe 2+ , 0.25 mM PS) system, respectively. MoS 2 addition simultaneously promoted the Fe 3+ /Fe 2+ cycle, the PMS and PS conversion, and the RhB mineralization. As a co-catalyst, MoS 2 exhibited excellent stability for eight successive cycles of use. The predominant oxidant was identified as SO 4 − in Fe 2+ /PMS/MoS 2 and Fe 2+ /PS/MoS 2 systems. Theoretical calculations and a kinetic model were employed to evaluate the catalytic performance of the systems. These novel findings indicate that the combination of a commercially available MoS 2 catalyst with a low dosage of Fe 2+ is a promising and effective approach for efficient activation of PMS and PS to produce SO 4 − and OH.