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

Abstract Activation of peroxymonosulfate (PMS) and persulfate (PS) by Fe2+ is widely used for oxidizing organic pollutants. However, their application is limited by the slow conversion rate of Fe3+ to Fe2+ and the accumulation of Fe3+. Here, we introduce commercial molybdenum disulfide (MoS2) to promote the activation of PMS and PS by Fe2+, and explore the mechanism of this promotion using experimental and theoretical methods. The Fe2+/PMS/MoS2 and Fe2+/PS/MoS2 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 Fe2+/PMS/MoS2 (54 μM Fe2+, 1 mM PMS) and Fe2+/PS/MoS2 (54 μM Fe2+, 0.25 mM PS) system, respectively. MoS2 addition simultaneously promoted the Fe3+/Fe2+ cycle, the PMS and PS conversion, and the RhB mineralization. As a co-catalyst, MoS2 exhibited excellent stability for eight successive cycles of use. The predominant oxidant was identified as SO4 − in Fe2+/PMS/MoS2 and Fe2+/PS/MoS2 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 MoS2 catalyst with a low dosage of Fe2+ is a promising and effective approach for efficient activation of PMS and PS to produce SO4 − and OH.