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.

Keywords: Advanced oxidation processes; Peroxymonosulfate; Persulfate; Sulfate radicals; Synergistic activation.