Enhanced decomposition of H2O2 by molybdenum disulfide in a Fenton-like process for abatement of organic micropollutants

Accelerating the rate-limiting step of Fe3+/Fe2+ conversion is a major challenge for H2O2 decomposition in conventional Fenton process. In this study, the catalytic mechanism of H2O2 by molybdenum disulfide (MoS2) nanoparticles and Fe3+ ions was revealed and the abatement of organic micropollutants was investigated. The presence of both MoS2 and Fe3+ can efficiently decompose H2O2. Reaction system of H2O2/MoS2/Fe3+ is found to remove most of the tested pollutants by over 80% (except 65.9% for carbamazepine) within 60 min at pH of 3.0. Effective pH range of this reaction system can be extended to pH of 5.0. Adding MoS2 to Fe3+/H2O2 system promotes the Fe3+/Fe2+ cycle and improves the reaction rate between Fe3+ and H2O2. The formation of Mo6+ ions and Mo6+ peroxo-complexes is beneficial to H2O2 decomposition and pollutant degradation. Electron paramagnetic resonance (EPR) measurements and quenching experiments confirm the important role of hydroxyl radicals in H2O2/MoS2/Fe3+ system. Chloride ions (Cl−) promote degradation, while bicarbonate ions (HCO3−) inhibit degradation. As H2O2 concentration increases from nil to 1.0 mM, the value of total EE/O decreases from 0.083 to 0.003 kWh L−1, and the most energy efficient condition is determined. This study provides a new pathway for efficient decomposition of H2O2 by Fe3+ ions in an extended pH range, which is considered a facile and promising strategy for wastewater treatment.