Enhanced decomposition of H_2O_2 by molybdenum disulfide in a Fenton-like process for abatement of organic micropollutants

摘要

Accelerating the rate-limiting step of Fe~(3+)/Fe~(2+) conversion is a major challenge for H_2O_2 decomposition in conventional Fenton process. In this study, the catalytic mechanism of H_2O_2 by molybdenum disulfide (MoS_2) nano-particles and Fe~(3+) ions was revealed and the abatement of organic micropollutants was investigated. The presence of both MoS_2 and Fe~(3+) can efficiently decompose H_2O_2. Reaction system of H_2O_2/MoS_2/Fe~(3+) 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 MoS_2 to Fe~(3+)/H_2O_2 system promotes the Fe~(3+)/Fe~(2+) cycle and improves the reaction rate between Fe~(3+) and H_2O_2. The formation of Mo~(6+) ions and Mo~(6+) peroxo-complexes is beneficial to H_2O_2 decomposition and pollutant degradation. Electron paramagnetic resonance (EPR) measurements and quenching experiments confirm the important role of hydroxyl radicals in H_2O_2/MoS_2/Fe~(3+) system. Chloride ions (Cl~-) promote degradation, while bicarbonate ions (HCO_3~-) inhibit degradation. As H_2O_2 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 H_2O_2 by Fe~(3+) ions in an extended pH range, which is considered a facile and promising strategy for wastewater treatment.