Molybdenum disulfide co-catalysis boosting nanoscale zero-valent iron based Fenton-like process: Performance and mechanism.

The conventional Fenton process has the drawbacks of low efficiency of Fe/Fe conversion, low utilization of HO, and narrow range of pH. In this paper, molybdenum sulfide (MoS) was used as a co-catalyst to boost the nanoscale zero-valent iron (nZVI) based heterogeneous Fenton-like process for the degradation of Rhodamine B (RhB). The catalytic performance, influences of parameters, degradation mechanism, and toxicity of intermediates were explored. Compared with the conventional like-Fenton process, the existence of MoS accelerated the decomposition of HO and the RhB degradation rate constant of MoS/nZVI/HO reached more than six times that of nZVI/HO. In addition, the effective pH range of MoS/nZVI/HO was broadened to 9.0 with 84.9% of RhB being removed within 15 min. The co-catalytic system of MoS and nZVI was stable and had high reusability according to the results of four consecutive runs. Quenching tests and electron paramagnetic resonance (EPR) demonstrated that hydroxyl radical (·OH), superoxide anions (·O), and singlet oxygen (O) were all involved in MoS/nZVI/HO. Compared with nZVI/HO system, MoS not only increased the corrosion of nZVI but also accelerated the conversion of Fe/Fe. ECOSAR analysis suggested that the overall acute and chronic toxicity of the degradation products decreased after treatment. Hence, this MoS co-catalytic nZVI based Fenton-like process can be used as a promising alternative for the treatment of organic wastewater.