MoS2 as highly efficient co-catalyst enhancing the performance of Fe0 based electro-Fenton process in degradation of sulfamethazine: Approach and mechanism

Molybdenum sulfide (MoS2) was for the first time used as a co-catalyst to enhance the performance of Fe-0 based heterogeneous electro-Fenton (Fe-0-EF) process for the degradation of sulfamethazine (SMT), which was belonging to the sulfonamide family and extensively used as growth promoters and antibacterial drugs. Compared with Fe-0-EF process, MoS2/Fe-0-EF process could enhance the rate constant of SMT degradation 2 times under the optimal conditions of current 50 mA, MoS2 dosage 0.02 g L-1, Fe-0 dosage 0.224 g L-1, and initial pH 4, in which SMT could be completely degraded within 10 min while 42% TOC could be achieved after 60 min reaction. The role of MoS2 as co-catalyst in MoS2/Fe-0-EF process and Fe2+/Fe3+ cycle was supported by iron elemental analysis, transmission election microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterizations. Owing to the characteristics of co-catalysis, MoS2 could greatly facilitate the Fe3+/Fe2+ recycle reaction by the exposed Mo4+ active sites, which significantly promoted the decomposition of H2O2 that generated in Fe-0-EF system and improved the generation of hydroxyl radical. Besides, a possible degradation pathway of SMT was proposed and the stability of MoS2/Fe-0-EF process for SMT removal and TOC mineralization was certified base on five consecutive runs. The real wastewater test and energy consumption and economic analysis confirmed its advantage and cost-effectiveness for application. In all, this study provides a new perspective for improving heterogeneous Fe-0-EF process with MoS2 for highly efficient and rapid degradation of antibiotics.

Automated summary

The study demonstrates that MoS2, as a co-catalyst, can significantly promote the Fe3+/Fe2+ cycle reaction in the Fe-0-EF process, thereby effectively decomposing the generated H2O2 and enhancing the generation of hydroxyl radicals for the degradation of SMT. Real wastewater testing and energy consumption and economic analysis confirm the stability and cost-effectiveness of the MoS2/Fe-0-EF process for SMT removal and TOC mineralization.