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

Abstract

Molybdenum sulfide (MoS2) was for the first time used as a co-catalyst to enhance the performance of Fe0 based heterogeneous electro-Fenton (Fe0-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 Fe0-EF process, MoS2/Fe0-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, Fe0 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/Fe0-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 Fe0-EF system and improved the generation of hydroxyl radical. Besides, a possible degradation pathway of SMT was proposed and the stability of MoS2/Fe0-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 Fe0-EF process with MoS2 for highly efficient and rapid degradation of antibiotics.