Removal efficiency and mechanism of refractory organic matter from landfill leachate MBR effluent by the MoS2-enhanced Fe0/H2O2 system

Abstract

In this study, molybdenum disulfide (MoS2) was used to enhance a zero-valent iron/hydrogen peroxide (Fe0/H2O2) Fenton-like system, which was able to remove refractory organic matter from the effluent produced during the treatment of landfill leachate by a membrane bioreactor (MBR). The MoS2/Fe0/H2O2 system could efficiently remove refractory organic matter (i.e., fulvic acid-like substances and humic-like substances) from the MBR effluent and also exhibited a strong synergistic effect. Under the conditions of initial pH = 3, H2O2 = 40 mmol/L, Fe0 = 0.4 g/L, MoS2 = 0.1 g/L, and t = 30 min, compared with a Fe0/H2O2 system, the absorbance UV254, chroma (CN), and total organic carbon (TOC) removal rates in MBR effluent treated with MoS2/Fe0/H2O2 increased to 48.68%, 63.85%, and 35.85%, respectively. Through the identification of reactive oxygen species (ROS), the hydroxyl radical (HO•) concentration and an analysis of the effective utilization rate of H2O2, as well as an analysis of the morphology of the material, the distribution of Fe compounds, valence changes, and the Fe ion concentration, it was proven that MoS2 promoted the cycling of Fe3+/Fe2+ in the Fe0/H2O2 process. The addition of MoS2 promoted the Fe3+/Fe2+ cycling reaction through the exposed Mo4+ active center, significantly promoting the decomposition of H2O2 and the formation of HO•. The MoS2/Fe0/H2O2 system was able to remove a wide range of aromatic organics, indicating the wide applicability of the system. This study developed a new method for the efficient removal of refractory organic matter from landfill leachate.