Efficient degradation of methylene blue by FeS2/MoS2 in heterogeneous Fenton-like process

Iron-based materials as Fenton catalysts exist the problems of low activation efficiency of hydrogen peroxide (H2O2) and narrow applicable pH range. Herein, we synthesized materials with different ratios of molybdenum to iron, named as MoS2/FeS2, and used them for the degradation of methylene blue (MB). Notably, the MB degradation rate of FeS2/MoS2/H2O2 system reached 99.9 % within 30 min under neutral conditions, and its degradation rate constant was 34.3 and 21.8 times than that of MoS2 alone and physical mixture of FeS2 + MoS2, respectively. The MB degradation rate was 81.4-99.9 % at solution pH of 3-11, suggesting that FeS2/MoS2 is applicable to the Fenton-like process at wide pH. The morphology and composition of materials were analyzed by X-ray diffraction (XRD), Barrett-Emmett-Teller (BET), Transmission electron microscopy (TEM) and Scanning electron microscope (SEM). The X-ray photoelectron spectroscopy (XPS) and experimental results showed that Mo and S accelerated Fe2+/Fe3+ cycling was the main reason for the enhancement of catalyst activity. The main reactive oxygen species (ROS) was singlet oxygen (1O2) in the system. After 4 applications of FeS2/MoS2, the MB degradation rate still reached more than 90 % within 30 min, which indicates the excellent stability of material. In summary, FeS2/MoS2 has promising prospects for the degradation of wastewater.