Enhanced Fe(Ⅲ)/PMS system by flower-like MoS2 nanosheet for rapid degradation of tetracycline

Despite the achievement of the MoS2/Fe(Ⅱ)/PMS system in the degradation of organic pollutants, the low stability of Fe(Ⅱ) and the poor catalytic effect of bulk MoS2 limit its practical application. Herein, multilayer flower-like MoS2 nanospheres with abundant active sites were successfully prepared by hydrothermal synthesis. It was used as a co-catalyst for the Fe(Ⅲ)/PMS system to stably reduce Fe(Ⅲ) to Fe(Ⅱ) and effectively activate PMS in a wide pH range (3.0–9.0) for tetracycline (TC) removal. The mechanism study showed that the redox cycling of Mo(Ⅳ)/Mo(Ⅵ) and iron with different valences promoted the formation of reactive oxygen species (SO4•-, •OH, FeⅣ = O, O2•-, and 1O2) in MoS2/Fe(Ⅲ)/PMS system, but 1O2 was the main active oxidants. Possible degradation pathways of TC were proposed, and the toxicity of by-products was predicted by toxicity evaluation. The degradation was inhibited by bicarbonate (HCO3-) and dihydrogen phosphate (H2PO4-). MoS2 showed good stability and reactivity for the degradation of TC after five consecutive cycles of experiments. In conclusion, the multilayer flower-like MoS2 nanosphere is a promising catalyst that can be used in advanced oxidation technology.