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 flowerlike 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 center dot-, center dot OH, FeIV = O, O2 center dot-, 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.

Automated summary

In this study, multilayer flower-like MoS2 nanospheres were successfully prepared and used as a co-catalyst for the Fe(III)/PMS system. The MoS2/Fe(III)/PMS system showed stable reduction of Fe(III) to Fe(II) and effective activation of PMS for tetracycline removal in a wide pH range. The mechanism study revealed that the formation of reactive oxygen species, particularly 1O2, played a crucial role in the degradation of tetracycline.