Introducing MXenes into the Heterogeneous Catalyst: Synthesizing Mo2CTx@Fe3O4 with Excellent Recoverability to Degrade Methylisothiazolinone in the Electro-Fenton System

Methylisothiazolinone (MIT) is a commonly used bactericide in wastewater treatment. Residual MIT in wastewater can lead to high environmental risks and toxicity. In this work, an emerging material MXenes has been introduced into the heterogeneous electro-Fenton catalysts to degrade MIT. Ti3C2Tx@Fe3O4, V2CTx@Fe3O4, and Mo2CTx@Fe3O4 were assessed as catalysts for MIT removal. The reasons for the differences among the three catalyst effects were analyzed according to different characterization results. Mo2CTx@Fe3O4 exhibited the best catalytic activity for MIT degradation. At pH = 3, the removal rate of MIT and corresponding chemical oxygen demand of catalyst Mo2CTx@Fe3O4 were 93.41% and 62.46% after 120 min. Among the three catalysts, Mo2CTx@Fe3O4 had larger surface area and porosity. Mo2CTx@Fe3O4 had the highest surface iron content, which meant that Fe3O4 was more easily loaded on the surface of Mo2CTX. What is more, Mo2CTX had the strongest ability to accelerate the regeneration of Fe2+. The durability of Mo2CTx@Fe3O4 was also evaluated. After four cycles, the removal efficiency of MIT only decreased from 92.51% to 89%. This work supports the development of heterogeneous electro-Fenton catalysts and the degradation of MIT.