Cu-coupled Fe/Fe3C covered with thin carbon as stable win-win catalysts to boost electro-Fenton reaction for brewing leachate treatment

Abstract

The electro-Fenton oxidation is one of the powerful approaches for achieving the complete mineralization of organic pollutants in water. The key dilemma for efficient industrial application of electro-Fenton oxidation is the complicated post-processing of iron sludge, and the cost and risk associated with H₂O₂ transportation and storage. Herein, Cu-coupled Fe/Fe₃C covered with carbon layer on carbon felt (Cu-Fe/Fe₃C@C), engineered by a hydrothermal reaction followed by the consequent thermal-treatment in N₂ atmosphere, as a self-supported integrated cathode were used for an onsite oxygen reduction reaction and a Fenton oxidation reaction. Experimental evidences demonstrate that, at the operating potential of -1.1 V, Fe₃C can selectively catalyze O₂ into H₂O₂ by 2e reduction pathways with assistance of metal Cu. Meanwhile, metal Fe and Cu incorporated into Cu-Fe/Fe₃C@C simultaneously motivate the onsite Fenton oxidation arose by H₂O₂. Such a win-win catalyst presented high activity in the electro-Fenton process. In acidic environment, the efficient mineralization rate of methylene blue, nitrobenzene, phenol, and bisphenol A can reach more than 70% in 60 min, as well as the excellent stability and durability due to the protection of graphited carbon layer. Compared with tradition electrochemical degrade system, the prepared Cu-Fe/Fe₃C@C electrode as cathode for practical refractory brewing leachate treatment reveal more efficient decolorization and mineralization, saving 14.3% of electricity.

Keywords: Cu-coupled Fe/Fe(3)C cathode Catalysts; Degradation; Electro-fenton reaction; Refractory waste-water.