Direct-writing of three-dimensional porous Fe3N/FeS electrode for efficient degradation of organic pollutants in water through Electro-Fenton process

Abstract

The Electro-Fenton process is getting a rapid development recently as a novel advanced electro-oxidation technology for the removal of organic pollutants from water. In this work, a three-dimensional (3D) porous Fe3N/FeS composite electrode was created from a Fe2(SO4)3-based composite ink by the direct-writing 3D printing technology combined with a high temperature heat treatment under ammonia atmosphere. Fe3N served as the conductive skeleton of the electrode, while FeS could provide Fe2+ to react with in-situ generated H2O2 in the Electro-Fenton process to generate ·OH radicals. Thus, it could eliminate the need of external ferrous ion addition. The 3D porous Fe3N/FeS composite electrode had desired 3D interconnected macro-channels for efficient mass transport and rough rod surfaces to provide more active sites, which resulted in its superior degradation performance on organics than its traditional two-dimensional (2D) plate counterpart. A two-step H2O2 production path was found on the 3D Fe3N/FeS composite electrode, which had been found to possess a faster reaction kinetics. It effectively degraded rhodamine B (RhB) within a wide pH range from ∼3 to ∼ 10, demonstrated stable performances in repeated uses, and had low iron ion leaching, all of which were beneficial for its potential applications. Furthermore, it also demonstrated effective degradation performances on antibiotics of amoxicillin (AMX) and tetracycline hydrochloride (TC-HCl) in both deionized (DI) water and tap water matrixes, indicating its potential to solve the emerging contaminant problem in real water treatment practices.