Enhanced mass transfer by 3D printing to promote the degradation of organic pollutants in electro-Fenton system

In this study, researchers constructed a monolithic 3D-FeO/C electrode with a macro-ordered pore structure using direct-write 3D printing technology. Experimental results showed that the 3D-FeO/C electrode possessed excellent degradation performance for ornidazole (ONZ) (complete degradation within 120 min) and pharmaceutical wastewater (51.13 % in TOC and 63.72 % in COD removal within 420 min). The detailed reaction mechanism of the EF system was revealed through characterization analysis, mass transfer simulation, and experimental results, in which the excellent EF performance is mainly due to the confinement effect of FeO active sites encapsulated in the carbon layer, as well as the enhancement of mass transfer induced by 3D printing macro-ordered structure network. In addition, the degradation pathway of ONZ, the toxicity of its degradation intermediates, and the degradation pathway of actual pharmaceutical wastewater were revealed in detail. This study proposes a new 3D printing method to enhance the mass transfer of electrode materials in EF systems, which has good potential for application to real wastewater.