Core-shell structured Fe/Ni@C ternary micro-electrolysis material for 4-nitrochlorobenzen removal: Performance assessment and mechanism insight

Abstract

In this work, core-shell iron/nickel@carbon (Fe/Ni@C) and conventional supported iron/nickel-carbon (Fe/Ni-AC) ternary micro-electrolysis materials were synthesized and utilized for the removal of 4-nitrochlorobenzene (4-NCB). The characterization of Fe/Ni@C were preliminarily investigated and compared with Fe/Ni-AC to highlight its superiority and feasibility in contaminants degradation. Results indicated that Fe/Ni@C with the core-shell structure possessed a higher oxidation resistance, electron transfer ability and oxygen utilization capacity. The degradation efficiency of 4-NCB was appreciably more significant than that of the Fe/Ni-AC system under diverse aeration conditions. This mainly was ascribed to the core-shell structure which reinforced the connection of dual-cathodes and anode and shortened the distance between zero-valent iron (Fe0) and zero-valent nickel (Ni0) for intensified electrons transfer. Electrons donated from Fe0 could enrich in high density on the surface of carbon. This high-density electronic release, on the one hand, could significantly promote the reduction of pollutants under N2. On the other hand, this enrichment realized the synergetic effect of reduction and oxidation in the absence of dissolved oxygen (DO). By combining the analysis of reduction intermediates, reactive oxidizing species and XPS, the reaction mechanisms of Fe/Ni@C under diverse aeration conditions were explored in-depth. These findings can contribute to the rational design of ternary micro-electrolysis systems with properties tailored to a variety of nitroaromatic organics in natural water remediation.