Enhanced reactivity and electron selectivity of GAC-Fe-Cu ternary micro-electrolysis system toward p-chloronitrobenzene under oxic conditions

Abstract

A novel GAC-Fe-Cu ternary micro-electrolysis system was synthesized for the removal of p-chloronitrobenzene (p-CNB) under oxic conditions. p-CNB could be efficiently removed by GAC-Fe-Cu at a wide initial pH range of 1.0–9.0. In particular, the p-CNB removal efficiency of 96.96 % was obtained at initial pH of 7.2, and the degradation (44.96 %) was the major removal pathway. Additionally, reduction and oxidation simultaneously contributed to the degradation of p-CNB. The results indicated that OH was the prime reactive species under acidic conditions while O2− dominated the degradation of p-CNB under neutral conditions. Reduction reaction was remarkably enhanced in the presence of dissolved oxygen and the iron corrosion could be accelerated by in-situ generated H2O2. Furthermore, XPS analysis of GAC-Fe-Cu revealed the surface-mediated electron transfer and oxidant generation process. The excellent degradation efficiency of p-CNB at initial pH of 7.2 was attributed to the enhanced electron selectivity of GAC-Fe-Cu as well as the high selectivity of near-surface generated O2− toward p-CNB and its intermediate products.