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

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 O-center dot(2)- 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 O-center dot(2)- toward p-CNB and its intermediate products.