The mechanism of 2-chlorobiphenyl oxidative degradation by nanoscale zero-valent iron in the presence of dissolved oxygen

Abstract

It has recently been demonstrated that the addition of nanoscale zero-valent iron (nZVI) to oxygen-containing water or soil aquifers results in the oxidation of organic compounds. However, there has been little insight about the generation of the reactive oxygen species (ROS) that play a vital role in the transformation of contaminants in the presence of nZVI. This study investigated (i) the degradation of 2-chlorobiphenyl (2-CB) by nZVI;(ii) the generation and role of ROS in this process. Under anaerobic and aerobic conditions, the removal efficiency of 2-CB was 65.5 and 59.4%, respectively, after 4 h at a pH of 5.0. The results demonstrated that both the reductive and oxidative processes account for 2-CB degradation under aerobic conditions. Hydroxyl radicals (· OH) generated by nZVI at low pH could efficiently degrade 2-CB, the main reductive dechlorination product was …