Degradation of PCB67 in soil using the heterogenous Fenton process induced by montmorillonite supported nanoscale zero-valent iron

Montmorillonite supported nanoscale zero-valent iron (MMT-nZVI) was prepared and proved to be able to induce the heterogenous Fenton process for better removal of 2,3',4,5-tetrachlorobiphenyl (PCB67) in a long-term polluted soil. PCB67 removal depended highly on the dosages of MMT-nZVI and H2O2, and the initial pH, with the highest removal rate of 76.38% at conditions of H2O2 45.99 g.kg(-1), MMT-nZVI 29.88 g.kg(-1) and initial pH 3.5 after 80 min of reaction. Furthermore, PCB67 could be removed in a wider pH range (from 3.5 to near neutrality), with a loss of 13.6% in removal rate at neutral pH. With an activation energy of 21.4 kJ.mol(-1), the degradation of PCB67 was an endothermic and diffusion-controlled process and followed the pseudo-first-order kinetics. That Fe2+ was supplied through aerobic corrosion of MMT-nZVI to activate H2O2 for center dot OH production was the possible mechanism of PCB67 degradation, leading to complete mineralization of PCB67 through two proposed pathways, with the intermediates of ethylbenzene and 3-hepten-2-one, as well as dibutyl phthalate and butyl acetate respectively.