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

• Published in: Journal of hazardous materials 2021-03, Vol.406, p.124305-124305, Article 124305
• Main Authors: Sun, Yun-man, Feng, Liu, Yang, Lei
• Format: Article
• Language: English
• Subjects: Chemical remediation; Heterogenous Fenton process; Montmorillonite supported nanoscale zero-valent iron; Polychlorinated biphenyl; Soil remediation
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.124305

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·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. [Display omitted] ●PCB67 could be better degraded in a MMT-nZVI induced heterogenous Fenton system.●Degradation of PCB67 followed pseudo-first-order kinetics.●Two potential degradation pathways and products of PCB67 were identified.●MMT-nZVI induced heterogenous Fenton process is promising for PCBs polluted soils.