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NameDr. Amel Garbou
OrganizationUniversity of Central Florida

Mechanistic and computational studies using DFT for hexachlorobenezene degradation by zero-valent magnesium/graphite (ZVMg/C) in acidified ethanol-ethyl lactate system


Garbou, Amel, Muqiong, Liu, Zou, Shengli, Clausen, Christian and Yestrebsky, Cherie

Author Location(s)

University of Central Florida (UCF)


Hexachlorobenzene (HCB), like many chlorinated organic compounds, has accumulated in the environment from agricultural and industrial activity. After its introduction as a fungicide in 1945, the extensive use of this toxic chemical has instigated its infiltration into all food types. Prohibition from commercial use was enforced in the United States in 1966, due to animal, and possible human carcinogenic effects. Because of the health risks, and the adverse impact imposed on various ecosystems, remediation of this contaminant is of vital concern. The objective of this study is to evaluate the proficiency of activated-magnesium metal in a protic solvent system to enhance the reductive dechlorination of HCB. Experimental results were compared with those predicted by quantum chemical calculation based on density functional theory (DFT). Multivariate analysis detected complete degradation of HCB within 30 minutes, having a rate constant of 0.262 min-1, at room temperature. The main degradation products formed within the first 10 minutes were pentachlorobenzene, 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene. The direct relationship between the decreasing number of Cl substituents, and dechlorination reaction kinetics, agrees with the ΔG values predicted by the computational model. Therefore, the lowest energy pathway for C-Cl bond dissociation predicted computationally agrees with the experimentally determined kinetic data. This methodology shows promise for the development of an economic and sustainable field application for the remediation of other chlorinated aromatic compounds.