Formation of chlorinated hydrocarbons from the reaction of chlorine atoms and activated carbon

Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

“…1-MCDD formation is better explained by invoking a radical/radical pathway. A similar assessment and conclusion has also been made by Khachatryan and Dellinger [56] using thermodynamic data obtained by ab initio calculations. The role of the active O/H radical pool, together with the Cl radical has also been considered by Dellinger's group [28,35,36] in developing comprehensive mechanisms for the formation of PCDDs and PCDFs from the oxidation and the pyrolysis of mono chlorinated and/or mono brominated phenol.…”

“…Thermodynamic parameters for the steps involved in the formation of PCDDs from chlorinated phenols have been estimated by employing Benson's thermodynamic group additivity methods [59,60] and by DFT methods [56,61]. Interestingly, thermodynamic calculations [59] found that the thermodynamic feasibility of the initial coupling reaction (being less endothermic) increases as the degree of chlorination of the reactants increases.…”

“…Khachatryan et al [56,70] in an attempt to address the shortcomings of the ST model concerning the rapid destruction of the phenoxy radical by the oxygen molecule (reaction 11), included radical/radical reactions in their kinetic models. Their elementary kinetic model for the gaseous formation of PCDD congeners from 2,4,6-trichlorophenol consists of 71 steps involving stable molecules and radicals [56].…”

“…Their elementary kinetic model for the gaseous formation of PCDD congeners from 2,4,6-trichlorophenol consists of 71 steps involving stable molecules and radicals [56]. The thermochemistries of a significant proportion of the species included in the model were estimated by ab initio calculations.…”

Potential formation of PCDD/Fs and related bromine-substituted compounds from heating processes for ashes

“…Indeed, the residual carbon in MSW incinerator fly ash plays an important role in both the formation and decomposition of dioxins [7]. The type of carbon also influences the formation reactions of dioxins from various carbon sources such as graphite and coke [8][9][10]. Activated carbon injected into ducts for flue gas-cleaning can be a source of chlorinated organic compound formation [6,10].…”