Modeling the formation of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the historical manufacture of 2,4,5-trichlorophenol

A universal model for the simulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin concentrations in the historical manufacture of 2,4,5-trichlorophenol was developed. The model successfully simulates the conversion of 1,2,4,5-tetrachlorobenzene to 2,4,5-trichlorophenol, and modeled the concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin with an r² of.941 against measured data from 38 experimental runs. The high r² supports the proposed formation mechanism (second order with respect to 2,4,5-trichlorophenol). Simultaneous degradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin by methoxylation/hydroxylation was hypothesized to play a role; however, modeling indicated this was insignificant in the industrial production of 2,4,5-trichlorophenol. This model can be a useful tool in environmental forensic investigations of sites where 2,4,5-trichlorophenol was produced.