Suppression of PCDD/Fs formation because of the presence of DEHP during the model slow combustion of 2,4,6-trichlorophenol

The thermal reactions of 2,4,6-T 3CP in the presence and absence of DEHP in a dry air stream was investigated using a silica flow reactor at a residence time of 10 s and a temperature range from 450 °C to 850 °C. Two isomers of T 4CDDs (1,3,6,8- and 1,3,7,9-T 4CDDs) were the most abundant products during the combustion of 2,4,6-T 3CP alone and were observed at temperatures ranging from 550 °C to 800 °C. In the presence of DEHP, we observed a remarkable decrease in the yields of T 4CDDs during the combustion of 2,4,6-T 3CP. The suppression ratio of the T 4CDDs formation was more than 90% in the case of the co-combustion with 10% DEHP in molar ratio. Other PCDD/Fs except for 2,7-/2,8-DCDD and 2,8-DCDF also decreased upon the combustion of 2,4,6-T 3CP in the presence of DEHP. During the co-combustion of 2,4,6-T 3CP and DEHP, the residual ratio of 2,4,6-T 3CP increased slightly and formations of lower chlorinated phenols were observed. The suppression of the T 4CDDs was strongly dependent on the DEHP ratio in the starting material. The prospective pathways of the suppressions of the T 4CDDs formations during the combustion of 2,4,6-T 3CP in the presence of DEHP were proposed.