Influence of experimental conditions on the formation of PCDD/Fs during the thermal reactions of 2,4,6-trichlorophenol.

In order to obtain information on thermochemical reactions of chlorophenols, which are well known as dioxin precursors, occurring during the combustion of municipal solid wastes, the combustion of 2,4,6-trichlorophenol (2,4,6-T(3)CP) in an air stream was investigated over a temperature range of 500-800 degrees C for a residence time of 1-20s using a quartz flow reactor. Gas chromatographic/mass spectrometric (GC/MS) analysis of the gaseous products and residues showed that 2,4,6-T(3)CP began to decompose at 500 degrees C and produced several compounds, with 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins (T(4)CDD) as the major products. In addition, more than fifty organic products were observed in our experimental conditions. The yields of polychlorinated benzenes, phenols, dibenzofurans, and dibenzo-p-dioxins formed during the combustion of 2,4,6-T(3)CP were plotted as a function of temperature and residence time. Furthermore, it was found that the yields and the compositions of these gaseous products were strongly dependent on the residence time in the flow reactor.