Formation of toxic species in oxidation of 4-chlorobiphenyl

In this study, 4-chlorobiphenyl (4-CB) was investigated in a laboratory-scale apparatus to determine the products of its thermal decomposition, under conditions similar to those that occur in fires and waste combustion. The apparatus consisted of a laminar flow reactor equipped with a sampling system for intercepting the volatile and condensable products. A XAD-2 cartridge was used to trap the volatile organic compounds (VOC) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F). The analysis of VOC involved high resolution gas chromatography (HRGC) - quadrupole mass spectrometry (QMS) while HRGC - ion trap (IT) MS/MS quantitated the PCDD/F produced. The VOC analysis revealed the formation of chlorophenols and chlorobenzenes, which are important precursors for the formation of PCDD/F. Other detected products included benzaldehyde, naphthalene, 3-ethylbenzaldehyde, 1-chloro-4-ethynylbenzene and benzofuran. The results indicative the formation of mono to acta PCDF, as well as mono, di and hexa to acta chlorinated DD, with monochlorodibenzofuran (MCDF) being the most abundant CDD/F formed. This contribution reports the yields of all PCDD/F homologue groups together with the equivalence of the toxic congeners from the oxidation of 4-CB at 600 °C.