Formation of polychlorinated dibenzo-p-dioxins and dibenzofurans from the pyrolysis of hexachlorocyclohexane in the presence of iron(III) oxide

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are formed by the pyrolysis of non-gamma isomers of hexachlorocyclohexane (HCH) in the presence of iron(III) oxide. The yield of PCDD/Fs depends on the concentration of iron(III) oxide, temperature and reaction time. The maximum yield is 4.5 μg/mg HCH. A possible pathway for the formation of PCDD/Fs is suggested. Iron(III) oxide is shown not only to be able to increase amounts of chlorophenols but also to catalyze the condensation reaction of chlorophenols into PCDD/Fs.