FORMATION OF POLYCHLORINATED DIBENZO-p-DIOXINS AND DIBENZOFURANS FROM THE PYROLYSIS OF HEXACHLOROCYCLOHEXANE IN THE PRESENCE OF IRON( Ⅲ ) OXIDE

摘要

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.