Dioxin radical formation and polymerization on Cu(II)-smectite

Decontamination of hazardous wastes containing dioxins (dibenzo-p-dioxin and its chlorinated analogues) remains a serious problem and new approaches for the degradation or alteration of dioxins are needed. We describe here dibenzo-p-dioxin radical cation formation and polymerization on a simple clay mineral (Cu(II)-smectite) in mild reaction conditions. Existence of the radical species was conclusively demonstrated using electron spin resonance (ESR), ultraviolet-visible, and infrared spectroscopy. The radical cation polymerized to form dimers and trimers as revealed by mass spectroscopy. Radical cations of 1- and 2-chlorodibenzo-p-dioxin were also formed on Cu(II)-smectite. The radical cations are formed by electron transfer from the dioxins to Cu(II). The formation of dioxin radicals may provide the basis for new detoxification methods in which the reactive radical species is coupled to other molecules or degraded by subsequent reactions.