Reduction of polychlorinated dibenzodioxins and dibenzofurans in contaminated muds by mechanically induced combustion reactions

Some selected results are reported from an ongoing study concerning mechano chemical dehalogenation reactions carried out under autopropagating high-te mperature regimes. Our work shows that instantaneous burning reactions can be ignited in highly exothermic systems involving chloroorganics when subje cted to intensive mechanical treatments. A reference trial using calcium hy dride-hexachlorobenzene is first presented. No residual traces of the organ ohalide compound were found in the reacted powders or in the gaseous phase sampled from the headspace of the milling reactor. The solid products of th e reaction were restricted to CaHCl and CaCl2 salts and graphite. Similar c ombustion-like phenomena were observed when contaminated mud samples were a dded to initial reactants. The contaminated mud was obtained from a waste s ite and contained traces of polychlorodibenzodioxins and polychlorodibenzof urans. It was observed that an effective chemical oven was created which ca used the thermochemical breakdown of the hazardous compounds. A transformat ion yield greater than 99.6% was obtained with a decrease of the toxic equi valent concentration from 2492 to 0.788 mu g/kg. Unlike conventional incine ration methods, the mechanically induced burst processes run under a strict ly confined environment and controlled conditions.