Some laboratory experimental designs for obtaining dynamic property data on dioxins.

The presence of polychlorinated p-dibenzodioxins and polychlorinated dibenzofurans (hereafter PCDD/F) in municipal waste incinerator effluents has sparked a variety of laboratory investigations in the last few years in the hope of learning more about the formation and destruction mechanisms of these compounds. In the course of the investigations a variety of approaches have been employed. It is the purpose of this paper to review these designs and to comment on them in general as well as in specifics. Since under the conditions of interest the quantities of PCDD/Fs are miniscule compared with other products and reactants and because there are nearly 200 congeners, quantitative information is difficult and expensive to obtain. A second aspect concerns the reaction rates involved. No intrinsic kinetic studies have been conducted and no intrinsic values for PCDD/F rates of formation exist. Such information will be necessary, however. As will be shown below, there seems to exist a basic conflict between reaction rates as may be inferred from some laboratory experiments and rates seemingly required by the time/temperature histories of gases and particles in incinerators. The paper is divided into four major parts: homogeneous formation and destruction, heterogeneous formation and destruction, comments on discrepancies, and suggested designs.