Study of the adsorption of CdCl2 vapor on various minerals using a drop tube furnace

Most of these studies were performed with fixed bed or thermogravimetric apparatus, and it is often difficult to correlate the results of these experiments with incineration flue gas conditions. To study more precisely the reaction between heavy metal vapor and suspended particles, the GRE laboratory has developed a drop tube furnace. With this experimental setup, it was possible to quantify the adsorption of cadmium chloride on different sorbents in conditions representative of incinerators; a dilute stream of particles was in contact with a counter current flow of metal vapors at high temperature during a few seconds. leaching was done to quantify the physisorbed and chemisorbed fractions of the metal. Silica, alumina, alumina-silica, and calcium oxide were used, and the influence of sorbent surface area, gas temperature, and metal vapor concentration was studied. alumina and calcium oxide were found to be more effective for cadmium capture. The leachable fraction of cadmium on each sorbent appears to be very low. This is in favor of a chemisorption mechanism. Results were correlated with Freundlich isotherms to get characteristic values of vapor chemisorption on theses sorbents.