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With dramatically increasing emission of heavy metals and chlorinated compounds from thermal treatments of fuels and wastes, kaolin, one of the widely used materials in the industry, was researched to control these pollutants in recent years. To investigate the retention of lead chloride (PbCl2) by kaolin and metakaolin obtained from thermal activation of kaolin, the PbCl2adsorption experiment in a two-stage furnace was conducted from 600 to 900 °C under N2, H2O, and O2. Furthermore, the toxicity leaching procedure was also utilized to evaluate the leachability of Pb from used sorbents. The results showed that the capture efficiency of PbCl2by the sorbents and leachability of Pb from the used sorbents were closely related to the increase of the experimental temperature. The retention of Pb by raw kaolin was superior to that by metakaolin; however, the leachability of Pb from the used metakaolin was totally lower. Adding H2O in the adsorption experiment can obviously increase the retention of Pb by the sorbents and decrease the leachability of Pb from the used sorbents. Besides, the effects of adding O2on promoting the retention of Pb by kaolin and reducing the leachability of Pb from used kaolin were also noticeable due to the influence of adding O2on enhancing chemical adsorption and melting behavior of kaolin. The maximum capture efficiency of Pb by kaolin and the minimum ratio of leachability from the used kaolin can reach 74.01% and 1.60%, respectively, with the addtion of O2in the adsorption experiment at 900 °C.

In China, coal, often with a high level of sulfur, is always mixed with municipal solid waste (MSW) in waste incineration plants due to the low heating value and high moisture content of MSW. The influence of sulfur compounds on the volatilization of heavy metals in MSW is of great concern for China’s waste incineration plants. In this study, the continuous dynamic volatilization process of Pb and Cd is investigated by adding different forms of sulfur compounds, elemental sulfur (S), and sodium sulfate (Na2SO4), to the simulated MSW in a laboratory incinerator, at both 1 and 3 wt %, respectively. The experimental results show that the added S begins to affect the volatilization of Pb and Cd at about 700 °C; adding S can lead up to 49.6% reduction in the volatilization of Pb, as the produced sulfur dioxide is promoting the formation of a condensed sulfate phase, and part of Pb is fixed in the form of PbS in the bottom ash. But for Cd, adding S causes up to 15.9% increase in its volatilization as S seizes part of O2in the air, which is conducive to forming the reducing atmosphere. In the reducing atmosphere, CdO can be easily reduced to Cd, which volatilizes more easily than CdO at high temperatures. In fact, in the reducing atmosphere, the volatilization of Cd far outweighs the volatilization of Pb at 700–800 °C. On the other hand, adding Na2SO4almost has no influence on the volatilization of lead and cadmium below 900 °C.