Fly Ash Capture of Mercuric Chloride Vapors from Exhaust Combustion Gas

Emissions of mercuric chloride from incineration of Municipal Solid Waste (MSW) constitute a severe environmental problem. Recent studies of the emissions from MSW incinerators indicate that, when fabric filters are used, fly ash may promote Hg emission control. In this investigation, a laboratory-scale apparatus was used to evaluate HgCl2 adsorption on MSW fly ash. A mixture of N2 and HgCl2 was used as gas phase, with HgCl2 concentration varying between 0.5 and 10 mg/m3. Fly ash samples collected, on the fabric filter of an industrial size MSW incinerator, were tested to understand the mechanisms involved in mercury fly ash sorption. The experiments led to the determination of the breakthrough curves for the fixed bed and of the adsorption isotherms at different temperatures in the range of 150−250 °C. The adsorption isotherms, which have a characteristic "Langmuir" shape, were used to evaluate the Langmuir parameters at the temperatures investigated and the heat of adsorption for the phenomenon.