"Adsorption of metallic mercury on activated carbon"

Gaseous emissions of mercury compounds from anthropic activities can cause severe harm to the ecosystem. The main sources of anthropic mercury emissions to the atmosphere are exhaust gases from coal combustion and municipal solid waste incineration. In this work, attention was focused on the adsorption of metallic mercury on commercially available activated carbon (Darco G60). The study was performed in an apparatus at laboratory scale in which a gas stream at a given temperature, Hg0 concentration, and mass flow rat was contacted with a fixed bed of adsorbent material. Breakthrough curves and adsorption isotherms were obtained for bed temperatures of 90°, 120°, and 150°C and for Hg0 concentrations in the gas in the range of 0.9-6.0 mg/m3. The experiments showed that the absorption process is favorable one, and the gas-solid equilibrium data were used to evaluate the Langmuir parameters. Furthermore, it appeared that the higher the temperature, the lower the adsorption capacity, with a heat of adsorption of about -22 kJ/mol. The differential equations modeling the adsorption phenomenon were integrated, leading to the evaluation of a kinetic parameter describing the experimentally determined breakthrough curves.