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 coalcombustion and municipal solid waste incineration. In this work, attention was focused on the adsorptionof metallic mercury on commercially available activated carbon (Darco G60). The study was performedin an apparatus at laboratory scale in which a gas stream at a given temperature, Hg0 concentration, andmass flow rate was contacted with a fixed bed of adsorbent material. Breakthrough curves and adsorptionisotherms were obtained for bed temperatures of 908, 1208, and 1508C and for Hg0 concentrations in thegas in the range of 0.9–6.0 mg/m3. The experiments showed that the adsorption process is a favorable one,and the gas–solid equilibrium data were used to evaluate the Langmuir parameters. Furthermore, it appearedthat the higher the temperature, the lower the adsorption capacity, with a heat of adsorption ofabout 122 kJ/mol. The differential equations modeling the adsorption phenomenon were integrated,leading to the evaluation of a kinetic parameter describing the experimentally determined breakthroughcurves.