REMOVAL OF MERCURIC-CHLORIDE FROM FLUE-GAS BY SULFUR IMPREGNATED ACTIVATED CARBON

In this work the attention was focused on the adsorption of mercuric c hloride on activated carbon and on Na2S impregnated activated carbon. The study was performed in an apparatus at laboratory scale in which s imulated flue gas at a given temperature and HgCl2 concentration flowe d through a fixed bed of adsorbent material. The experiments showed th at the impregnation process definitely enhances the adsorption capacit y of the carbon, and that the higher the temperature the lower the ads orption capacity, with an effect almost independent of the presence of Na2S. A possible interpretation of the experimental results is that i mpregnation with Na2S facilitates HgCl2 capture by activated carbon, p ossibly by increasing the concentration of sites available for adsorpt ion. However the heat of adsorption, which was found to be about 25 kJ /mol both for raw and impregnated activated carbon, indicates that the process taking place can be defined as a physical adsorption. The gas -solid equilibrium data were used to evaluate the Langmuir's parameter s for the three different materials under investigation, The different ial equations modeling the adsorption phenomenon were integrated, lead ing to the evaluation of a kinetic parameter describing the experiment ally determined breakthrough curves.