Influence of surface ionization on the adsorption of aqueous mercury chlorocomplexes by activated carbons

The adsorption of aqueous mercury species from chloride solutions on a number of activated carbons has been studied. It was found that whereas the adsorption of neutral HgCl, or positive Hg’+ was very low, significant quantities of the tetrachloromercury(I1) complex, HgCI$-, were adsorbed. Adsorption isotherms of this complex were measured at different pH values, and the results analysed by the Langmuir equation and by a simple surface ionization and specific adsorption model in order to obtain estimates of the adsorption stoichiometry and the mean free energy of adsorption