engleski

Adsorption of carrageenans on mercury surface in sodium chloride solution and seawater

Adsorption of natural sulfated polysaccharides from algal sources on mercury surface was studied by out of phase a.c. voltammetry. Adsorption studies were performed in a wide concentration range (10 mg/L up to 15 g/L) and the influence of the adsorbed layer on the reduction of cadmium ions, used as a probe, was studied as well. The adsorption was measured at two potentials, -0.2V and -0.6V vs. Ag/AgCl reference electrode. The stronger, one step adsorption, was obtained at the potential of -0.2V. At the potential of -0.6V, the first adsorption plateau was established at the concentration of app. 100 mg/L of added polysaccharide while at the concentration of few g/L a second adsorption plateau was established. The oxido-reduction processes of Cd2+ ions were influenced by the presence of sulphopolysaccharides only in the concentration range of a few grams/L. At the potential of E=-0.6V after the first adsorption plateau, adsorption is a slow process, determined by both the concentration of polymer in the solution and the time of adsorption. It is most probable that transformations of the adsorbed layer occur.

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