ADSORPTION OF SULFATED POLYSACCHARIDES ON MERCURY AND GAMMA-AL2O3 PARTICLES IN SODIUM-CHLORIDE SOLUTION AND SEAWATER

Adsorption of Dextran sulfate and natural sulfated polysaccharides fro m algal sources, iota-, kappa- and lambda-carrageenans on the mercury surface and on the gamma-Al2O3 particles were studied by out of phase a.c. voltammetry. On the mercury surface, the adsorption of Dextran su lfate and adsorption of carrageenans are of similar extent. Comparativ e studies of the adsorption of polysaccharides on aluminium particles showed a considerable adsorption of iota-carrageenan and Dextran-sulfa te onto gamma-Al2O3 particles (Gamma = 300 mg/g and 100 mg/g, respecti vely). Adsorption studies were conducted at pH = 4 in 0.55 M NaCl and in natural seawater (pH = 7.9). Adsorption of iota-carrageenans at the mercury/NaCl solution interface is stronger at the potential of -0.2 V than at -0.6 V vs. Ag/AgCl reference electrode. In seawater, the dif ference between adsorption of iota-carrageenan at two potentials is di minished for concentrations of polysaccharide lower than 10 mg/L, wher e the concentrations of calcium and magnesium ions present are high en ough for neutralization of sulfate groups.The results support the idea , that in seawater, adsorption on particles may play an important role in the transformation, removal and transport of polysaccharides to th e sea bottom.