ADSORPTION OF STARCH AND OLEATE AND INTERACTION BETWEEN THEM ON CALCITE IN AQUEOUS SOLUTIONS

Adsorption of starch and oleate on calcite was studied to understand the nature of their interaction at the solid-solution interface and thereby to elucidate the mechanism by which starch depresses the hydrophobic character of calcite particles in oleate solutions. Streaming potential and calcium solubility measurements helped to clarify the mechanism of oleate adsorption and starch adsorption at the calcite-solution interface. Results obtained for the adsorption of oleate and starch on calcite as a function of the concentration of the other showed the presence of mutual enhancement of adsorption, possibly owing to the formation of a helical starch-oleate clathrate with the oleate held inside the starch helix and the interaction of oleate with calcium bound to starch. The hydrophilic nature of calcite in the presence of oleate and starch is suggested to result because the adsorbed oleate is obscured from solution by such wrapping in starch helixes and is also simply overwhelmed by massive starch species. © 1969.