Sulfonate Adsorption and Wetting Behavior at Solid-Water Interfaces

The electrophoretic mobilities of silver iodide sol particles have been measured as a function of pAg in the presence of var,ious concentrations of C5, C8, C10, C12 and C14 sodium alkyl sulfonates at constant ionic strength and temperature. Contact angles in the solid-air-solution system both in the absence and in the presence of the C14 sulfonate have also been determined. These results have been compared with previously reported work on the effect of alkyl sulfonates on the electrokinetic and wetting behavior of alumina. Application of the Stern-Grahame model of the electrical double layer allows delineation of the various mechanisms contributing to the adsorption phenomena. In the case of the aluminasulfonate system the adsorption process is purely physical, viz. electrostatic and hydrocarbon chain-chain interactions, while for the AgI-sulfonate system both physical and chemical processes are involved, viz. electrostatic, hydrocarbon chain-solid, chain-chain, and solid-polar head interactions