Organization of amphiphiles

A systematic study on the adsorption behavior of decylethoxylene nonyl phenol (NP-10) on silica has been carried out in order to elucidate the mechanism that governs the formation of the adsorbed layer of the nonionic surfactants. Effects of pH and silica-water ratio on adsorption isotherm indicate that the adsorption of NP-10 at silica-water interface results from the contribution of both hydrophobic and hydrophilic parts of the surfactant and the surface charge of silica. The cooperative association of the hydrocarbon chain at silica-water interface has been proposed. Measurements of the electrokinetic properties of the silica with adsorbed surfactants reveal the adsorbed layer to mask the surface charge of silica significantly.