Organization of amphiphiles: Part IV. Characterization of the microstructure of the adsorbed layer of decylethoxylene nonyl phenol

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.