Kinetics of adsorption of anionic, cationic, and nonionic surfactants

The kinetics of adsorption of anionic, nonionic, and cationic surfactants on a cellulose-water interface were investigated. The effects of monovalent, divalent, and a mixture of mono- and divalent salts on the adsorption kinetics of anionic surfactant were also investigated. The cellulose surface is shown to have dual sites of hydrophobic and hydrophilic nature. It is shown that anionic and nonionic surfactant molecules mostly adsorb on the hydrophobic site while cationic surfactant molecules mostly adsorb on the hydrophilic site. A simple model based on two-site adsorption is developed to describe the kinetics of adsorption. The values of rate constants are determined by using the experimental data and are compared with those reported in the literature. The rate constants show that the rates of adsorption of sodium dodecylbenzenesulfonate (NaDBS) and polyethoxylated tert-octylphenol (TX-100) are same and cetyltrimethylammonium bromide is higher than NaDBS and TX-100 at the cellulose-water interface.