Adsorption rates and capacities of ten kinds of anionic, cationic and nonionic surfactants on various clay minerals such as kaolinite, Korean kaoline, montmorillonite, bentonites and sepiolite were investigated.
The adsorption rates of all the surfactants on the clay minerals were rapid, and the equilibriums were attained within about thirty minutes. The adsorption isotherms of these surfactants for the clay minerals were conformed to the Freundlich equation. The adsorption capacities of these surfactants on the clay minerals were large in the following order; cationic surfactants> nonionic surfactants> anionic surfactants.
Montmorillonite and bentonites, which have large cation exchange capacities, adsorbed much amount of the cationic surfactants. Sepiolite, montmorillonite and bentonites, which have many micro-pores, adsorbed much amount of the nonionic surfactants. On the other hand, kaolinite and Korean kaoline, which have small cation exchange capacities, adsorbed more the anionic surfactants than the other clay minerals.
Concequently, it would be suggested that cationic and nonionic surfactants were much adsorbed and accumulated in suspended solids and sediments in the river, lake and sea. Furthermore, it would be possible to use the clay minerals for treatment of wastewater containing these surfactants.