Adsorption of quaternary ammonium surfactants on Fuller's earth

The ability of Fuller's earth to adsorb quaternary ammonium surfactants from aqueous solutions was studied as a function of the molecular weight of surfactants, the particle size of adsorbent and the solution pH. The adsorption of these compounds on Fuller's earth was found to be a relatively slow process, particularly when the particle size range of earth is 150 to 180-mu-m. The adsorption isotherms were of the Langmuir-type. The equilibrium adsorption capacity increased as the molecular weight of surfactant was increased or a finer grain size fraction of earth was used. The change in the solution pH over the range of 7.0 to 9.0 did not affect the adsorption of surfactants studied on Fuller's earth.