STABILIZATION OF KAOLINITE SUSPENSIONS BY ANIONIC-NONIONIC SURFACTANT MIXTURES

Kaolinite dispersion in aqueous solutions of a nonionic ethoxylated alcohol (C12EO8) was found to be enhanced significantly by the addition of anionic sodium dodecyl sulfate (SDS). The adsorption of C12EO8 with the ethylene oxide chains protruding into the bulk liquid is proposed to cause steric stabilization of the suspension. Such an oriented adsorption would render the surface hydrophilic, an interpretation which is supported by skin flotation data which show a marked decrease in flotation with increased C12EO8 adsorption. Correlation of settling rate with zeta potential data showed the increase in zeta potential caused by added SDS to play only a minor role in the observed increase in suspension stability.