Effect of Surfactants on Suspensibility of Kaolinite Clay and Diatomaceous Earth in Aqueous Suspension

Abstract

The suspension stability of two mineral carriers were investigated in various hard water with or without surfactants. As the hardness of water increased, the suspensibility of kaolinite clay decreased because its primary particles coagulated due to the lower 0-potential.However, an addition of sodium dodecylbenzene sulfonate to kaolinite clay effectively raised the suspensibility by providing high c-potential to particles. On the other hand, the suspensibility of diatomaceous earth was lower with the surfactant than without, while the c-potential was higher with it. The adhesion tension of diatomaceous earth was reduced by the surfactant, while that of kaolinite clay was raised by it. This suggested that the surfactant raised the interfacial energy of diatomaceous earth, causing coagulation occurred.The difference in the effect of surfactants on the adhesion tension between diatomaceous earth and kaolinite clay seemed to come from the difference in the hydrophilicity of their surfaces: the former had relatively high affinity for water, while the latter was hydrophobic.