The Behavior of Zeta Potential of Silica Suspensions

Abstract

Zeta potential is one of the most relevant parameters controlling therheological behavior of ceramic suspensions. In this work, it was observed thatfor pH values below the isoelectric point (IEP), the positive value of zetapotential of water suspensions of α-quartzand α-cristobalite, experiences asudden steep increase with the increase in specific surface area of thepowders. For pH values above the IEP, the zeta potential values of crystallineforms of silica (α-quartz and α-cristobalite), get gradually morenegative with the increase in pH. Conversely in the case of vitreous silica,for pH values above 6, there occurs a steep change towards more negative valuesof zeta potential than those presented by quartz and cristobalite. Thesefindings have not yet been accounted for in the DLVO theory but may providesubsidies for better understanding of how to stabilize and destabilizecrystalline and vitreous silica water suspensions.