The Behavior of Zeta Potential of Silica Suspensions

José Antonio Alves Júnior,João Baptista Baldo

doi:10.4236/njgc.2014.42004

José Antonio Alves Júnior, João Baptista Baldo

Open Access

https://doi.org/10.4236/njgc.2014.42004

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Abstract

Zeta potential is one of the most relevant parameters controlling the rheological behavior of ceramic suspensions. In this work, it was observed that for pH values below the isoelectric point (IEP), the positive value of zeta potential of water suspensions of α-quartz and α-cristobalite, experiences a sudden steep increase with the increase in specific surface area of the powders. For pH values above the IEP, the zeta potential values of crystalline forms of silica (α-quartz and α-cristobalite), get gradually more negative 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 values of zeta potential than those presented by quartz and cristobalite. These findings have not yet been accounted for in the DLVO theory but may provide subsidies for better understanding of how to stabilize and destabilize crystalline and vitreous silica water suspensions.

Highlights

Zeta Potential is an electro-kinetic parameter indirectly determined by the surface charge of particles when suspended in a polar media
The aim of this paper is to discuss the behavior of zeta potential versus pH, in the vicinity and away from the isoelectric point (IEP), presented by suspensions of several silica raw materials of different crystal structures and specific surface area
It can be seen that the vitreous silica #100 was the coarsest among all the samples

Summary

Introduction

Zeta Potential is an electro-kinetic parameter indirectly determined by the surface charge of particles when suspended in a polar media. The magnitude of zeta potential by itself can not guaranty the stability of suspensions [1]. Through its manipulation, guidelines can be taken towards stabilization or destabilization of ceramic slurries. The charged particles in suspensions can be set into motion under the action of an electric field [1]. The movement is in the direction of the oppositely charged electrode and can be dragged of by the viscous hydrodynamic forces of the solution. At equilibrium the particles can move at constant speed. The constant velocity acquired under unitary electric field strength is called unitary electrophoretic mobility (μe) [3]

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