The Hamaker constant of anatase aqueous suspensions.

The linear relationship of the yield stress with the square zeta potential may be used to determine the Hamaker constants in suspensions. In this work we have obtained the Hamaker constant for the attractive forces between anatase particles in aqueous suspensions using this method and compared them with those obtained by contact angle measurement. The results show excellent agreement.

Stern-layer parameters of alumina suspensions.

The specific adsorption of Mg(+2) and S(2)O(-2)(8) ions onto the gamma-alumina particle surface has been demonstrated. An estimation algorithm based upon the correlation between electrophoretic mobility and conductivity increment experimental data, employing a dynamic Stern-layer theory, has been developed and used to get the adsorption parameters into the Stern layer for different gamma-alumina/Mg(+2) and S(2)O(-2)(8) aqueous solutions interface.

An experimental test of Booth's primary electroviscous effect theory.

The primary electroviscous effect has been investigated in dilute suspensions of titanium oxide (anatase), the viscosities of which were measured by means of a capillary viscometer with automatic timing. The linear relation between viscosity and solids volume fraction was first determined at the isoelectric point of the particles when the particles are uncharged, and the electroviscous contribution to the intrinsic viscosity was then determined at other values of pH. Booth's theory (Proc. R. Soc. London Ser. A203, 533 (1950)) agrees well with the experimental results when the particle zeta potential is small and the double layer is thin (kappa alpha approximately 7.3), but agreement is poor when the double layer is thick (kappa alpha approximately 0.6).

Primary Electroviscous Effect with a Dynamic Stern Layer: Low kappaa Results.

The classical treatments of the primary electroviscous effect show important discrepancies with respect to the experimental data. A possible better agreement may be found if the contribution of the ions adsorbed on the Stern layer, which can move tangentially near the particle surface, is taken into account. This contribution has been incorporated into the Watterson-White theory. A study of the influence of the Stern-layer parameters on the primary electroviscous coefficient has been made. Copyright 2000 Academic Press.