Correlation between the zeta potential and rheological properties of anatase dispersions

The viscosity at an arbitrarily selected shear rate of 1.16 s(-1) and the yield stress of anatase dispersions are linearly correlated, and both show a maximum at the isoelectric point (IEP) at pristine conditions. The rheological properties of anatase dispersions respond; to the shift in the IEP to higher pH values, which is observed in concentrated solutions of 1-1 electrolytes and in the presence of the organic cosolvents, but the shift in the pH corresponding to a maximum viscosity does not exactly match the shift in the IEP. In contrast with the electrokinetic curves, the rheological curves at high ionic strengths are rather insensitive to the nature of the supporting electrolyte. The acidic branch of the viscosity(pH) curves is relatively insensitive to the ionic strength while the slope of the basic branch decreases when the ionic strength increases. (C) 1999 Academic Press.