Viscosity, density, and refractive index of aqueous sodium and potassium aluminate solutions

The viscosities, densities, and refractive indices of synthetic sodium and potassium aluminate solutions are reported as a function of aluminum and caustic concentration, total caustic to Al(III) molar ratio, and temperature. The influence of hydrogen isotope was also explored through complementary studies on deuterated solutions. A significant alkali metal ion effect on the viscosity and density is indicated, the influence of the other primary variables shown to range from strong to moderate. Under similar solution conditions, the sodium ions display stronger solute interactions and greater solution structure-making ability, reflected in higher solution viscosity (and enhanced density), than do potassium ions. The effect of Al(III) solute concentration, caustic to Al(III) ratio, ionic strength, and hydrogen isotope on the solution bulk properties is discussed and their relevance to speciation and the interactions of species in Payer liquors is highlighted. Empirical models for viscosity and density are proposed.