Hydrodynamics of Dissolution in a Newtonian and a Non-Newtonian Solution

Abstract

The dissolution rate of benzoic acid was measured in various concentrations of aqueous solutions of propylene glycol and colloidal solutions of guar gum. In polymeric solutions of guar gum the dissolution rate was influenced primarily by the effect of viscosity on the hydrodynamic shear in the dissolution medium. In the aqueous solutions of propylene glycol the dissolution rate was a complex function of kinematic viscosity, solubility, diffusivity and rotational speed. By means of dimensionless analysis it appears that the difference in the hydrodynamics of the true and colloidal solutions causes a difference in dissolution rate because of dissimilar fluid flow patterns.