On the Growth Rate and the Solubility of K-alum by Interferometric Measurement

Abstract

It has usually been assumed that the overall growth rate of crystallization is determined by the relative rates of two processes occurring in series, viz., diffusion of solute from the bulk solution to the solution-crystal interface, followed by integration of the solute atoms or molecules into the crystal lattice. To determine the rates of two processes individually, direct measurements of the interfacial concentration must be made.
Using the Mach-Zehnder Interferometer, the concentrations near the (111) face of a crystal and interfacial ones of aluminium potassium sulphate were measured at 30°C and the relations between interfacial concentration, supersaturation, solution velocity and rate coefficients were obtained.
In addition, it was found that the optical method was useful in determining the solubility.