Purification by crystallization from solutions of various viscosities

The crystallization of potassium sulfate has been studied from aqueous solutions of different viscosities. The model for purification by crystallization was based on boundary layer theory. Boundary layer theory can be used to determine the impurity concentration at the crystalline surface. The model explained well the impurity results that were obtained experimentally. The linear crystal growth rates were calculated from the measured crystal size distributions. The obtained results showed that the impurity level was higher with the high viscosity solution than that with a solution of low viscosity. On the other hand, the crystal growth rate was higher in the low viscosity solution than that in the solution of high viscosity. (C) 1999 Elsevier Science B.V. All rights reserved.