Crystallization of potassium sulfate from pure aqueous solution and in presence of surfactants

Abstract

AbstractThe use of surfactants offers an interesting possibility to control the crystallization from solutions. There are already some applications in technical scale. Yet, little knowledge exists on the mechanism of the effect and his dependence on surfactant concentration. Therefore, the displacement rates of selected single crystal faces of K2SO4 in pure aqueous solutions and in presence of different amounts of tensides have been measured. Furthermore, in order to get insight into the state of surfactant solutions existing in the interesting concentration interval, the critical micelle concentrations have been determined. In comparison with growth from pure solution, the admixtures caused at concentrations below 10−5 mol/l no drastic alterations. On the contrary, above a transition region characterized by a very irregular growth, a practically totally inhibition of growth as well as of dissolution was observed. The changes of surface morphology induced by surfactants have been investigated using the phase contrast microscopy.