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Nucleation and growth mechanisms and kinetics of crystals of an amino acid salt were investigated in a methanol-water system by measuring and evaluating the induction time as a function of the supersaturation ratio and temperature in batch salting out crystallization experiments. Discrimination between the possible crystallization mechanisms, and estimation of the kinetic parameters were carried out using nonlinear parameter identification. The results concerning the growth mechanism obtained were checked additionally by measuring the induction time as a function of number density of seed crystals.

NILLSBN'S cyuat ion has been applied for cooling crystallization of KC'I from watcry soltitioils. In tho calculations activities are used instead of concentratioris, the temperature and coricontration deperidencc of both the activity and diffusion cocfficients are COIIsidered. It is found that a) the interfacial tension betwocri the crystal and its saturated solution is < 2.5 wg/crn2, which is less by t w o orders of magnitude than that of between crystal and vacuum; b) homogeneous nucleation can take place even at very small supersaturations (In 8 < < 0.01), which is unusual 111 precipitation.

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