TECHNIQUES FOR DEVELOPING NUCLEATION AND GROWTH-KINETICS FROM MSMPR DATA FOR SUCROSE CRYSTALLIZATION IN THE PRESENCE OF GROWTH-RATE DISPERSION

In the past, crystallization kinetics from MSMPR data have been obtained by extrapolation of the linear portion of the size distribution in the standard semi-logarithmic plot of log population density versus particle size. In some systems, a significant upwards curvature is found in this plot which may be attributed to the phenomenon of growth rate dispersion. Obtaining actual nucleation and growth kinetics from this information is very difficult. In this paper, several techniques for obtaining nucleation and growth rate data are reviewed and discussed. Continuous crystallization data for the sucrose-water system are analyzed by several techniques to obtain nucleation and growth rate kinetics. The traditional technique of linear extrapolation yields an effective value for nucleation rate while the growth rate obtained from this linear portion is attributed to product sized crystals. The high number of small, slow growing crystals, which are not accounted for in the above technique, cause the average growth rate for the suspension to be significantly lower while the actual nucleation rate is significantly higher. Numerical techniques for extracting nucleation and growth data will be discussed and the results compared with the traditional linear extrapolation technique.