1989 Volume 15 Issue 6 Pages 1120-1125
Changes in light transmittance and electrical conductivity of solution with elapsed time and the change in light transmittance due to the sedimentation of final product crystals in a batchwise reactor were inputted directly and continuously in a microcomputer, and the size distribution of final products, secondary nucleation rate and linear growth rate were obtained automatically.
This system was applied to the crystallization of [A] : L-aspartic acid (S0 = 2.9-3.9) and [B] : fumaric acid (S0 = 1.3) from aqueous solution. The following results were obtained for [A]. 1) Secondary nucleation rate and the minimum size rmin were dependent on agitation rate and initial supersaturation ratio. 2) Secondary nuclei were born mainly by collision of mother crystals larger than rmin, and the secondary nucleation rate was estimated to be expressed by dN/dt=knNm2S10, where Nm, is the number of crystals larger than rmin in unit volume. 3) Crystal growth rate is determined by surface two-dimensional nucleation rate, and surface energy σ and the radius of two-dimensional critical nucleus rc' were estimated to be 8.0 erg·cm-2 and 0.39 nm at S =2.0. For [B], crystal growth rate is explained by the BCF theory.
