(164b) Batch Crystallisation of L-Isoleucine Using on-Line Monitoring System

L-Isoleucine is a product of significant commercial importance for the food and pharmaceutical industries, and is also an important raw material for many processes. The current work uses a 250 mL jacketed crystalliser equipped with on-line measurement system such as turbidity, pH meter and PT100. A mechanical stirrer called retreat curve impeller is also used for homogenous mixing. In this slow cooling crystallisation study, comparison between two materials with the effect of impurities and their influence upon primary nucleation of L-isoleucine is carried out. The materials used are isoleucine with purity of 99.9% which is obtained from commercial manufacturer and also isoleucine with some impurities as a result from the product of downstream process fermentation using Corynebacterium glutamicum. The metastable zone width (MSZW) and solution properties (the enthalpies and entropies of dissolution) as well as the nucleation reaction orders are measured. The nucleation parameters, which may be obtained from MSZW measurements, are shown to be dependent on certain physicochemical properties of both of the solutes. The presence of impurities also are found to effect MSZW and in the evaluated surface free energy of the resulting solid.