Morphological population balance modelling of the effect of crystallisation environment on the evolution of crystal size and shape of para-aminobenzoic acid

Abstract

A current morphological population balance (MPB) modelling methodology, which integrates crystal morphology, facet growth kinetics with multi-dimensional population balance, is overviewed and demonstrated, hence providing an attractive approach for modelling crystallisation processes. MPB modelling is applied to simulate the batch crystallisation of the alpha-form of para-aminobenzoic acid from ethanolic solutions as a function of the crystallisation environment including cooling rate, seeding temperature and seed conditions (loading, size and shape). The evolution of crystal shape/size and their distributions revealed that higher loading led to smaller and less needle-like crystals with similar yields, hence potentially being an important parameter for process control. Examination of the development of the fracture surface for broken seeds, mimicking the seed conditions after milling in practice in the simulated processes, demonstrated that these faces grew fast and then rapidly disappeared from the external crystal morphology. Restriction and challenges inherent in the current model are also highlighted.