Crystal shape modification through cycles of dissolution and growth: Attainable regions and experimental validation

The impact of particle shape on end-use efficacy and downstream processing efficiency has driven industrial and academic efforts to control/manipulate the shapes obtained by crystallization. Strategies for controlling crystal shape have focused primarily on chemical routes; with shapes optimized through either solvent selection or the use of growth inhibiting additives. However, the chemical design space for crystallization may be limited, and/or the additional separation and purification steps required to remove additives or engineered solvents may be uneconomical. The application of cycles of dissolution and growth as a means for attaining desired crystal shapes is examined. A dynamic model for determining the shapes that can be attained by cycling is developed, and the results of proof of concept experiments performed using adipic acid and paracetamol are presented. The predictions obtained using the dynamic model were shown to be in good agreement with the results from the paracetamol experiments. (c) 2011 American Institute of Chemical Engineers AIChE J, 2012