Agglomeration Control of l-Ornithine Aspartate Crystals by Operating Variables in Drowning-out Crystallization

The agglomeration of l-ornithine aspartate crystallized by the drowning-out method was investigated in a turbulent agitated semi-batch reactor. To modify the agglomeration conditions, the crystallization operating factors, including the agitation, feed flow rate, feed concentration, and drowning ratio (volume ratio of antisolvent to feed solution), were all varied. The mean particle size of the l-ornithine aspartate in the product suspension increased with increasing feed concentration, drowning ratio, and feeding time, as crystal agglomeration was promoted via an increased crystal population and holding time in the agitated reactor. Conversely, it was sensitively reduced with increasing agitation speed because of the enhanced external force of the turbulent impact. Furthermore, the agglomeration behavior of the crystals was monitored during and after the crystallization to determine the role of supersaturation and turbulent fluid motion.