Jia Wei Chew

Stable polymorphs: difficult to make and difficult to predict

Because α-glycine grows 500 times faster than γ-glycine, the small thermodynamic preference for γ-glycine is difficult to predict, detect and exploit.

Advances in the Modeling and Control of Batch Crystallizers

Abstract Despite the widespread application of crystallization, there are still a disproportionate number of problems associated with its control. These problems have become important in recent years as increased interest has been directed towards the crystallization of pharmaceuticals and proteins, which have additional complications compared to the inorganic crystallizations studied extensively in the past 50+ years. This paper covers recent advances in batch crystallization modeling and control. This includes a comparison in simulations and experiments between the classical temperature control approach developed in the 1970-90s with new concentration control approach developed in the last few years. The new approach, which uses ATR-FTIR spectroscopy and feedback control to follow a setpoint trajectory in the solution concentration as a function of temperature, results in reduced sensitivity of the product quality to disturbances. The resulting guidelines from the simulations are applied to the crystallization of paracetamol in water.