Identification of kinetic parameters in multidimensional crystallization processes

Advances in sensor technology and increased competition in the pharmaceutical industry have generated significant interest in the identification of models for the solution formation of crystals with multiple characteristic dimensions. A procedure is proposed that uses a small number of batch experiments to identify the kinetic parameters for multidimensional crystallization processes. The parameters are estimated simultaneously from the on-line measurement of infrared spectra and from cross-moments of the crystal size distribution. The identification procedure maximizes the informativeness of the data produced by each experiment, produces an estimate of the accuracy of the kinetic parameters, and allows the consideration of competing hypotheses for characterizing the crystallization kinetics. The parameter identification strategy is applied to the batch crystallization of potassium dihydrogen phosphate, which forms two-dimensional crystals from solution. To the best of the authors' knowledge, this is the first time that the kinetic parameters for a multidimensional crystallization process are identified from a small number of batch experiments.