Continuous Antisolvent Crystallization of alpha-Lactose Monohydrate: Impact of Process Parameters, Kinetic Estimation, and Dynamic Analysis

摘要

Continuous crystallization has recently gained attention in industrial crystallization. This paper summarizes the study of continuous antisolvent crystallization of alpha-lactose monohydrate using ethanol as an antisolvent. The main objective of this work is to develop a process for continuous antisolvent crystallization and to determine the impact of operating parameters such as initial concentration of solute, residence time, impurity, recycle (with and without fines), and antisolvent addition rate on the crystal size, shape, and the polymorphic form. The mathematical model is developed for continuous antisolvent crystallization comprising population balance equation, material balance, and crystallization kinetics. Results show that with an increase in residence time and initial lactose concentration, size of lactose crystals increased; however, no change in morphology is observed. It is also observed that incorporation of whey proteins as impurities reduces the crystal size as well as residual lactose recovery. To increase the yield, recycle, with and without fines, is also studied and a considerable enhancement in the lactose recovery was observed. It is found that with an increase in antisolvent addition rate, formation of beta-lactose occurs preferentially. The kinetic parameters, i.e., growth and nucleation parameters, are estimated by fitting the model with the experimental data. The transient dynamics shown by the profiles obtained during the trial are also discussed. This work shows that there is a potential to achieve the desired shape, size, and polymorphic form of lactose crystals by changing the process parameters.