Continuous Precipitation of L-Asparagine Monohydrate in a Micromixer: Estimation of Nucleation and Growth Kinetics

An experimental setup based on a static micromixer is used to determine nucleation and growth kinetics of L-asparagine monohydrate precipitated via antisolvent addition. Mixing in static micromixers was characterized previously using competitive-parallel reactions and computational fluid dynamics (Lindenberg et al., Chem Eng Sci. 2008;63:4135-4149). In this work, the mixer setup is used to determine nucleation and growth kinetics of L-asparagine at high supersaturations, i.e., true kinetics which are not affected by transport limitations. The method is based on measuring the particle size distribution obtained at different residence times. A population balance equation model of the process is used for the design of a continuous precipitation process. Finally, an analysis of the characteristic time scales of nucleation, growth, and mixing shows that, under the conditions in this study, mixing is much faster than precipitation and that the two processes can be decoupled. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 942-950, 2011