(626f) Population Balance and Online Analytics for Batch Crystallization of Adipic Acid

Batch crystallization of organic components is a gentle and effective separation process. Due to consecutive treatment as filtration, formulation etc., control of retrieved particle size distribution is of great interest. Because online and in-situ analytics are indispensable to gain knowledge about crystal birth and growth behaviour, in the presented work concentration data as well as information about evolution of the solid phase are retrieved during batch experiments by means of the online analytical techniques ATR-FTIR-spectroscopy and FBRM particle measurement. Besides these batch techniques, independent growth measurements for crystallization of adipic acid were also performed in a single crystal growth cell. Growth rates for every crystal face were obtained by means of optical measurements. The obtained face-dependent growth parameters are taken into account by the presented population balance, allowing the modelling of concentration run during batch crystallization as well as size and shape evolution during batch experiments. Supersaturation during crystallization is calculated in terms of activities by use of the PC-SAFT equation of state. While calculated concentration runs are directly comparable to concentration data retrieve by ATR-FTIR-spectroscopy, a comparison of calculated and measured size distribution efforts further considerations. The FBRM-particle probe provides a statistical chordlength distribution. Calculated particle distributions were processed in an analogue statistical way, with knowledge of size and shape of the entire crystal population, to obtain a comparable statistical chordlength distribution. A comparison of measured (solid line) and calculated concentration (dashed line) run is shown in fig.1, analogue fig.2 shows a comparison of measured (solid line) and calculated (dashed line) chordlength distribution for batch crystallization of adipic acid from solution with 1-propanol.