Volume 40, Issue 7 pp. 1339-1346
Research Article

Influence of Liquid-Liquid Phase Separation on the Crystallization of L-Menthol from Water

Ian de Albuquerque

Ian de Albuquerque

ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, 8092 Zurich, Switzerland

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Marco Mazzotti

Corresponding Author

Marco Mazzotti

ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, 8092 Zurich, Switzerland

Correspondence: Marco Mazzotti ([email protected]), ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, 8092 Zurich Switzerland.Search for more papers by this author
First published: 04 May 2017
Citations: 19

Abstract

The crystallization of L-menthol in water was investigated, with the intent of understanding the effect that liquid-liquid phase separation (LLPS) has on the properties of product crystals. First, the binary phase diagram was measured, comprising both solid-liquid and liquid-liquid equilibrium regions. Calibration for the online monitoring of solid and liquid-liquid suspension densities was performed using Raman spectroscopy, thus enabling the detection of LLPS and crystallization. Crystallization was monitored online also by Raman spectroscopy. Offline characterization was performed using differential scanning calorimetry, powder X-ray diffraction, and Karl-Fisher. Crystallization followed by LLPS led to the formation of the most stable polymorphic form, yet those solids contained solvent inclusions. The initial amount of inclusions proved to be a function of operating conditions, namely cooling rate and suspension density.

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