h1

TY  - THES
AU  - Thien, Julia Jutta
TI  - A microfluidic platform for the efficient determination of liquid-liquid equilibria using Raman microspectroscopy; 1. Auflage
VL  - 54
PB  - RWTH Aachen University
VL  - Dissertation
CY  - Aachen
M1  - RWTH-2025-01450
SN  - 978-3-95886-542-6
T2  - Aachener Beiträge zur Technischen Thermodynamik
SP  - 1 Online-Ressource : Illustrationen
PY  - 2025
N1  - Druckausgabe: 2025. - Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University
N1  - Dissertation, RWTH Aachen University, 2024
AB  - Experimental liquid-liquid equilibrium (LLE) data are of major importance for many applications ranging from extraction column design to water partitioning of organics in the environment. However, conventional LLE experiments are time consuming and need large sample volumes. Therefore, in the first part of this work, a measurement setup is presented for the time- and material-efficient determination of LLE data. The measurement setup combines the advantages of microfluidics and Raman microspectroscopy. The small dimensions of the used H-cell microchannel lead to rapid equilibration and small sample consumption while Raman microspectroscopy allows for rapid in-situ quantification of all components. The measurement setup has successfully been validated by measuring the LLE of the ternary system cyclohexane – methanol – toluene. Since highest efficiency and user independence can be reached by automation, the setup has been adapted in the second part of the manuscript to allow for an automated workflow from calibration to data analysis. Pure components are premixed online using a micromixer resulting in a closed system with the additional advantage of avoiding potential losses of volatile components. In the automated setup, one experiment generates several data points for calibration and LLE data measurements. The automated setup and workflow are successfully validated with respect to both the integrated calibration and the LLE measurements. For this purpose, the two ternary systems cyclohexane – toluene – methanol and n-heptane – acetonitrile – ethanol were studied. However, a stable parallel microfluidic flow regime cannot be established for numerous industrially relevant aqueous-organic LLE systems since they tend to form plug flows. These plug flows have the advantage that inner circulations in the plugs enhance the mass transfer, leading to a much faster equilibration. Therefore, a measurement setup is presented for LLE in microfluidic plug flows in the third part of this thesis. In the setup, a capillary is moved against the flow direction. Thereby, one plug of either aqueous or organic phase is hold in the laser focus during the Raman measurement. Full automation is established for the premixing of the components, the calculation of the plug lengths and speeds and the Raman measurements of both phases. The setup and automated measurement procedure are successfully validated for the LLE of the ternary system acetone – toluene – water. Using both presented setups, it is now possible to measure the liquid-liquid equilibria of many different systems in a highly efficient manner.
LB  - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
DO  - DOI:10.18154/RWTH-2025-01450
UR  - https://publications.rwth-aachen.de/record/1004464
ER  -