Dissertation/Thesis Abstract

Theoretical and Experimental Studies on Interfacial Properties of Ternary Liquid Mixtures
by Grunert, Tommy, Eng.D., Technische Universitaet Berlin (Germany), 2014, 91; 10695009
Abstract (Summary)

Extraction is a very common thermal separation technique, which is based on the demixing behaviour of the involved substances. An actual, not fully understood phenomenon is the transport of substances across the liquid-liquid phase boundary, as well as the laws of coalescence. According to the current state of research, interfacial properties play a crucial role in those phenomena. While the interfacial tension between the two liquid phases is experimentally accessible with some measurement effort, the study of the phase boundaries is almost impossible due to their small extension. Therefore, this work deals with experimental, as well as theoretical studies of the phase boundary between two liquid phases by using a new, modified version of the density gradient theory to predict interfacial tensions, as well as the concentration profiles in the interface and their spatial extent. The predictions of interfacial tensions are in excellent agreement with experimental data for various systems, including the reference system for extraction consisting of water + acetone + toluene. Based on those results, a counterflow extraction column was simulated using the concept of equilibrium stages. Then for the first time the interfacial tensions, as well as the concentration profiles on the equilibrium stages were calculated. By varying the operating parameters of the column, such as the ratio between the feed and solvent flow, as well as different temperatures of the incoming flows, the surface tension could be affected within the column as a function over the height. Furthermore, an enrichment of the solubilising component in the interface is predicted. This accumulation inside the interface is not considered in today's mass transport models, but can be taken into account to develop new or to improve existing models. Similarly, this work allows for the improvement of models of Marangoni convection, as well as coalescence, which can be used for a more efficient design of the extraction column. In summary, this work presents a new concept for predicting hard to measure interfacial tensions, which can be used in the context of extraction columns for simulation and optimisation.

Indexing (document details)
Advisor: Enders, Sabine
School: Technische Universitaet Berlin (Germany)
School Location: Germany
Source: DAI-C 81/1(E), Dissertation Abstracts International
Subjects: Chemical engineering, Fluid mechanics
Keywords: Liquid phase boundaries
Publication Number: 10695009
ISBN: 9781392629475
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