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.
|School:||Technische Universitaet Berlin (Germany)|
|Source:||DAI-C 81/1(E), Dissertation Abstracts International|
|Subjects:||Chemical engineering, Fluid mechanics|
|Keywords:||Liquid phase boundaries|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be