Abstract
A fundamental understanding of interfacial properties is imperative for the design and optimization of liquid-liquid extraction processes. Especially the interfacial mass trans-fer is mainly governed by interfacial properties, which are not yet fully understood. With a rigorous thermodynamic modelling framework, the demand for time and cost inten-sive experimental studies for new plant designs could be greatly reduced.
Therefore, a thermodynamically consistent model to describe and predict the diffusive interfacial mass transfer in liquid-liquid systems is implemented within this thesis. The model framework incorporates spatially resolved interfacial properties, such as the en-richment of transferring components at liquid-liquid interfaces, and their influence on the mass transfer. Moreover, chemical reactions are incorporated into the model to describe the interfacial mass transfer in systems with a simultaneous chemical reaction in the bulk phase. For that purpose, the concentration gradient theory (CGT) is applied to incompressible liquid-liquid systems and coupled with the Koningsveld-Kleint-jens (KK) gE-model and a reaction rate law. To parametrize and validate the model, extensive experimental investigations were conducted. Ternary and quaternary phase equilibria were measured, and their interfacial tension was determined. Moreover, the chemical rate law of a model reaction, the self-condensation of acetone to diacetone alcohol, was established. The interfacial mass transfer for reactive and non-reactive mixtures was systematically investigated in a Nitsch-cell.
With the established model the interfacial mass transfer was modeled in exceptional accordance with experimental data. Moreover, the mass transfer in quaternary sys-tems could be quantitatively predicted from ternary data by adjustment of only a single additional mobility coefficient. The simultaneous diffusion and chemical reaction were accurately predicted without the requirement of further adjustable parameters. Further-more, the relation between interfacial properties in equilibrium and the interfacial mass transfer was studied. It was found that the enrichment of transferring components at the interface significantly influences the interfacial mass transfer. Therefore, the results of this thesis contribute to a deeper understanding of the fundamental phenomena which govern the mass transfer in liquid-liquid extraction
Therefore, a thermodynamically consistent model to describe and predict the diffusive interfacial mass transfer in liquid-liquid systems is implemented within this thesis. The model framework incorporates spatially resolved interfacial properties, such as the en-richment of transferring components at liquid-liquid interfaces, and their influence on the mass transfer. Moreover, chemical reactions are incorporated into the model to describe the interfacial mass transfer in systems with a simultaneous chemical reaction in the bulk phase. For that purpose, the concentration gradient theory (CGT) is applied to incompressible liquid-liquid systems and coupled with the Koningsveld-Kleint-jens (KK) gE-model and a reaction rate law. To parametrize and validate the model, extensive experimental investigations were conducted. Ternary and quaternary phase equilibria were measured, and their interfacial tension was determined. Moreover, the chemical rate law of a model reaction, the self-condensation of acetone to diacetone alcohol, was established. The interfacial mass transfer for reactive and non-reactive mixtures was systematically investigated in a Nitsch-cell.
With the established model the interfacial mass transfer was modeled in exceptional accordance with experimental data. Moreover, the mass transfer in quaternary sys-tems could be quantitatively predicted from ternary data by adjustment of only a single additional mobility coefficient. The simultaneous diffusion and chemical reaction were accurately predicted without the requirement of further adjustable parameters. Further-more, the relation between interfacial properties in equilibrium and the interfacial mass transfer was studied. It was found that the enrichment of transferring components at the interface significantly influences the interfacial mass transfer. Therefore, the results of this thesis contribute to a deeper understanding of the fundamental phenomena which govern the mass transfer in liquid-liquid extraction
| Original language | English |
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| Qualification | Doctor of Technology |
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| Award date | 20 Jul 2022 |
| Publication status | Published - 2022 |