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Influence of Electrolytes on Liquid-Liquid-Equilibria in Extraction Processes


The aim of this work is to study the influence of electrolytes on liquid-liquid equilibria of the quaternary systems water/organic solvent/biomolecule/salt for extraction processes. The LLEs are investigated experimentally in a first step. On the basis of these data the thermodynamic equation of state ePC-Saft [1] will be applied to model and predict the influence of electrolytes on phase equilibria.


Electrolytes play an important role in biological processes, for example in the production process of organic molecules in the industrial biotechnology. Some of the biological reactions are only feasible in addition of salt. Further, salts are used for the separation of biotechnological products, e.g. extraction processes. However, the influence of electrolytes is neglected or only estimated in the design of the process. This project shall close this scientific gap as it is well-known that only a small amount of electrolytes can influence the phase equilibrium in liquid-liquid systems. A systematic use of salts can thus be used as a powerful tool to enhance the separation efficiency without increasing the energy demand of a process. In previous works the influence of electrolytes on amino acid and osmolyte solutions was investigated. It could be seen that the salt influence is ion-specific and not negligible. Furthermore, it was possible to describe and predict this influence with ePC-Saft [2]. The aim of this study is to examine systematically (experimentally and by thermodynamic modeling) the influence of electrolytes on the distribution of a biomolecule in water/solvent/salt systems. On the basis of this study it should be possible to predict qualitatively, which condition (solvent, electrolyte, concentration, temperature) is recommended for the best thermodynamic extraction efficiency of a biomolecule.




[1] L. F. Cameretti, G. Sadowski and J. M. Mollerup:
"Modeling of aqueous electrolyte solutions with perturbed-chain statistical associated fluid theory"
Industrial & Engineering Chemistry Research, vol. 44, pp. 3355-3362, 2005
[2] C. Held, T. Neuhaus and G. Sadowski:
"Thermodynamic properties of aqueous ectoine, proline, and urea solutions – Measurement and Modeling"
Biophysical Chemistry, vol. 152, pp. 28-29, 2010



Foto von PD Dr.-Ing. Christoph Held

PD Dr.-Ing. Christoph Held


TU Dortmund
Fakultät Bio- und Chemieingenieurwesen
Emil-Figge-Str. 70
44227 Dortmund

Raum G2-513