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ISBN 9783843916189

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978-3-8439-1618-9, Reihe Verfahrenstechnik

Axel Prinz
Enzyme Separation Using Aqueous Two-Phase Extraction: Experiment, Model and Simulation

177 Seiten, Dissertation Technische Universität Dortmund (2014), Softcover, A5

Zusammenfassung / Abstract

Aqueous two-phase extraction (ATPE) constitutes a promising process technology for the separation and purification of enzymes. Despite scalability and mild extraction conditions, commercial application is scarce due to multiplicity of process variables, which lead to significant experimental efforts towards designing an ATPE process.

Laccase from a Pleurotus sapidus culture supernatant spiked with laccase from Trametes versicolor was chosen as model system for investigating the selective separation and purification of enzymes applying ATPE. In the course of the investigation, a PEG3000-phosphate aqueous two-phase system was selected and the relevant extraction parameters, i.e., molar mass of the polymer, tie line length, phase ratio, sodium chloride mass fraction and initial enzyme activity were varied. Depending on sodium chloride mass fraction, it was possible to either purify both laccases in one phase or separate these enzymes. Based on an equilibrium-stage approach, an extraction model was developed for the separation of enzymes using ATPE. Model parameters were fitted to data from single-stage experiments. The model was used to simulate a three-stage counter-current extraction process under varying extraction conditions in terms of salt mass fraction and feed stage. Finally, the simulated extraction process was realized experimentally in a mixer-settler miniplant. Hereby, scale-up from lab- to miniplant scale and change from batch to continuous operation was performed successfully. By converting the process to multi-stage operation, clearance factors and activity recoveries increased, compared to single-stage extraction. In addition, the proposed multi-stage extraction model was successfully validated applying experimental multi-stage results.

This thesis demonstrates the application potential of ATPE for the selective separation of enzymes in single- as well as in multi-stage processes. Additionally, modeling of multi-stage enzyme extraction processes based on single-stage data was shown. Thus, this work contributes to increase the acceptance of ATPE as a powerful process technology for the separation of enzymes.