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Partition Coefficients in Mixed Surfactant Systems

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Partition Coefficients in Mixed Surfactant Systems Partition coefficients in mixed surfactant systems Application of multicomponent surfactant solutions in separation processes Vom Promotionsausschuss der Technischen Universität Hamburg-Harburg zur Erlangung des akademischen Grades Doktor-Ingenieur genehmigte Dissertation von Tanja Mehling aus Lohr am Main 2013 Gutachter 1. Gutachterin: Prof. Dr.-Ing. Irina Smirnova 2. Gutachterin: Prof. Dr. Gabriele Sadowski Prüfungsausschussvorsitzender Prof. Dr. Raimund Horn Tag der mündlichen Prüfung 20. Dezember 2013 ISBN 978-3-86247-433-2 URN urn:nbn:de:gbv:830-tubdok-12592 Danksagung Diese Arbeit entstand im Rahmen meiner Tätigkeit als wissenschaftliche Mitarbeiterin am Institut für Thermische Verfahrenstechnik an der TU Hamburg-Harburg. Diese Zeit wird mir immer in guter Erinnerung bleiben. Deshalb möchte ich ganz besonders Frau Professor Dr. Irina Smirnova für die unermüdliche Unterstützung danken. Vielen Dank für das entgegengebrachte Vertrauen, die stets offene Tür, die gute Atmosphäre und die angenehme Zusammenarbeit in Erlangen und in Hamburg. Frau Professor Dr. Gabriele Sadowski danke ich für das Interesse an der Arbeit und die Begutachtung der Dissertation, Herrn Professor Horn für die freundliche Übernahme des Prüfungsvorsitzes. Weiterhin geht mein Dank an das Nestlé Research Center, Lausanne, im Besonderen an Herrn Dr. Ulrich Bobe für die ausgezeichnete Zusammenarbeit und der Bereitstellung von LPC. Den Studenten, die im Rahmen ihrer Abschlussarbeit einen wertvollen Beitrag zu dieser Arbeit geleistet haben, möchte ich herzlichst danken. Für den außergewöhnlichen Einsatz und die angenehme Zusammenarbeit bedanke ich mich besonders bei Linda Kloß, Annette Zewuhn, Dierk Claus, Pierre Bräuer, Heike Mushardt, Zaineb Doggaz und Vanya Omaynikova. Für die freundliche Arbeitsatmosphäre, erfrischenden Kaffeepausen und hilfreichen Gespräche am Institut danke ich meinen Kollegen Carlos, Carsten, Christian, Mohammad, Krishan, Pavel, Raman, René und Sucre. Bei Kai und Lilia bedanke ich mich für die außerordentlich nette Bürogemeinschaft. Sven, Sandra, Philipp, Thomas G. und Evgenia danke ich für die überragende Teamarbeit. Mein besonderer Dank gilt Thomas Ingram für die konstruktive und freundschaftliche Zusammenarbeit. Es hat Spaß gemacht mit euch allen. Bedanken möchte ich mich weiterhin bei Steffi, dafür, dass sie viel mehr tut als ihren Job. Außerdem geht mein Dank an das technische Team Marianne, Ralf und Thomas für die helfenden Hände. Vielen Dank auch an Herrn Carstens und Herrn Block vom Zentrallabor für die unfassbare Geduld, Hilfsbereitschaft und Experimentierfreude bei jedem noch so komplizierten analytischen Problem. Bei Lissi, Judith und Susa bedanke ich mich für die vielseitige Unterstützung, vom Verreisen bis zum Korrekturlesen, bei Eva und Benni für die graphische Unterstützung. Danke an die Volleyballer für die regelmäßige Ablenkung und Ausflüge ins Leben jenseits der Wissen- schaft. Vielen Dank den Kommilitonen, die mir zu unverzichtbaren Freunden geworden sind, danke den lieben Menschen, die mich in Hamburg begleitet haben. Ganz besonders danke ich meiner Familie, auf deren Vertrauen und Unterstützung ich mich immer verlassen kann. Abstract It is their unique surface activity and self-assembly properties that make surfactants suitable for a wide range of applications. Though, the relevant phase equilibria are not yet described sufficiently. Of particular interest are the surfactant/ water phase behavior and the partition coefficient of the target compound between the micelles and the surrounding aqueous phase. Therefore, in this work different methods for the determination of micelle/ water partition coefficients are evaluated. Based on the partition coefficients and considering the surfactant/ water phase behavior the optimization of the decisive process parameters is aimed. The main focus is on the description of the effect of surfactant mixtures, the pH value, and additives to provide the basis for an effective control of processes, utilizing surfactants. It is shown that with the chosen experimental methods, namely the micellar liquid chromatography (MLC), the micellar enhanced ultrafiltration, molar solubilization ratio measurements, and cloud point extraction, micelle/ water partition coefficients in various surfactant systems are determined reliably. Each of these methods is limited regarding the surfactant type and the magnitude of the partition coefficient. Yet, combining different methods, partition coefficients are measured with a high quality in a variety of mixed surfactant solutions. Thus, appropriate techniques for the evaluation of partition coefficients in mixed micellar systems are provided. Further, the thermodynamic model COSMO-RS is evaluated for the prediction of partition coefficients in multicomponent surfactant solutions. It is demonstrated, that the composition of the micelles is the essential parameter for the successful prediction of partition coefficients in mixed surfactant systems. Since these data are difficult to measure, COSMO-RS based methods are introduced, to evaluate the micellar composition. Based on the applied experimental methods and the a priori prediction surfactant based processes can now be designed and optimized, as demonstrated by the following potential implementations: Application of the introduced methods to unknown systems, which are challenging to handle: the partition coefficient of retinol (vitamin A) in a lipid derived surfactant is determined for possible food applications. Optimizing the operating conditions in MLC: based on predicted partition coefficients, the retention behavior of the solutes is determined for different mobile phase compositions. Reactive separation of sugars from an aqueous solution: phenylboronic acid was used as carrier to solubilize sugars in the micelles. Optimized parameters are defined to increase the separation efficiency. Table of Contents 1 Introduction ...................................................................................................................... 1 2 State of the Art ................................................................................................................ 4 2.1 Thermodynamic Fundamentals ................................................................................................ 4 2.2 The COSMO-RS Model ............................................................................................................ 7 2.3 Surfactants and Micelles .........................................................................................................10 2.4 Partition Coefficients in Surfactant Solutions ..........................................................................25 2.5 Applications of Surfactants in Separation Processes .............................................................31 3 Material and Methods .................................................................................................... 45 3.1 Chemicals ...............................................................................................................................45 3.2 Experimental Methods ............................................................................................................47 3.3 Prediction with COSMO-RS ....................................................................................................53 4 Results and Discussion ................................................................................................. 58 4.1 Determination of Partition Coefficients in Surfactant Solutions ..............................................58 4.2 Influence of Alcohols on the Partition Equilibrium ...................................................................66 4.3 Partition Coefficients of Dissociated Solutes ..........................................................................71 4.4 Partition Coefficients in Mixed Micellar Solutions ...................................................................74 4.5 Partition Coefficients in Food Applications..............................................................................83 4.6 Prediction of the Retention Behavior in MLC ..........................................................................88 4.7 Reactive Micellar Separation of Sugars ..................................................................................90 5 Conclusions ................................................................................................................... 99 References ......................................................................................................................... 102 Directories .......................................................................................................................... 124 Appendix ............................................................................................................................ 131 1 Introduction „It‘s more effective, it’s more efficient, it’s more elegant, it’s simply better chemistry.” That is how Paul Anastas describes the term ”green chemistry“, which he introduced in the early 1990th.1 Since then green chemistry became the buzzword for sustainability in chemical research and industry. Its relevance becomes obvious considering the increasing amount of publications related to green chemistry in recent years.2 Even the implementation in industry was realized, in particular the pharmaceutical industry reduced the environmental factor (E- factor) significantly and thus successfully met Anastas’ slogan. However, green chemistry
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