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Item type:Publication, Access status: without files , Solute partitioning in micelles: combining molecular dynamics simulations, COSMOmic, and experiments(Soc., 2017-06-06); ; ; ; The partition equilibria of solutes between micelles and an aqueous phase is a key factor in many applications. Depending on the task, many micelle-solute combinations are possible. Therefore, theoretical methods to predict the partition behavior in micellar systems are needed. Here, two predictive methods are evaluated and compared. First, it is shown how molecular dynamics simulations (MD) with the umbrella sampling method can be used to calculate free energy profiles in micellar systems. The second applied method is an extension of the COSMO-RS theory to anisotropic systems termed COSMOmic. Both methods are compared by means of free energy profiles and experimental micelle/water partition coefficients. A particular focus is on the partitioning of ionized solutes. As experimental data for partitioning in micelles especially for charged solutes is rare, partition coefficients were also determined experimentally. To get a general understanding of micelles examples of all micelle classes (classified by headgroup charge) are studied: nonionic Triton X-114 (TX114), zwitterionic miltefosine (HePC), anionic sodium dodecyl sulfate (SDS), and cationic cetyltrimethylammonium bromid (CTAB). The free energy profiles of neutral solutes obtained from MD simulations and COSMOmic are in an overall good agreement, and partition coefficients from both methods are in good agreement with experimental data. Depending on the system, the results for charged solutes show some deviations between the methods and experimental data.Publicationtype: Journal Article115 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Enzymatic Reactive Distillation: Kinetic Resolution of rac-2-Pentanol with Biocatalytic Coatings on Structured Packings(American Chemical Society (ACS), 2015-09-07); ; ; ; An enantioselective biocatalytic reaction was carried out for the first time in a fully integrated batch reactive distillation setup. The investigated reaction was the lipase catalyzed kinetic resolution of a racemic mixture of (R/S)-2-pentanol with ethyl butyrate. The reaction is strongly limited by the reaction equilibrium so that the reactive distillation helped to shift the equilibrium toward the product side. The enantioselectivity of the applied lipase was high with ee values >99% for 2-pentanol at conversions of 69 ± 3%. As established in our previous work, the biocatalyst was again immobilized within a hydrophobic silica coating for structured packings. The production of the biocatalytic coating was further developed as a spray-coating method to allow reproducible coatings which also can be applied on larger surfaces. The influence of the coating on separation efficiency and pressure drop was studied as well as the stability of the coating under the required process conditions. Overall, this work demonstrates the first kinetic resolution in a reactive distillation setup with structured packings and presents the catalytic coating as an alternative structure for (bio)catalytic columns internals.Publicationtype: Journal Article62 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , XtremRisK - Integrated flood risk analysis for extreme storm surges at open coasts and in Estuaries: Methodology, key results and lessons learned(2015-03-30); ; ; ; A brief overview of the joint research project XtremRisK is given. The project has been focusing on developing/improving/expanding the knowledge, methods and models with respect to (i) physically possible extreme storm surge for current conditions and scenarios for climate change, (ii) failure mechanisms of flood defenses, (iii) assessment of intangible losses (social and ecological) and their integration with direct/indirect economic losses, (iv) reliability analysis of flood defense systems and (v) source-pathway-receptor (SPR)-based integrated flood risk analysis involving both tangible and intangible losses and its implementation for two selected pilot sites (representative for an open coast and an urban estuarine area in Germany). The key results are briefly summarized and the lessons learned for future flood risk studies are finally drawn.Publicationtype: Journal Article69