The Experts below are selected from a list of 134103 Experts worldwide ranked by ideXlab platform
Hans Hasse - One of the best experts on this subject based on the ideXlab platform.
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Estimating activity coefficients of Target Components in poorly specified mixtures with NMR spectroscopy and COSMO-RS
Fluid Phase Equilibria, 2020Co-Authors: Thomas Specht, Fabian Jirasek, Kerstin Münnemann, Hans HasseAbstract:Abstract Poorly specified mixtures are common in process engineering, especially in bioprocess engineering. The properties of such mixtures of unknown composition cannot be described using conventional thermodynamic models. The NEAT method, which has recently been developed in our group, enables the calculation of activity coefficients of known Target Components in such poorly specified mixtures. In NEAT, the group composition of the mixture is determined by NMR spectroscopy and a thermodynamic group contribution method is used for calculating the activity coefficients. In all previous studies with NEAT, the UNIFAC group contribution method was used. In the present work, we demonstrate that NEAT can also be applied with another important method for predicting activity coefficients: COSMO-RS. COSMO-RS (OL) developed in Oldenburg together with its group contribution version GC-COSMO-RS (OL) is used here. The new version of NEAT was successfully tested. For a variety of aqueous mixtures excellent agreement of the NEAT predictions, for which only information on the Target Component was used, with results that were obtained using the full knowledge on the composition of the mixture was found. The results demonstrate the generic nature of the idea of NEAT and the broad applicability of the method.
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NEAT—NMR Spectroscopy for the Estimation of Activity Coefficients of Target Components in Poorly Specified Mixtures
Industrial & Engineering Chemistry Research, 2019Co-Authors: Fabian Jirasek, Jakob Burger, Hans HasseAbstract:Mixtures of which the composition is not fully known are important in many fields of engineering and science, for example, in biotechnology. Owing to the lack of information on the composition, such mixtures cannot be described with common thermodynamic models. In the present work, a method is described with which this obstacle can be overcome for an important class of problems. The method enables the estimation of the activity coefficients of Target Components in poorly specified mixtures and is based on a combination of NMR spectroscopy with a thermodynamic group contribution method. It is therefore called the NEAT method (NMR spectroscopy for the Estimation of Activity coefficients of Target Components in poorly specified mixtures). In NEAT, NMR spectroscopy is used to obtain information on the concentrations of chemical groups in the mixture. The elucidation of the speciation is not required, only the Target Component has to be known. Modified UNIFAC (Dortmund) is applied in the present work as group ...
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Application of NEAT for determining the composition dependence of activity coefficients in poorly specified mixtures
Chemical Engineering Science, 2019Co-Authors: Fabian Jirasek, Jakob Burger, Hans HasseAbstract:Abstract Poorly specified mixtures, of which the composition is only partially known, are important in many fields. In a recent work of our group, the method NEAT for estimating activity coefficients of Target Components in such mixtures was introduced. In the present work, it is shown that based on a single NMR analysis of a poorly specified mixture not only the activity coefficient of the Target Component in that mixture but also its composition dependence can be predicted with NEAT. Hence, based on a single NMR analysis, the activity coefficient of the Target Component in many mixtures can be predicted with NEAT. This is possible, if the unknown part of the mixture remains unchanged, which is the case e.g. when the Target Component is selectively removed or when a known solvent is added or removed. The approach is successfully tested using several aqueous test mixtures.
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Method for Estimating Activity Coefficients of Target Components in Poorly Specified Mixtures
Industrial & Engineering Chemistry Research, 2018Co-Authors: Fabian Jirasek, Jakob Burger, Hans HasseAbstract:Mixtures that contain a known Target Component but are otherwise poorly specified are important in many fields. Previously, the activity of the Target Component, which is needed, e.g., to design separation processes, could not be predicted in such mixtures. A method was developed to solve this problem. It combines a thermodynamic group contribution method for the activity coefficient with NMR spectroscopy, which is used for estimating the nature and amount of the different chemical groups in the mixture. The knowledge of the Component speciation of the mixture is not required. Test cases that are inspired by bioprocess engineering applications show that the new method gives surprisingly good results.
Andreas Seidel-morgenstern - One of the best experts on this subject based on the ideXlab platform.
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Optimal cut-times finding strategies for collecting a Target Component from overloaded elution chromatograms
Computers & Chemical Engineering, 2013Co-Authors: Balamurali Sreedhar, Annegret K. Wagler, Malte Kaspereit, Andreas Seidel-morgensternAbstract:Abstract The determination of accurate cut-times plays an important role in the design and implementation of preparative chromatography. Modeling and optimization studies involving preparative isolation of Target Components from multi-Component mixtures overwhelmingly depend on the Target amount collected, defined by specific cut-times. The task of finding these times can be quite challenging for complex chromatograms of experimental or theoretical origin. In this study, two new alternate strategies to find optimal cut-times are introduced. Using simple linear and complex overloaded chromatograms, the performances of these new methods are compared with that an established technique based on evaluating local purities. To demonstrate the methods, concentration profiles were generated theoretically using empirical functions and the equilibrium dispersive model. The methods are compared in terms of their accuracy, speed, robustness and also their ability to find multiple fractionation intervals.
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Optimization of gradient elution conditions in multiComponent preparative liquid chromatography.
Journal of chromatography. A, 2005Co-Authors: Yichu Shan, Andreas Seidel-morgensternAbstract:Gradient elution is widely applied in analytical chromatography to reduce the separation time and/or to improve the selectivity. Increasingly the potential of modulating the solvent strength during gradient operation is exploited in preparative liquid chromatography. The purpose of this paper is to investigate theoretically the effect of optimizing free parameters available in gradient chromatography (extents and shapes of gradients) on the productivity of isolating a Target Component in a multiComponent mixture. An equilibrium stage model was used to quantify and compare different modes of operation (isocratic and various variants of gradient elution). By combining experimental design and artificial neural network concepts, optimal conditions were identified for the production of the second eluting Component in a ternary mixture. The strong impact of the shape of gradients on process performance is elucidated.
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Isolation of a Target Component from a Multi‐Component Mixture by Coupling Batch and Continuous Countercurrent Chromatography
Chemical Engineering & Technology, 2005Co-Authors: Yichu Shan, Andreas Seidel-morgensternAbstract:A typical situation in preparative chromatography is that a certain Target Component elutes somewhere in the middle of a train of other Components present in the feed. In order to isolate efficiently this Target Component the operating conditions of conventional batch chromatography have to be optimized carefully. Nevertheless, the achievable production rates and recovery yields are frequently low. Recently a possible alternative was suggested [1] based on using batch chromatography just as a first step providing fractions where the Target Component has the highest or lowest retention time. Subsequently, these fractions could be processed using continuous countercurrent chromatography in order to isolate the Target Component. Such a coupled process is analyzed theoretically for the case of linear adsorption isotherms. Based on results of simulations using a) the ideal model of chromatography and b) the equilibrium dispersive model it is demonstrated that the coupled process arrangement could possess advantages, compared to the application of batch chromatography alone.
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Analysis of the isolation of a Target Component using multiComponent isocratic preparative elution chromatography.
Journal of Chromatography A, 2004Co-Authors: Yichu Shan, Andreas Seidel-morgensternAbstract:The separation of a certain Target Component from a multiComponent mixture using isocratic preparative elution chromatography was studied theoretically. In particular, the important and most complicated case was considered that the Target Component does not elute in the first or last position. To specify the productivity of collecting this Component different options are suggested to identify suitable times for fractionation. Using a conventional Craig model, capable to quantify chromatographic processes, the impact of several essential parameters (e.g. threshold concentration, desired purity, injection volume, separation factor between neighboring Components, composition of the mixture) is evaluated for a ternary system based on parametric calculations. The paper provides simple tools to evaluate and optimize the productivity and other objective functions relevant in multiComponent preparative chromatography.
Fabian Jirasek - One of the best experts on this subject based on the ideXlab platform.
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Estimating activity coefficients of Target Components in poorly specified mixtures with NMR spectroscopy and COSMO-RS
Fluid Phase Equilibria, 2020Co-Authors: Thomas Specht, Fabian Jirasek, Kerstin Münnemann, Hans HasseAbstract:Abstract Poorly specified mixtures are common in process engineering, especially in bioprocess engineering. The properties of such mixtures of unknown composition cannot be described using conventional thermodynamic models. The NEAT method, which has recently been developed in our group, enables the calculation of activity coefficients of known Target Components in such poorly specified mixtures. In NEAT, the group composition of the mixture is determined by NMR spectroscopy and a thermodynamic group contribution method is used for calculating the activity coefficients. In all previous studies with NEAT, the UNIFAC group contribution method was used. In the present work, we demonstrate that NEAT can also be applied with another important method for predicting activity coefficients: COSMO-RS. COSMO-RS (OL) developed in Oldenburg together with its group contribution version GC-COSMO-RS (OL) is used here. The new version of NEAT was successfully tested. For a variety of aqueous mixtures excellent agreement of the NEAT predictions, for which only information on the Target Component was used, with results that were obtained using the full knowledge on the composition of the mixture was found. The results demonstrate the generic nature of the idea of NEAT and the broad applicability of the method.
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NEAT—NMR Spectroscopy for the Estimation of Activity Coefficients of Target Components in Poorly Specified Mixtures
Industrial & Engineering Chemistry Research, 2019Co-Authors: Fabian Jirasek, Jakob Burger, Hans HasseAbstract:Mixtures of which the composition is not fully known are important in many fields of engineering and science, for example, in biotechnology. Owing to the lack of information on the composition, such mixtures cannot be described with common thermodynamic models. In the present work, a method is described with which this obstacle can be overcome for an important class of problems. The method enables the estimation of the activity coefficients of Target Components in poorly specified mixtures and is based on a combination of NMR spectroscopy with a thermodynamic group contribution method. It is therefore called the NEAT method (NMR spectroscopy for the Estimation of Activity coefficients of Target Components in poorly specified mixtures). In NEAT, NMR spectroscopy is used to obtain information on the concentrations of chemical groups in the mixture. The elucidation of the speciation is not required, only the Target Component has to be known. Modified UNIFAC (Dortmund) is applied in the present work as group ...
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Application of NEAT for determining the composition dependence of activity coefficients in poorly specified mixtures
Chemical Engineering Science, 2019Co-Authors: Fabian Jirasek, Jakob Burger, Hans HasseAbstract:Abstract Poorly specified mixtures, of which the composition is only partially known, are important in many fields. In a recent work of our group, the method NEAT for estimating activity coefficients of Target Components in such mixtures was introduced. In the present work, it is shown that based on a single NMR analysis of a poorly specified mixture not only the activity coefficient of the Target Component in that mixture but also its composition dependence can be predicted with NEAT. Hence, based on a single NMR analysis, the activity coefficient of the Target Component in many mixtures can be predicted with NEAT. This is possible, if the unknown part of the mixture remains unchanged, which is the case e.g. when the Target Component is selectively removed or when a known solvent is added or removed. The approach is successfully tested using several aqueous test mixtures.
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Method for Estimating Activity Coefficients of Target Components in Poorly Specified Mixtures
Industrial & Engineering Chemistry Research, 2018Co-Authors: Fabian Jirasek, Jakob Burger, Hans HasseAbstract:Mixtures that contain a known Target Component but are otherwise poorly specified are important in many fields. Previously, the activity of the Target Component, which is needed, e.g., to design separation processes, could not be predicted in such mixtures. A method was developed to solve this problem. It combines a thermodynamic group contribution method for the activity coefficient with NMR spectroscopy, which is used for estimating the nature and amount of the different chemical groups in the mixture. The knowledge of the Component speciation of the mixture is not required. Test cases that are inspired by bioprocess engineering applications show that the new method gives surprisingly good results.
Andreas Seidelmorgenstern - One of the best experts on this subject based on the ideXlab platform.
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center cut separation of intermediately adsorbing Target Component by 8 zone simulated moving bed chromatography with internal recycle
Journal of Chromatography A, 2016Co-Authors: Dawid Kiwala, Jadwiga Mendrella, Dorota Antos, Andreas SeidelmorgensternAbstract:An 8-zone simulated moving bed chromatography with internal recycle (8ZSMB-IR) has been designed for center-cut separation, that is, for isolating an intermediately adsorbed Component out of a multiComponent mixture. The system consists of two integrated subunits and operates in a fully continuous manner. In the first subunit the feed mixture is split into two fractions containing either a single Component or a binary mixture. The binary mixture is recycled through the internal raffinate or extract port into the second subunit, where the Target product is isolated. Additionally, the solvent is also recycled internally. For a case study, the separation of a ternary mixture of cycloketones as a model system under weakly non-linear isotherm conditions has been investigated. A few novel configurations of the 8ZSMB-IR unit including the arrangement of the internal recycle of extract, raffinate and solvent streams between two subunits have been examined with respect to various performance indicators for the process realization. The unit performed best with the developed configuration when the internal raffinate stream was recycled and the solvent recycling loop was closed between the last and the first zone of the first subunit. That configuration has further been analyzed experimentally and numerically. On the basis of the results a strategy for determining reliable operating conditions for the 8ZSMB-IR process has been developed. The procedure exploited a model of the process dynamics, which was implemented to refine the isotherm coefficients and to quantify the mixing effect of the liquid stream inside the recycling loops. The upgraded model with the adjusted parameters has been validated based on experimental data and successfully applied for optimizing the operating conditions of the separation.
Yichu Shan - One of the best experts on this subject based on the ideXlab platform.
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Optimization of gradient elution conditions in multiComponent preparative liquid chromatography.
Journal of chromatography. A, 2005Co-Authors: Yichu Shan, Andreas Seidel-morgensternAbstract:Gradient elution is widely applied in analytical chromatography to reduce the separation time and/or to improve the selectivity. Increasingly the potential of modulating the solvent strength during gradient operation is exploited in preparative liquid chromatography. The purpose of this paper is to investigate theoretically the effect of optimizing free parameters available in gradient chromatography (extents and shapes of gradients) on the productivity of isolating a Target Component in a multiComponent mixture. An equilibrium stage model was used to quantify and compare different modes of operation (isocratic and various variants of gradient elution). By combining experimental design and artificial neural network concepts, optimal conditions were identified for the production of the second eluting Component in a ternary mixture. The strong impact of the shape of gradients on process performance is elucidated.
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Isolation of a Target Component from a Multi‐Component Mixture by Coupling Batch and Continuous Countercurrent Chromatography
Chemical Engineering & Technology, 2005Co-Authors: Yichu Shan, Andreas Seidel-morgensternAbstract:A typical situation in preparative chromatography is that a certain Target Component elutes somewhere in the middle of a train of other Components present in the feed. In order to isolate efficiently this Target Component the operating conditions of conventional batch chromatography have to be optimized carefully. Nevertheless, the achievable production rates and recovery yields are frequently low. Recently a possible alternative was suggested [1] based on using batch chromatography just as a first step providing fractions where the Target Component has the highest or lowest retention time. Subsequently, these fractions could be processed using continuous countercurrent chromatography in order to isolate the Target Component. Such a coupled process is analyzed theoretically for the case of linear adsorption isotherms. Based on results of simulations using a) the ideal model of chromatography and b) the equilibrium dispersive model it is demonstrated that the coupled process arrangement could possess advantages, compared to the application of batch chromatography alone.
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Analysis of the isolation of a Target Component using multiComponent isocratic preparative elution chromatography.
Journal of Chromatography A, 2004Co-Authors: Yichu Shan, Andreas Seidel-morgensternAbstract:The separation of a certain Target Component from a multiComponent mixture using isocratic preparative elution chromatography was studied theoretically. In particular, the important and most complicated case was considered that the Target Component does not elute in the first or last position. To specify the productivity of collecting this Component different options are suggested to identify suitable times for fractionation. Using a conventional Craig model, capable to quantify chromatographic processes, the impact of several essential parameters (e.g. threshold concentration, desired purity, injection volume, separation factor between neighboring Components, composition of the mixture) is evaluated for a ternary system based on parametric calculations. The paper provides simple tools to evaluate and optimize the productivity and other objective functions relevant in multiComponent preparative chromatography.
