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Article ; Online: Influence of Salts on the Adsorption of Lysozyme on a Mixed-Mode Resin

Jannette Kreusser / Fabian Jirasek / Hans Hasse

Adsorption Science & Technology, Vol

2021 Volume 2021

Abstract: Mixed-mode chromatography (MMC), which combines features of ion exchange chromatography (IEC) and hydrophobic interaction chromatography (HIC), is an interesting method for protein separation and purification. The design of MMC processes is challenging ... ...

Abstract	Mixed-mode chromatography (MMC), which combines features of ion exchange chromatography (IEC) and hydrophobic interaction chromatography (HIC), is an interesting method for protein separation and purification. The design of MMC processes is challenging as adsorption equilibria are influenced by many parameters, including ionic strength and the presence of different salts in solution. Systematic studies on the influence of those parameters in MMC are rare. Therefore, in the present work, the influence of four salts, namely, sodium chloride, sodium sulfate, ammonium chloride, and ammonium sulfate, on the adsorption of lysozyme on the mixed-mode resin Toyopearl MX-Trp-650M at pH 7.0 and 25°C was studied systematically in equilibrium adsorption experiments for ionic strengths between 0 mM and 3000 mM. For all salts, a noticeable adsorption strength was observed over the entire range of studied ionic strengths. An exponential decay of the loading of the resin with increasing ionic strength was found until approx. 1000 mM. For higher ionic strengths, the loading was found to be practically independent of the ionic strength. At constant ionic strength, the highest lysozyme loadings were observed for ammonium sulfate, the lowest for sodium chloride. A mathematical model was developed that correctly describes the influence of the ionic strength as well as the influence of the studied salts. The model is the first that enables the prediction of adsorption isotherms of proteins on mixed-mode resins in a wide range of technically interesting conditions, accounting for the influence of the ionic strength and four salts of practical relevance.
Keywords	Physical and theoretical chemistry ; QD450-801
Subject code	660
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	Hindawi - SAGE Publishing
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Adsorption of oleic acid dissolved in isopropanol–water mixtures on hydrotalcite

Agnes Fröscher / Hans Hasse

Adsorption Science & Technology, Vol

2018 Volume 36

Abstract: Fatty acids are an interesting class of educts for chemical processes as they are available from renewable resources. For obtaining high-purity fatty acids, efficient separation techniques are needed. An interesting option is adsorption. In the present ... ...

Abstract	Fatty acids are an interesting class of educts for chemical processes as they are available from renewable resources. For obtaining high-purity fatty acids, efficient separation techniques are needed. An interesting option is adsorption. In the present work, therefore, the adsorption of oleic acid on hydrotalcite, a readily available adsorbent, is studied. The focus is on studying the influence of the composition of the solvent on the adsorption. Adsorption isotherms are reported for oleic acid in pure isopropanol and mixtures of isopropanol and water at temperatures between 278 and 308 K. Even though the solubility of oleic acid in isopropanol is higher than in mixtures of isopropanol and water, the highest capacity of the adsorber is found for pure isopropanol. The reasons are discussed. No significant influence of the temperature was observed.
Keywords	Physical and theoretical chemistry ; QD450-801
Language	English
Publishing date	2018-05-01T00:00:00Z
Publisher	Hindawi - SAGE Publishing
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Experimental Study of the Influence of the Adsorbate Layer Composition on the Wetting of Different Substrates with Water

Michaela Heier / Rolf Merz / Stefan Becker / Kai Langenbach / Michael Kopnarski / Hans Hasse

Adsorption Science & Technology, Vol

2021 Volume 2021

Abstract: Wetting is strongly influenced by adsorbate layers, which are omnipresent on surfaces. The influence of the composition and thickness of adsorbate layers on the water contact angle of sessile drops on different substrates was systematically investigated ... ...

Abstract	Wetting is strongly influenced by adsorbate layers, which are omnipresent on surfaces. The influence of the composition and thickness of adsorbate layers on the water contact angle of sessile drops on different substrates was systematically investigated in the present work. Measurements were carried out for gold-sputtered substrates. These new results are compared to results from a previous study, in which corresponding measurements were carried out for technical steel and titanium substrates. In all experiments, different pretreatments of the samples were used to obtain variations of the adsorbate layer. The samples were either exposed to an oil bath or not, and different cleaning agents were used. The analysis of the adsorbate layer was carried out with X-ray photoelectron spectroscopy (XPS). The results for the different substrates reveal that the water contact angle depends mainly on the composition of the adsorbate layer. The substrate has only an indirect influence, as it influences the composition of the adsorbate layer. The thickness of the adsorbate layers was between 1.4 and 14 nm and was large enough to prevent a direct influence of the substrate on the water contact angle. It is shown that using the information on the adsorbate layer composition from XPS and the results for the water contact angle obtained for the gold samples alone, the water contact angles on the steel and titanium samples can be predicted.
Keywords	Physical and theoretical chemistry ; QD450-801
Subject code	530
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	Hindawi - SAGE Publishing
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Influence of mixed electrolytes and ph on adsorption of bovine serum albumin in hydrophobic interaction chromatography

Hackemann, Eva / Hans Hasse

Journal of chromatography. 2017,

2017

Abstract: Using salt mixtures instead of single salts can be beneficial for hydrophobic interaction chromatography (HIC). The effect of electrolytes on the adsorption of proteins, however, depends on the pH. Little is known on that dependence for mixed ... ...

Abstract	Using salt mixtures instead of single salts can be beneficial for hydrophobic interaction chromatography (HIC). The effect of electrolytes on the adsorption of proteins, however, depends on the pH. Little is known on that dependence for mixed electrolytes. Therefore, the effect of the pH on protein adsorption from aqueous solutions containing mixed salts is systematically studied in the present work for a model system: the adsorption of bovine serum albumin (BSA) on the mildly hydrophobic resin Toyopearl PPG-600M. The pH is adjusted to 4.0, 4.7 or 7.0 using 25mM sodium phosphate or sodium citrate buffer. Binary and ternary salt mixtures of sodium chloride, ammonium chloride, sodium sulfate and ammonium sulfate as well as the pure salts are used at overall ionic strengths between 1500 and 4200mM. The temperature is always 25Â°C. The influence of the mixed electrolytes on the adsorption behavior of BSA changes completely with varying pH. Positive as well as negative cooperative effects of the mixed electrolytes are observed. The results are analyzed using a mathematical model which was recently introduced by our group. In that model the influence of the electrolytes is described by a Taylor series expansion in the individual ion molarities. After suitable parametrization using a subset of the data determined in the present work, the model successfully predicts the influence of mixed electrolytes on the protein adsorption. Furthermore, results for BSA from the present study are compared to literature data for lysozyme, which are available for the same adsorbent, temperature and salts. By calculating the ratio of the loading of the adsorbent for both proteins particularly favorable separation conditions can be selected. Hence, a model-based optimization of solvents for protein separation is possible.
Keywords	adsorbents ; adsorption ; ammonium chloride ; ammonium sulfate ; aqueous solutions ; bovine serum albumin ; electrolytes ; hydrophobic interaction chromatography ; hydrophobicity ; ionic strength ; lysozyme ; mathematical models ; pH ; sodium chloride ; sodium citrate ; sodium phosphate ; sodium sulfate ; solvents ; temperature
Language	English
Size	p. .
Publishing place	Elsevier B.V.
Document type	Article
Note	Pre-press version
ZDB-ID	218139-3
ISSN	0021-9673 ; 0378-4355 ; 0376-737X
ISSN	0021-9673 ; 0378-4355 ; 0376-737X
DOI	10.1016/j.chroma.2017.09.024
Database	NAL-Catalogue (AGRICOLA)

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Article: Method for Estimating Activity Coefficients of Target Components in Poorly Specified Mixtures

Jirasek, Fabian / Hans Hasse / Jakob Burger

Industrial & engineering chemistry process design and development. 2018 May 16, v. 57, no. 21

2018

Abstract: 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 ... ...

Abstract	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.
Keywords	bioprocess engineering ; nuclear magnetic resonance spectroscopy ; process design ; thermodynamics
Language	English
Dates of publication	2018-0516
Size	p. 7310-7313.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	1484436-9
ISSN	1520-5045 ; 0888-5885
ISSN (online)	1520-5045
ISSN	0888-5885
DOI	10.1021/acs.iecr.8b00917
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Solvent cleaning and wettability of technical steel and titanium surfaces

Stefan Becker / Rolf Merz / Hans Hasse / Michael Kopnarski

Adsorption Science & Technology, Vol

2016 Volume 34

Abstract: The ability of the cleaning agents such as cyclohexane, acetone, isopropanol and hydrogen peroxide to remove oil from technical steel and titanium samples was studied in systematic experiments. The composition of the organic residues and the layer ... ...

Abstract	The ability of the cleaning agents such as cyclohexane, acetone, isopropanol and hydrogen peroxide to remove oil from technical steel and titanium samples was studied in systematic experiments. The composition of the organic residues and the layer thickness on the differently cleaned surfaces were determined via X-ray photoelectron spectroscopy analysis, and the corresponding water contact angles were measured. The ability of the cleaning agents to remove oil was found to increase in the following order: acetone, isopropanol, cyclohexane and hydrogen peroxide. The relationship between the chemical composition of the residues and the observed contact angles is investigated, and a quantitative correlation is developed.
Keywords	Physical and theoretical chemistry ; QD450-801
Language	English
Publishing date	2016-06-01T00:00:00Z
Publisher	Hindawi - SAGE Publishing
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Conceptual Design of a Novel Process for the Production of Poly(oxymethylene) Dimethyl Ethers from Formaldehyde and Methanol

Schmitz, Niklas / Eckhard Ströfer / Hans Hasse / Jakob Burger

Industrial & engineering chemistry process design and development. 2017 Oct. 11, v. 56, no. 40

2017

Abstract: Poly(oxymethylene) dimethyl ethers (OME) are environmentally benign alternative fuels. This work presents the conceptual design of a novel OME process which employs aqueous solutions of formaldehyde and methanol as feedstock. In this process, OME of the ... ...

Abstract	Poly(oxymethylene) dimethyl ethers (OME) are environmentally benign alternative fuels. This work presents the conceptual design of a novel OME process which employs aqueous solutions of formaldehyde and methanol as feedstock. In this process, OME of the desired chain lengths n = 3–5 and water are separated from the reactive mixture (formaldehyde + water + methanol + methylal + OME). Thermodynamic limits are identified by studying distillation boundaries and chemical equilibria. By that it is shown that OME of chain lengths n = 3–5 can be separated from the reactor outlet by distillation. The separation of water is carried out using either an adsorption or a membrane process. Adsorption isotherms of water on Zeolite 3A are determined experimentally. The OME process is simulated and optimized using a reduced process model accounting for the mass balances and the thermodynamic limits. Favorable operating points of the process are identified using multi-objective optimization.
Keywords	adsorption ; alternative fuels ; aqueous solutions ; distillation ; ethers ; feedstocks ; formaldehyde ; methanol ; models ; process design ; sorption isotherms ; thermodynamics ; zeolites
Language	English
Dates of publication	2017-1011
Size	p. 11519-11530.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	1484436-9
ISSN	1520-5045 ; 0888-5885
ISSN (online)	1520-5045
ISSN	0888-5885
DOI	10.1021/acs.iecr.7b02314
Database	NAL-Catalogue (AGRICOLA)

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Article: NMR Spectroscopic Study of Chemical Reactions in Mixtures Containing Oleic Acid, Formic Acid, and Formoxystearic Acid

Fröscher, Agnes / Kai Langenbach / Erik von Harbou / Werner R. Thiel / Hans Hasse

Industrial & engineering chemistry process design and development. 2019 Mar. 14, v. 58, no. 14

2019

Abstract: Oleic acid (OA) and formic acid (FA) react to formoxystearic acid (FSA), in the presence of acidic catalysts. This reaction is of interest as OA can be obtained from renewable resources and FSA is a potential precursor for biopolymers. We have recently ... ...

Abstract	Oleic acid (OA) and formic acid (FA) react to formoxystearic acid (FSA), in the presence of acidic catalysts. This reaction is of interest as OA can be obtained from renewable resources and FSA is a potential precursor for biopolymers. We have recently studied the liquid–liquid equilibrium (LLE) in the uncatalyzed nonreacting system OA + FA + FSA. This work is extended here to the reactive system, in which a reactive liquid–liquid equilibrium (RLLE) exists. The reaction equilibrium is studied by quantitative NMR spectroscopy at temperatures between 333 and 353 K in homogeneous OA-rich mixtures. This information is combined with that on the LLE to determine the RLLE. The physicochemical equilibria are modeled in a thermodynamically consistent way using the associating lattice cluster theory (ALCT). Furthermore, data on the chemical equilibrium of the formation of the OA-isomer elaidic acid (EA) is supplied. Also the decomposition of FA and the formation of estolides (EL), which are oligomers of OA and EA, was observed and quantified.
Keywords	biopolymers ; catalysts ; chemical equilibrium ; chemical reactions ; elaidic acid ; estolides ; formic acid ; nuclear magnetic resonance spectroscopy ; oleic acid ; process design ; renewable resources ; spectral analysis ; temperature ; thermodynamics
Language	English
Dates of publication	2019-0314
Size	p. 5622-5630.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	1484436-9
ISSN	1520-5045 ; 0888-5885
ISSN (online)	1520-5045
ISSN	0888-5885
DOI	10.1021/acs.iecr.8b05715
Database	NAL-Catalogue (AGRICOLA)

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Article: Vapor−Liquid Interface of the Lennard-Jones Truncated and Shifted Fluid: Comparison of Molecular Simulation, Density Gradient Theory, and Density Functional Theory

Stephan, Simon / Hans Hasse / Jinlu Liu / Kai Langenbach / Walter G. Chapman

Journal of physical chemistry. 2018 Oct. 05, v. 122, no. 43

2018

Abstract: The vapor–liquid interface of the Lennard-Jones truncated and shifted (LJTS) fluid with a cutoff radius of 2.5σ is investigated for temperatures covering the range between the triple point and the critical point. Three different approaches to model the ... ...

Abstract	The vapor–liquid interface of the Lennard-Jones truncated and shifted (LJTS) fluid with a cutoff radius of 2.5σ is investigated for temperatures covering the range between the triple point and the critical point. Three different approaches to model the vapor–liquid interface are used: molecular dynamics (MD) simulation, density gradient theory (DGT), and density functional theory (DFT). The surface tension, pressure, and density profiles, including the oscillatory layering structure of the fluid at the interface, are investigated. The PeTS (Perturbed Truncated and Shifted) equation of state and PeTS-interfacial functional, based on perturbation theory, are used to calculate the Helmholtz free energy in the DGT and DFT approach. They are consistent with the LJTS force field model. Overall, both DGT and DFT describe the results from computer experiments well. An oscillatory layering structure is found in MD and DFT.
Keywords	computers ; density functional theory ; equations ; Gibbs free energy ; liquid-air interface ; mathematical theory ; models ; molecular dynamics ; surface tension ; temperature
Language	English
Dates of publication	2018-1005
Size	p. 24705-24715.
Publishing place	American Chemical Society
Document type	Article
ISSN	1932-7455
DOI	10.1021/acs.jpcc.8b06332
Database	NAL-Catalogue (AGRICOLA)

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Article: Temperature dependence of adsorption of PEGylated lysozyme and pure polyethylene glycol on a hydrophobic resin: Comparison of isothermal titration calorimetry and van’t Hoff data

Werner, Albert / Eva Hackemann / Hans Hasse

Journal of chromatography. 2014 Aug. 22, v. 1356

2014

Abstract: The influence of temperature on the adsorption of PEGylated lysozyme and pure PEG on Toyopearl PPG-600M, a hydrophobic resin, is studied by batch equilibrium measurements and pulse response experiments. Differently PEGylated lysozymes are used for the ... ...

Abstract	The influence of temperature on the adsorption of PEGylated lysozyme and pure PEG on Toyopearl PPG-600M, a hydrophobic resin, is studied by batch equilibrium measurements and pulse response experiments. Differently PEGylated lysozymes are used for the studies, enabling a systematic variation of the solute properties. Either ammonium sulfate or sodium chloride are added. The enthalpy of adsorption is calculated from a van’t Hoff analysis based on these data. It is also directly measured by Isothermal Titration Calorimetry. In the investigated temperature range from 5°C to 35°C adsorption is favored by higher temperatures and hence endothermic. The results of the van’t Hoff analysis of the equilibrium and the pulse response data agree well. Discrepancies between enthalpies of adsorption obtained by calorimetry and van’t Hoff analysis are found and discussed. We conclude that the most likely explanation is that thermodynamic equilibrium is not reached in the experiments even though they were carried out carefully and in the generally accepted way.
Keywords	adsorption ; ammonium sulfate ; calorimetry ; chromatography ; endothermy ; enthalpy ; hydrophobicity ; lysozyme ; polyethylene glycol ; sodium chloride ; solutes ; temperature ; titration
Language	English
Dates of publication	2014-0822
Size	p. 188-196.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	218139-3
ISSN	0021-9673 ; 0378-4355 ; 0376-737X
ISSN	0021-9673 ; 0378-4355 ; 0376-737X
DOI	10.1016/j.chroma.2014.06.056
Database	NAL-Catalogue (AGRICOLA)

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