Investigation of interfacial properties of aqueous two-phase systems by density gradient theory

Chicaroux, Andres Kulaguin; Zeiner, Tim

doi:10.1016/j.fluid.2015.05.039

Cited by 31 publications

(5 citation statements)

References 50 publications

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“…Since the lattice models exploit a discrete representation of the structure of nonuniform fluids, it is instructive to compare our predictions with the results from the square-gradient theory ,,− that provides the continuous description.…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…Rational design of numerous devices and processes, including drug delivery, micelle-mediated separation, and enhanced oil recovery, requires knowledge of the structural details of spatially nonuniform fluids. Among the theories capable of describing such fluids, − the most theoretically refined and powerful molecular-based approach is iSAFT (interfacial Statistical Associating Fluid Theory). − A remarkable advantage of iSAFT is its applicability to strongly nonuniform fluids containing chainlike molecules that may take part in strong specific interactions leading to association, e.g., the formation of hydrogen bonds. Extending the widely known SAFT model to the nonuniform fluids, iSAFT is based on the same principle of cutting the chainlike molecule into monomeric units and then turning on an infinite attraction between these units to ensure the stoichiometric locking of the separated monomers, thus restoring the connectivity of the original chain .…”

Section: Introductionmentioning

confidence: 99%

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Local Structure of Nonuniform Fluid Mixtures Containing Associating and Chainlike Molecules from a Multilayer Quasichemical Model

Sorina,

Victorov

2024

Langmuir

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In this work, we develop a theory for predicting details of the local structure in nonuniform multicomponent fluids that may contain chainlike and associating components. This theory is an extension�to the fluid interfaces and mesoscopic structures of different geometry�of the multilayer quasichemical model originally proposed by Smirnova to describe liquid solution in the vicinity of a planar solid wall. The basis of the theory is the "cut-and-bond" approach, much in spirit of SAFT, where an infinite attraction between the separated monomeric units of a chainlike molecule mimics the chemical bonds of the chain. We describe the equilibrium structure of the mixture, including the spatial distribution of the monomeric units and the local orientation of the chemical bonds in chainlike molecules, and discuss the contribution of chemical bonds to the local chemical potential in a nonuniform fluid. To test the new theory, we apply it to mixtures containing combinations of model components: a strongly associating solvent, an inert substance of varying chain length, and a chainlike amphiphile. To compare predictions from the multilayer model with the results of continuous description of nonuniform fluids, we also address the square-gradient theory and derive an analytical expression for the influence parameter that takes into account pair correlations in the quasichemical approximation. The multilayer quasichemical model developed in this work predicts formation of aggregates in liquid solution and describes the local structure of the interfaces between the coexisting liquid phases in the mixture. Our theoretical predictions agree on a qualitative level with the accumulated knowledge about the structure of different types of systems studied in this work.

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Section: Theoretical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Local Structure of Nonuniform Fluid Mixtures Containing Associating and Chainlike Molecules from a Multilayer Quasichemical Model

Sorina,

Victorov

2024

Langmuir

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“…30 There are plenty of research works employing thermodynamics to calculate the surface tension. [31][32][33][34][35][36][37][38] In particular, Prigogine and collaborators presented a relatively simple theory to explain the surface tension of polymer solutions on the basis of thermodynamics. 31 Afterward, the surface tension of several polymer solutions is investigated by Siow and Patterson on the basis of the F-H theory.…”

Section: Introductionmentioning

confidence: 99%

“…Thermodynamic modeling for the surface tension of mixtures are typically derived on the assumption that the interface is considered a thin layer separated from the vapor and bulk liquid 30 . There are plenty of research works employing thermodynamics to calculate the surface tension 31–38 . In particular, Prigogine and collaborators presented a relatively simple theory to explain the surface tension of polymer solutions on the basis of thermodynamics 31 .…”

Section: Introductionmentioning

confidence: 99%

Phase equilibria and surface tension in castor oil‐based polyols‐water–methanol mixture: Thermodynamic basis

Moon

Yang

Lee

et al. 2020

J of Applied Polymer Sci

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Considering the current environmental issues with petro-polymers, castor oil is a promising green alternative to the polyols to be used as the main raw material for polyurethane. However, the basic information regarding the processability of castor oil-based polyol (CP) such as its miscibility in different solvents is still elusive. Herein we have investigated the phase equilibria and surface tension of various CP solutions using thermo-optical analysis and pendent drop method, respectively. The modified double lattice (MDL) model was employed to theoretically describe those phase equilibria and surface behaviors. The phase diagrams of CPs/methanol binary systems represent upper critical solution temperature (UCST) behaviors, and CPs/methanol/water ternary systems show Treybal Type 2 behaviors. The surface tension results exhibit preferential solvent adsorption, which means affinity of the solvent to be present in surface is higher than that of the polymer. The calculated results showed good agreement with the experimental observations.

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“…Such a theoretical framework, which permits the calculation of the interfacial tension related to the LLE was established twenty years ago [7]. The basic idea of this approach is the applica-tion of the density gradient theory, originally developed by Van der Waals [8] and rediscovered by Cahn-Hilliard [9], to incompressible fluids, where the Helmholtz energy can be replaced by the Gibbs energy and consequently the thermodynamic properties can be modelled with a g E model rather than an equation of state [10,11] The method was used for different binary [12][13][14][15][16][17][18][19][20][21], ternary [14,21,[22][23][24][25][26] and quaternary mixtures [21,[27][28][29]. Recently, also the time-dependency of the interfacial tension caused by diffusion [14,16,24,27] or caused by a chemical reactions [21,29] were studied.…”

Section: Introductionmentioning

confidence: 99%

Liquid‐Liquid Equilibrium and Interfacial Properties of the System Water + Hexylacetate + 1‐Hexanol

Danzer

Enders

2019

Chemie Ingenieur Technik

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Experimental and theoretical investigations of the phase diagram and the interfacial tension are presented. The theoretical framework was able to predict the phase behavior and the interfacial tension with a high accuracy, where only binary experimental data enter the model parameter. The theory permits the calculation of the concentration profiles across the interface. The profiles show that 1‐hexanol will be enriched, which was expected. In same circumstances a competition between hexylacetate and 1‐hexanol was figured out leading to slight minima in the profile of 1‐hexanol.

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Investigation of interfacial properties of aqueous two-phase systems by density gradient theory

Cited by 31 publications

References 50 publications

Local Structure of Nonuniform Fluid Mixtures Containing Associating and Chainlike Molecules from a Multilayer Quasichemical Model

Local Structure of Nonuniform Fluid Mixtures Containing Associating and Chainlike Molecules from a Multilayer Quasichemical Model

Phase equilibria and surface tension in castor oil‐based polyols‐water–methanol mixture: Thermodynamic basis

Liquid‐Liquid Equilibrium and Interfacial Properties of the System Water + Hexylacetate + 1‐Hexanol

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