The validity of the potential model in predicting the structural, dynamical, thermodynamic properties of the unary and binary mixture of water-alcohol: Ethanol-water case

Obeidat, Abdalla; Al-Salman, Rakan; Abu-Ghazleh, Hind

doi:10.1063/1.5040852

Cited by 9 publications

(4 citation statements)

References 41 publications

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“…We note that these force fields allow for flexibility of the ethanol and water molecular structures during the course of the simulations. Several recent molecular dynamics studies − have shown how such force fields provide a reliable description of the structure of ethanol–water mixtures, with excellent reproduction of the experimental radial distribution functions in most cases. To have a statistically significant sample in the extreme regions of the concentration range, i.e., where the content of water or ethanol is particularly low, the volume of the slab representing the system must be particularly large and, at the same time, must have a transversal dimension adequate to be able to distinguish a surface region from a bulk region.…”

Section: Surface Properties Of Ethanol Aqueous Solutionsmentioning

confidence: 99%

Ethanol in Aqueous Solution Studied by Microjet Photoelectron Spectroscopy and Theory

et al. 2022

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Metrics & MoreArticle Recommendations CONSPECTUS: By combining results and analysis from cylindrical microjet photoelectron spectroscopy (cMJ-PES) and theoretical simulations, we unravel the microscopic properties of ethanol−water solutions with respect to structure and intermolecular bonding patterns following the full concentration scale from 0 to 100% ethanol content.In particular, we highlight the salient differences between bulk and surface. Like for the pure water and alcohol constituents, alcohol−water mixtures have attracted much interest in applications of X-ray spectroscopies owing to their potential of combining electronic and geometric structure probing. The water mixtures of the two simplest alcohols, methanol and ethanol, have generated particular attention due to their delicate hydrogen bonding networks that underlie their structural and thermodynamic properties. Macroscopically ethanol−water seems to mix very well, however microscopically this is not true. The aberrant thermodynamics of water−alcohol mixtures have been suggested to be caused by energy differences of hydrogen bonding between water−water, alcohol− alcohol and alcohol−water molecules. These networks may perturb the local character of the interaction between X-rays and matter, calling for analysis that go beyond the normally applied local selection and building block rules and that can combine the effects of light−matter, intra-and intermolecular interactions. However, despite decades of ongoing research there are still controversies of the precise nature of hydrogen bonding networks that underlie the mixing of these simple molecules. Our combined analysis indicates that at low concentration ethanol molecules form a film at the surface since ethanol at the surface can expose its hydrophobic part to the vacuum retaining its two (or three) possible hydrogen bonds, while water at the surface cannot retain all its four possible hydrogen bonds. Thus, ethanol at the surface becomes energetically favorable. Ethanol molecules show a tilting angle variation of the C−C axis with respect to the surface normal as large as 60°at very low concentration. In bulk, around ca. ten %, the ethanol oxygen atoms tend to make a third acceptor hydrogen bond to water molecules. At ca. 20 %, there is a U-shaped change in the CH 3 to CH 2 OH binding energy (BE) shift indicating the presence of ring-like agglomerates called clathrate structures. At the surface, between 5 and 25%, ethanol forms a closely packed layer with the smallest C−C tilting angle variation down to ∼20°. Above 25% and below the azeotrope at the surface, ethanol shows an increase in the tilting angle variation, while at very high ethanol concentrations water tends to move to the surface so giving a microscopic explanation of the azeotrope effect. This migration is connected to the presence of longer (shorter) ethanol chains in the bulk (surface). A brief comparison with discussions and predictions from other spectroscopic techniques is also given. We emphasize the execution of an integrated a...

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Section: Surface Properties Of Ethanol Aqueous Solutionsmentioning

confidence: 99%

Ethanol in Aqueous Solution Studied by Microjet Photoelectron Spectroscopy and Theory

et al. 2022

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“…The simulation results that are presented here have been obtained by using a classical nonpolarizable model interaction potential for neat ethanol (TraPPE-UA) and neat water (SPC/E) These model interaction potentials are known to successfully predict a number of neat liquid properties measured under ambient conditions. The TraPPE-UA interaction parameters were found to successfully predict the temperature-dependent experimental diffusivities, composition-dependent surface tension, dielectric relaxation properties, and static structure factors of aqueous solutions of alcohol. − In addition, the experimental azeotropic conditions for ethanol-hexane and ethanol-benzene binary mixtures were successfully predicted by the TraPPE-UA potential . All these provide confidence that these model potentials for neat systems may also be employed to generate, at least, a qualitatively correct understanding of the composition-dependent structural and dynamical properties of ethanol–water binary mixtures at different temperatures.…”

Section: Computational Methods and Experimental Detailsmentioning

confidence: 70%

Identical Diffusion Distributions and Co-Cluster Formation Dictate Azeotrope Formation: Microscopic Evidences and Experimental Signatures

Chowdhury,

Ghorai,

Maity

et al. 2023

J. Phys. Chem. B

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What selects azeotropic pairs and governs the azeotropic conditions (composition and temperature) is an open and intriguing question. A combined simulation and experimental work presented here investigates this by considering ethanol–water mixtures. We find identical distributions of center-of-mass diffusion coefficients for ethanol and water molecules under the azeotropic condition (95.5 wt % ethanol +4.5 wt % water, T azeo = 351.1K). Moreover, the particle displacements show strong interspecies correlations at T azeo. Interestingly, simulated reorientation time distributions become identical at T azeo but at a composition different from that at which the translational diffusion distributions overlapped. Cluster analyses indicate that solutions at T azeo with x water ≤ 15 wt % are more microheterogeneous than those with higher water content, although no anomaly in the composition-dependent solution structural properties was detected. Ethanol–water and ethanol–ethanol interaction energies show pronounced nonideal composition dependence, but the size of the relative fluctuations in them remained small (∼0.5k B T). Rare water–water H-bonding, predominant water–ethanol H-bonding, and a sizable population of “free” water molecules characterize the azeotropic solutions. The red edge excitation spectroscopic (REES) measurements with a dissolved anionic fluorescent dye, coumarin343 (C343), support the predicted solution microheterogeneity by showing a nonmonotonic composition dependence of the excitation energy-induced changes in the fluorescence emission spectral frequencies and bandwidths, the largest changes being under the azeotropic condition. Subsequent dynamic anisotropy measurements reveal a nonmonotonic composition dependence of C343 rotation times with a peak under the azeotropic condition. In summary, equalization of the component translational diffusion coefficients and solution microheterogeneity with regular composition dependence of the solution structure appear to characterize the ethanol–water azeotrope.

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“…In this study, we chose the best two potential models based on their success in our previous works; [62][63][64] the Optimized Potentials for Liquid Simulations all-atoms (OPLSAA) 66 and Transferable Potentials for Phase Equilibria unite-atom (TraPPE-UA) 67 force elds. The number of interaction sites in a TraPPE-UA force eld is designed to be as small as possible without losing excessive accuracy.…”

Section: Potential Modelsmentioning

confidence: 99%

“…In our previous work, 62–65 we studied the properties of pure 1-alkanol and its mixtures with water using various models, most notably the OPLS-AA 66 and TraPPE-UA 67 models. These models demonstrated good efficiency in predicting different physical properties when compared to experimental values.…”

Section: Introductionmentioning

confidence: 99%

Self-diffusion and shear viscosity of pure 1-alkanol unary system: molecular dynamics simulation and review of experimental data

Jaradat,

Al-Salman,

Obeidat

2024

RSC Adv.

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The validity of the potential model in predicting the structural, dynamical, thermodynamic properties of the unary and binary mixture of water-alcohol: Ethanol-water case

Cited by 9 publications

References 41 publications

Ethanol in Aqueous Solution Studied by Microjet Photoelectron Spectroscopy and Theory

Ethanol in Aqueous Solution Studied by Microjet Photoelectron Spectroscopy and Theory

Identical Diffusion Distributions and Co-Cluster Formation Dictate Azeotrope Formation: Microscopic Evidences and Experimental Signatures

Self-diffusion and shear viscosity of pure 1-alkanol unary system: molecular dynamics simulation and review of experimental data

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