The study of hydrophobic hydration in supercritical water–methanol mixtures

Киселев, М. Г.; Noskov, Sergei Y.; Puhovski, Yu.P.; Kerdcharoen, Teerakiat; Hannongbua, Supot

doi:10.1016/s1093-3263(00)00100-5

Cited by 18 publications

(5 citation statements)

References 20 publications

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“…Thus, alcohols are sometimes seen as soluble hydrocarbons, and models to explain the properties of their mixtures with water are still discussed. − Molecular simulations are certainly the methods of choice to elucidate the properties of these systems on a microscopic level. Most theoretical efforts have used molecular dynamics (MD) simulations to study the structure, the dynamic properties, and the properties of mixing, separately or together. − A number of experimental investigations have also been performed over the years, and most properties such as the density, − the diffusion, the properties of mixing, − and the structure ,, are well known.…”

Section: Introductionmentioning

confidence: 99%

Water–Methanol Mixtures: Simulations of Mixing Properties over the Entire Range of Mole Fractions

Soetens

Bopp

2015

J. Phys. Chem. B

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Numerous experimental and theoretical investigations have been devoted to the hydrogen bond in pure liquids and mixtures. Among the different theoretical approaches, molecular dynamics (MD) simulations are predominant in obtaining detailed information, on the molecular level, simultaneously on the structure and the dynamics. Water and methanol are the two most prominent hydrogen-bonded liquids, and they and their mixtures have consequently been the subject of many studies; we revisit here the problem of the mixtures. An important first step is to check whether a classical potential model, the components of which are deemed to be satisfactory for the pure liquids, is able to reproduce the known thermodynamic excess properties of the mixtures sufficiently well. We have used the available BJH (water) and PHH (methanol) flexible models because they are by construction mutually compatible and also well suited to study, in a second step, some dynamic property characteristic of hydrogen-bonded liquids. In this article we show that these models, after a slight reparametrization for use in NpT simulations, reproduce the essential features of the excess mixing and molar properties of water-methanol mixtures. Furthermore, in the pure liquids, the agreement of the radial distribution functions with experiment remains as satisfactory as before. Similarly, the translation self-diffusion coefficients D are modified by less than 10%. In the mixtures, they evolve nonmonotonously as a function of mole fraction.

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Section: Introductionmentioning

confidence: 99%

Water–Methanol Mixtures: Simulations of Mixing Properties over the Entire Range of Mole Fractions

Soetens

Bopp

2015

J. Phys. Chem. B

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“…This effect is quantified through the extent to which a given water molecule and its surrounding neighbors adopt a tetrahedral arrangement. To characterize the tetrahedral arrangement around a reference water molecule, we used two widely used definitions, the first one being sensitive to the mutual orientation of water molecules forming the tetrahedron – and the second one being sensitive to their radial distribution. – In order to understand the effect of urea on the tetrahedral arrangement of water molecules; we used the nearest neighbor approach – to get information on the radial and mutual orientation of the water molecules around a reference one. We also investigated the effect of adding urea on the tetrahedral local structure of water molecules in the first hydration shell of urea as well as in the vicinity of the amine and carboxyl groups of urea.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Urea on the Structure of Water: A Molecular Dynamics Simulation

et al. 2010

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This paper reports an analysis using molecular dynamics simulations of the effect of urea on the structure of water. Two definitions of the tetrahedral distributions are used to quantify this effect. The first one is sensitive to the mutual orientation between a reference water molecule and the water molecules forming the tetrahedron, and the second is sensitive to their radial distribution. The analysis shows that increasing urea mole fraction results in a reduction of the structured tetrahedral arrangement contribution in favor of an unstructured one. In order to understand this behavior, we used the nearest neighbor approach which allows us to get unambiguous information on the radial and orientation distributions of the water molecules around a probe one. The results indicate that the decrease of the tetrahedral arrangement of the nearest neighbors around a probe water molecule is associated with both the increase of the fluctuation in their radial distances as well as with the loss of their mutual orientations with respect to those observed in pure water. The tetrahedral distribution of water in the hydration shell of urea as well as that around its carbonyl and amine groups is also discussed.

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“…The methanol-water binary system was chosen because methanol is the simplest amphiphilic molecule, and methanol aqueous solution has often been used as a prototype to study the coexistence of hydrophilic and hydrophobic hydrations. 7 Recent experiments and simulations indicate that methanol aqueous solutions are immiscible at a molecular level, even though they are completely miscible across the entire range of concentration. 8 9 Despite these studies, significant controversies exist concerning the size and topology of clusters formed in methanol aqueous solutions.…”

Section: Introductionmentioning

confidence: 99%

Nanoimmiscibility: Selective Absorption of Liquid Methanol–Water Mixtures in Carbon Nanotubes

Liu¹,

Consta²,

Goddard³

2010

J. Nanosci. Nanotech.

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Despite the continuing research interests in CNT-liquid systems, the microscopic structure and transport behavior of liquid mixtures in carbon nanotubes (CNTs) remain poorly understood. Methanol and water liquids are completely miscible across the entire range of concentration; however, recent research reveals that they are immiscible at a molecular level. In this work, we carried out classical molecular dynamics to study the molecular distribution, structure ordering, clustering and transport behavior of liquid methanol-water mixtures within CNT confinement. We found that CNTs preferentially absorbed methanol over water molecule even though the latter has a smaller molecular size, indicating that chemical effect such as molecular hydrophilicity plays a crucial role in the molecular absorption of CNTs. Due to the selective absorption of CNTs, methanol aqueous solution changes from microscopically immiscible to macroscopically immiscible at nanoscale. This nanoscale immiscibility may be utilized in various applications of CNTs including direct methanol fuel cells, nanosensors, molecular sieves, nanofluidic chips, and capsules for drug delivery.

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The study of hydrophobic hydration in supercritical water–methanol mixtures

Cited by 18 publications

References 20 publications

Water–Methanol Mixtures: Simulations of Mixing Properties over the Entire Range of Mole Fractions

Water–Methanol Mixtures: Simulations of Mixing Properties over the Entire Range of Mole Fractions

The Effect of Urea on the Structure of Water: A Molecular Dynamics Simulation

Nanoimmiscibility: Selective Absorption of Liquid Methanol–Water Mixtures in Carbon Nanotubes

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