Vapor−Liquid Interfacial Properties of Mutually Saturated Water/1-Butanol Solutions

Abstract

Adsorption and ordering at the vapor-liquid interfaces of mutually saturated water/1-butanol solutions at a temperature of 298.15 K were investigated using configurational-bias Monte Carlo simulations in the Gibbs ensemble and compared to the surface properties of neat water and 1-butanol liquids. A dense 1-butanol monolayer is observed at the surface of the water-rich phase, which results in a substantial decrease of its surface tension. In contrast, there is no enrichment of water molecules at the surface of the butanol-rich phase, and its surface tension is not significantly changed. Analysis of the interfacial structures reveals that these systems exhibit orientational ordering and composition heterogeneity. Analysis of the hydrogen-bonding distributions suggests that the formation of the 1-butanol monolayer is driven by an excellent match between water and the primary alcohol; that is, additional hydrogen bonds are formed between the excess free hydrogens of surface water and the excess hydrogen-bond acceptor sites of 1-butanol.

Collision dynamics and uptake of water on alcohol-covered ice

“…10 in Lawrence et al, 2005) and argue that high mobility and density fluctuations in the butanol layer readily allow for evaporation. Our experimental temperature range ≤ 200 K and monolayer coverages, are distinctly different from the Chen et al (2002) simulations at 298.15 K, and the Lawrence et al (2005) experiments with sub-monolayer films. In our case solid ice is completely covered by the alcohol monolayers, yet still the transport rate of D 2 O from the top of the film to the subsurface ice outstrips the rate of desorption allowing nearly all of the D 2 O to quickly penetrate the alcohols.…”

“…Previous work has suggested that long-chain surfactants form well ordered impermeable domains separated by regions of more disorder where "accessible surface" exists (Barnes, 1997). For shorter chain alcohols this argument is supported by simulations that show a monolayer butanol structure is mutually beneficial for the alcohol and water due to excess hydrogen bond matching at the interface, that results in orientational ordering but compositional heterogeneity (Chen et al, 2002). Lawrence et al (2005) used this idea to explain their observation of no evaporative impediment for D 2 O leaving ≈ 80% butanol covered sulfuric acid.…”

“…Clearly, in this configuration impinging water can access the ice surface. In the case of 1-butanol simulated monolayers are well-organized but include density fluctuations that lead the butanol to have more conformational disorder than molecules with longer alkyl tails, like hexanol (Chen et al, 2002).…”

Inhomogeneous Monte Carlo simulation of the vapor-liquid equilibrium of benzene between 300 K and 530 K

“…This method can also be modified in order to study the liquid-liquid equilibria between two immiscible liquids [19,20]. The use of boxes with interface in the Gibbs Ensemble Monte Carlo also represents a powerful technique which enables us to study the properties of interfaces between vapor and saturated solution of two immiscible liquids [21][22][23]. Molecular Dynamics (MD) simulations in such boxes were also used in studying the free surface of alkane oligomers [24][25][26].…”

From Organic Geochemistry to Statistical Thermodynamics: the Development of Simulation Methods for the Petroleum Industry

“…Many other improvements are worth testing, such as the non-Boltzman sampling and the gradual insertion technique. With the explicit simulation of interface, it will be possible to predict interfacial tensions and achieve a detailed understanding of the role of surfactants (Goujon et al, 2001;Chen et al, 2002). In a nearby area, network calculations help to consider much larger systems (a few tens of nanometers) thereby helping to simulate micellar systems that are inaccessible with classical atomistic techniques.…”