title: 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.
authors.affiliation: Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104-6323, USA. binchen@cmm.chem.upenn.edu
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: J Ilja
authors.initials: JI
authors.lastname: Siepmann
authors.forename: Michael L
authors.initials: ML
authors.lastname: Klein
mesh_terms: D020001:1-Butanol / Q000737:chemistry*; D003198:Computer Simulation; D008956:Models, Chemical; D009010:Monte Carlo Method; D012996:Solutions; D014835:Volatilization; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D020001:1-Butanol