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Investigation of the liquid-vapour interface of aqueous methylamine solutions by computer simulation methods
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SYSNO ASEP 0508960 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Investigation of the liquid-vapour interface of aqueous methylamine solutions by computer simulation methods Author(s) Horváth, R. A. (HU)
Fábián, Balázs (UOCHB-X) ORCID
Szöri, M. (HU)
Jedlovszky, P. (HU)Article number 110978 Source Title Journal of Molecular Liquids. - : Elsevier - ISSN 0167-7322
Roč. 288, Aug 15 (2019)Number of pages 14 s. Language eng - English Country NL - Netherlands Keywords methylamine-water mixtures ; intrinsic surface analysis ; computer simulation ; liquid-vapour interface Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry Method of publishing Limited access Institutional support UOCHB-X - RVO:61388963 UT WOS 000480664700075 DOI 10.1016/j.molliq.2019.110978 Annotation Molecular dynamics simulations of the liquid-vapour interface of water-methylamine mixtures of eight different compositions, including neat water, are performed on the canonical (N,V,T) ensemble at 280 K. The molecules constituting the first three individual molecular layers beneath the liquid surface are identified by the Identification of the Truly Interfacial Molecules (ITIM) method. The results indicate that methylamine molecules are strongly adsorbed in the first, and somewhat depleted in the second molecular layer, while the composition of the third layer agrees well with that of the bulk liquid phase. On the other hand, methylamine molecules do not show considerable self-association within the surface layer. The orientational preferences of the methyl amine molecules at the liquid surface are clearly governed by the requirement of maximizing their hydrogen bonding interaction. As a consequence, methylamine molecules point by their apolar CH3 group straight to the vapour, while by the potential hydrogen bonding directions of the NH2 group flatly to the liquid phase. Further, within the surface layer, methylamine molecules stay, on average, noticeably farther from the bulk liquid phase than waters. Increasing methylamine mole fraction leads to the gradual breaking up of the lateral percolating H-bonding network of the surface molecules. Finally, methylamine molecules accelerate, while water molecules slow down the exchange of both species between the liquid surface and the bulk liquid phase. Further, methyl amine molecules slow down the lateral diffusion of each other, and even prevent water molecules from showing noticeable lateral diffusion within the surface layer. The reason for this latter effect is that the mean residence time of the water molecules at the liquid surface becomes considerably shorter than the characteristic time of their lateral diffusion in the presence of methylamine. Workplace Institute of Organic Chemistry and Biochemistry Contact asep@uochb.cas.cz ; Kateřina Šperková, Tel.: 232 002 584 ; Jana Procházková, Tel.: 220 183 418 Year of Publishing 2020 Electronic address https://www.sciencedirect.com/science/article/abs/pii/S0167732219318161?via%3Dihub
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