eprintid: 7192
rev_number: 2
eprint_status: archive
userid: 1
dir: disk0/00/00/71/92
datestamp: 2023-11-09 16:18:59
lastmod: 2023-11-09 16:18:59
status_changed: 2023-11-09 16:08:42
type: article
metadata_visibility: show
creators_name: Almeida, H.F.D.
creators_name: Carvalho, P.J.
creators_name: Kurnia, K.A.
creators_name: Lopes-da-Silva, J.A.
creators_name: Coutinho, J.A.P.
creators_name: Freire, M.G.
title: Surface tensions of ionic liquids: Non-regular trend along the number of cyano groups
ispublished: pub
keywords: Atmospheric pressure; Atmospheric temperature; Entropy; Hydrogen bonds; Ions; Liquids; Negative ions; Positive ions; Surface tension; Temperature, COSMO-RS; Critical temperatures; Cyano-based; Imidazolium-based; Surface enthalpies; Surface entropies, Ionic liquids
note: cited By 23
abstract: Ionic liquids (ILs) with cyano-functionalized anions are a set of fluids that are still poorly characterized despite their remarkably low viscosities and potential applications. Aiming at providing a comprehensive study on the influence of the number of -CN groups through the surface tension and surface organization of ILs, the surface tensions of imidazolium-based ILs with cyano-functionalized anions were determined at atmospheric pressure and in the (298.15-343.15) K temperature range. The ILs investigated are based on 1-alkyl-3-methylimidazolium cations (alkyl = ethyl, butyl and hexyl) combined with the SCN-, N(CN)2-, C(CN)3- and B(CN)4- anions. Although the well-known trend regarding the surface tension decrease with the increase of the size of the aliphatic moiety at the cation was observed, the order obtained for the anions is more intricate. For a common cation and at a given temperature, the surface tension decreases according to: N(CN)2- > SCN- > C(CN)3- > B(CN)4-. Therefore, the surface tension of this homologous series does not decrease with the increase of the number of -CN groups at the anion as has been previously shown by studies performed with a more limited matrix of ILs. A maximum in the surface tension and critical temperature was observed for N(CN)2-based ILs. Furthermore, a minimum in the surface entropy, indicative of a highly structured surface, was found for the same class of ILs. All these evidences seem to be a result of stronger hydrogen-bonding interactions occurring in N(CN)2-based ILs, when compared with the remaining CN-based counterparts, and as sustained by cation-anion interaction energies derived from the Conductor Like Screening Model for Real Solvents (COSMO-RS). © 2015 Elsevier B.V.
date: 2016
publisher: Elsevier
official_url: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947237803&doi=10.1016%2fj.fluid.2015.10.044&partnerID=40&md5=484665ceddee203bda4686fb77b36268
id_number: 10.1016/j.fluid.2015.10.044
full_text_status: none
publication: Fluid Phase Equilibria
volume: 409
pagerange: 458-465
refereed: TRUE
issn: 03783812
citation:   Almeida, H.F.D. and Carvalho, P.J. and Kurnia, K.A. and Lopes-da-Silva, J.A. and Coutinho, J.A.P. and Freire, M.G.  (2016) Surface tensions of ionic liquids: Non-regular trend along the number of cyano groups.  Fluid Phase Equilibria, 409.  pp. 458-465.  ISSN 03783812