TY  - JOUR
ID  - scholars7192
KW  - Atmospheric pressure; Atmospheric temperature; Entropy; Hydrogen bonds; Ions; Liquids; Negative ions; Positive ions; Surface tension; Temperature
KW  -  COSMO-RS; Critical temperatures; Cyano-based; Imidazolium-based; Surface enthalpies; Surface entropies
KW  -  Ionic liquids
N2  - 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.
VL  - 409
A1  - Almeida, H.F.D.
A1  - Carvalho, P.J.
A1  - Kurnia, K.A.
A1  - Lopes-da-Silva, J.A.
A1  - Coutinho, J.A.P.
A1  - Freire, M.G.
JF  - Fluid Phase Equilibria
UR  - https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947237803&doi=10.1016%2fj.fluid.2015.10.044&partnerID=40&md5=484665ceddee203bda4686fb77b36268
Y1  - 2016///
TI  - Surface tensions of ionic liquids: Non-regular trend along the number of cyano groups
SP  - 458
N1  - cited By 23
AV  - none
EP  - 465
PB  - Elsevier
SN  - 03783812
ER  -