Journal
JOURNAL OF PHYSICAL CHEMISTRY B
Volume 116, Issue 14, Pages 4228-4238Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jp3010844
Keywords
-
Categories
Funding
- Conseil Regional de la region Centre
Ask authors/readers for more resources
We present a study on the transport properties through conductivity (sigma), viscosity (eta), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids-pyrrolidinium hydrogen sulfate, [Pyrr][HSO4], and pyrrolidinium trifluoroacetate, [Pyrr][CF3COO]-and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then ivestigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other word, for Such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content the labile protons are in solution as H3O+. This water weight fraction appears to be the solvation limit of the H+ ions by water molecules in these two PILs solutions. However, [Pyrr][HSO4] and [Pyrr][CF3COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF3COO], eta, sigma, D and the attractive potential, E-pov between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO4], the strong H-bond between the HSO4- anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS.cm(-1) for water weight fraction close to 60% at 298 K.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available