TY - JOUR
T1 - Effects of cations and anions on transport properties in tetrafluoroborate-based ionic liquids
AU - Wu, Tzi Yi
AU - Sun, I-Wen
AU - Gung, Shr Tusen
AU - Lin, Ming Wei
AU - Chen, Bor Kuan
AU - Wang, Hong-Paul
AU - Su, Shyh-Gang
PY - 2011/5/1
Y1 - 2011/5/1
N2 - The self-diffusion coefficient, diffusion radius, dissociation and association degree, and transport numbers of various cations (methylpyrrolidinium, 1-methyl-2-oxopyrrolidinium, methylpiperidinium, ethylmorpholinium, and methylmorpholinium) and tetrafluoroborate anion in ionic liquids are measured by observing 1H and 19F nuclei using the pulsed-field gradient spin-echo (PGSE) NMR technique at various temperatures. The self-diffusion coefficients determined for the cations and anions of ionic liquids by PGSE NMR method exhibit tetrafluoroborate anion have higher value than cations over a wide temperature range. The temperature dependence of the self-diffusion coefficient obeys the Vogel-Tamman-Fulcher (VTF) equation, and the VTF parameters were presented. The self-diffusion coefficient is analyzed in terms of the Stokes-Einstein equation and the Nernst-Einstein equation, the hydrodynamic radius of ILs is calculated from Stokes-Einstein equation and the molar conductivity (ΛNMR) calculated from the Nernst-Einstein equation is derived without considering ionic association. The dissociation degree of cations and anions range from 72 to 86% for [PipMe][BF4], [PyrMe][BF4], [MorMe][BF4], and [MorEt][BF4], whereas the ratio is 32% for [PyrOMe][BF4] at 303K, this difference can be explained by taking the ionic association into consideration for [PyrOMe][BF4].
AB - The self-diffusion coefficient, diffusion radius, dissociation and association degree, and transport numbers of various cations (methylpyrrolidinium, 1-methyl-2-oxopyrrolidinium, methylpiperidinium, ethylmorpholinium, and methylmorpholinium) and tetrafluoroborate anion in ionic liquids are measured by observing 1H and 19F nuclei using the pulsed-field gradient spin-echo (PGSE) NMR technique at various temperatures. The self-diffusion coefficients determined for the cations and anions of ionic liquids by PGSE NMR method exhibit tetrafluoroborate anion have higher value than cations over a wide temperature range. The temperature dependence of the self-diffusion coefficient obeys the Vogel-Tamman-Fulcher (VTF) equation, and the VTF parameters were presented. The self-diffusion coefficient is analyzed in terms of the Stokes-Einstein equation and the Nernst-Einstein equation, the hydrodynamic radius of ILs is calculated from Stokes-Einstein equation and the molar conductivity (ΛNMR) calculated from the Nernst-Einstein equation is derived without considering ionic association. The dissociation degree of cations and anions range from 72 to 86% for [PipMe][BF4], [PyrMe][BF4], [MorMe][BF4], and [MorEt][BF4], whereas the ratio is 32% for [PyrOMe][BF4] at 303K, this difference can be explained by taking the ionic association into consideration for [PyrOMe][BF4].
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U2 - 10.1016/j.jtice.2010.09.006
DO - 10.1016/j.jtice.2010.09.006
M3 - Article
AN - SCOPUS:79958217025
VL - 42
SP - 513
EP - 522
JO - Journal of the Taiwan Institute of Chemical Engineers
JF - Journal of the Taiwan Institute of Chemical Engineers
SN - 1876-1070
IS - 3
ER -