A group contribution method for viscosity estimation of ionic liquids

Based on experimental viscosity data collected from the literature and using density data obtained from a predictive method previously roposed by the authors, a group contribution method is proposed to estimate viscosity of imidazolium-, pyridinium-, and pyrrolidiniumased ILs containing hexafluorophosphate (PF6), tetrafluoroborate (BF4), bis(trifluoromethanesulfonyl) amide (Tf2N), chloride (Cl), acetate CH3COO), methyl sulfate (MeSO4), ethyl sulfate (EtSO4), and trifluoromethanesulfonate (CF3SO3) anions, covering wide ranges of temperture, 293–393 K and viscosity, 4–21,000 cP. It is shown that a good agreement with literature data is obtained. For circa 500 data points f 29 ILs studied, a mean percent deviation (MPD) of 7.7% with a maximum deviation smaller than 28% was observed. 71.1% of the estiated viscosities present deviations smaller than 10% of the experimental values while only 6.4% have deviations larger than 20%. The roup contribution method here developed can thus be used to evaluate the viscosity of new ionic liquids in wide ranges of temperatures t atmospheric pressure and, as data for new groups of cations and anions became available, can be extended to a larger range of ionic iquids. 2008 Elsevier B.V. All rights reserved.