High-pressure volumetric properties of ionic liquids: 1-butyl-3-methylimidazolium tetrafluoroborate, [C4mim][BF4], 1-butyl-3-methylimidazolium methylsulfate [C4mim][MeSO4] and 1-ethyl-3-methylimidazolium ethylsulfate, [C2mim][EtSO4]

Pressure-density-temperature measurements of the following pure ionic liquids-1-buty1-3-methylimidazolium tetrafluoroborate, [C(4)mim]BF4], 1-butyl-3-methylimidazolium methylsulfate [C(4)mim][MeSO4] and 1-ethyl-3-methylimidazolium ethylsulfate [C(2)mim][EtSO4] were performed using a vibrating tube densimeter over the temperature range (283.15 to 353.15)K and the pressure range (0.1 to 35)MPa. Experimental densities have been correlated by the Tait equation with the temperature dependent parameters. The isobaric expansivity and isothermal compressibility have been calculated. The influence of the cation alkyl chain length and the character of anion on the measured properties were discussed. (C) 2011 Elsevier B.V. All rights reserved.