Measurement and correlation of high pressure densities of ionic liquids, 1-ethyl-3-methylimidazolium L -lactate ([emim][Lactate]), 2-hydroxyethyl- trimethylammonium L -lactate ([(C₂H₄OH)(CH ₃)₃N][Lactate]), and 1-butyl-3-methylimidazolium chloride ([bmim][Cl])

Pressure-density-temperature (pρT) data for three types of ionic liquid, [emim][lactate], [(C₂H₄OH)(CH₃) ₃N][lactate], and [bmim][Cl], were measured with a bellows type dilatometer at temperatures up to 452 K and at pressures up to 200 MPa. The Tait equation could correlate the density data as a function of temperature and pressure to within an average relative deviation (ARD) of 0.014 %. The thermal expansion coefficients and the isothermal compressibilities were estimated with the Tait equation, and their variations with temperature and pressure, dα_p/dT and dk_T/dp, were found to be negative. Lattice type equations of state were applied to correlate the data. The densities could be correlated to within an ARD of 0.21 % and 0.067 %, for the Sanchez-Lacombe equation of state and the ε-modified Sanchez-Lacombe equation of state, respectively. The equation-of-state parameters determined should be useful in estimating the properties of mixtures and in estimating the phase equilibria of binary and multicomponent systems.