Volumetric, ultrasonic and optical studies of molecular interactions in binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with N-octyl-2-pyrrolidinone at temperatures from 298.15 to 323.15Â K

Excess molar volumes, VmE as function of mole fraction, x1 of [Bmim][NTf2] of [Bmim][NTf2] + NOP binary mixtures