Binary Liquid–Liquid Equilibria for Systems of Mono- or Disubstituted Haloalkanes (Cl, Br) and Pyridinium-Based Ionic Liquids. Advances in the Experimentation and Interpretation of Results

This work presents the measurements made to define the temperature–composition curves for a set of binary systems composed of several pyridinium-based ionic liquids (ILs) [bpy][BF4] and [bYmpy][BF4] (Y = 2,3,4) with mono- and dihaloalkanes (Cl and Br) in the temperature interval [280–473] K and at atmospheric pressure. With the exception of the short chain dichloroalkanes (1,1- and 1,2-), all the compounds present some degree of immiscibility with the ionic liquids selected. Solubility points (xIL,T) are determined by an image identification experimental procedure, which is described in detail and permits a more accurate definition of the liquid–liquid equilibria coexistence curves. A semiempirical model is proposed to correlate the experimental results of liquid–liquid equilibria (LLE) and the fits are compared with those obtained with the NRTL model. In both cases, a rigorous procedure is proposed to estimate LLE data considering the isoactivity criteria and a global test to guarantee the stability of t...