Global phase diagrams of model and real binary fluid mixtures: Lorentz–Berthelot mixture of attractive hard spheres

Abstract

The phase behavior and global phase diagram of binary mixtures of attractive hard spheres described by a hard-sphere mixture equation of state with a mean field term and the Lorentz–Berthelot combining rule are examined in detail in dependence on the ratio of (i) the hard-sphere diameters and (ii) the strength of the mean field attraction. It is shown that in addition to the usual phenomena, the studied mixture exhibits also the closed liquid–liquid immiscibility loop (Type VI and VII behavior) and a variety of new azeotropic phenomena. Topology of phase diagrams is discussed in detail with emphasis on the boundary states and is compared with that based on the one-fluid van der Waals equation approach.