Liquid–Liquid Equilibria for the Systems: Heptane + Benzene + Solvent (Propylene carbonate, <i>N,N</i>-Dimethylformamide, or Mixtures) at Temperatures from (303.2 to 323.2) K

The extraction of benzene from heptane by the solvents such as <i>N,N</i>-dimethylformamide (DMF), propylene carbonate, and complex solvent (DMF + propylene carbonate) were researched. The liquid–liquid equilibrium (LLE) data were experimentally obtained for the ternary systems heptane + benzene + DMF and heptane + benzene + propylene carbonate at 313.2 K and atmospheric pressure and for the quaternary systems heptane + benzene + DMF + propylene carbonate at (303.2, 313.2, and 323.2) K and atmospheric pressure. The nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) models were used to correlate the LLE data satisfactorily, and the selectivity and distribution coefficients of benzene were calculated. Due to its high selectivity and suitable distribution coefficient, DMF + propylene carbonate can be used as a potential extracting solvent to separate benzene from heptane