Phase equilibria Study of the (benzene+ cyclohexane+N,N-dimethylformamide+ potassium thiocyanate) quaternary systems

• A novel composite solvent KSCN + DMF was used as extractant in extracting benzene from cyclohexane.
• LLE data for benzene + cyclohexane + DMF + KSCN were measured at 298.15 K.
• The two phase region and selectivity coefficients increased with the increasing of KSCN.
• The experimental data could be correlated well with the NRTL model.
• Equilibrium data revealed the DMF + KSCN complex solvent had a high selectivity for benzene.

This work demonstrates the ability of N,N-dimethylformamide + potassium thiocyanate(DMF + KSCN) to act as a novel complex solvent for the removal of benzene from its mixture with cyclohexane. The (liquid + liquid) equilibria (LLE) were measured for a quaternary system of (DMF + KSCN + benzene + cyclohexane) under atmospheric pressure and at temperature 298.15 K. The tie-line data for quaternary mixtures of (DMF + KSCN + benzene + cyclohexane) are also presented. The selectivity coefficients from these LLE data were calculated and found to be better than those previously reported in the literature for the (DMF + benzene + cyclohexane) systems. Excellent correlation of data by the nonrandom two-liquid (NRTL) model was seen for the quaternary system and the predicted results were found to be in fairly good agreement with experimental data.

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