The physical nature of the interaction in DMSO extraction separation of C8H10 isomer/n-decane systems

In this study, the liquid-liquid equilibrium of DMSO-C8H10 aromatic isomer-n-decane systems was measured at 30 °C under atmospheric pressure at first, followed by Othmer-Tobias equation data reliability verification and NRTL/UNIQUAC activity coefficient model correlation. Moreover, intermolecular interaction energies and molecular polarity indexes (MPI) were calculated to interpret the extraction results. Finally, a set of wave function analyses was accomplished to elaborate the physical nature of the interaction in the DMSO extraction process. These investigations show that: (1) intermolecular interaction energy and the MPI results corroborate the aromatic and alkane extraction distribution coefficients well. (2) The interactions between aromatics and DMSO are weak hydrogen bonding and van der Waals (vdW) interactions. The attractive part mainly involves dispersion (49.57-53.30%) and electrostatic (35.49-37.83%) effects. (3) The interactions between aromatics and n-decane are vdW interactions, dominated by attractive dispersion (70.41-70.93%) and repulsive exchange effects.