Ionic liquids (ILs) are gaining attention as potential substitutes for classical organic solvents in extraction processes. This article reports the results of a study on the use of the IL 1,3-dimethylimidazolium methyl sulfate ([MMIM][MeSO4]) as an extraction solvent in petrochemical processes for the removal of heptane from its mixtures with ethanol. The separation of heptane and ethanol is valuable but difficult because of the formation of an azeotropic mixture. Knowledge of the liquid-liquid equilibria (LLE) of this mixture is essential for the design of separation techniques. For this reason, the experimental LLE for the ternary system heptane + ethanol + [MMIM][MeSO4] were investigated at 298.15 K. The solvent capacity of [MMIM][MeSO4] was compared with those of other ILs. The extraction process derived from the use of this solvent was simulated using conventional software, and the obtained results are reported. Experimental data were obtained in a laboratory-scale packed-column extraction system for the separation of this azeotropic mixture using [MMIM][MeSO4]. A comparison with the experimental column data for other ILs is included. Moreover, it is concluded that [MMIM][MeSO4] has the highest extraction efficiency. Also, this IL can be recycled, meaning that the separation process results in a vast reduction of energy consumption.