Liquid–Liquid Equilibrium Measurement and Thermodynamic Modeling for Ternary Mixtures (Methyl <i>tert</i>-Butyl Ether + Methanol + Ethylene Glycol/Ethanolamine/Diethanolamine) at 298.15 K

Methyl tert-butyl ether (MTBE) is a colorless and transparent liquid that exhibits excellent miscibility with gasoline. It is employed extensively in gasoline formulations due to its efficacy in augmenting the octane number. Additionally, high-purity MTBE can be applied as a pharmaceutical intermediate. For the purification of MTBE during its production, it can form an azeotrope with methanol. In this work, to purify MTBE from the azeotrope via extraction, the efficacy of three organic solvents ethylene glycol, ethanolamine, and diethanolamine as potential extractants was assessed. The liquid–liquid equilibrium data of the ternary systems (methanol + MTBE + ethylene glycol/ethanolamine/diethanolamine) were ascertained at 298.15 K. The effectiveness of the extracting agents was evaluated with the calculated selectivity and the distribution coefficient. The findings demonstrated that ethanolamine displays a superior extraction capacity for extracting methanol. The ascertained data were correlated by applying the NRTL model, achieving the root-mean-square deviation values that did not exceed 0.01. The reliability of the model’s optimal parameters was verified by topological analysis, confirming its coherence with the experimental data.