Separation of water/butan-1-ol with ionic liquids in ternary liquid-liquid phase equilibrium

Highlights: • ILs in separation of water/butan-1-ol. • Ternary LLE measurements using GLC. • Large selectivity of separation with [P_4,4,4,4][NTf₂] at T = 328.15 K. -- Abstract: In this work ionic liquids (ILs) as a novel popular solvents are proposed for removing butan-1-ol from the aqueous fermentation media. Ternary liquid-liquid phase equilibrium data are presented for mixtures of {ionic liquid (1) + butan-1-ol (2) + water (3)} at T = 328.15 K and ambient pressure. The ILs with long alkane chains such as hexadecyltrimethylammonium bis{(trifluomethyl)sulfonyl}imide, [N_16,1,1,1][NTf₂], 1,3-didecyl-2-methylimidazolium dicyanamide, [D₂MIM][DCA] and tetrabutylphosphonium bis{(trifluomethyl)sulfonyl}imide, [P_4,4,4,4][NTf₂] have been tested. The results are discussed in terms of the selectivity and solute distribution ratio of separation of related systems. The complete miscibility in the binary liquid systems of butan-1-ol with three used ILs was observed. The ammonium-based IL in comparison with phosphonium-based IL shows lower selectivity and solute distribution ratio. The non-random two liquid NRTL model was used successfully to correlate the experimental tie-lines and to calculate the phase composition error in mole fraction in the ternary systems.