Experimental and Theoretical Studies on the Effectiveness of Phosphonium-Based Ionic Liquids for Butanol Removal at T = 298.15 K and p = 1 atm

Abstract

Biobutanol obtained via an acetone–butanol–ethanol (ABE) fermentation process is now considered a potential biofuel. In recent times low density phosphonium cations were found to remove butanol from aqueous solutions. In this regard, low density phosphonium-based ionic liquids (ILs) trihexyl(tetradecyl)phosphonium dicyanamide [TDTHP][DCA] and trihexyl(tetradecyl)phosphonium decanoate [TDTHP][DEC] have been used for the separation of 1-butanol from aqueous solution. Ternary liquid–liquid equilibrium data for IL(1)–1-butanol(2)–water(3) are measured at T = 298.15 K and p = 1 atm. Butanol partition coefficients are obtained in the range of 25–85 and 20–290 for [TDTHP][DCA] and [TDTHP][DEC], respectively. 1H NMR spectra indicates the absence of IL and water in the raffinate and extract phase, respectively. This experimentally confirms that there will be negligible cross-contamination of water and IL in either phase. The separation factor of butanol over water approaches infinity for both systems. A wider spre...