Solubility of Galactose in Aqueous Ionic Liquids, 1-Butyl-3-Methyl Imidazolium Bromide, 1-Hexyl-3-Methyl Imidazolium Bromide and 1-Butyl- 3-Methylimidazolium Chloride at T = (298.15 and 308.15) K: Measurement and Modeling

Recently, ionic liquids as benign and biofriendly solvents have gained much interest in different fields of chemistry due to their tunable properties such as low melting point, negligible vapor pressure, wide liquid range and high thermal and electrochemical stability [1]. Especially the researchers focused their attention in converting saccharides as abundant, cheap and renewable feed stocks by ionic liquids into valuable intermediates. Ionic liquids have some advantages in comparison to other pretreatment methods. They need a remarkably shorter processing time to convert pretreated biomass to fermentable sugars. In addition, the degradation of monosaccharides and formation of inhibitors is less than other methods. Furthermore, dissolution and hydrolysis reactions can be performed in relatively mild conditions [2]. Recently, researchers suggested that a mixture of ionic liquid and water instead of pure ionic liquid can be used for pretreatment of biomass [3]. In this paper the solubility of galactose in aqueous solutions containing ionic liquids, 1-butyl-3-methyl imidazolium bromide, [BMIm]Br, 1-hexyl-3-methyl imidazolium bromide, [HMIm]Br and 1-butyl-3-methylimidazolium chloride [BMIm]Cl has been measured at different ionic liquid concentrations at T = (298.15 and 308.15) K using gravimetric method. The obtained solubility values of galactose in pure water and aqueous ionic liquid solutions were correlated successfully with the segment-based local composition models such as Wilson, NRTL, modified NRTL, NRF-NRTL and UNIQUAC. In this study, the effects of chain length and anion type of ionic liquids on solid–liquid equilibrium behavior in (galactose + ionic liquid + water) systems have also been investigated.