The soluting-out effect in aqueous solutions of 1-butyl-3-methylimidazolium tetrafluoroborate and carbohydrates at various temperatures

Phase diagrams and liquid–liquid equilibrium (LLE) data of the aqueous 1-butyl-3-methylimidazoliumtetrafluoroborate+ carbohydrate two-phase systems were determinedexperimentally at 298.15, 303.15, 308.15, 313.15and 318.15 K.The soluting-out effect of four carbohydrates including sucrose, maltose monohydrate, D-(+)-glucose,and D-(-)-fructose on the aqueous ionic liquid solutionswere investigated.It was found that adecreasing in temperatureand increasing the number of hydroxyl groups from monosaccharides (glucose and fructose) to disaccharides (sucroseandmaltose monohydrate) caused the expansion of two-phase region. Although glucose and fructose are structuralisomers and the numbers of their hydroxyl groups are equal, the soluting-out capability of glucose is more than that offructose.The soluting-out powersofdisaccharides obey the order:maltose> sucrose.It was also found that theconcentration of carbohydrate, which is in equilibrium witha certain concentration of ionic liquid, increases byincreasing temperature. Based on the cloud point values, the GC values for all systems are negative and becomes morenegative by decreasing the temperature and increasing the hydrophilicity of the carbohydrates.

کلیدواژه ها:

Soluting-out effect ، Aqueous biphasic system ، Ionic liquid ، Cloud point