In order to study the effects of number of hydroxyl groups and stereochemical properties of sugar molecules, as well as temperature on the phase separation capability and vapor-liquid equilibria behavior of the carbohydrate + IL aqueous systems, the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and seven carbohydrates including monosaccharides (l-(+)-arabinose, d-(+)-xylose, d-(+)-glucose and d-(−)-fructose), disaccharides (maltose and sucrose), and a polyol (maltitol) were selected and their vapor-liquid equilibria and phase diagram behaviors were studied. For these systems, the constant water activity lines in mono- and biphasic regions show large negative deviations from the linear isopiestic relation (Δ0 < 0) and these deviations in monophasic region are larger than biphasic region. The values of Δ0 as well as the phase separation capability of the investigated ternary systems were increased with decreasing temperature and increasing hydrophilicity of the carbohydrates.
