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کلیدواژهها
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Salt effect, Aqueous biphasic systems, Carbohydrate, Ionic liquid, Alkaloid, Corrosion, Isomax, Ammonium bisulfide
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چکیده
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In the first part of this work, in order to study thermodynamic of salting effect in aqueous ionic liquid – carbohydrate systems and to better understanding of its molecular mechanism, comprehensive studies included the liquid–liquid equilibria (LLE), vapor–liquid equilibria (VLE) with isopiestic and vapor pressure osmometery (VPO) technics, solid–liquid equilibria (SLE), volumetric and compressibility, on aqueous IL - carbohydrate systems were carried out at various temperatures. For this propose, three ionic liquids [Bmim][BF4], [Bmim][Br], and [Bmim][HSO4] with different hydrophilicity and seven carbohydrates including monosaccharides (D-(+)-xylose, L-(+)-arabinose, D-(-)-fructose and D-(+)-glucose), disaccharides (maltose and sucrose), and a polyol (maltitol) were selected. The water activity data showed that the hydrophilicity of the investigated solutes obey the following order: [Bmim][HSO4] > [Bmim][Br] ≥ carbohydrates >> [Bmim][BF4]. The most hydrophobic IL, [Bmim][BF4], salted-out from the aqueous solutions by the sugars and formed the aqueous biphasic system (ABS). For these systems, the constant water activity lines in mono- and biphasic regions show large negative deviations from the the semi-ideal behavior (m_IL/(m_(IL )^0 )+m_C/(m_(C )^0 )-1<0) and these deviations in monophasic region are larger than biphasic region. Values of salting-out coefficients, ks, for the ABSs were positive (salting-out effect). The values of ks and magnitude of deviations m_IL/(m_(IL )^0 )+m_C/(m_(C )^0 )-1 were increased with decreasing temperature and increasing hydrophilicity of the carbohydrates. The VPO studies showed that the unfavorable IL-carbohydrate interactions can be lead to reducing the water activity and vapor pressure of ternary solution relative to the semi-ideal solution model (aw + 1 < a°wIL + a°wC and ∆p < ∆p°IL + ∆p°C). In the case of aqueous [Bmim][BF4]/carbohydrate systems which has a phase separation capability, the salting-out power of the carbohydr
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