Equilibrium Phase Behavior of Aqueous Two-Phase Systems Containing 1-Alkyl-3-methylimidazolium Tetrafluoroborate and Ammonium Tartrate at Different Temperatures: Experimental Determination and Correla

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• 作者：Juan Han ; Yun Wang ; Yanfang Li ; Cuilan Yu ; Yongsheng Yan
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2011
• 出版时间：September 8, 2011
• 年：2011
• 卷：56
• 期：9
• 页码：3679-3687
• 全文大小：843K
• 年卷期：v.56,no.9(September 8, 2011)
• ISSN：1520-5134

文摘

Binodal data of the aqueous 1-alkyl-3-methylimidazolium tetrafluoroborate ([C_nmim]BF₄, n = 2, 3, 4) + ammonium tartrate ((NH₄)₂C₄H₄O₆) aqueous two-phase systems (ATPSs) have been determined experimentally at T = (288.15, 298.15 and 308.15) K. Three empirical equations were used to correlate the binodal data. The effect of temperature on the binodal curves was also studied, and it was observed that the biphasic region expanded with a decrease in temperature. The calculated effective excluded volume (EEV) and the binodal curves plotted in molality both indicate that the phase-separation abilities of the investigated ILs are in the order of [C₄mim]BF₄ > [C₃mim]BF₄ > [C₂mim]BF₄. On the basis of the empirical equation of binodal curve with the highest accuracy and lever rule, the liquid鈥搇iquid equilibrium data were calculated by MATLAB. The reliability of the tie-line compositions was proved by the empirical correlation equations given by Othmer鈥揟obias and Bancroft equations. Furthermore, a relatively simply two-parameter equation was successfully used to correlate the tie-line data. Finally, the slope of the tie lines decreases with an increase in temperature and increases with an increase in cation alkyl chain length of the investigated ILs.