吡啶硝酸盐与醇二元混合体系物化性能研究

Physical and chemical properties of binary mixture of N-butylpyridinium nitrate and alcohol

采用MDY-2电子密度仪和德国DCAT21全自动表面张力仪,在298.15K下测定了离子液体N-丁基吡啶硝酸盐(N-butylpyridinium nitrate,[BuPy]NO3)与有机溶剂甲醇、乙醇、正丁醇在全浓度范围内(离子液体在有机溶剂中的摩尔分数为0～1)的密度和表面张力,计算了二元体系{[BuPy]NO3+CH3OH},{[BuPy]NO3+C2H5OH}和{[BuPy]NO3+C4H9OH}的超额摩尔体积VE和表面张力偏差δγ,分别利用Redlich-Kister方程对二元体系的超额摩尔体积VE和表面张力偏差δγ进行了拟合。结果表明:二元体系{[BuPy]NO3+CH3OH}和{[BuPy]NO3+C2H5OH}的超额摩尔体积VE在全摩尔组成范围内均为负值,而{[BuPy]NO3+C4H9OH}二元体系在低离子液体摩尔分数时为正值,随着离子液体摩尔分数的增大由正值变为负值。在全摩尔组成范围内,{[BuPy]NO3+CH3OH}的表面张力偏差δγ为正值,{[BuPy]NO3+C2H5OH}和{[BuPy]NO3+C4H9OH}的δγ为负值,随着醇碳链的增长,表面张力偏差出现由正到负的变化趋势。

In this paper, MDY-2 electronic densitometer and Germany DCAT21 automatic surface tension meter are used to measure the density and surface tension over the whole concentration range （the molar fraction of ionic liquids in oganic solvents is 0~1） for the binary mixtures of ionic liquids N-butylpyridinium nitrate （[-BuPy]NO3） and organic solvents such as metha nol, ethanol and butanol at the temperature of 298. 15 K. The excess molar volumes VE and the surface tension deviations 87 of binary mixtures { [BuPy]NO3 ＋CH3 OH}, { [BuPy]NO3 ＋C2 H5 OH} and { [-BuPy]NO3 ＋C4 H9 OH} are determined. VE and δr are fitted by using the Redlich-Kister equation. The results show that the excess molar volumes of binary mixtures of { [BuPy]NO3 ＋CH3 OH} and { [-BuPy]NO3 ＋C2 H5 OH} are negative over the whole composition range, while the VE of binary mixture {[BuPy]NOa ＋C4 H9, OH} has positive values at low molar fraction of ionic liquid, passing through a maximum and then decreases and becomes negative, showing minimum at higher ionic liquid molar fraction. The surface tension deviations δr of {[BuPy]NO3 ＋CH3 OH} systems are positive, but those of {[BuPy]NO3 if-C2 HsOH} and { [BuPy]NOa -ffC4 HgOH} systemsare negative over the entire molar fraction range. It seems that surface tension deviations δr varys from positive to negative with the increase of alkyl chain length of alcohols.