物理化学学报 >> 2005, Vol. 21 >> Issue (07): 813-816.doi: 10.3866/PKU.WHXB20050723

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水+甲酰胺+环己烷+二乙二醇丁醚拟三元系的三临界现象

侯海云; 安学勤; 沈伟国   

  1. 兰州大学化学系, 兰州 730000; 南京师范大学化学与环境科学学院, 南京 210097; 华东理工大学化学系, 上海 200237
  • 收稿日期:2004-11-30 修回日期:2005-02-02 发布日期:2005-07-15
  • 通讯作者: 沈伟国 E-mail:shenwg@lzu.edu.cn

Tricritical Phenomena in Quasi-ternary Solutions of Water+Formamide+Cyclohexane+Diethylene Glycol Monobutyl Ether

HOU Hai-yun; AN Xue-qin; SHEN Wei-guo   

  1. Department of Chemistry, Lanzhou University, Lanzhou 730000; College of Chemistry and Environment Science, Nanjing Normal University, Nanjing 210097; Department of Chemistry, East China University of Science and Technology, Shanghai 200237
  • Received:2004-11-30 Revised:2005-02-02 Published:2005-07-15
  • Contact: SHEN Wei-guo E-mail:shenwg@lzu.edu.cn

摘要: 用改进的体积法研究了拟三元体系水+甲酰胺+环己烷+二乙二醇丁醚的三临界现象. 以水+甲酰胺作为拟“纯组分”,通过控制甲酰胺在拟“纯组分”中的质量分数w,逐渐向三临界点逼近,当w从0增加到0.206时,三相区范围ΔT从1.500 ℃减小到0.228 ℃. 由实验数据得到体系的临界质量分数w=0.286±0.003,临界温度为(54.8±0.7) ℃. 实验发现平均温度下三相区三角形的水-油边与三角坐标中的水-油边几乎平行,而且三相区三角形水-油边的边长及其对应的高与ΔT的指数关系符合三临界的经典理论.

关键词: 相体积, 拟三元体系, 三临界现象, 二乙二醇丁醚

Abstract: The tricritical phenomena of quasi-ternary solutions of H2O+formamide(FA)+cyclohexane+diethylene glycol monobutyl ether have been studied by measurements of the volume ratios of the coexisting phases for a series of solutions with various overall compositions at various temperatures. Taking (H2O+FA) as a quasi “pure” component, the mass fraction FA in the quasi “pure” component controlled the approach to the tricritical point. As the mass fraction increased from 0 to 0.206, the ΔT of the three-phase region reduced from 1.500 ℃ to 0.228 ℃. By extrapolation of the experimental data, the tricritical mass fraction of FA in the quasi “pure” component and the tricritical temperature were obtained to be 0.286±0.003 and (54.8±0.69) ℃, respectively. It was found that the water-oil sides of three-phase triangles at the middle temperatures of the three-phase regions were almost parallel to the water-oil sides of the triangle coordinates. The dependences of lengths of the water-oil side of the three-phase triangle and the corresponding altitude to the water-oil side on ΔT were consistent with the classical theory.

Key words: Phase volume, Quasi-ternary system, Tricritical phenomena, Diethylene glycol monobutyl ether