物理化学学报 >> 2009, Vol. 25 >> Issue (05): 847-852.doi: 10.3866/PKU.WHXB20090515

研究论文 上一篇    下一篇

2,6-二甲基哌啶+水体系临界性质的氘代同位素影响

柴守宁 安学勤 王金收 吕和坤 沈伟国   

  1. 兰州大学化学化工学院, 兰州 730000; 华东理工大学化学系, 上海 200237; 南京师范大学, 江苏省生物功能材料重点实验室, 南京 210097
  • 收稿日期:2008-12-10 修回日期:2009-01-12 发布日期:2009-05-04
  • 通讯作者: 沈伟国 E-mail:shenwg@lzu.edu.cn

Deuterium Isotope Effects on the Critical Behavior of 2,6-Dimethylpiperidine+Water System

 CHAI Shou-Ning, AN Xue-Qin, WANG Jin-Shou, LV He-Kun, SHEN Wei-Guo   

  1. College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China; Department of Chemistry, East China University of Science and Technology, Shanghai 200237, P. R. China; Jiangsu Key Laboratory of Biofunctional Materials, Nanjing Normal University, Nanjing 210097, P. R. China
  • Received:2008-12-10 Revised:2009-01-12 Published:2009-05-04
  • Contact: SHEN Wei-Guo E-mail:shenwg@lzu.edu.cn

摘要:

用等体积法分别确定2,6-二甲基哌啶+水和2,6-二甲基哌啶+重水体系的临界组成, 并测定各自的临界温度. 采用折射率法在较宽温度范围内测定两个体系的温度-折射率(T-n)共存曲线, 利用标φ曲线法将其转化为温度-摩尔分数(T-x)和温度-体积分数(T-φ)共存曲线, 求得临界指数β、指前因子B、Wegner校正项因子B1及与共存曲线直径ρd相关的参数. 研究结果表明, 氘代后, 体系低临界温度下降了约3.2 K, 临界组成和共存曲线形状不变, 在近临界点临界指数β仍符合三维伊辛模型(3D-Ising)的理论值(0.327).

关键词: 共存曲线, 临界现象, 折射率, 氘代同位素

Abstract:

Critical compositions and critical temperatures of (2,6-dimethylpiperidine+water) and (2,6-dimethylpiperidine+heavy water) were determined. Coexistence curves of (T-n) (T is temperature and n is refractive index) for two systems were determined by the measurements of refractive indices of coexisting phases. Coexistence curves of (T-n) were converted to coexistence curves of (T-x) and (T-φ) (x is mole fraction and φ is volume fraction) through standard curves determined by the measurements of refractive indices at various mole fractions and temperatures. The experimental data were analyzed to obtain critical exponents (β), critical amplitudes (B), Wegner correction amplitudes (B1) and parameters for diameters (ρd) of coexistence curves. We found that when H2O was substituted by D2O in the system the low critical temperature decreased by 3.2 K while the critical exponent was also consistent with the three-dimensional Ising model (3D-Ising) value (0.327) near the critical point. The critical composition and shape of coexistence curves were almost unchanged.

Key words: Coexistence curve, Critical phenomenon, Refractive index, Deuteriumisotope

MSC2000: 

  • O642