物理化学学报 >> 2016, Vol. 32 >> Issue (5): 1143-1150.doi: 10.3866/PKU.WHXB201602184

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利用X射线衍射和拉曼光谱法对KCl和NaCl混合溶液微观结构的研究

袁俊生1,3,*(),刘子禹2,3,李非1,3,李申予1,3   

  1. 1 河北工业大学海洋科学与工程学院,天津300130
    2 河北工业大学化工学院,天津300130
    3 教育部海水资源高效利用技术工程研究中心,天津300130)
  • 收稿日期:2015-12-11 发布日期:2016-05-07
  • 通讯作者: 袁俊生 E-mail:jsyuan2012@126.com
  • 基金资助:
    河北省重点基础研究项目(13963103D);长江学者和创新团队发展计划(IRT14R14);和国家科技支撑计划项目(2015BAB09B00)

Study of the Hydrated Structure of KCl and NaCl Mixed Solutions Using X-ray Diffraction and Raman Spectroscopy

Jun-Sheng YUAN1,3,*(),Zi-Yu LIU2,3,Fei LI1,3,Shen-Yu LI1,3   

  1. 1 School of Marine Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
    2 School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
    3 Engineering Research Center of Seawater Utilization Technology of Ministry of Education, Tianjin 300130, P. R. China
  • Received:2015-12-11 Published:2016-05-07
  • Contact: Jun-Sheng YUAN E-mail:jsyuan2012@126.com
  • Supported by:
    the Basic Research Project of Applied Basic Research Plan of Hebei Province, China(13963103D);Program for Changjiang Scholars and Innovative Research Team in University, China(IRT14R14);National Key Technology R & D Program, China(2015BAB09B00)

摘要:

利用X射线衍射法和拉曼光谱法系统研究了25 ℃下, 0-26%质量分数浓度范围内KCl和NaCl混合溶液的结构。通过分析X射线衍射法所得的混合溶液的差值结构函数F(Q)以及差值对分布函数G(r)发现,混合溶液组分中的K+的水化层半径及其水化数均大于Na+,从而揭示出常温下NaCl在水中的溶解度大于KCl的原因。在拉曼光谱的研究中,观察到溶液中水分子的四面体氢键受破坏程度随KCl浓度的增加和NaCl浓度的减少,先增大后减小,并结合X射线衍射法的结果,推断混合溶液中Na+对水溶液中氢键结构的破坏程度比K+严重,且加入适量的K+会使Na+由结构缔造者转变为打破结构者,对水溶液结构的破坏增强。

关键词: X射线衍射, 拉曼光谱, KCl, NaCl, 溶液结构

Abstract:

Research on the hydrated structure of KCl and NaCl mixed solutions with a concentration range between 0 and 26% was conducted using X-ray diffraction and Raman spectroscopy at 25 ℃. Their reduced structure functions, F(Q), and reduced pair distribution functions, G(r), obtained from X-ray diffraction indicate that compared with Na+, the hydration numbers and shell radii of the hydrated K+ ions are larger. This explains why the solubility of NaCl is higher than that of KCl at 25 ℃. According to the Raman spectroscopy, the tetrahedral hydrogen bonds of water molecules will be destroyed with the increase in KCl concentration and the decrease in NaCl concentration. The extent of the bond destruction has systematic variations; for example, increasing at first and then decreasing. These results show that the destruction of the hydrogen bond structure resulting from Na+ is more serious than from K+. Also, with the appropriate K+ content in the NaCl solution, Na+ will behave as a structure breaker instead of a structure maker, which enhances the destructiveness of the solution structure.

Key words: X-ray diffraction, Raman spectroscopy, Potassium chloride, Sodium chloride, Solution structure

MSC2000: 

  • O641