物理化学学报 >> 2010, Vol. 26 >> Issue (09): 2323-2330.doi: 10.3866/PKU.WHXB20100903

热力学、热化学和溶液化学 上一篇    下一篇

过饱和五硼酸钠溶液结构

周永全1,2, 房春晖1, 房艳1   

  1. 1. 中国科学院盐湖资源与化学重点实验室,中国科学院青海盐湖研究所,西宁 810008;
    2. 中国科学院研究生院,北京 100049
  • 收稿日期:2010-01-20 修回日期:2010-06-01 发布日期:2010-09-02
  • 通讯作者: 房春晖, 房艳 E-mail:fangch@isl.ac.cn, fangy8@isl.ac.cn
  • 基金资助:

    国家重点基础研究发展计划前期专项(2008CB617612)和国家自然科学基金(20873172)资助项目

Structure of Supersaturated Aqueous SodiumPentaborate Solution

ZHOU Yong-Quan1,2, FANG Chun-Hui1, FANG Yan1   

  1. 1. CAS Key Laboratory of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China;
    2. Graduate School of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2010-01-20 Revised:2010-06-01 Published:2010-09-02
  • Contact: FANG Chun-Hui, FANG Yan E-mail:fangch@isl.ac.cn, fangy8@isl.ac.cn
  • Supported by:

    The project was supported by the Major State Basic Research Development Programof China (973) General Program(2008CB617612) and National Natural Science Foundation of China (20873172).

摘要:

用快速X 射线衍射法测量了298 和323 K 时过饱和五硼酸钠溶液的时间空间平均结构, 得到了溶液径向分布函数. 通过模型设计及理论计算获得了B-B、B-O、O-O、Na-O、Na-B 原子对相互作用的理论偏径向分布函数, 并讨论了浓度和温度对五硼酸钠溶液结构的影响. 在五硼酸钠过饱和溶液中六水合Na+形成八面体结构,其平均配位数随浓度和温度变化不大, 作用距离随温度升高及浓度减小而减小;给出了溶液中主要硼酸盐离子B3O3(OH)-4、B5O6(OH)-4和B(OH)3的水合结构, 较高温度及较高浓度有利于更高聚合的多聚硼酸根离子的形成;浓度对硼酸盐离子的第一水合层的水合数影响较大, 在较浓的五硼酸钠过饱和溶液中, 五硼酸根离子的一个端氧单齿配位到Na+上形成离子对, Na-B 特征距离为0.328 nm.

关键词: 溶液结构, X 射线衍射, 五硼酸钠, 过饱和溶液, 径向分布函数, 多聚硼酸根离子

Abstract:

We determined the time-averaged and space-averaged structures of supersaturated aqueous sodiumpentaborate solutions by rapid liquid X-ray diffractometry at 298 and 323 K. Difference radial distribution functions (DRDF) and their theoretical partial radial distribution functions for B-B, B-O, O-O, Na-O and Na-B atom pairs were obtained from accurate diffraction data. The effects of concentration and temperature on the structure of the solutions were also discussed. Three main species (B3O3(OH)- 4, B5O6(OH)- 4 and B(OH)3) were found to exist in supersaturated aqueous sodium pentaborate solutions and their hydrated structures were determined by model design and quantitative calculations. Higher temperature and higher concentration result in higher polyborates. As the concentration decreases, interaction distances and the average coordination number of the octahedral hexahydrated Na+ ion hardly changes while the hydration number of the polyborate increases. In concentrated solutions, the terminal-oxygen of the polyborates connects with the hydrated Na+ in a monodentate formto produce a contact ion pair with a characteristic distance of 0.328 nm.

Key words: Solution structure, X-ray diffraction, Sodiumpentaborate, Supersaturated aqueous solution, Radial distribution function, Polyborate anion

MSC2000: 

  • O645