化学学报 ›› 2004, Vol. 62 ›› Issue (3): 268-273. 上一篇    下一篇

研究论文

过饱和MgSO4溶液结构的X射线衍射研究

房春晖, 房艳, 郭亚梅, 杨波, 雷亚川   

  1. 中国科学院青海盐湖研究所, 西宁, 810008
  • 投稿日期:2003-07-03 修回日期:2003-12-30 发布日期:2014-01-26
  • 通讯作者: 房春晖,E-mail:fangch@pub.xaonline.com;frankfangchisl@tom.com.cn E-mail:fangch@pub.xaonline.com;frankfangchisl@tom.com.cn
  • 基金资助:
    国家自然科学基金(No.20373083)资助项目.

An X-ray Diffraction Study on the Structure of the Supersaturated MgSO4 Solutions

FANG Chun-Hui, FANG Yan, GUO Ya-Mei, YANG Bo, LEI Ya-Chuan   

  1. Institute of Salt Lake, Chinese Academy of Sciences, Xining 810008
  • Received:2003-07-03 Revised:2003-12-30 Published:2014-01-26

用X射线衍射法研究了过饱和MgSO4溶液298 K的水合结构.用经验黄金规则r=0.618λ/sin θ推断实验衍射曲线的结构信息,而另一个r=0.618×4π/s阐述结构函数曲线的峰.结构模型的计算表明,过饱和溶液中存在着水共享离子对和接触离子对.接触离子对的Mg-S特征距离为0.328 nm,表明硫酸根离子大多是以单齿形式配位到镁离子.Mg2+与硫酸根氧原子Mg-OS(1)距离为0.205 nm,与Mg-H2O是等价的;Mg-OS(2)和Mg-OS(3)很接近,大约为0.355 nm; Mg-OS(4)距离为0.456 nm.随着浓度增加,接触离子对明显增加.水共享离子对Mg-S距离被确定在0.492 nm,并同时与接触离子对共存.硫酸根配合物的形成,降低了硫酸根水合结构的对称性.

关键词: 溶液结构, 过饱和溶液, MgSO4, X射线衍射

The hydration structure of the supersaturated MgSO4 solutions has been investigated by means of X-ray diffraction at 298 K. An empirical golden rule, r=0.618λ/sin θ, has been used to extract some structural information from the experimental diffraction curve, and the other, r=0.618×4π/s, to expound some peaks on the structural function curve. The calculation of the structural model shows there exist the water-shared ion-pair and the contact ion-pair in the supersaturated solutions. The characteristic Mg-S distance of the contact ion-pair has been determined to be about 0.328 nm. It shows that the contaction-pair MgSO40 is a unidentate complex. The Mg-OS(1) distance between magnesium ion and the nearest oxygen atom in sulfate ion has been measured to be 0.205 nm and is equivalent to that of Mg-H2O. The Mg-OS(2) distance is close to that of Mg-OS(3), about 0.355 nm. The Mg-OS(4) distance is situated at about 0.456 nm. The number of ion-pairs obviously increases with the increasing of concentration. The marked Mg-S distance of the water-shared ion-pair coexisting with the contact ion-pair was refined to be 0.492 nm. The symmetry of the hydration structure of sulfate ion is lowered by complex formation of magnesium ion with sulfate anion.

Key words: liquid structure, supersaturated solution, MgSO4, X-ray diffraction