Acta Chimica Sinica ›› 2012, Vol. 0 ›› Issue (04): 445-452.DOI: 10.6023/A1105313 Previous Articles     Next Articles

Full Papers


朱发岩a,b, 房春晖a, 房艳a, 周永全a, 许沙a,b, 陶松a,b, 曹领帝a,b   

  1. a 中国科学院青海盐湖研究所 西宁 810008;
    b 中国科学院研究生院 北京 100049
  • 投稿日期:2011-05-31 修回日期:2011-08-03 发布日期:2011-09-26
  • 通讯作者: 房春晖
  • 基金资助:

    中国科学院与国家基金委大科学工程联合基金(No. 11079047)和中国科学院知识创新性工程重要方向项目(No. KZCX2-EW-307)资助项目.

Structure of Aqueous Potassium Tetraborate Solutions

Zhu Fayana,b, Fang Chunhuia, Fang Yana, Zhou Yongquana, Xu Shaa,b, Tao Songa,b, Cao Lingdia,b   

  1. a Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008;
    b Graduate University of Chinese Academy of Sciences, Beijing 100049
  • Received:2011-05-31 Revised:2011-08-03 Published:2011-09-26
  • Supported by:

    Project supported by Joint Fund for Large Science Project of the National Natural Science Foundation of China and the Chinese Academy of Sciences (No. 11079047) and Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences (No. KZCX2-EW-307).

The pH of aqueous K2B4O7 solutions at 298.15 and 323.15 K at a wide range of concentration has been determined and the chemical species distribution of the solutions calculated from equilibrium constants by Newton iterative algorithm. The chemical species of typical samples were confirmed by Raman spectrum. The results show that the major species B4O5(OH)42? and the minor chemical species B3O3(OH)4? and B(OH)4? exist in highly concentrated aqueous solutions. The structure of highly concentrated aqueous K2B4O7 solutions at 298 and 323 K was studied by X-ray scattering further. The interactions of intra-anion, interionic and intermolecular of B4O5(OH)42?, B3O3(OH)4? and B(OH)4? were descripted quantitatively by geometrical model and calculated by least square method. The model calculation and refinement provided distance and coordination number between atoms in boroxol six-member ring, which are in good agreement with the crystal structure. The order degree in intra-anion is high in concentrated aqueous solutions. At the same time, we gained information about the hydration number and hydration distance of K+, borate ions and contact ion-pair. We also briefly discussed the effect of temperature and concentration on solvent structure.

Key words: potassium tetraborate, solution structure, x-ray scattering, contact ion-pair, chemical species distribution