多聚硼酸铷铯溶液结构研究

With the aim of the science frontier issues of solution chemistry and the boron resource development in Qaidam salt lakes, aqueous solution structure of polyborates, such as metaborate, tetraborate and pentaborate, of rubidium and cesium with the longest hydration distance and the largest hydration number, will be focused ours attention on in this science project. Firstly, we intend to measure the structural sensitive properties, such as pH, conductivity and viscosities, of aqueous borate solutions in the wide range of concentration and temperature so that determine composition of the complex species in the solutions; Secondly, intend to use the measurement of Raman and NMR spectroscopy characteristics of the typical samples in the above systems and to verify further distribution of the different species in the solutions; Thirdly, intend to measure accurately the scattering intensity of supersaturated or high concentrated aqueous systems of polyborates of rubidium and cesium by a new method of X-Ray scattering that has recently been explored by us in the Large-scale Scientific Facilities——the synchrotron radiation facility; Fourthly, intend to obtain the structural function and the radial distribution function (RDF) of the solutions from the scattering intensity; Fifthly, intend to give all kinds of intra-ionic inter-atomic distance and atom-pair number, such as B-O, B-B, and O-O, in polyborate, intermolecular distance and atom-pair number of Rb+/Cs+-H2O, B-H2O and O-H2O in hydrated cation, anion and ion-pairs in the solutions, from the composition of the species distribution in the solution from structural sensitive properties and geometric model calculation. Lastly, intend to measure accurately the local coordination environment of rubidium and cesium ion in the aqueous polyborate solutions. The chemical natures of the hydration degree, hydration structure, hydrolysis, and polycondensation of polyborates will be elaborated in the work. A theoretical source in design for its engineering application of borates in Qinghai-Tibetan Plateau will be supplied at the molecular level.

本项目瞄准盐湖硼资源开发和溶液化学的前沿,聚焦于具有最大水合距离和水合数铷和铯偏硼酸盐、四硼酸盐和五硼酸盐水溶液体系溶液结构研究。拟开展全浓度范围pH、电导率和粘度等结构敏感性质精确测量,确定溶液中物种组成;拟开展典型样品Raman和NMR等光谱学性质测量,进一步核实物种分布;用我们新近开发的同步辐射光源X射线散射新方法,精确测量铷和铯偏硼酸盐、四硼酸盐和五硼酸盐体系过饱和或高浓度水溶液散射强度，计算溶液结构函数和径向分布函数,由物种组成和几何模型计算给出多聚硼酸根离子内各种B-O、B-B和O-O,阳离子与水分子,水合阴离子B-H2O和O-H2O水合距离以及水合离子对原子间距和原子对数;由EXAFS精确测量上述多聚硼酸盐溶液的铷和铯离子局部配位环境。阐明水合程度、水合结构、水解反应、缩聚反应和稀释成盐现象的化学本质，为青藏高原硼酸盐类型盐湖开发利用提供分子水平的理论依据。

本项目顺利完成了科学基金计划的各项研究任务。本项目进行了具有最大水合距离、最大水合数和复杂Voinoi多面体的铷和铯偏硼酸盐、四硼酸盐和五硼酸盐水溶液体系溶液结构研究。我们开展了全浓度范和给定温度下溶液pH、电导率和粘度等结构敏感性质精确测量,确定溶液中物种组成;用典型样品Raman和NMR等光谱学性质进一步定性鉴定了物种分布;用X射线散射方法,精确测量了铷和铯偏硼酸盐、四硼酸盐和五硼酸盐体系高浓度水溶液散射强度，计算了溶液结构函数和径向分布函数,由物种组成和几何模型计算给出了多聚硼酸根离子内各种B-O、B-B和O-O,阳离子与水分子,水合阴离子B-H2O和O-H2O水合距离以及水合离子对原子间距和原子对数;由EXAFS精确测量了上述多聚硼酸盐溶液的铷和铯离子局部配位环境。本工作还大胆尝试了Rb/Cs11B(OD)4,Rb2/Cs211B4O5(OD)4和Rb/Cs11B5O6(OD)4-D2O 溶液的中子散射实验和计算方法研究。用DFT计算了四硼酸根和五硼酸根离子的分步水解过程，阐明了水合程度、水合结构、水解反应和缩聚反应的化学本质。该项目执行期间，共发表论文37篇。其中本项目12篇。