四硼酸钾水溶液结构

• 作 者: 朱发岩 房春晖 房艳 周永全
• 机 构: 中国科学院青海盐湖研究所,西宁810008／中国科学院研究生院,北京100049;中国科学院青海盐湖研究所,西宁,810008
• 出 处: 化学学报
• 发表日期: 2012年4期
• 关键词: potassium tetraborate solution structure x-ray scattering contact ion-pair chemi

研究了298.15和323.15K广泛浓度范围内四硼酸钾溶液pH,并根据化学反应平衡常数和牛顿迭代法计算获得了溶液化学物种分布图.典型样品用拉曼光谱进行核实.研究表明,高浓溶液中存在主要化学物种是B4O5（OH）24-,次要化学物种是B3O3（OH）4-和B（OH）4-.用X射线散射法研究了298和323K高浓四硼酸钾溶液结构.用几何模型定量描述B4O5（OH）42-,B3O3（OH）-4和B（OH）-4离子内、离子间、分子间的相互作用,并用最小二乘法进行精修.模型计算和精修给出硼氧六元环内原子间距和配位数,并与晶体结构很好一致,表明高浓溶液中离子内有序程度较高.同时给出K＋和硼酸根离子水合数和水合距离,以及接触离子对的结构信息,并进一步简单讨论温度和浓度变化对溶剂结构的影响.“,”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 con-stants by Newton iterative algorithm.The chemical species of typical samples were confirmed by Raman spectrum.The results show that the major species and the minor chemical species and exist in highly concentrated aqueous solutions.The structure of highly concen-trated aqueous K2B4O7 solutions at 298 and 323 K was studied by X-ray scattering further.The interactions of intra-anion,interionic and intermolecular of,and were descripted quantitatively by geometrical model and calculated by least square method.The model calculation and re-finement 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.