高校化学工程学报2016，Vol.30Issue(5)：1007-1013,7.DOI:10.3969/j.issn.1003-9015.2016.05.004
308.15 K下MgB4O7-H2O体系热力学性质研究
Thermodynamic Properties of the MgB4O7-H2O System at 308.15 K
摘要
Abstract
The solubility and transforming behavior of hungtsaoite (MgB4O7·9H2O) at 308.15 K were studied using an isothermal dissolution equilibrium method. The results show that hungtsaoite is stable for 12 h in water, and then the solid phase transforms into inderite. Mole fractions of polyborates were calculated following equilibrium constants of borates and experimental pH in the literature, and related chemical reactions and mechanism were suggested for the dissolution and transformation processes. The solubility of hungtsaoite at 308.15 K is 0.04813 mol·kg−1. The isopiestic molalities and water activities of the MgB4O7-H2O system at 308.15 K were measured by an isopiestic method with ion strength of 0.1066~0.2680 mol·kg−1. The osmotic coefficients and the saturated vapor pressures of the system were calculated. The profiles of how osmotic coefficient and saturated vapor pressure change with ion strength for the ternary system were demonstrated. Pitzer’s single electrolyte parameter of β(0), β(1), β(2), Cφ for MgB4O7 is 39.3990, −61.5421, −655.1369 and−86.0430, respectively, with standard deviations of 0.00723, which are obtained using a multivariant linear regression method. The experimental and calculated osmotic coefficient values are in good agreement with the Pitzer model. The thermodynamic data obtained is essential to construct complex thermodynamic models for magnesium and borate brine containing systems.关键词
MgB4O7-H2O体系/相转变/等压法/渗透系数/Pitzer模型Key words
MgB4O7-H2O system/phase transformation/isopiestic method/osmotic coefficient/pitzer model分类
化学化工引用本文复制引用
戈海文,邓天龙,姚燕..308.15 K下MgB4O7-H2O体系热力学性质研究[J].高校化学工程学报,2016,30(5):1007-1013,7.基金项目
国家自然科学基金(41503061，20836009)；天津市海洋资源与化学重点实验室(天津科技大学)开放基金(201406)。 （41503061，20836009）
