中文摘要：

采用等温溶解法对章氏硼镁石（MgB_4O_7-9H_2O）在纯水中溶解及转化进行研究,结果表明章氏硼镁石在308.15K下稳定存在12 h,溶解度为0.04813 mol×kg（-1）;12 h后,平衡固相向多水硼镁石（Mg_2B_6O_（11）·15H_2O）转化。根据文献的化学平衡常数以及实验pH值,计算液相中硼酸根离子摩尔分数在溶解转化过程中变化规律,并给出溶液中可能存在的反应及其相应的机理。采用等压法研究了308.15 K下MgB4O_7-H_2O体系离子强度为0.1066-0.2680 mol×kg（-1）的等压平衡浓度和水活度,计算了渗透系数及饱和蒸汽压,获得了该体系渗透系数和饱和蒸汽压随离子强度的变化规律;应用Pitzer离子相互作用模型,对实验数据进行多元线性回归,得到308.15 K下MgB_4O_7-H_2O体系的纯盐参数β（0）、β（1）、β（2）和Cφ分别为39.3990、-61.5421、655.1369、-86.0430,标准偏差为0.00723。Pitzer离子相互作用模型计算的渗透系数值与实验结果一致,这对完善含镁、硼盐湖卤水体系的热力学模型具有重要意义。

英文摘要：

The solubility and transforming behavior ofhungtsaoite （MgB4079H20） at 308.15 K were studiedusing 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 followingequilibrium constants of borates and experimental pH in the literature, and related chemical reactions andmechanism were suggested for the dissolution and transformation processes. The solubility of hungtsaoite at308.15 K is 0.04813 mol.kg-l. The isopiestic molalities and water activities of the MgB407-H20 system at308.15 K were measured by an isopiestic method with ion strength of 0.1066-0.2680 mol.kg-1. The osmoticcoefficients and the saturated vapor pressures of the system were calculated. The profiles of how osmoticcoefficient and saturated vapor pressure change with ion strength for the temary system were demonstrated.Pitzer＇s single electrolyte parameter of fβ（0）、β（1）、β（2）,Cφ for MgB407 is 39.3990, -61.5421, -655.1369 and-86.0430, respectively, with standard deviations of 0.00723, which are obtained using a multivariant linearregression method. The experimental and calculated osmotic coefficient values are in good agreement with thePitzer model. The thermodynamic data obtained is essential to construct complex thermodynamic models formagnesium and borate brine containing systems.