在288.15K时H3BO3-MgCl2-MgSO4-H2O四元体系的溶解度等温线

研究了MgCl₂-MgSO₄-H₂O、H₃BO₃-MgCl₂-H₂O、H₃BO₃-MgSO₄-H₂O三个三元体系及由它们所组成的四元体系H₃BO₃-MgCl₂-MgSO₄-H₂O在288.15K的溶解度等温线。确定了六水硫酸镁的存在,讨论了各相之间的关系及各化合物相互间的盐析作用。     

三元体系H3BO3-MgCl2-H2O在308.15K和323.15K稳定相平衡研究

采用等温溶解法研究了三元体系H3BO3 - MgCl2 - H2O在308.15 K和323.15 K的稳定相平衡;测定了上述体系液相中各组分的平衡溶解度及液相密度,并绘制了相应相图和平衡溶液密度组成图.结果表明,该体系在308.15 K和323.15 K时有一个共饱点、两条饱和溶解度曲线和两个结晶相区,无复盐及固溶体...     

NH4VO3在NH4H2PO4-H2O和(NH4)3PO4-H2O体系中的溶解度

采用等温溶解法测定了偏钒酸铵(NH₄VO₃)在NH₄H₂PO₄-H₂O和(NH₄)₃PO₄-H₂O体系中T = 298.15-328.15 K时的溶解度以及溶液的密度和pH值。结果表明, NH₄VO₃的溶解度随着(NH₄)₃PO₄或NH₄H₂PO₄溶液浓度的增大,先降低后升高,这是由于同离子效应、化学反应平衡及离子活度的共同作用。比较T = 298.15K时, NH₄VO₃分别在NH₄H₂PO₄-H₂O、(NH₄)₂HPO₄-H₂O和(NH₄)₃PO₄-H₂O体系中溶解度,发现在相同的磷酸盐浓度下, NH₄VO₃的溶解度在NH₄H₂PO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在(NH₄)₂HPO₄-H₂O体系中最小。进一步地,在T = 298.15 K和磷酸盐浓度C = 0.5 mol·kg^-1时,结合pH值和反应溶度积常数K_SP等计算三个体系中的平均离子活度系数(γ_±),发现γ_±值在(NH₄)₂HPO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在NH₄H₂PO₄-H₂O体系中最小,与溶解度规律一致。     

273.15K时LiCl-Li2SO4-H2O体系热力学性质的等压研究

0℃下用改进的等压设备和改进的实验方法测定了纯水溶液(LiCl 0.5～9.2mol·kg-1,Li2SO40.3～2.5mol·kg-1)以及混合水溶液(离子强度0.5～9.5mol·kg-1)的水活度和渗透系数.该体系的等水活度线与Zdanovskii规则非理想混合溶液表达式的标准偏差为0.0088,当Li2SO4溶液达到饱和后,用Zdanovskii规则扩展式计算,标准偏差为0.0027.根据Pitzer离子相互作用模型对实验数据进行了理论分析,用本文和不同来源的文献数据拟合求取了0℃下该体系的Pitzer纯盐参数和混合参数,计算值与实验值相吻合.     

MgSO4-H3BO3-H2O体系水热条件下结晶动力学

自然界中硼铁矿属于多元素(Ｆｅ、Ｂ、Ｍｇ)共生矿,使用价值很高,是我国未来硼资源的主要来源.根据我国硼铁矿品位低的特点,东北大学提出了硼铁矿高炉铁硼分离生产含硼生铁及富硼渣、富硼渣硫酸浸出一步法生产硼酸的火法工艺路线[1],矿石中的镁以硫酸镁的形式存在于母液中.母液经浓缩、过滤,主要成分为硫酸镁和硼酸水溶液,母液中硫酸镁和硼酸分离是目前急需解决的问题.当温度高于80℃时,硫酸镁在水中的溶解度随温度的升高而降低,硼酸的溶解度随温度的升高而增加[2].根据硫酸镁和硼酸的溶解度特点,在常温下将两者分离是不可能的,通过高温结晶…     

MgSO4-H3BO3-H2O体系水热条件下结晶动力学

The solution of MgSO4-H3BO3-H2O system containing 20%(mass fraction)MgSO4 and 2.5% H 3BO 3 was prepared and the experimental study of its crystallization at 180℃ were carried out in a high pressured vessel. Only a solid phase MgSO4•H2O was separated out from the system. The experimetal data were fitted. With the aid of simplex optimum method and Runge-Kutta digital solution of a set of differential equations, Single-nuclear interface reaction model (MB2) was selected to describe the process of crystallization of kieserite. the dynamic equation is as follows:
-dc/dt=0.064(2.24-c) 4/3 (c-0.290)2     

Li2SO4-K2SO4-MgSO4-H2O体系及次级体系298.15K时的热化学研究

用连续滴定量热法研究Li2SO4-K2SO4-MgSO4-H2O体系及次级体系Li2SO4-K2SO40H2O、Li2SO4-MgSO4-H2O和K2SO4-MgSO4-H2O 298.15K时在离子强度为15-0.1范围内的比热容和稀释热, 并结合Debye-Huckel焓极限公式研究离子强度在15-0.0001范围内的表观摩尔焓。     

K2CO3-Na2CO3-Li2CO3-H2O四元体系288K的相平衡

水盐体系;碳酸盐;溶解度;盐湖卤水;K2CO3-Na2CO3-Li2CO3-H2O四元体系288K的相平衡     

CO(NH2)2-H3BO3-H2O体系相平衡研究

农作物不仅需要吸收C、H、O、N、P、K、Ca、Mg等营养元素,而且还需要吸收B、Mn、Zn等营养元素,以维持它们正常生长的需要.尿素是一种含氮量很高(46.60%)、性能很好的氮肥,而硼化合物又是一种很重要的微量元素肥料.因此,研究尿素与硼化合物间的相互作用,以得到既含氮又含硼的一种化合物,是一种很有意义的工作。目前,国外已开展了尿素与硼酸间相互作用的研究工作.研究结果表明,在一定条     

K2B4O7-Na2B4O7-Li2B4O7-H2O四元体系273 K介稳相平衡

采用等温蒸发平衡法研究了四元体系K2B4O7-Na2B4O7-Li2B4O7-H2O在273 K时的介稳相平衡及平衡液相的密度. 研究发现该四元体系为简单共饱和型, 无复盐及固溶体形成, 根据溶解度数据绘制了相图, 相图中有一个共饱点E, 三条单变度曲线E3E, E2E, E1E; 三个平衡固相分别为K2B4O7·4H2O、Na2B4O7·10H2O 和LiBO2·8H2O. 并简要讨论了实验结果.     

Solid-liquid Metastable Equilibria in Quaternary System （NaCl＋Na2CO3＋Na2SO4＋H2O） at 273.15 K

The metastable phase equilibria of the quaternary system NaCl+Na2CO3+Na2SO4+H2O were studied at 273.15 K. The salts' solubilities, densities and pH values of the equilibrated solution in this system were determined. According to the experimental data, the metastable equilibrium phase diagram, the diagram of density vs. composition and pH vs. composition diagram were plotted. The phase diagram consists of five univariant curves, four crystallization fields and two invariant points. The four crystallization fields correspond to sodium carbonate decahydrate (Na2CO3·10H2O), sodium sulfate decahydrate(Na2SO4·10H2O), sodium chloride(NaCl) and burkeite(2Na2SO4· Na2CO3), respectively. The crystallization field of sodium sulfate decahydrate(Na2SO4·10H2O) is the largest, which indicates that sodium sulfate is easy to saturate and crystallize from solution at 273.15 K.     

Phase Equilibria of Quaternary System NaCl-NaBr-Na2B4O7-H2O at 348 K

The phase equilibria of quaternary system NaCl-NaBr-Na₂B₄O₇-H₂O at 348 K were studied by the isothermal equilibrium method. The solubilities and densities of the equilibrium solution were determined. According to the experimental data, the phase diagram, density-composition diagrams and water content diagram of the quaternary system at 348 K were plotted respectively. And the phase diagram consists of one univariant curve, two crystallization fields and without any invariant point of the quaternary system. The equilibrium solid phases of the two crysta- llization fields were Na(Cl, Br) and Na₂B₄O₇·5H₂O. The experimental results show that the quaternary system contained solid solution. The densities of the solution decrease with increasing NaCl concentration and increase with increasing NaBr concentration.     

Measured and Predicted Solubility Phase Diagrams of Quaternary Systems LiBr-NaBr-MgBr2-H2O and LiBr-KBr-MgBr2-H2O at 298.15 K

The stable phase equilibria of quaternary systems LiBr-NaBr-MgBr₂-H₂O and LiBr-KBr-MgBr₂-H₂O at 298.15 K were studied by both experimental measurement(isothermal solution saturation method) and theoretical prediction(Pitzer model). The solubilities of the saturated solution have been determined experimentally and two stable phase diagrams and relevant water diagrams of the two quaternary systems were obtained. Results show that quaternary system LiBr-NaBr-MgBr₂-H₂O is hydrate II type as NaBr and NaBr·2H₂O coexistence. Its phase diagram consists of only one invariant point, four univariant curves, and five crystallization fields. The quaternary system LiBr-KBr-MgBr₂-H₂O is a complex type as the double salt KBr·MgBr₂·6H₂O formed. In addition to this double salt, the three single salts LiBr·2H₂O, KBr and MgBr₂·6H₂O also crystallize. In this paper, the solubilities of phase equilibria in above quaternary systems were also calculated by the Pitzer's electrolyte solution model. All the needed parameters can be obtained from the literature or be fitted by experimental data. On the Basis of the experimental and calculated results, the phase diagram of the quaternary system was plotted for comparison. It shows that the calculation results are consistent with the experimental ones.     

NH4+-Mg2+-pO3-4-H+-H2O体系的优势区相图

通过优势区相图的构建对NH4+-Mg2+-PO43-H+-H2O体系的热力学平衡关系进行了研究.在不同镁、磷物质的量比和离子强度的条件下绘制了lgCT,Mg-lgC,T,P和lgCT,p-pH相图,确定了MgNH4PO4·6H2O、Mg3(PO4)2· 8H2O、MgHPO4· 3H2O和Mg(OH)2的热力学稳定区.结果表明,在相当广的pH范围内,MgNH4PO4·6H2O和Mg3(PO4)2·8H2O都是主要存在的固相;在较低pH和较高磷浓度的条件下,MgNH4PO4·6H2O和MgHPO4· 3H2O可以共存;而MgNH4PO4·6H2O和Mg(OH)2在碱性条件下更为稳定.当MgNH4PO4·6H2O、Mg3(PO4)2· 8H2O与液相共存、pH=9.08～9.52时,溶液总氮浓度达到最低值.lgCT,Mg-lgCT,P和lgCT,P-pH相图可以用于指导磷酸铵镁的沉淀-溶解平衡过程,有利于废水中氨氮的脱除和回收.