【作者】 桑世华；

【导师】 张允湘；

【作者基本信息】 四川大学 ， 化学工艺， 2002， 博士

【摘要】 采用等温溶解平衡法研究了五元体系Li⁺，Na⁺，K⁺∥CO₃^2-，B₄O₇^2-—H₂O及其九个三元子体系、五个四元子体系288K相平衡关系；采用等温蒸发的方法研究了该五元体系288K介稳相平衡关系。测定了上述各体系288K平衡液相中各组份的溶解度及主要物化性质（密度，pH及电导率）；绘制了三元子体系的相图，物化性质—组成图；绘制了四元子体系的干盐图及相应的水图；完成了该五元体系稳定及介稳平衡体系为Li₂CO₃饱和的投影相图，水含量图。 在所研究的三元子体系Na₂CO₃—K₂CO₃—H₂O 288K相图中发现，钾钠复盐为NaKCO₃·6H₂O，与298K时该三元体系相图相比，Na₂CO₃·7H₂O相区在288K时消失；其它三元子体系均为简单共饱和型，无复盐及固溶体形成；Na₂B₄O₇—K₂B₄O₇—H₂O 288K三元体系中发现K₂B₄O₇对Na₂B₄O₇有明显增溶作用，该增溶作用在K₂B₄O₇—Na₂B₄O₇—K₂B₄O₇—H₂O四元体系288K相平衡中也存在；而在含K₂CO₃的三元子体系及四元子体系中发现K₂CO₃对其它盐具有强烈的盐析作用；由于K₂CO₃浓度大，对平衡液相中物化性质影响巨大，使液相呈明显碱性，且使溶液电导率的变化曲线出现抛物线型。 四元子体系相图中，Li⁺，Na⁺，K⁺∥CO₃^2-—H₂O及Na⁺，K⁺∥CO₃^2-，B₄O₇^2-—H₂O体系中均出现了NaKCO₃·6H₂O的相区，而其他四元子体系均为简单共饱和型，仍未发现Na₂CO₃·7H₂O存在相区。 五元体系Li⁺，Na⁺，K⁺∥CO₃^2-，B₄O₇^2-—H₂O 288K稳定相图中，有六个Li₂CO₃饱和的结晶区：K₂CO₃·3／2H₂O，K₂B₄O₇、·4H₂O，Na₂CO₃·10H₂O，Na₂B₄O₇·10H₂O，NaKCO₃·6H₂O及Li₂B₄O₇·3H₂O；九条单变度曲线及四个无变度点。 五元体系 Li＋，N才，义 ／／ CO／，B。O7‘二q大O 288K介稳相图中六个为 LiZCO3所饱和的结晶区分别为：KZCO3·3／2H2O，NazCO3·10H。O，及复盐NaKCO3·6HZO，而硼酸盐却分别以 LiZBZO4·16HZO，NazBZO。·SHZO及KZB4O7巧 形式存在；比较该五元体系稳定及介稳相图发现：碳酸盐平衡固相一致，而硼酸钠及硼酸理由四硼酸盐转化为二硼酸盐，硼酸钾则以K贞。O／SH刃形式存在；在介稳相图中，N3人O3门。O结晶区较稳定相图明显增大，由此可见，介稳条件下有利于 NazCOs·10HZO的析出。 用288K时二元及三元体系的溶解度数据，运用多元线性回归的方法拟合了PitZer方程中288K时该五元体系所涉及各盐的单盐参数及混合参数；计算出了各盐288K时溶解平衡常数，运用PitZer方程对四元及五元稳定体系相平衡进行了理论模拟，计算结果基本令人满意。并就PitZer方程对上述体系的预测结果做了相应的分析与讨论。更多还原

【Abstract】 In this paper, phase equilibria of quinary reciprocal system Li+, Na% KV/ C032. B4O72~-H2O and its subsystems (nine ternary systems and five quaternary systems) at 288K were studied by isothermal method; An experimental study on metastable equilibria at 288K in the quinary system was done by isothermal evaporation method, also. Solubilities and physico-chemical properties (density, Conductivity, and pH) in the solution of these systems were determined. According to the experimental data, equilibria phase diagrams and physico-chemical property -composition diagrams of ternary systems were plotted; Equilibrium phase diagrams and corresponding water content diagrams of quaternary systems were finished; Stable and metastable phase diagrams, corresponding water content diagrams of the quinary systems at 288K (saturated with Li2CO3) were also plotted.Potassium and Sodium Carbonate double salt NaKCO3 - 6H2O was found in the ternary system Na2CO3-K2CO3-H2O at 288K, comparison with phase diagram at 298K of one, crystallization field of Na2CO3 ?7H2O disappeared at 288K. Other ternary systems all were of simple eutectic type and no double salt or solid solution was found. Potassium borate (K2B4O7) had obviously salting-in effect on Na2B4O7 in the ternary system K-,B4O7-Na2B4O7-H:O at 288K, which was also found in the quaternary system K2B4O7-Na;B4O7-Li2B407-H20 at 28 8K. On the contrary, Potassium carbonate (K2CO3) had strong salting-out effect on other salts in the systems including K2CO3. Double salt NaKCO3 - 6H2O was also found in quaternary system: Li+, Na+, KV/CO32--H:O , Na*, KV/CO32, B4072- -H2O and in the stable and metastable equilibrium quinary system Lf, Na+, KV/CO32~, B4O72 -H2O at 288K.In stable equilibrium phase diagram of quinary system Li+, Na+, KV/CO/’, B4O72 -H2O at 288K, there are six crystallization fields (saturated with Li2CO3): K2CO3 -3/2H2O, NajCO, ?10H2O, KjB4PO7 MH2O, NajB4O7- 10H2O, Li2B4O7 -3H2O and NaKCO3 - 6H2O; nine invariant curves; four invariant points.In metastable equilibrium phase diagram of quinary system Li+, Na+, KV/C032", B4O72 -H2O at 288K, there are six crystallization fields (saturated with Li2CO3): K2CO3 -3/2H2O, Na2CO3 MOHjO, NaKCO3 -6H2O, K2B4O7 5H2O, Li,B2O4 -16H2O and Na2B2O4 8H2O. nine univariant curves; four invariant points.Some differences were found between stable phase diagram and metastable one at 288K. The crystallization fields of K,B4O7 ?4HLO, Li,B4O7 - 3H,O and Na2B4O7 -10H2O which were found in the stable phase diagram disappeared in themetastable one and replaced by K2B4O7 - 5H2O, Li2B2O4 - 16H2O and Na2B2O4 - 8H2O, respectively. The crystallization field of Na2CO3 - 10H,O in metastable phase diagram obviously became bigger than in stable one.Using the solubilities data of binary and ternary systems at 288K, the single salt ion-interaction parameters and corresponding ion-interaction mixing parameters for Pitzer’s equations were fitted by multiple linear regression method. Equilibrium constant of salts for (liquid +solid) equilibrium at 288 K were evaluated with Pitzer’s model. The solubilities of quaternary and quinary system were calculated by Pitzer ’s equations. The prediction results were in agreement with the experimental results essentially. Corresponding discussion of prediction results was finished.更多还原