298K下Na~+,K~+//Cl~ˉ,SO_4~(2ˉ),NO_3~ˉ-H_2O五元体系液固介稳相平衡

研究了298 K下,五元体系Na+,K+//Clˉ,SO42ˉ,NO3ˉ-H2O的液固介稳相平衡。采用等温蒸发法确定了溶液的介稳平衡溶解度。根据实验数据,绘制出了该体系介稳相图中氯化钠介稳饱和区以及氯化钠饱和条件下的介稳相平衡投影相图。相图中,有四个四盐共饱的零变量点、九个三盐共饱的单变量线和六个两盐结晶区:Na2SO4·Na NO3·H2O+Na Cl,3K2SO4·Na2SO4+Na Cl,Na NO3+Na Cl,KNO3+Na Cl,Na2SO4+Na Cl和KCl+Na Cl。该体系在298 K下的介稳相图和稳定平衡相图存在一定的差别,复盐3K2SO4·Na2SO4的结晶区明显缩小。     

Solubility measurement and prediction of phase equilibria in the quaternary system LiCl + NaCl + KCl + H_2O and ternary subsystem LiCl+ NaCl + H_2O at 288.15 K

Using isothermal dissolution method, the phase equilibrium relationship in quaternary system LiCl + NaCl + KCl+ H_2O and the ternary subsystem LiCl + NaCl + H_2O at 288.15 K were investigated. Each phase diagram of two systems was drawn. The phase diagram of LiCl + NaCl + H_2O system contains two solid phase regions of crystallization LiCl·2H_2O and NaCl. In the phase diagram of LiCl + NaCl + KCl + H_2O system, there are three crystallization regions: LiCl·2H_2O, NaCl and KCl respectively. In this paper, the solubilities of phase equilibria in two systems were calculated by Pitzer's model at 288.15 K. The predicted phase diagrams generally agree with the experimental phase diagrams.     

298．16K下K^＋，Mg^2＋／／NO3^-，SO4^2- -H2O和Na^＋，K^＋，Mg^2＋／／NO3^- -H2O体系的液固相平衡

采用等温溶解平衡法研究了298.16 K下四元体系K , Mg2 //NO3-, SO42--H2O和Na , K , Mg2 //NO3--H2O的液固相平衡,并根据获得的溶解度数据分别绘制出了平衡相图及投影图.结果表明:在298.16 K下,四元交互体系K , Mg2 //NO3-, SO42--H2O相图中有五个单盐结晶区,七条单变量溶解度曲线和三个零变量点.五个单盐结晶区分别对应于KNO3、K2SO4、Mg(NO3)2·6H2O、MgSO4·7H2O和复盐K2SO4·MgSO4·6H2O;具有同离子的四元体系Na , K , Mg2 //NO3--H2O相图中有三个单盐结晶区,三条单变量溶解度曲线和一个零变量点.三个结晶区分别对应于NaNO3、KNO3、Mg(NO3)2·6H2O.K2SO4和KNO3的结晶区比较大,Mg(NO3)2·6H2O的结晶区最小.     

10℃下 K+, Ca2+∥Cl-,SO42-,36%NH3-H2O体系相图的研究

为了探讨CaSO4·2H2O和KCl复分解生产K2SO4的工艺及最佳生产条件,特用恒温法研究了10℃K+,Ca2+∥Cl-,SO42-,36%NH3-H2O体系相图.溶剂NH3-H2O中氨的浓度之所以选为36%,目的在于扩大K2SO4及CaSO4·K2SO4·H2O的结晶区;反应温度选为10℃,可降低氨的蒸气压.研究结果表明:在上述条件下,体系中存在K2SO4和CaSO4·K2SO4·H2O、CaSO4·K2SO4·H2O和CaSO4·2H2O的共饱线;存在K2SO4-CaSO4·K2SO4·H2O-KCl以及CaSO4·2H2O-CaSO4·K2SO4·H2O-KCl的三盐共饱点;K2SO4结晶区要比25℃,溶剂NH3-H2O中氨的浓度为25%的同体系相图大得多:K2SO4-CaSO4·K2SO4·H2O-KCl的三盐共饱点更偏向氯化钙一角,因此有利于CaSO4·2H2O和KCl复分解生产K2SO4:最佳工艺条件为2KCl(mol):CaSO4(mol):36%NH3-H2O(kg)=1:0.9023:0.5740,KCl的理论转化率可达90.22%;若想进一步提高KCl的理论转化率,必须加大氨的浓度.     

10℃下K~+,Ca~(2+)//Cl~-,SO_4~(2-),36%NH_3-H_2O体系相图的研究

为了探讨CaSO4·2H2O和KCl复分解生产K2SO4的工艺及最佳生产条件,特用恒温法研究了10℃K+,Ca2+//Cl?,SO42?,36%NH3-H2O体系相图。溶剂NH3-H2O中氨的浓度之所以选为36%,目的在于扩大K2SO4及CaSO4·K2SO4·H2O的结晶区;反应温度选为10℃,可降低氨的蒸气压。研究结果表明:在上述条件下,体系中存在K2SO4和CaSO4·K2SO4·H2O、CaSO4·K2SO4·H2O和CaSO4?2H2O的共饱线;存在K2SO4-CaSO4·K2SO4·H2O-KCl以及CaSO4·2H2O-CaSO4·K2SO4·H2O-KCl的三盐共饱点;K2SO4结晶区要比25℃,溶剂NH3-H2O中氨的浓度为25%的同体系相图大得多;K2SO4-CaSO4·K2SO4·H2O-KCl的三盐共饱点更偏向氯化钙一角,因此有利于CaSO4?2H2O和KCl复分解生产K2SO4;最佳工艺条件为2KCl(mol):CaSO4(mol):36%NH3-H2O(kg)=1:0.9023:0.5740,KCl的理论转化率可达90.22%;若想进一步提高KCl的理论转化率,必须加大氨的浓度。     

258.15K下五元体系Na~+,K~+//Cl~-,SO_4~(2-),NO_3~-―H_2O相平衡研究

采用等温溶解平衡法研究了258.15 K下五元体系Na~+,K~+//Cl~-,SO_4~(2-),NO_3~-―H_2O及其子体系Na~+,K~+//Cl~-,NO_3~-―H_2O的相平衡关系。测定了两个体系各盐的溶解度及溶液密度(冰相区除外),并绘制相图。研究结果表明:在258.15 K,氯化钠饱和时,该五元体系平衡干盐相图由四个两盐结晶区、五条单变量溶解度曲线和两个零变量点构成,四个两盐结晶区分别对应于Na Cl×2H_2O+Na NO_3,Na Cl×2H_2O+KNO_3,Na Cl×2H_2O+KCl,Na Cl×2H_2O+Na_2SO_4×10H_2O;与该体系298.15 K下的相图相比,K_3Na(SO_4)2和Na NO_3×Na_2SO_4×H_2O结晶区消失,Na_2SO_4×10H_2O结晶区扩大,相图大为简化;在258.15 K时,上述四元体系的平衡干盐相图由四个单盐结晶区(除冰区外)、五条单变量溶解度曲线和两个零变量点构成,四个单盐结晶区分别对应于Na NO_3、Na Cl×2H_2O、KNO_3和KCl;与该体系在298.15 K下的相图相比,硝酸钾结晶区扩大很多。     

三元体系MgCl_2+NH_4Cl+H_2O 298.15K稳定相平衡

采用等温溶解平衡法研究了三元体系MgCl2+NH4Cl+H2O 298.15 K的稳定相平衡,测定了平衡时各组分的溶解度及平衡液相的密度、折光率等物化性质。该三元体系在298.15 K时的稳定相图含有2个共饱点E1,E2,3条单变量曲线AE1,E1E2,E2B,3个结晶区。3个结晶区分别对应MgCl2.6H2O,NH4Cl及复盐铵光卤石(NH4Cl.MgCl2.6H2O)。2个共饱点中,E1为不相称共饱点,对应的平衡固相为NH4Cl.MgCl2.6H2O+NH4Cl,平衡液相组成为w(NH4Cl)=7.79%,w(MgCl2)=21.90%;E2为相称共饱点,对应的平衡固相为NH4Cl.MgCl2.6H2O+MgCl2.6H2O,平衡液相组成为w(NH4Cl)=0.21%,w(MgCl2)=32.27%。研究结果表明:该三元体系为复杂三元体系,有不相称复盐NH4Cl.MgCl2.6H2O生成。MgCl2对NH4Cl有强烈的盐析作用。平衡液相的密度和折光率随着溶液中MgCl2质量分数的增加而增大。采用经验公式对密度和折光率进行计算,计算值与实验值吻合度较好,相对偏差小于0.012。     

CaCl2-LiBr-LiNO3-KNO3/H2O工质对的热物性和腐蚀性

The new working pair of CaCl2?LiBr?LiNO3?KNO3 (mass ratio 16.2:2:2:1)/H2O was systematically evaluated in terms of the crystallization temperature and the saturated vapor pressure. The corrosion rates of the carbon steel, 316L stainless steel and copper in CaCl2?LiBr?LiNO3?KNO3/H2O were measured with a weight loss method. The results showed that under the same refrigeration conditions, the temperature required for collecting solar energy or the generation temperature of CaCl2?LiBr?LiNO3? KNO3/H2O for a single-stage absorption refrigeration cycle decreases by 6.2℃ comparing with LiBr/H2O. The corrosion rates of 316L and copper are low enough for practical applications.     

1,6-二磷酸果糖三钠盐·8H2O结晶新方法的研究

In order to overcome the elementary heterogeneous nucleation while octahydro trisodium salt of fructose-1,6-diphosphate(FDPNa3 8H2O) is crystallized with ethanol precipitation at low temperature, a new crystallization method with alcohol precipitation combined with salt precipitation has been presented. The ethanol-sodium acetate system for crystallization of salt of fructose-1,6-diphosphate is based on the mechanism of crystallization of FDPNa3 8H2O in the ethanol-low temperature system. It is found that crystal size may be controlled by regulating temperature or pH value of solution in the crystallization process, and the crystal yield increases to 95% from 78% which obtained in the ethanol-low temperature system.     

基于非平衡态成盐相图实现苦卤资源高效利用(英文)

Salt-forming regions for a complex salt-water system in non-equilibrium state of evaporation process are usually different from those in solubility diagrams.To understand the solid-forming region of NaCl and improve the utilization of bittern resources,experiments were carried out to evaporate 20 representative mixture solution samples of Na +,Mg 2+ //Cl-,2 4 SO-H2O system with an average evaporation intensity of(1.4±0.4) g·L-1 ·min-1(water) at boiling temperature 348 K,and determine the NaCl solid-forming regions in non-equilibrium state.Because of the complexity of salt-forming region,a maximal region and a minimal region were proposed to express the non-equilibrium state salt-forming region with different crystal seed,and a conditional salt-forming region was proposed to present the characteristic region of non-equilibrium salt-forming phase diagram.The areas of the maximal and minimal regions are 2.00 and 1.56 times those in solubility diagram,so it is possible to utilize bittern resources in high efficiency.The recovery rates of NaCl were 99.65%,93.14%,88.57%,72.76%,and 83.68%for six typical bittern sources from Tulantai Salt Lake(China),Dongtai Salt Lake(China) ,Jilantai Salt Lake(China),Qarun Salt Lake(Egypt) and seawater,respectively.It is testified that the non-equilibrium state salt-forming phase diagram can be used in industrial processes.     

-5℃下低品位钾硫酸镁亚型卤水的蒸发结晶规律

采用低温冷冻方法研究了青海大浪滩地区低品位钾的晶间卤水在-5℃时的蒸发结晶规律。该晶间卤水为典型的硫酸镁亚型卤水,依据0℃下Na+,K+,Mg2+//Cl-,SO42-—H2O五元体系的介稳相图,绘制出在-5℃下低温冷冻时卤水的低温蒸发结晶规律。利用X射线衍射仪和偏光显微镜鉴定其固相组成。通过对不同液相组成的分析,确定了-5℃低温蒸发该晶间卤水时伴随NaCl·2H2O的析盐结晶顺序为:Na2SO4·10H2O、MgSO4·7H2O、KCl·MgCl2·6H2O、MgCl2·6H2O,该结果为低温盐田工艺的开发提供了基础数据和理论依据。     

50℃下K~+,Na~+//Cl~-,SO_4~(2-),NO_3~--H_2O体系相平衡研究

通过查阅文献,整理获得完整的50℃下K+,Na+//Cl-,SO42-,NO3--H2O体系相平衡实验数据,据此绘制出了该体系的平衡相图以及氯化钠饱和时的干盐投影图,并进行了分析。结果表明:在50℃下K+,Na+//Cl-,SO42-,NO3--H2O体系存在8个单盐结晶区、18个两盐共饱面、16条三盐共饱曲线和5个零变量点。8个单盐结晶区分别是:NaCl、NaNO3、3K2SO4·Na2SO4、KCl、KNO3、Na2SO4、Na2SO4·NaNO3·H2O、K2SO4,其中Na2SO4、K2SO4及复盐3K2SO4·Na2SO4的结晶区较大,对应的溶解度较小,NaNO3、Na2SO4·NaNO3·H2O盐的结晶区较小,对应溶解度较大。在氯化钠饱和时的干盐图中,有6个两盐共饱面、9条单变量曲线和4个零变量点。和25℃下的相图相比,复盐3K2SO4·Na2SO4和Na2SO4·NaNO3·H2O的饱和区均有较大程度地缩小。     

298K下Na+,K+//NO3-,Cl--H2O体系中硝酸盐介稳程度的研究

采用等温蒸发法研究了四元体系Na+,K+//NO3-,Clˉ-H2O在298 K时NaNO3-KNO3共饱曲线的介稳程度及湿度对该共饱曲线介稳程度的影响。结果表明：在298 K时,不管在高湿度还是在低湿度下该四元体系的NaNO3-KNO3单变量曲线介稳现象均不明显。     

醇对正负离子表面活性剂双水相性质的影响

The effect of alcohol on the aqueous two-phase system properties of SDS/CTAB/H2O/Na2SO4 system was studied by the pseudo ternary phase diagram. The electrostatic forces (both attraction and repulsion) between cationic surfactant and anionic surfactant decreased because of the interaction of alcohol hydroxyl group and surfactant polar group. As a result, the phase area width of aqueous two-phase system increased. Long chain alcohol (more than five carbonatoms), which was in high concentration in the SDS/CTAB/H2O/Na2SO4) system, caused the anionic aqueous two-phase system area to vanish and the cationic aqueous two-phase system area to become wider. The CTAB rich phase turned from top phase to bottom phase.     

K+,Na+//Cl-,SO2-4 ,NO-3-H2O体系热力学研究

通过引入表达离子缔合或离子间的短程静电作用项,提高了局部组成模型关联单一电解质水溶液体系热力学性质的精度,并通过建立新的计算多元混合体系作用参数的方法,将其推广应用到多离子电解质溶液体系.在此基础上,预测了Na+//Cl-,SO2-4,NO-3,H2O、K+//Cl-,SO2-4,NO-3,H2O、K+ ,Na+//Cl-,SO2-4,H2O、K+ ,Na+//Cl-,NO-3,H2O、K+,Na+// SO2-4,NO-3,H2O 5个四元体系及K+,Na+//Cl-,SO2-4,NO-3,H2O 五元体系的溶解度,模型参数均通过上述体系所包含的二元、三元体系的溶解度数据获得,计算结果满意.     

Na+,K+∥Br-,B4O2-7-H2O交互四元体系348K相平衡研究

采用等温溶解平衡法研究了348 K时交互四元体系Na+,K+//Br-,B4O2-7-H2O的相平衡及平衡液相,测定了平衡液相的溶解度以及密度,补充了该体系在348 K下的溶解度和密度数据.研究结果发现,该体系属于简单共饱和体系,无复盐和固溶体生成.根据实验数据绘制了相应的相图、密度-质量分数图和含水量图,相图中有2个共饱点,5条单变量曲线,4个结晶区.4个结晶区的平衡固相分别为:Na2B4O7·5H2O,K2B4O7·4H2O,KBr和NaBr.从相图上可以看出,该体系在348 K时Na2B4O7·5H2O的结晶区最大,NaBr的结晶区最小.     

Synthesis of high purity Li_2CO_3 and MgCO_3·3H_2O in a homogeneous-like organic phase

Herein, three kinds of Li_2CO_3 and two kinds of MgCO_3·3H_2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li_2CO_3 ranging from micro-flaky, flower to nanobranch, MgCO_3·3H_2O ranging from nanosphere to nanorod. Compared with coupled reaction and solvent extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology.Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.     

10℃下K^＋，Ca^2＋//Cl^-，SO4^2-，36%NH3-H2O体系相图的研究

为了探讨CaSO4·2H2O和KCl复分解生产K2SO4的工艺及最佳生产条件,特用恒温法研究了10℃K+,Ca2+∥Cl-,SO42-,36%NH3-H2O体系相图.溶剂NH3-H2O中氨的浓度之所以选为36%,目的在于扩大K2SO4及CaSO4·K2SO4·H2O的结晶区;反应温度选为10℃,可降低氨的蒸气压.研究结果表明在上述条件下,体系中存在K2SO4和CaSO4·K2SO4·H2O、CaSO4·K2SO4·H2O和CaSO4·2H2O的共饱线;存在K2SO4-CaSO4·K2SO4·H2O-KCl以及CaSO4·2H2O-CaSO4·K2SO4·H2O-KCl的三盐共饱点;K2SO4结晶区要比25℃,溶剂NH3-H2O中氨的浓度为25%的同体系相图大得多K2SO4-CaSO4·K2SO4·H2O-KCl的三盐共饱点更偏向氯化钙一角,因此有利于CaSO4·2H2O和KCl复分解生产K2SO4最佳工艺条件为2KCl(mol)CaSO4(mol)36%NH3-H2O(kg)=10.90230.5740,KCl的理论转化率可达90.22%;若想进一步提高KCl的理论转化率,必须加大氨的浓度.     

Thermodynamic modeling and phase diagram prediction of salt lake brine systems Ⅱ. Aqueous Li~+-Na~+-K~+-SO_4~(2-) and its subsystems

It is still a challenging task to accurately and temperature-continuously express the thermodynamic properties and phase equilibrium behaviors of the salt-lake brine with multi-component,multitemperature and high concentration.The essential subsystem of sulfate type brine,aqueous Li~+-Na~+-K~'-SO_4~(2-) and its subsystems across a temperature range from 250 K to 643 K are investigated with the improved comprehensive thermodynamic model.Liquid parameters(Δg_(IJ),Δh_(IJ),and ΔC_(p,IJ)) associated with the contributions of Gibbs energy,enthalpy,and heat capacity to the binary interaction parameters,i.e.the temperature coefficients of eNRTL parameters formulated with a Gibbs Helmholtz expression,are determined via multi-objective optimization method.The solid constants Δ_fG_k°~((298.15)) and Δ_fH_k°~((298.15)) of11 solid species occurred in the quaternary system are rebuilt from multi-temperature solubilities.The modeling results show the accurate representation of(1) solution properties and binary phase diagram at temperature ranges from eutectic points to 643 K;(2) isothermal phase diagrams for Li_2SO_4-Na_2SO_4-H_2O,Li_2SO_4-K_2SO_4-H_2O and Na_2SO_4-K_2SO_4-H_2O ternary systems.The predicted results of complete structure and polythermal phase diagram of ternary systems and the isothermal phase diagrams of quaternary system excellently match with the experimental data.     

三元体系NaCl-Na_2B_4O_7-H_2O 363.15K下介稳相平衡研究

采用等温蒸发法研究了三元体系Na Cl-Na2B4O7-H2O 363.15 K下的介稳相平衡,测定了平衡时各组分的溶解度及平衡液相的密度、p H等物化性质。该三元体系在363.15 K下的介稳相图含有1个共饱点E,2条单变量曲线AE,EB,2个结晶区。2个结晶区分别对应单盐Na Cl和单盐Na2B4O7·5H2O。共饱点E对应的平衡固相为Na Cl+Na2B4O7·5H2O,平衡液相组成为w(Na Cl)24.84%,w(Na2B4O7)7.18%,w(H2O)67.98%。研究结果表明,该三元体系为简单三元体系,无复盐和固溶体生成。