锂硼酸盐产品因其优越的性能广泛的应用于无机盐化工、玻璃制造、电池加工、医药和农业等领域。我国西部青藏高原地区的盐湖以富含锂硼资源而闻名于世,迄今为止发现的天然形成的锂硼酸盐矿物主要有LiBO2·8H2O,Li2B4O7·3H2O和LiB5O8·5H2O,然而,这些锂硼酸盐体系的热力学数据极为缺乏。因此,本文针对青藏高原地区富含锂硼盐湖卤水资源,开展了不同形态锂硼酸盐的提纯、合成、表征及其水溶液体系热力学性质的研究,取得的主要结论如下。本文首先利用冷凝回流的方法对四硼酸锂进行了重结晶,获得了高纯的三水合四硼酸锂,以—水氢氧化锂和硼酸为原料合成了五水合五硼酸锂,并通过X-ray粉晶衍射、TG-DSC和化学分析的方法对提纯和合成的锂硼酸盐进行了鉴定与表征。采用U型振荡管高精度密度计测定了至今未见报道的不同浓度五硼酸锂水溶液体系在温度范围为283.15～363.15 K时的密度。基于测定结果计算得到了热膨胀系数、表观摩尔体积和偏摩尔体积等体积性质参数,并利用Pitzer离子相互作用模型对实验结果进行了关联,首次拟合获得了五硼酸锂水溶液在不同温度下的Pitzer单盐参数及温度关联式。采用自主研发的高精度精密等压仪测定了三元体系（LiBO2+Li2B4O7+H2O）和（Li2B4O7+LiB5O8+H2O）及其子体系在288.15 K下的等压平衡能浓度。基于测定结果计算获得了水活度和渗透系数等热力学性质参数,并通过Pitzer离子相互作用模型拟合求取了 288.15 K下相应锂硼酸盐的单盐及混合作用参数。

The solubilities and the densities in the aqueous ternary system (MgCl2 + MgSO4 + H2O) at 323.15 K were determined by the isothermal evaporation method. The phase diagram was drawn for this system at 323.15 K. The phase diagram consists of two invariant points, three univariant curves, and three crystallization regions corresponding to bischofite (MgCl2 · 6H2O), tetrahydrate (MgSO4 · 4H2O) and hexahydrite (MgSO4 · 6H2O). Neither double salts nor solid solution was found. Based on the Pitzer and Harvie–Weare (HW) model, the solubility equilibrium constants for the salts were fitted with the solubilities in this research work, and the solubilities of the ternary system at 323.15 K were calculated. Comparisons between the calculated and measured solubilities show that the predicted data agree well with the experimental results. © 2018, Pleiades Publishing, Ltd.

The solubilities and the densities in the aqueous ternary system (MgCl₂ + MgSO₄ + H₂O) at 323.15 K were determined by the isothermal evaporation method. The phase diagram was drawn for this system at 323.15 K. The phase diagram consists of two invariant points, three univariant curves, and three crystallization regions corresponding to bischofite (MgCl₂ · 6H₂O), tetrahydrate (MgSO₄ · 4H₂O) and hexahydrite (MgSO₄ · 6H₂O). Neither double salts nor solid solution was found. Based on the Pitzer and Harvie–Weare (HW) model, the solubility equilibrium constants for the salts were fitted with the solubilities in this research work, and the solubilities of the ternary system at 323.15 K were calculated. Comparisons between the calculated and measured solubilities show that the predicted data agree well with the experimental results.
© 2018, Pleiades Publishing, Ltd.

Solubilities, densities, and refractive indices in the quaternary system (Li2B4O7 + Na2B4O7 + Mg2B6O11 + H2O) at T = 298.15 K and p = 0.1 MPa were investigated experimentally with the method of isothermal dissolution equilibrium. According to the experimental data, the phase diagrams and the diagrams of densities and refractive indices versus lithium tetraborate composition in the solution were plotted, respectively. In the phase diagrams of the quaternary system at 298.15 K, there are one invariant point, three univariant isotherm dissolution curves, and three crystallization regions corresponding to Li2B4O7 center dot 3H(2)O, Na2B4O7 center dot 10H(2)O and Mg2B6O11 center dot 15H(2)O, respectively. The size of crystallization areas of salt is in the order Mg2B6O11 center dot 15H(2)O > Na2B4O7 center dot 10H(2)O > Li2B4O7 center dot 3H(2)O, which demonstrates Mg2B6O11 center dot 15H(2)O can be more easily separated from solution in this quaternary system. The solution density and refractive index of the quaternary system at 298.15 K change regularly with the increasing of Li2B4O7 concentration. The calculated values of density and refractive index using empirical equations of the quaternary system are in good agreement with the experimental values.

Sediment cores were collected at an upstream site (Jintang) and a downstream site (Neijiang) in summer and winter in the Tuohe River, which is one of the five largest tributaries of the Changjiang (Yangtze) River in China. A sequential leaching procedure was applied to determine the concentrations of the different forms of solid phosphorus, including exchangeable phosphorus (Exc-P) as well as phosphorus associated with iron oxides (Fe-P), with aluminum oxides (Al-P), with apatite (Ca-P) and with the residual fraction (Res-P), as correlated with water content and total organic carbon. The seasonal variations and the vertical distributions of phosphorus species in sediments at both sampling sites demonstrated that: 1) total phosphorus (TP) in summer and winter were ranged between 1 313-2 330, 1 491-2 228 mg/kg in Jintang and 543-2 128, 603-1 175 mg/kg in Neijiang, respectively. It can predicated the pollution of TP in Jintang is serious than that in Neijiang both in summer and winter; 2) total inorganic phosphorus (TIP) was the dominant form of TP; 3) Ca-P was the main chemical forms of TIP in the sediments. Based on the profiles in sediments and bio-available phosphorus data, it revealed that bio-available phosphorus (BAP) represented only a minor portion (0.61%-3.59%) of TP, and the vertical distribution of soluble reactive phosphorus (SRP) in corresponding porewaters was more abundant in the upper layer of the sediment, which suggests that BAP may be converted to non-bioavailable phosphorus in deeper layer of the sediment of this dynamic system.

Densities of aqueous solutions of lithium tetraborate in the (0.01 to 0.12) mol·kg−1 concentration range at a 5 K intervals from 283.15 K to 363.15 K and 101.325 kPa were measured using a precise Anton Paar Digital vibrating-tube densimeter. Apparent molar volumes are obtained on the basis of experimental density data, and then the 3D diagram of (mi, T, Vϕ) apparent molar volumes against temperature and molality were plotted. On the basis of Pitzer ion-interaction equation of the apparent molar volume model, the Pitzer single-salt parameters (βM,X(0)v, βM,X(1)v), βM,X(2)v and CM,X(v)), and their temperature-dependence correlation F(i, p, T) = a1 + a2T + a3T2 + a4/T + a5ln(T) + a6/(T−263) + a7/(680−T) (where T is temperature in Kelvin, p is a pressure in 101.325 kPa, ai are model parameters) for Li2B4O7 are obtained, which is not reported in the literature. The deviations of the experimental and calculated values of Pitzer single-salt parameters βM,X(0)v, βM,X(1)v, βM,X(2)v and CM,X(v) for Li2B4O7 are all within ±0.1, and those results indicate that the single salt parameters and their relational coefficients of temperature-dependence for Li2B4O7 obtained in this work are reliable. © 2018 Elsevier Ltd

The solubilities and the densities in the aqueous ternary system (MgCl2 + MgSO4 + H2O) at 323.15 K were determined by the isothermal evaporation method. The phase diagram was drawn for this system at 323.15 K. The phase diagram consists of two invariant points, three univariant curves, and three crystallization regions corresponding to bischofite (MgCl26H(2)O), tetrahydrate (MgSO44H(2)O) and hexahydrite (MgSO46H(2)O). Neither double salts nor solid solution was found. Based on the Pitzer and Harvie-Weare (HW) model, the solubility equilibrium constants for the salts were fitted with the solubilities in this research work, and the solubilities of the ternary system at 323.15 K were calculated. Comparisons between the calculated and measured solubilities show that the predicted data agree well with the experimental results.

中国西部高海拔青藏高原腹地拥有众多盐湖,这些盐湖以富含锂而闻名世界。其卤水组成可用Li^+,Na^+,K^+,Mg^(2+)//Cl^-,SO_4^(2-),CO_3^(2-),borate-H_2O表示。开展多组分复杂盐湖卤水体系相平衡及热力学性质研究,不仅对该种类型盐湖卤

The phase and physicochemical properties diagrams of the quaternary system (Li2B4O7 + Na2B4O7 + Mg2B6O11) at 288.15 K and 0.1 MPa were constructed using the solubilities, densities, and refractive indices measured. In the phase diagrams of the system there are one invariant point, three univariant isothermic dissolution curves, and three crystallization regions corresponding to Li2B4O7 · 3H2O, Na2B4O7 · 10H2O, and Mg2B6O11 · 15H2O, respectively. The solution density, refractive index of the quaternary system changes regularly with the increasing of Li2B4O7 concentration. The calculated values of density and refractive index using empirical equations of the quaternary system are in good agreement with the experimental values. © 2017, Pleiades Publishing, Ltd.