Li＋, Na＋//SO42－, CO32－-H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li^＋, Na^＋// SO₄^2－, CO₃^2－-H₂O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na₃Li(SO₄)₂•6H₂O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li₂SO₄•H₂O, Na₂SO₄, Na₃Li(SO₄)₂•6H₂O, Li₂CO₃, Na₂CO₃•10H₂O. 复盐Na₃Li(SO₄)₂•6H₂O和一水硫酸锂(Li₂SO₄•H₂O)的结晶区较小, 而Li₂CO₃的结晶区最大; 该四元体系介稳平衡条件下未发现Na₂SO₄•10H₂O的结晶区.     

Li＋, Na＋//SO42－, CO32－-H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li^＋, Na^＋// SO₄^2－, CO₃^2－-H₂O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na₃Li(SO₄)₂•6H₂O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li₂SO₄•H₂O, Na₂SO₄, Na₃Li(SO₄)₂•6H₂O, Li₂CO₃, Na₂CO₃•10H₂O. 复盐Na₃Li(SO₄)₂•6H₂O和一水硫酸锂(Li₂SO₄•H₂O)的结晶区较小, 而Li₂CO₃的结晶区最大; 该四元体系介稳平衡条件下未发现Na₂SO₄•10H₂O的结晶区.     

Na+，K+//Br-，SO42--H2O四元体系323 K相平衡研究

采用等温溶解平衡法研究了四元体系Na⁺,K⁺//Br^-,SO₄^2--H₂O在323 K的相平衡关系,测定了该体系323 K的溶解度及平衡液相的密度,绘制了该体系的相图。研究发现：平衡体系存在复盐钾芒硝Na₂SO₄·3K₂SO₄的结晶区。其相图由3个共饱和点,7条单变量曲线和5个结晶区组成。相区分别对应NaBr·2H₂O、Na₂SO₄、K₂SO₄、KBr和Na₂SO₄·3K₂SO₄结晶区。其中复盐钾芒硝Na₂SO₄·3K₂SO₄,Na₂SO₄和K₂SO₄有较大结晶区,而NaBr·2H₂O和KBr有较小结晶区。对比了等温条件下四元体系Na⁺,K⁺//Cl^-,SO₄^2--H₂O相平衡结果。实验结果表明溴化物对硫酸盐有较强盐析作用。     

Li2SO4-Na2SO4-H2O和Li2SO4- K2SO4-H2O溶液的体积性质

本文用高精度数字式振荡管密度计测定了288K至318K温度范围内Li₂SO₄ + Na₂SO₄ + H₂O和 Li₂SO₄ + K₂SO₄ + H₂O三元体系的密度。混合溶液的离子强度范围从0.1到4.5 mol.kg_–1,混合溶液中Na₂SO₄和K₂SO₄的离子强度分数为0.2,0.4,0.6和0.8。用密度实验值拟合得到了不同温度下Pitzer离子相互作用模型混合参数θ_V和 ψ_V,模型的计算值与实验值的偏差在±0.002 g.cm_–3以内。用Pitzer模型计算了不同离子强度下三元体系的混合体积。     

Li+，Na+//SO42-，B4O72--H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li⁺，Na⁺//SO₄^2-，B₄O₇^2--H₂O 288 K介稳相平衡及平衡液相物化性质(密度、电导率、折光率、粘度和pH值)，测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质。根据实验数据绘制了相应的介稳相图及物化性质组成图。研究发现：该体系介稳平衡中有复盐Li₂SO₄·Na₂SO₄形成。其介稳相图中有3个共饱和点，7条单变量曲线，平衡固相为：Li₂SO₄·H₂O，Na₂SO₄，Li₂SO₄·Na₂SO₄，Li₂B₄O₇·3H₂O，Na₂B₄O₇·10H₂O。复盐Li₂SO₄·Na₂SO₄和一水硫酸锂(Li₂SO₄·H₂O)有较小的结晶区，而Li₂B₄O₇·3H₂O和Na₂B₄O₇·10H₂O有较大的结晶区；该四元体系介稳平衡条件下未发现Na₂SO₄·10H₂O的结晶区。     

光电催化降解活性艳红K-2BP中电解质NaCl和Na2SO4的作用研究

以TiO₂/Ti为阳极, Ti网为阴极, 研究了活性艳红K-2BP在NaCl和Na₂SO₄电解质中的降解情况, 深入探讨了两种电解质在光电催化降解染料中的作用, 研究了电解质浓度、溶液pH值的影响, 并讨论了在混合盐电解质存在下, 活性艳红K-2BP的降解行为. 研究表明, 以NaCl为电解质时, Cl^－会转化为氧化性很强的活性氯, 活性氯及光电的共同作用, 加速了染料的降解. 以Na₂SO₄为电解质时, SO₄^2－在光电的作用下将发生两类反应, 一部分SO₄^2－捕获光生空穴和HO•, 对光电催化降解染料起抑制作用; 另一部分SO₄^2－将发生反应生成H₂O₂, 对染料降解起促进作用. 关键词 光电催化; 活性艳红K-2BP; TiO₂/Ti电极; 电解质     

光电催化降解活性艳红K-2BP中电解质NaCl和Na2SO4的作用研究

以TiO₂/Ti为阳极, Ti网为阴极, 研究了活性艳红K-2BP在NaCl和Na₂SO₄电解质中的降解情况, 深入探讨了两种电解质在光电催化降解染料中的作用, 研究了电解质浓度、溶液pH值的影响, 并讨论了在混合盐电解质存在下, 活性艳红K-2BP的降解行为. 研究表明, 以NaCl为电解质时, Cl^－会转化为氧化性很强的活性氯, 活性氯及光电的共同作用, 加速了染料的降解. 以Na₂SO₄为电解质时, SO₄^2－在光电的作用下将发生两类反应, 一部分SO₄^2－捕获光生空穴和HO•, 对光电催化降解染料起抑制作用; 另一部分SO₄^2－将发生反应生成H₂O₂, 对染料降解起促进作用. 关键词 光电催化; 活性艳红K-2BP; TiO₂/Ti电极; 电解质     

五元体系Li+，Na+//CO32-，SO42-，B4O72--H2O 288 K介稳相平衡研究

采用等温蒸发法研究五元体系Li⁺,Na⁺//CO₃^2-,SO₄^2-,B₄O₇^2--H₂O 288 K介稳相平衡关系,测定在288 K条件下的介稳平衡溶液中各组分的溶解度和溶液密度,根据实验数据绘制相应的介稳平衡相图及密度组成图。研究结果表明该五元体系介稳相平衡中有复盐Na₃Li(SO₄)₂·6H₂O生成,其介稳相图中有4个共饱点,9条单变量曲线,6个Li₂CO₃饱和的结晶区分别为LiBO₂·8H₂O,Na₂B₄O₇·10H₂O,Na₂CO₃·10H₂O,Na₂SO₄,Li₂SO₄·H₂O和复盐Na₃Li(SO₄)₂·6H₂O。     

离子液体C3MIBF4和C5MIBF4溶解焓的研究

在298.15 K下利用等温环境溶解反应热量计测定了离子液体C₃MIBF₄(四氟硼酸1-甲基-3-丙基咪唑)和C₅MIBF₄(四氟硼酸1-甲基-3-戊基咪唑)不同浓度水溶液的摩尔溶解焓(Δ_sH_m). 借助Pitzer电解质溶液理论, 得到了它们的标准摩尔溶解焓 和Pitzer焓参数: 和 , 并计算了表观相对摩尔焓. 根据Glasser理论计算了离子液体晶格能, 进而估算了离子液体C₅MIBF₄和C₃MIBF₄中正离子的水化焓分别为－171 kJ•mol^－1 (C₅MI^＋)和－207 kJ•mol^－1 (C₃MI^＋).     

核酸适体修饰纳米金共振散射光谱探针快速检测痕量Pb2＋

以柠檬酸三钠做稳定剂, 用硼氢化钠还原氯金酸制备了粒径为5 nm的纳米金. 用铅离子核酸适体aptamer保护纳米金获得了检测铅离子的适体纳米金(aptamer-NG)共振散射光谱探针. 在pH 7.0的Na₂HPO₄-NaH₂PO₄缓冲溶液中及30 mmol•L^－1 NaCl存在下, aptamer-NG稳定而不聚集. Pb^2＋可与该探针中的aptamer形成非常稳定的G-四分体结构, 并释放出纳米金. 在NaCl作用下纳米金聚集形成较大的微粒, 导致552 nm处共振散射峰强度增大. Pb^2＋浓度在0.07～42 nmol•L^－1范围内与552 nm处共振散射强度增大值ΔI成线性关系, 其回归方程为ΔI＝12.0c＋9.2, 线性相关系数为0.9965, 方法检出限为0.03 nmol•L^－1 Pb^2＋. 该方法用于水样中铅离子检测, 结果与石墨炉原子吸收光谱法结果一致.     

Thermodynamics of solvent extraction of thallium with diethylhexyl phosphoric acid

The equilibrium molalities Tl⁺ were measured in {Tl₂SO₄ + Na₂SO₄ + D₂EHPA + n-C₈H₁₈ + Water} system at ionic strength from 0.1 to 2.0 mol kg^?1 containing Na₂SO₄ as supporting electrolyte in aqueous phase and at constant molality extractant at temperatures from 278.15 K to 303.15 K in organic phase. The standard extraction constants K ⁰ at various temperatures were obtained by methods of extrapolation and polynomial approximation. Thermodynamic quantities for the extraction process were calculated.     

Studies on the thermodynamics of solvent extraction of indium (III) with HDEHMTPCA

The equilibrium molalities In³⁺ in {In₂(SO₄)₃ + Na₂SO₄ + HDEHMTPCA + n-C₈H₁₈ + water} were measured at ionic strength from (0.1 to 2.0) mol · kg⁻¹ containing Na₂SO₄ as supporting electrolyte in aqueous phase and at constant molality extractant at temperatures from (278.15 to 303.15) K in organic phase. The standard extraction constants K⁰ at various temperatures were obtained by methods of extrapolation and polynomial approximation. Thermodynamic quantities for the extraction process were calculated.     

Studies on extraction of In(III) with 8-hydroxyquinoline

The equilibrium molalities of In³⁺ in extraction reaction: In³⁺(aq)+3HOx(org) = In(Ox)₃(org) + 3H⁺(aq) were measured at ionic strengths from 0.13 to 2.54 mol·kg^?1 in the aqueous phase containing Na₂SO₄ as the supporting electrolyte and at constant initial molality of extractant, HOx, in the organic phase at temperatures from 278.15 to 308.15 K, where HOx and Ox mean 8-hydroxy-quinoline and its anion, respectively. The standard extraction constants K at various temperatures were obtained by two methods proposed in our previous paper.     

Extraction of H+, NH4 +, Ag+ and Tl+ into nitrobenzene by using sodium dicarbollylcobaltate in the presence of tetramethyl p-tert-butylcalix[4]arene tetraketone

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺(aq)+NaL⁺(nb)⇔ML⁺(nb)+Na⁺(aq) taking place in the two-phase water-nitrobenzene system (M⁺ = H⁺, NH₄⁺, Ag⁺, Tl⁺; L = tetramethyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the ML⁺ complexes in water saturated nitrobenzene were calculated; they were found to increase in the order Tl⁺<NH₄⁺<Ag⁺ <H⁺ <Na⁺.     

The effect of salts on the conformation and microstructure of poly(N‐isopropylacrylamide) (PNIPA) in aqueous solution

We present an experimental investigation of the conformation and microstructure of Poly(N‐isopropylacrylamide) (PNIPA) in aqueous solution in the presence of salts. As a model, a strong salting–out salt (Na₂SO₄) and a strong salting–in salt (NaSCN) were chosen. Light scattering measurements show that Na₂SO₄ decreases the radius of gyration of PNIPA compared to its value in water, whereas NaSCN increases it. Moreover, the NaSCN solution was found to be a better solvent for PNIPA compared to water, whereas Na₂SO₄ solution is worse. Small‐angle neutron scattering measurements of semidilute PNIPA solutions, at temperatures well below the phase‐transition temperature, exhibit the behavior predicted by the model of dynamic concentration fluctuations characterized by a single correlation length. Excess scattering at low angles is observed in salt solutions at temperatures that are near, yet below, the phase‐transition temperature. This may indicate intrachain heterogeneities on the scale of 6–8 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3713–3720, 2004     

Trithallium hydrogen bis(sulfate), Tl3H(SO4)2, in the super‐ionic phase by X‐ray powder diffraction

The structure of trithallium hydrogen bis­(sulfate), Tl₃H(SO₄)₂, in the super‐ionic phase has been analyzed by Rietveld analysis of the X‐ray powder diffraction pattern. Atomic parameters based on the isotypic Rb₃H(SeO₄)₂ crystal in space group Rm in the super‐ionic phase were used as the starting model, because it has been shown from the comparison of thermal and electric properties in Tl₃H(SO₄)₂ and M₃H(SO₄)₂ type crystals (M = Rb, Cs or NH₄) that the room‐temperature Tl₃H(SO₄)₂ phase is isostructural with the high‐temperature Rm‐symmetry M₃H(SO₄)₂ crystals. The structure was determined in the trigonal space group Rm and the Rietveld refinement shows that an hydrogen‐bond O—­H?O separation is slightly shortened compared with O—H?O separations in isotypic M₃H(SeO₄)₂ crystals. In addition, it was found that the distortion of the SO₄ tetrahedra in Tl₃H(SO₄)₂ is less than that in isotypic crystals.     

Speciation and Structural Properties of Hydrothermal Solutions of Sodium and Potassium Sulfate Studied by Molecular Dynamics Simulations

Aqueous solutions of salts at elevated pressures and temperatures play a key role in geochemical processes and in applications of supercritical water in waste and biomass treatment, for which salt management is crucial for performance. A major question in predicting salt behavior in such processes is how different salts affect the phase equilibria. Herein, molecular dynamics (MD) simulations are used to investigate molecular‐scale structures of solutions of sodium and/or potassium sulfate, which show contrasting macroscopic behavior. Solutions of Na?SO₄ exhibit a tendency towards forming large ionic clusters with increasing temperature, whereas solutions of K?SO₄ show significantly less clustering under equivalent conditions. In mixed systems (Na_xK_2?xSO₄), cluster formation is dramatically reduced with decreasing Na/(K+Na) ratio; this indicates a structure‐breaking role of K. MD results allow these phenomena to be related to the characteristics of electrostatic interactions between K⁺ and SO₄^2?, compared with the analogous Na⁺?SO₄^2? interactions. The results suggest a mechanism underlying the experimentally observed increasing solubility in ternary mixtures of solutions of Na?K?SO₄. Specifically, the propensity of sodium to associate with sulfate, versus that of potassium to break up the sodium–sulfate clusters, may affect the contrasting behavior of these salts. Thus, mutual salting‐in in ternary hydrothermal solutions of Na?K?SO₄ reflects the opposing, but complementary, natures of Na?SO₄ versus K?SO₄ interactions. The results also provide clues towards the reported liquid immiscibility in this ternary system.     

Syntheses and Structures of Na2Mg3(OH)2(SO4)3·4H2O and K2Mg3(OH)2(SO4)3·2H2O

The crystal structures of Na₂Mg₃(OH)₂(SO₄)₃ · 4H₂O and K₂Mg₃(OH)₂(SO₄)₃ · 2H₂O, were determined from conventional laboratory X‐ray powder diffraction data. Synthesis and crystal growth were made by mixing alkali metal sulfate, magnesium sulfate hydrate, and magnesium oxide with small amounts of water followed by heating at 150 °C. The compounds crystallize in space group Cmc2₁ (No. 36) with lattice parameters of a = 19.7351(3), b = 7.2228(2), c = 10.0285(2) Å for the sodium and a = 17.9427(2), b = 7.5184(1), c = 9.7945(1) Å for the potassium sample. The crystal structure consists of a linked MgO₆–SO₄ layered network, where the space between the layers is filled with either potassium (K⁺) or Na⁺‐2H₂O units. The potassium‐bearing structure is isostructural to K₂Co₃(OH)₂(SO₄)₃ · 2(H₂O). The sodium compound has a similar crystal structure, where the bigger potassium ion is replaced by sodium ions and twice as many water molecules. Geometry optimization of the hydrogen positions were made with an empirical energy code.     

Solvent extraction of univalent cations into nitrobenzene using sodium dicarbollylcobaltate and tetraphenyl p-tert-butylcalix[4]arene tetraketone

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the equilibrium M ⁺(aq) + 1 · Na⁺ (nb) ⇄ 1 · M ⁺ (nb) + Na⁺ (aq) taking place in the two-phase water-nitrobenzene system (M ⁺ = Li⁺, H₃O⁺, NH₄ ⁺, Ag⁺, K⁺, Rb⁺, Tl⁺, Cs⁺; 1 = tetraphenyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the 1 · M ⁺ complexes in water saturated nitrobenzene were calculated; they were found to increase in the order Cs⁺ < Rb⁺ < Tl⁺ < K⁺ < NH₄ ⁺ < Ag⁺ < H₃O⁺ < Li⁺. Correspondence: Emanuel Makrlík, Faculty of Applied Sciences, University of West Bohemia, Pilsen, Czech Republic.     

Solid‐Liquid Equilibria in the Quinary Na+, K+//Cl−, SO2−4, B4O2−7‐H2O System at 298 K

The solid‐liquid equilibria in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K had been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured experimentally. Based on the experimental data, the dry‐salt phase diagram and water content diagram of the quinary system were constructed, respectively. In the equilibrium diagram of the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K, there are five invariant points F1, F2, F3, F4 and F5; eleven univariant curves E1F1, E2F2, E3F3, E4F5, E5F2, E6F4, E7F5, F1F4, F2F4 F1F3 and F3F5, and seven fields of crystallization saturated with Na₂B₄O₇ corresponding to Na₂SO₄, Na₂SO₄·10H₂O, Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄, K₂B₄O₇·4H₂O, NaCl and KCl. The experimental results show that Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄ and K₂B₄O₇·4H₂O have bigger crystallization fields than other salts in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K.