Studies on primary hydrated complexes of Li+, Na+ and K+ ions by the extended Hückel method

The potential curves for aquacomplexes of Li⁺, Na⁺ K⁺ ions with the coordination numbers, n, equal to 4, 6 and 8 have been calculated by the extended Hückel method. The equilibrium values of the hydrated shell radius and the binding energy have been determined. The complexes of Li⁺ with n = 6 and Na⁺ and K⁺ with n = 8 were found to be the most advantageous energetically. As could be expected the contribution of the 3d-orbitals to the binding for the K⁺ion is much more considerable than for the Na⁺ion. The character of the potential curves for aquacomplexes of sodium and potassium ions is quite different. In the case of the K⁺ion the curves are found to be very smooth and slowly decreasing with distance, which can be attributed to the poor hydratability of this ion and the “loosening” of water structure by it.     

Liquid-liquid equilibrium of aqueous two-phase systems composed of poly(ethylene oxide) 1500 and different electrolytes ((NH4)2SO4, ZnSO4 and K2HPO4): Experimental and correlation

Phase diagrams of aqueous two-phase systems composed of PEO1500 + salt (di-potassium phosphate + potassium hydroxide or ammonium sulfate or zinc sulfate) + water were determined at (283.15, 298.15, and 313.15) K. All systems produce a large two-phase region; however the influence of temperature on the binodal position seems to be very small. By analyzing the effects of ammonium sulfate or zinc sulfate, it was observed that zinc was more effective in promoting phase separation than ammonium. The consistency of the tie-line data was ascertained by applying the Othmer-Tobias correlation. In this paper, aqueous two-phase systems data for nine ternary systems are correlated by using the NRTL model and UNIFAC for the activity coefficient. The results are very satisfactory, with root mean square deviations between experimental and calculated compositions as low as 0.99 and 1.21%, respectively. However the NRTL model better represents the systems in study, when compared with UNIFAC.     

Phase diagram for the system KVO3 + NH4HCO3 + NH4VO3 + KHCO3 + H2O at 303 K

Solubility data of the KVO₃ + NH₄HCO₃ + NH₄VO₃ + KHCO₃ + H₂O system at 303 K were determined under varying pressure conditions. The results were used to construct a phase diagram in the oblique projection according to Jänecke's method. At constant p and T this diagram includes two invariant points, five double saturated liquid curves, and four crystallization fields corresponding to KVO₃, NH₄HCO₃, NH₄VO₃, and KHCO₃. It has been found that ammonium meta-vanadate is a sparingly soluble salt. NH₄VO₃ and KHCO₃ compose the stable pair of salts, whereas KVO₃ and NH₄HCO₃ form the unstable salt-pair. A thorough knowledge of the solubility phase diagram for this reciprocal quaternary salt system is the theoretical basis of the carbonation process of the potassium meta-vanadate saturated ammonia solution.     

水蒸气气化条件下碳酸钾对煤灰烧结和矿物质演化的影响

在水蒸气气化气氛（水蒸气-氢气-一氧化碳-二氧化碳混合气氛）下考察了反应压力对负载碳酸钾煤灰烧结温度的影响，建立了包含煤的灰分、煤灰化学组成、催化剂负载量及反应压力因素的煤灰烧结温度预测关系式，预测结果与实测烧结温度的误差在±15℃（2%）范围内。利用X射线衍射仪和FactSage热力学计算软件对不同气氛和压力下煤灰中的矿物组成及含量的变化规律进行了分析。结果表明，碳酸钾与煤灰中的硬石膏、方解石反应生成硫酸钾和碳酸钾钙；水蒸气气化气氛下硫酸钾和赤铁矿被还原，碳酸钾钙的分解温度随反应压力的增大而升高；负载催化剂煤灰中氢氧化钾的量随温度和压力的提高而增加，不同压力下煤灰的最低烧结温度与氢氧化钾的含量有关，当氢氧化钾的含量达到一定值时，不同压力下对应的温度与实验测得的煤灰烧结温度接近。     

Synthesis and spectral properties of the Co2+ and Co3+ complexes with octaaryltetraazaporphyrins

Complexes Co²⁺ and Co³⁺ with octaphenyltetraazaporphyrin, octa(4-bromphenyl)tetraazaporphyrin and octa(4-nitrophenyl)tetraazaporphyrin were obtained and identified. The influence of the composition of reaction medium on the oxidation processes of the complexes Co²⁺ → Co³⁺ in DMF was revealed and the optimum conditions of formation of the corresponding compounds were determined.     

Determination of oxygen content in YBa2Cu3O6.5+x

A method for determining the oxygen content of the high-temperature superconductor YBa₂Cu₃O_6.5+x is described. The superconductor is dissolved in 4.4 M hydrobromic acid, forming bromine. The mixture is then diluted with hydrochloric acid to obtain a solution of bromine and Cu(II) in 0.44 M hydrobromic acid and 1.1 M hydrochloric acid. As(III) is added in slight excess of that required to react with the bromine and the unreacted As(III) is determined by titration with potassium bromate. Oxygen does not interfere. The results of this method are in agreement with those of other iodimetric procedures. The dissolution of the superconductor in 4.4 M hydrobromic acid is much faster than in hydrochloric acid, the medium used in one iodimetric technique. YBa₂Cu₃O_6.5+x sintered fibers and powder samples weighing from ca. 0.5 to 200 mg were analyzed for oxygen content.     

Studies of potassium ferrite K1+xFe11O17. I. Electronic conductivity and defect structure

The electronic conductivity of the nonstoichiometric potassium ferrite phase (with the β-alumina structure) has been measured as a function of temperature and potassium ion concentration. The latter was varied by coulometric titration using the cell: K_11q/K-β-alumina/K_1+xFe₁₁O₁₇. At 523°K the conductivity increased nearly linearly as x was increased from 0.09 to 0.65 while the activation energy for conduction decreased from 0.1 to 0.07 eV. The cell emf was completely reversible. The results are consistent with the view that the excess potassium ions are charge compensated by reduction of Fe³⁺ to Fe²⁺, and a comparison with results in the literature for some ironcontaining spinels suggests that a similar small polaron electron hopping mechanism operates.     

Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O system

Solubility in the Na₂Cr₂O₇-(NH₄)₂Cr₂O₇-K₂Cr₂O₇-H₂O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.     

An analysis of the EPR spectral parameters and the electronic state of the low-symmetry complexes of 67Zn+, 111Cd+, and 205Tl2+ns1 ions in crystals with the potassium sulfate structure

The electronic structures of the low-symmetry complexes of 4s ¹-⁶⁷Zn⁺, 5s ¹-¹¹¹Cd⁺, and 6s ¹-²⁰⁵Tl²⁺ ions in isostructural crystals of potassium sulfate, rubidium sulfate, and potassium selenate were studied by the EPR data. The sp-mixing of the atomic orbitals of the paramagnetic ion in the molecular orbital of the ground state was established. The parameters of the EPR spectra were analyzed. The sp-mixing was shown to result in negative shifts of the Zeeman interaction parameters. The signs of components of the hyperfine coupling tensor (A tensor) were considered. The determining role of the contribution from the isotropic hyperfine coupling to the components of the A tensor was found. The anomalously low observed values of the hyperfine coupling parameters of the thallium complexes were interpreted.     

Adsorption of H2O, CO2, C6H6, and n-C7H16 on Ca-, Mg-, K-, and H-forms of granulated X zeolite without binders

Adsorption capacities for water, carbon(IV) oxide, benzene, and linear hexane were determined for samples of X zeolite whose grains are entire aggregation of crystals with the maximum degree of exchange of sodium cations for cations of calcium, magnesium, potassium, and hydrogen.     

n-InP在Fe3+/Fe2+溶液中光脉冲暂态行为(IV)

研究了波长、温度及表面处理对n-InP光脉冲暂态行为的影响. 结果表明, 波长对时间常数无影响; 随着温度升高, 峰值下降, 衰减变快. 讨论了表面处理的影响, 并对实验结果作了必要的解释.     

Ionic conductivity in Na+, K+, and Ag+ β″-alumina

This paper presents measurements of the ionic conductivity in single crystals of β″-alumina (0.84 M₂O · 0.67 MgO · 5.2 Al₂O₃, M = Na, K, Ag). Single crystals of sodium β″-alumina were grown from a melt of Na₂O, MgO, and Al₂O₃ at 1660 to 1730°C. Selected crystals were converted to the other isomorphs by ion exchange. The conductivity of sodium β″-alumina varies from 0.18 to 0.01 (ohm · cm)^?1 at 25°C depending upon crystal growth conditions. Potassium β″-alumina has the unusually high room temperature conductivity of 0.13 (ohm · cm)^?1. Silver β″-alumina has a slightly lower conductivity, 4 × 10^?3 (ohm · cm)^?1 at 25°C. The activation energies of sodium and potassium β″-alumina decrease with increasing temperature, while that of silver β″-alumina is constant from ?80 to 450°C.     

Optical oscillator strengths of 3p63d 2D → 3p53d22po, 2Do, 2Fo transitions in Co8+, Cu1O+ and Zn11+ ions

We have calculated the excitation thresholds and optical oscillator strengths (OOS) for 3p⁶3d ²D → 3p⁵3d²²po, ²Do and ²F^o transitions Co⁺⁸, Cu¹⁰⁺ and Zn¹¹⁺ ions of the potassium isoelectronic sequence using Hartree-Fock (HF) and configuration interaction (Cl) wavefunctions for both initial and final states. Our Cl values of the length and velocity form of OOS are in good agreement with each other. The trends in the oscillator strengths for the potassium isoelectronic sequence are plotted.     

K~+、Na~+、Ca~(2+)、Mg~(2+)对胜利褐煤平衡复吸水的影响

以胜利褐煤为研究对象,利用FT-IR等手段,用灰分、不同湿度下的平衡复吸水含量等,系统研究了不同相对湿度下K+、Na+、Ca2+、Mg2+的水合作用对胜利褐煤平衡复吸水含量的影响。结果表明,相同浓度不同类型的金属离子与煤样的交换能力的趋势为Ca2+Na+K+Mg2+。金属离子对胜利褐煤平衡复吸水含量影响力的顺序为Mg2+Ca2+Na+≈K+。相对湿度高时,平衡复吸水含量的主要控制因素为游离水分子之间的分子作用力;相对湿度中等时,平衡复吸水含量的主要控制因素为金属水簇与毛细管之间的毛细管作用力;相对湿度低时,平衡复吸水含量的主要控制因素为金属离子的水合作用。     

Synthesis of potassium tungstate in the K2CO3-KNO3-WO3 system

The interaction of the components in the potassium carbonate-potassium nitrate-tungsten(VI) oxide system was studied. The reaction of WO₃ with a potassium carbonate-potassium nitrate mixture was found to occur at a higher rate than the reaction with pure potassium carbonate at the same temperature. A variant of the synthesis of high-purity potassium tungstate with a high yield of the target product was developed on the basis of the obtained data. Original Russian Text ? G.K. Shurdumov, Z.V. Shurdumova, Z.A. Cherkesov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 1, pp. 138–141.     

A low-energy passage for C+ + H2 → CH+(1Σ+) + H

Ab initio (SCF and CI) calculations have been performed for the linear approach (C_∝v) of C⁺ to H₂. For the ² Σ⁺ surface the saddle point and barrier height were determined. The interaction of the ²Σ⁺ and ²Π surfaces was investigated, leading to the conclusion that in near-C_∝v symmetry a low-energy path exists by which CH⁺¹ Σ⁺ can be formed, with negligible barrier in excess of endothermicity.     

Bi3+敏化的SrSiO3:Eu3+,Bi3+发光体的合成与发光

本文采用高温固相扩散法合成出一种新的发光体ＳｒＳｉＯ３：ｅＵ＾３＾＋，Ｂｉ＾３＾＋。研究了激活剂Ｅｕ＾３＾＋与敏化剂Ｂｉ＾３＾＋浓度变化与发光强度的关系。实验发现，组成为Ｓｒ０．８１７Ｌｉ０．０９１５ＳｉＯ３：Ｅｕ＾３＾＋０．０７５，Ｂｉ＾３＾＋的发光体其发光强度最大。给出了发光体ＳｒＳｉＯ３：Ｅｕ＾３＾＋，ＳｒＳｉＯ３：Ｅｕ＾３＾＋，Ｂｉ＾３＾＋的激发光谱与发光光谱；测定了发光体的Ｘ射线粉...     

纳米负载型V2O5-WO3/TiO2催化剂碱中毒及再生研究

实验制备了陶瓷颗粒为骨架的纳米级V₂O₅-WO₃/TiO₂(C)催化剂。采用浸渍法模拟碱金属中毒,研究了中毒及再生对催化剂脱硝活性的影响,运用XRD、FT-IR、H₂-TPR、XPS技术表征分析了碱金属对催化剂的失活作用。实验表明,碱金属能使催化剂活性降低,钾的毒性大于钠。FT-IR结果显示,催化剂以Lewis酸作为活性酸位。H₂-TPR、XPS结果表明,钾的加入降低了催化剂的氧化能力,主要影响了催化剂表面的吸附氧。采用单纯的水洗方法并不能提高催化剂活性,而酸洗再生后催化剂在较高反应温度下活性得到较好的恢复。     

Reactions of O+4 and O+2 with methane

Rate coefficients and products were determined for the title reactions employing a drift tube mass spectrometer apparatus. The implications of these reactions for the ion chemistry of the stratosphere is discussed.     

土壤颗粒表面电场作用下固-液界面Mg2+-K+与Ca2+-K+交换动力学的比较研究

通过恒流法研究了不同表面电场作用下Mg2+、Ca2+吸附动力学. 结果发现: (1)实验初期阶段是强静电力作用下的零级动力学过程和一定反应时间后的弱静电力作用下的一级动力学过程, 且零级速率过程和一级速率过程之间存在明显的转折点; (2)不同电解质构成中Ca2+的吸附速率明显快于Mg2+的, 平衡吸附量也大于Mg2+的, 且Ca2+在土壤颗粒表面的覆盖度比Mg2+在土壤颗粒表面的覆盖度高; (3)离子的相对有效电荷系数与土壤颗粒表面电场作用的不同是各体系中Ca2+、Mg2+吸附动力学有差别的根本原因; (4)根据离子吸附的理论模型可以分别计算出速率系数、平衡吸附量、离子在土壤颗粒表面的覆盖度以及固定液的体积, 这些参数可以定量评估土壤颗粒表面电场对离子吸附动力学的影响.