Interaction parameters and (solid + liquid) equilibria calculation for KCl–H2O–HCl–C2H5OH,K2SO4–H2O–H2SO4 and K2SO4–H2O–C2H5OH mixed solvent-electrolyte systems

This work deals with the prediction and experimental measurements of the (solid + liquid) equilibrium (SLE) in acid medium for industrial purposes. Specific systems including KCl–ethanol–water–HCl and K₂SO₄–water–H₂SO₄ were analyzed. At first, a critical discussion of SLE calculations was given, based on the well-known UNIQUAC extended and LIQUAC models. Two new proposals were derived, considering the explicit necessity of a new reference state for SLE calculations for the studied (solvents + acid) mixtures. The solubility of KCl in water–ethanol–HCl mixed solvents was measured in the temperature range of 300.15 to 315.15 K using an analytical gravimetric method. These results combined with some other experimental data reported in the open literature let us to propose a set of parameters for the new models. They included the interaction parameters between ethanol and the H⁺ ion. The prediction capability of the new models, for calculations in acid medium, was illustrated. Experimentally, it was observed that the (K₂SO₄ + water + H₂SO₄) system presented the unusual behavior of increasing K₂SO₄ solubility with an increase in the sulfuric acid concentration. This was accurately predicted by the newly proposed models.     

On the electrodialysis of aqueous H2SO4–CuSO4 electrolytes with metallic impurities

This work aims to contribute to the characterization of the electrodialysis (ED) of aqueous sulfuric acid–copper sulfate solutions. The presence of impurities such as As and Sb, typical of copper electrorefining electrolytes, is also studied. Results from kinetic studies carried out in ED cells with and without re-circulation are presented. The concentrations were: 3–9 g l⁻¹ copper, 50 g l⁻¹ sulfuric acid, 3 g l⁻¹ arsenic and 0.025 g l⁻¹ antimony; the temperatures, 22 and 44 °C; the transport rates, depending on experimental conditions, 0.2–0.6 mol h⁻¹ m⁻²of membrane for copper, 0.65–2.8 for sulfate, and 0.016–0.03 for arsenic. A speciation model has been developed and applied in order to interpret the experimental results and the performance of the studied cells has been evaluated. The main conclusion is that ED can be applied to the separation and concentration of chemical species in these systems.     

H2O2—H2SO4体系电化学振荡行为的研究

Ｈ２Ｏ２参与的电化学振荡反应长期以来倍受人们的关注［１,２,３］,文献［１］报道了Ａｇ电极在Ｈ２Ｏ２－ＨＣｌＯ４水溶液中的电势振荡现象;文献［２］报道了Ｐｔ电极Ｈ２Ｏ２－Ｈ２ＳＯ４体系在控电流条件下的电势振荡,其实验的Ｈ２Ｏ２浓度范围为０．０２～０．...     

Experimental Study on Phase Equilibria in Na2B4O7–Na2SO4–H2O and Li2B4O7–Na2B4O7–H2O Aqueous Ternary Systems at 273 K

Russian Journal of Physical Chemistry A - The solubility data for ternary systems Na2SO4–Na2B4O7–H2O and Li2B4O7–Na2B4O7–H2O at 273 K were obtained experimentally by the...     

CoFe2O4–SiO2–SO3H nanocomposite as a magnetically recoverable catalyst for oxidative bromination of alkynes

A hybrid catalyst has been prepared by incorporating sulfonic acid onto cobalt ferrite magnetic nanoparticles. The catalyst was successfully applied for rapid (20?min) synthesis of α,α-dibromoketones directly from alkynes and NBS. The reaction works well in the presence of 10?wt% of the catalyst at room temperature to produce the desired products in high yield. The catalyst could be recovered using an external magnet and reused without appreciable change in activity.     

H2SO4-SiO2固体酸的结构及酸性研究

以溶胶-凝胶法制备了H2SO4-SiO2固体酸催化剂，并对其结构和酸性进行了系统表征．FT—IR和^29Si—NMR结果表明H2SO4和SiO2间存在相互作用，因此硫酸与硅胶形成稳定的固体、XRD、SEM和TEM结果表明，H2SO4-SiO2固体酸是一多孔无定型材料；BET法测定的H2SO4-SiO2固体酸的比表面积和孔体积结果表明，随着H2SO4与SiO2质量比增加，其比表面减少，孔体积增大；H2SO4-SiO2固体酸的酸强度和液体浓硫酸相当，酸强度与干燥温度和H2SO4加入量有关，固体酸的这一性质以^1H—MAS NMR进行了系统的表征．     

Measurements of the Solid–Liquid Equilibria in the Quaternary System NaCl–NaBr–Na2SO4–H2O at 323 K

Phase equilibria of the quaternary NaCl–NaBr–Na₂SO₄–H₂O system at 323 K were studied by the isothermal dissolution equilibrium method. The solubilities of salts and densities of saturated solutions were determined. Solid solutions [Na(Cl, Br)] were found in the experiments. The phase diagram of the quaternary system has no invariant point, but has one univariant curve at the boundary of Na(Cl, Br) and Na₂SO₄ crystallization fields. The experimental results show that an increase of the NaBr concentration is accompanied by an obvious increase of the solution density and the decrease of the solubilities of NaCl and Na₂SO₄.     

Solid–liquid Equilibria in the Quaternary System Na+, Mg2+//Cl–, SO2–4–H2O at 25 and 30°C

The isoplethic sections in the diagram of the quaternary system Na⁺ , Mg²⁺ //Cl^– , SO^2– ₄ –H₂ O were established at 25 and 30oC by analytical and conductometric measurements. Three compounds can be observed in the isoplethic sections: NaCl, Na₂ SO₄ and MgNa₂ (SO₄ )₂ 4 H₂ O. Seven fields are determined, relating to the precipitation of one, two or three salts. The solubility range of MgNa₂ (SO₄ )₂ 4 H₂ O is wide, while the liquidus curve of Na₂ SO₄ is very short. The compositions, expressed in Jänecke coordinates, at the eutonic and peritonic points, respectively, were: 42.70% Cl^– and 745% H₂ O; 79.47% Cl^– and 787% H₂ O; 71.6% Cl^– and 744% H₂ O at 25°C; and 48.80% Cl^– and 715% H₂ O; 80.20% Cl^– and 778% H₂ O; 70.14% Cl^– and 707% H₂ O at 30°C.     

碱性水溶液中4Na2SO4·2H2O2·NaCl的分解动力学

以低浓度(30(wt)%)的双氧水制备了硫酸钠-过氧化氢-氯化钠加合物,各组分的含量均接近于理论值,其纯度为99.3%;在323K和333K下,研究了4Na2SO4*2H2O2*NaCl于碱性水溶液中的分解动力学.结果表明,在不同条件下,其分解均为一级反应;随着温度和pH的增加,其分解速率加快.置信水平为95%时k和C0的联合置信域均为椭圆形且面积较小,求得的参数精确度较高;优化出的模型能较准确地描述4Na2SO4*2H2O2*NaCl于碱性水溶液中的分解过程.     

Thermochemical investigations of the systems KCl−KBr−H2O,K2SO4−(NH4)2SO4−H2O and KNO3−NH4NO3−H2O at 298.15 K

For the equilibrium solid phases occurring in the systems: KCl?KBr?H₂O, K₂SO₄?(NH₄)₂SO₄?H₂O and KNO₃?NH₄NO₃?H₂O, the concentration dependencies of differential solution enthalpies, Δ_sol H ₂ for several crystallization paths, were measured. The limiting differential solution enthalpies, Δ_sol H ₂ ⁰ , were determined by extrapolation of the above dependencies to the ionic strength,I _m ⁰ , corresponding to the appropriate binary solutions. For KCl?KBr?H₂O system only, the clear dependence between Δ_sol H ₂ ⁰ andI _m ⁰ values was found and discussed.     

Flow injection determination of cyromazine in natural water samples using diperiodatoargentate(III)–H2SO4–chemiluminescence system

A simple and sensitive chemiluminescence (CL) procedure is proposed for the determination of cyromazine (CYR) using flow injection technique. CYR has strong enhancing effect on the CL reaction of diperiodatoargentate-(III) complex (DPA) in H₂SO₄ medium. The CL intensity with solid phase extraction (SPE) technique and with and without using online ion exchange resin column (IERC; OH-form) was proportional to the concentration of CYR over the range 0.1–200, 10–1000 and 2–2500 µg L^–1 (R² = 0.9974, 0.9980 and 0.9990, n = 7 each), respectively. Under the conditions, the limits of detection (S/N = 3) 0.029, 2.5 and 0.5 µg L^–1, relative standard deviations (n = 3) 1.9–3.6%, 1.4–2.7% and 1.0–3.0% and sample throughputs were 120, 80 and 120 h^–1. The effect of reagents concentration, flow rate, sample loop volume, photomultiplier voltage and IERC length was optimised. The mean results for natural water samples analysed by the proposed method were not significantly different at 95% confidence limit with the previously reported HPLC method. Interference from chloride ions could be eliminated by using SPE procedure or incorporating an in-line IERC. The CL mechanism of DPA–H₂SO₄–CYR system was also discussed briefly.     

H2S对丙炔醇在Fe/H2SO4体系中缓蚀作用的影响

铁腐蚀;硫化氢;H2S对丙炔醇在Fe/H2SO4体系中缓蚀作用的影响     

Synthesis and Crystal Structure of [Cu(phen)2(SO4)(H2O)]·0.5C4H4O4·7H2O

The title compound, [Cu(phen)2(SO4)(H2O)]·0.5C4H4O4·7H2O (phen = 1,10-phe-nanthroline and C4H4O4 = fumaric acid), has been synthesized and characterized by single-crystal X-ray diffraction. The crystal is of triclinic, space group P with a = 11.4827(2), b = 11.9086(2), c = 13.77350(10)(A), α = 80.6830(10), β = 66.6480(10), γ = 64.0480(10)o, V = 1554.63(4) (A)3, Mr = 722.17, Z = 2, Dc = 1.543 g/cm3, μ = 0.845 mm-1, F(000) = 750, R = 0.0349 and wR = 0.0837 for 4754 observed reflections (I > 2σ(I)). The compound contains a six-coordinated copper(II) center, which is surround by four N atoms of two phen ligands (Cu-N distances in the range of 1.997(2)～2.225(2)(A)), one sulfate O atom (Cu-O = 2.0037(17) (A)) and one water O atom (Cu-O(5w) = 2.719(2) (A)) in a distorted octahedral geometry. Extensive hydrogen-bonding interactions are involved in water molecules, ligated sulfate anions and fumaric acid molecules. In addition, π-π interactions via aromatic nitrogen-containing ligands are also discussed. The combination of non-covalent interactions leads to the formation of a 3-D network structure.     

Preparation and characterization of SO4 2−/Fe2O3–TiO2–Nd2O3 catalyst

This paper reports on the preparation of SO₄ ^2?/Fe₂O₃–TiO₂–Nd₂O₃ (SFTN) by combustion method. The effect of Nd content on catalytic activity was investigated. The prepared materials doped and undoped by Nd were compared by means of TG-DTG, XRD, FT-IR, NH₃-TPD and TEM techniques. Results indicated that the introduction of Nd improved the catalytic activities of the catalysts. Catalytic activity of SFTN was the highest with 98.3 % menthol conversion when Nd content was at 2 wt%. The introduction of Nd stabilized the coordination bond between the sulfate irons and the metallic oxides, helping in the formation of solid acid sites, enhancing the dispersion of catalyst particles, and inhibiting the growth of catalyst particles under heating.     

镉离子在H2SO4溶液中极谱行为的研究

本文研究了在没有动物胶的0.5M H_2SO_4溶液中镉离子的极谱行为,得到了如下的结果:(1)在0.050～20.0mM CdSO_4 0.5M H_2SO_4的十种溶液中测得的电流-电位曲线都有良好的波形、恒定的极限扩散电流和易于确定的半波电位.这些曲线上都没有极谱极大出现;其极限扩散电流(波高)与镉离子的浓度成正比.在镉离子低浓度(0.050～0.20mM)时,半波电位保持不变,在镉离子高浓度(1.00～20.0mM)时,也仅有很小的变化.故镉离子在0.5MH_2SO_4,溶液中的电流-电位曲线可供定量和定性测定之用.(2)镉离子在低浓度时的极谱波是一种可逆波.(3)前人在H_2SO_4溶液中研究镉离子时之所以没有能得到令人满意的极谱行为的原因是他们在H_2SO4溶液中添加了动物胶的缘故.(4)作者从得到的波形良好的电流-电位曲线上,测定了25±0.2℃时镉离子在0.5M H_2SO_4溶液中的扩散电流常数、半波电位和电极反应中得失的电子数.结果如下: i_d/cm~(2/3)t~(1/6)=3.97μA/mM·mg~(2/3)·s~(-1/2) E_(1/2)=-1.011V(0.5M硫酸亚汞电极)=-0.559V(饱和甘汞电极) n=2 这些数据比Lingane的数据,扩散电流常数2.6μA/mM·mg~(2/3)·s~(-1/2)和半波电位-0.59V(饱和甘汞电极)],要合理些.     

H3PO4-BF3/ZrO2及H3PO4-BF3H2SO4/ZrO2催化剂上异丁烷/丁烯的烷基化反应

研究了H₃PO₄-BF₃/ZrO₂及H₃PO₄-BF₃-H₂SO₄/ZrO₂催化剂对异构烷烃烷基化反应的催化作用。就载体的焙烧温度、活性组分的浓度、BF₃及H₂SO₄的添加及反应温度对催化剂活性的影响进行了较为详尽的研究。     

Hydrothermal Synthesis and Structure Characterization of Diamine-templated Two-dimenisional Cerium Sulfate, [C6N2H14][Ce(SO4)2(H2O)2]·0.5SO4·2.5H2O

Open-framework materials are of great interest from both the theoretical and practical points of view due to their catalytic, absorbent, and ion-exchange properties[1].     

Critical temperatures,pressures, and densities for the mixtures CO2–C3H8, CO2–nC4H10, C2H6–C3H8, and C3H8–nC4H10

A simple method is developed to estimate mixture critical temperatures (T_c), pressures (P_c), and densities (ρ_c) as a function of overall composition (X) from near critical region experimental coexistence data. This three-step method is applied to four mixtures, CO₂–C₃H₈, CO₂–nC₄H₁₀, C₂H₆–C₃H₈, and C₃H₈–nC₄H₁₀. Isothermal liquid–vapor coexistence data, which includes temperature, vapor pressure, coexisting densities (ρ^ℓ and ρ^v), and coexisting compositions for the more volatile component (x₁^v and x₁^ℓ) are used. In the first step, the difference of the saturated liquid and vapor densities (ρ^ℓ−ρ^v) is fitted to an empirical function in ((P_c−P)/P_c) to obtain P_c. Then P/P_c and ((ρ^ℓ+ρ^v)/2ρ_c) are simultaneously fitted to functions of a polynomial in (X₁−(x₁^v+x₁^ℓ)/2) yielding estimates of ρ_c and X₁. Finally, the discrete estimated critical data points are fitted with an equation to provide a continuous representation of the critical lines. The method is successfully tested for the mixtures, CO₂–C₃H₈ and CO₂–nC₄H₁₀, for which there is a reasonable amount of isothermal data. The procedure is then applied to the mixtures, C₂H₆–C₃H₈ and C₃H₈–nC₄H₁₀, for which there are sparse data. For all four mixtures, the critical temperature line, T_c vs. X₁, matches literature values within ±0.5%. The critical pressure line, P_c vs. X₁, and critical density line, ρ_c vs. X₁, match literature values, in general, within ±2%.     

Solubility and stability of (NH4)2SO4 · H2O2 in aqueous solutions and change in some crystallographic parameters of (NH4)2SO4 precipitates

Stability of (NH₄)₂SO₄ · H₂O₂ aqueous solutions and some structural changes in ammonium sulfate in the course of its solvation and subsequent desolvation were studied.