Water and solute activities of H2SO4-Fe2(SO4)3-H2O and HCl-FeCl3-H2O solution systems: Part i. activities of water

The activities of water of the H₂SO₄-Fe₂(SO₄)₃-H₂O solution system were determined by an isopiestic method and those of HCl-FeCl₃-H₂O by a transpiration method both at 298 K. The experimentally determined water activities satisfactorily obeyed the Zdanovskii rule. The activities of water in these solution systems were also calculated using the Robinson-Bower empirical equation. The water activities determined experimentally showed satisfactory agreement with the calculated values when the formation of Fe(III) complexes and the dissociation of acids were taken into consideration. This finding indicates that the empirical additivity rule proposed by Robinson and Bower is useful in estimating the water activities for these solution systems on the basis of composition data of mixed solutions.     

Water and solute activities of the solution systems of H2So4-Cuso4-H2O and Hci-Cuci2-H2O

The activities of water, α(H₂O), in the solution system of H₂SO₄-CuSO₄-H₂O were determined by an isopiestic method and those in the solution system of HCl-CuCl₂-H₂O by a transpiration method, both at 298 K. The activities of H₂SO₄ and H⁺ in the solution system of H₂SO₄-CuSO₄-H₂O were also determined at 298 K by the emf method. The water activities in both systems obeyed the Zdanovskii rule relatively well. The α(H₂O) experimentally determined in the sulfate system showed a satisfactory agreement with those calculated from the Robinson-Bower equation, assuming the complete dissociations of H₂SO₄ and CuSO₄, whereas a good agreement between the calculated and experimentally determined α(H₂O) for the chloride system was obtained when the formation of Cu(II) chloro-complexes was taken into consideration. The mean activity coefficients, γ_±, of solutes, including H₂SO₄, HC1, and CuCl₂ in these solution systems, were calculated at 298 K by the McKay-Perring method using the activity data. The γ_±(H₂SO₄) values in the solution system of H₂SO₄-CuSO₄-H₂O were in good agreement with those determined by the emf method. On the other hand, the γ_±(CuSO₄) were calculated at the same temperature based upon the Gibbs-Duhem equation using both measured α(H₂O) and calculated γ_±(H₂SO₄) values, because of solubility limitations.     

Activities of water and solutes in the solution system H2SO4−Cr2(SO4)3−H2O

The activities of water in the solution systems of Cr₂(SO₄)₃−H₂O and H₂SO₄−Cr₂(SO₄)₃−H₂O were determined at 298 K by an isopiestic method. Properties of the green and violet isomers of Cr₂(SO₄)₃ were considered separately. The activities of water in aqueous solutions containing violet Cr₂(SO₄)₃ alone are considerably smaller than those of the green isomer. The water activities of aqueous H₂SO₄ solutions containing the violet isomer of Cr₂(SO₄)₃ satisfactorily obey the Zdanovskii rule, while those of the green isomer show an upward deviation from the Zdanovskii linearity. The activities of water in these solution systems were also calculated, using the Robinson-Bower empirical equation, and showed satisfactory agreement with the calculated values, whether the formation of the sulfato-complex, CrSO ₄ ⁺ , and the dissociation of H₂SO₄ were taken into consideration or not. The mean activity coefficients of H₂SO₄ and Cr₂(SO₄)₃, for the solution systems studied in this work, were calculated by applying the McKay-Perring method and its modified form, using the measured water activity data of these solution systems. The concentration dependencies of the mean activity coefficients of H₂SO₄ and Cr₂(SO₄)₃ in the solutions containing the green isomer are quite different from those of the violet isomer. Particularly, it was found that the activity values of water and solutes in the solution system of H₂SO₄-violet Cr₂(SO₄)₃−H₂O are similar to those of the solution system of H₂SO₄−Fe₂(SO₄)₃−H₂O. formerly Graduate Student with Kyoto University     

H_2O_2-Fe_2(SO_4)_3-H_2SO_4体系中辉铜矿的浸取研究

以H_2O_2和Fe_2(SO_4)_3为氧化剂、NaCl为助浸剂,在H_2SO_4溶液中浸出辉铜矿中的铜。结果表明,在反应温度85℃,反应时间180 min,H_2O_2、Fe_2(SO_4)_3、NaCl、H_2SO_4浓度分别为0.2、0.25、0.5、0.5mol/L的条件下,铜浸出率可达94.33%。采用XRD和EDS等手段对不同反应时间浸出残渣进行了表征与分析,初步揭示了辉铜矿浸取反应历程。     

Water and solute activities in the aqueous H2SO4 -(NH4)2SO4 solutions

The activities of water in H₂SO₄-(NH₄)₂SO₄-H₂O solutions, the concentrations of which ranged from 0.1 to 4.0 mol kg_-1 H₂SO₄ and 0.1 to 5.0 mol kg_-1 (NH₄)₂SO₄, were determined by an isopiestic method at 298 K. The experimentally determined water activities showed considerable deviation from the Zdanovskii rule. The activities of water were not in agreement with those calculated from the Robinson-Bower equation, even though the formation of sulfato-complexes of NH₄(I) and the dissociation of sulfuric acid were taken into consideration. The behavior of H₂SO₄-(NH4)₂SO₄ solu-tions is quite different from other systems. Water activities of aqueous solutions of H₂SO₄-Li₂SO₄ and H₂SO₄-Na₂SO₄ can be calculated from the Robinson-Bower equation with satisfactory accuracy. The interesting behavior of (NH₄)₂SO₄ can be attributed to the water structure-breaking property of NH₄ ⁺ ions. An additivity equation for estimating the water activity of aqueous H₂SO₄ solutions con-taining (NH₄)₂SO₄ was proposed by considering the contributing effects of solutes on the structure of water. The proposed equation satisfactorily described the solution system under investigation. The mean activity coefficients of H₂SO₄ and (NH₄)₂SO₄ in the solution system, H₂SO₄-(NH₄)₂SO₄-H₂O, at 298 K, were calculated by the McKay-Perring method using the water activities experimentally determined. It is believed that the calculated values for concentrated solutions of more than one sol-ute are sufficiently accurate since the mean activity coefficients of H₂SO₄ agree with the values measured by the emf method.     

Thermodynamic study of Fe2O3-Fe2(SO4)3 equilibrium using an oxyanionic electrolyte (Na2SO4-I)

The emf of the cell, Pt, Ar + O₂ + SO₂ + SO₃/Na₂SO₄-I/Fe₂O₂ + Fe₂(SO₄)₃, Pt, has been measured in the temperature range 800 to 1000 K, using a gas mixture of known input composition as the reference electrode. The equilibrium composition of the reference gas at the measuring temperatures was computed using the thermodynamic data on the gaseous species reported in the literature. A mixture of ferric oxide and sulfate was kept in a closed system to ensure establishment of equilibrium partial pressure at the electrode. The cell was designed to avoid physical contact between Fe₂(SO₄)₃ and Na₂SO₄ electrolyte. Uncertainties arising from the formation of sulfate solid solution were thus eliminated. The Gibbs’ energy of formation of ferric sulfate calculated from the emf is discussed in comparison with data reported in the literature. There is no evidence for the formation of oxysulfates in the Fe-S-0 system. Based on the results obtained in the present study for Fe₂(SO₄)₃ and literature data for other phases, chemical potential diagrams have been constructed for the Fe-S-O system at 900 and 1100 K.     

Effects of iron and temperature on solubility of light rare earth sulfates in multicomponent system of Fe2(SO4)3-H3PO4-H2SO4 synthetic solution

Numerous light rare earth elements (LREE) minerals containing Fe and P were processed by sulfuric acid roasting method, and the leaching solution mainly comprises LREE sulfate, Fe₂(SO₄)₃, H₃PO₄, and H₂SO₄, however, the solubility data of LREE sulfates in this system is few. This work studies the solubility of LREE sulfates in independent LREE sulfate system RE₂(SO₄)₃-Fe₂(SO₄)₃-H₃PO₄-H₂SO₄ (RE = La, Ce, Pr or Nd) and mixed LREE sulfates system (La,Ce,Pr,Nd)₂(SO₄)₃-Fe₂(SO₄)₃-H₃PO₄-H₂SO₄ at different temperature (25–65 °C) and concentrations of Fe₂(SO₄)₃ (Fe₂O₃, 0–50.13 g/L), H₂SO₄ (0.5 mol/L), and H₃PO₄ (P₂O₅, 20.34 g/L) based on the industrial operating condition at low liquid and solid ratio 2:1. The solubility of each LREE sulfate in the independent system (La₂O₃, 12.25–20.88 g/L; CeO₂, 41.93–62.35 g/L; Pr₆O₁₁, 37.34–56.69 g/L; Nd₂O₃, 26.60–37.63 g/L) is much higher than that of the mixed system (La₂O₃, 6.95–11.03 g/L; CeO₂, 10.63–21.51 g/L; Pr₆O₁₁, 11.56–20.36 g/L; Nd₂O₃, 12.36–19.79 g/L) under the same other conditions. The results also indicate that, in the two systems, both Fe and the temperature have negative effects on the solubility of LREE sulfates. That may occur due to the complication reactions between the complexes of RESO₄⁺ and Fe(SO₄)₂^–. However, the influence degree of temperature and iron concentration on the LREE sulfates solubility varies in the two systems and among different LREE species. This research is of theoretical significance for optimizing the conditions of the sulfuric acid process for recovering the LREE from the mixed LREE bearing minerals as well as the single LREE containing secondary rare earth scraps.     

Cu(Ⅱ)-NH3-(NH4)2SO4-H2O体系浸出-电积生产铜的工艺研究

对氨法炼铜新工艺进行了探索性的研究,得到了NH3-(NH4)2SO4-H2O体系中浸出铜锌精矿焙砂及在氨性硫酸铜溶液中电积生成铜板的最佳工艺条件.在浸出时间2 h,氨水浓度3 mol/L,液固比6:1,温度40℃的条件下,铜的浸出率为65.39%;电积最佳条件为铜离子浓度30 g/L,电解液温度40℃,电流密度200A/m2,电流效率达到85.66%.     

用氧化镧改性硫酸钛

硫酸钛掺杂La2O3后经高温焙烧制得一类稀土改性固体酸,用吸附吡啶的红外光谱表征其表面酸的性质,用合成丙酸丁酯的酸催化反应考察其催化活性。结果表明:固体酸中引入稀土元素,使得催化剂表面在保持Bronsted酸中心的同时,产生了新的Lewis酸中心;利用稀土的引入量不但可以调节固体酸表面B/L酸的比例,而且能提高固体酸中B酸的热稳定性。在催化合成丙酸丁酯化反应中,改性后的固体酸不但具有更好的酸催化活性,稀土含量少、反应后沉降快、易分离和回收、可重复使用多次,容易再生等优点,而且大大简化了反应的后处理工艺、产物无色、清亮透明。并获得催化剂制备优化条件为:镧含量5%,焙烧温度400℃。稀土改性后的固体酸是一种环境友好催化剂。     

PEG-PVP组合表面活性剂-(NH4)2SO4-H2O双水相体系萃取Eu3+的研究

研究了聚乙二醇1500—聚乙烯吡咯烷酮(PVP,K30)组合表面活性剂水溶液在(NH4)2SO4存在下形成双水相体系的条件;讨论了以偶氮氯磷 作萃取剂,在该萃取体系中Eu3+、Pb2+、Cu2+的萃取行为。在一定pH条件下实现了Eu3+-Pb2+、Eu3+-Cu2+的定量萃取分离与测定。初步探讨了组合表面活性剂相的萃取机理。     

Calculation of equilibrium species for the aqueous solution systems of UO2SO4−U(SO4)2−H2SO4−HF and UO2Cl2−UCl4−HCl−HF at 298 K

Speciation models for aqueous solutions of UO₂SO₄−U(SO₄)₂−H₂SO₄−HF and UO₂Cl₂−UCl₄−HCl−HF were proposed based on chemical reaction equilibria, mass balances, charge balance, and stoichiometry of UF₄(s). The equilibrium concentrations of uranium and fluoride species in these solutions were calculated at 298 K, and are of relevance to the electrolytic reduction of U(VI), followed by the precipitation of UF₄(s). In these calculations, the reduction ratios of U(VI) were set at 25, 50, 75, and 100 pct. In the sulfate system the stable domains of U⁴⁺, U(SO₄) _n ⁴⁻²ⁿ , UF _n ⁴⁻ⁿ , and UF₄(s) as U(IV) species and UO ₂ ²⁺ , UO₂(SO₄) _n ²⁻²ⁿ , and UO₂F _n ²⁻ⁿ , as U(VI) species are strongly dependent on theC _T(F)/C _T(U(IV)) value. On the other hand, the stable domains of U⁴⁺ UCl³⁺, UF _n ^/4−n , and UF₄(s) as U(IV) species and UO ₂ ²⁺ , UO₂Cl⁺, and UO₂F _n ²⁻ⁿ as U(VI) species are also strongly affected by theC _T(F)/C _T(U(IV)) ratio in the chloride system. The initiation and precipitation of UF₄(s) in both the sulfate and chloride systems are a function of the reduction ratio of U(VI). The higher the reduction ratio, the lower theC _T(F)/C _T(U(IV)) values required. Compared to the chloride system, UF₄(s) precipitation in the sulfate system starts at a lower value ofC _T(F)/C _T(U(IV)). The addition of an excess amount of HF does not cause the dissolution of UF₄(s) precipitates because HF is a weak acid. KOJI SATO, formerly Graduate Student, Department of Metallurgy, Kyoto University, Kyoto, Japan     

[Nd(PW11O39)(H2O)3](H2bpy)2·4H2O的水热合成及晶体结构

采用水热法合成稀土无机有机杂化化合物[Nd(PW11O39)(H2O)3 ](H2bpy)2·4H2O.采用NdCl3·6H2O,(NH4)3PW12O40·3H2O, 4,4'-联吡啶(bpy),和去离子水(摩尔比为4∶1∶4∶3900, pH=6)在130℃下进行水热反应3天,得到标题化合物的紫红色块状晶体,并进行了红外光谱分析,元素分析.用单晶X射线衍射法测得晶体结构,属三斜晶系,空间群为P-1,晶胞参数为a=1.18824(9) nm,b =1.35707(10)nm,c=1.77691(13)nm,α=71.551(2)°,β=82.478(2)°,γ=80.568(2)°.该晶体由无机的共价链∞1[Nd(PW11O39)(H2O)3]4- 和有机的二质子化的4,4'-联吡啶(H2bpy)2 及结晶水分子堆积而成的, 是一个新的稀土磷钨酸盐无机有机杂化化合物.     

Syntheses of novel 3-amino-2(1H)-thioxo-4(3H)-quinazolinones and evaluation of their immunotropic activity. Part III

The synthesis of two series of derivatives containing the quinazolinone-4 moiety is described. 3-Amino-2(1H)-thioxo-4(3H)-quinazolinone (1) was subjected to reactions with halogenoketones and halogenoaldehydes, leading to the production of the corresponding ketones, aldehydes, Schiff bases, and 6-oxo-1,4,5-thiadiazin[2,3-b]quinazoline derivatives. Subsequently, 1 was condensed with selected alpha, beta-unsaturated carbonyl compounds, aldehydes, ketones, acid chlorides, and esters. The compounds were tested for their potential activity in a model of humoral and cellular immune response. The tests showed that the compounds exhibited differential immunotropic activities. Of particular interest is compound 19, exhibiting a strong stimulatory activity with regard to cellular immune response and compound 16 exerting a strong inhibitory action in both types of the immune response.     

The ion-association-interaction approach as applied to aqueous H2SO4-Al2(SO4)3-MgSO4 solutions at 250 °C

A hybrid ion-association-interaction approach is implemented to describe the chemistry and thermodynamics of aqueous H₂SO₄-Al₂(SO₄)₃-MgSO₄ solutions at 250 °C. These solutions are relevant to the sulfuric acid pressure leaching of nickeliferous laterites. Strong complexes in solution are handled via the ion-association approach. Nonidealities, including weak ion pair formations, are treated through the Pitzer ion-interaction theory. The existing complexes in solution and the Pitzer ion-interaction parameters were identified through processing solubility data in the binary (H₂SO₄-Al₂(SO₄)₃ and H₂SO₄-MgSO₄) as well as the ternary (H₂SO₄-Al₂(SO₄)₃-MgSO₄) electrolyte solutions at or near 250 °C. The existing aqueous aluminum-bearing species identified were Al³⁺, Al(SO₄)⁺, and Al₂(SO₄) ₃ ⁰ , with Al₂(SO₄) ₃ ⁰ as the dominant species at moderate to high H₂SO₄ concentrations. The existing aqueous magnesium-bearing species found were Mg²⁺ and MgSO ₄ ⁰ , with Mg²⁺ being dominant except at low concentrations of H₂SO₄. The dominant species identified for Al and Mg explain why a higher H₂SO₄ concentration in solution is required during the processing of high-magnesium laterites.     

Solid Phase Synthetic Reaction of Sodium Pyroxene for Na2 CO3-Fe （OH） 3-H2 SiO3 System

In order to explore synthetic method of pure sodium pyroxene,the pure chemical reagents of Na2CO3,Fe(OH)3 and H2SiO3were used as raw materials,and the possible solid phase reactions for Na2CO3-Fe(OH)3-H2SiO3system in heating process had been studied by means of differential thermal analysis(DTA)and X-ray diffraction(XRD). The influencing factors of sodium pyroxene(NaFeSi2O6)synthetic reaction,such as sintering temperature and holding time,had also been studied.The results show that sodium pyroxene can be largely synthesized at 737℃;it is helpful for synthesis of sodium pyroxene to increase sintering temperature appropriately,and the best temperature should be controlled at 900℃or so,because it will melt and decompose at temperatures higher than 900℃.In those influencing factors of sodium pyroxene synthesis the most important is temperature.The results will be helpful for providing pure NaFeSi2O6for further research on the formation of SFCA for NaFeSi2O6-KAlSi2O3-CaO-Fe2O3-CaF2 system in the sintering process of Bayan-obo iron ore.     

Resistance of titanium carbide powders synthesized by various methods,to the action of an H2O2 and H2SO4 solution

Translated from Poroshkovaya Metallurgiya, No. 3, pp. 102–105, March, 1992.     

稀土配合物[REL3(4-picNO)H2O]的合成与表征

合成了2,3-二氯异丁酸根和4-甲基吡啶氮氧化物稀土三元配合物(RE=La、Ce、Pr、Nd、Sm、Eu).通过元素分析、红外、紫外、荧光、X射线粉末衍射、XPS、热分析以及摩尔电导等分析手段,确定了配合物的组成为[REL3(4-picNO)H2O](L= CH3C2H2Cl2COO -),并对它们的性质进行了讨论.