Specific Features of Anodic Dissolution of Copper in H2SO4 + H2O and H2SO4 + CuSO4 + H2O Systems

We investigate anodic dissolution of copper in H₂SO₄ + H₂O and H₂SO₄ + H₂O + CuSO₄ systems, which model solutions for the electrochemical production of copper (+2) sulfate. Ultimate densities of anodic current in the temperature range 20–80°C for a voltage up to 8 V were found. We show that a concentration of copper ions ( Cu²⁺) of 1.5–2.0 moles/liter in the anolyte is the limiting one in the electrochemical production of solutions of copper (+2) sulfate.     

Recovery of H2SO4 from waste acid solution by a diffusion dialysis method

A diffusion dialysis method using anion exchange membrane was used to recover H2SO4 from waste sulfuric acid solution produced at the diamond manufacturing process. Effects of flow rate, operation temperature, and metal ion concentration on the recovery of H2SO4 were investigated. The recovery of H2SO4 increased with the concentration of H2SO4 and operation temperature. It also increased with the flow rate ratio of water/H2SO4 solution up to 1, above which no further increase was observed. The flow rate did not affect the rejection of Fe and Ni ions. About 80% of H2SO4 could be recovered from waste sulfuric acid which contained 4.5M free-H2SO4 at the flow rate of 0.26x10(-3) m3/hm3. The concentration of recovered H2SO4 was 4.3M and the total impurity was 2000 ppm. Preliminary economic evaluation has revealed that the dialysis system is highly attractive one that has payback period of only few months.     

Dielectric properties of K2Zn2(SO4)3 and (NH4)2 Mg2(SO4)3

Dielectric constant (ɛ), dielectric loss (tan δ) and conductivity (σ) for K₂Zn₂(SO₄)₃ and (NH₄)₂ Mg₂(SO₄)₃ have been measured over the frequency range 100 Hz — 100 kHz and in temperature range 30°C — 400°C. The values of static dielectric constant at room temperature are 7.67 and 4.80 for K₂Zn₂(SO₄)₃ and (NH₄)₂ Mg₂(SO₄)₃ respectively. The plots of log σ against reciprocal temperature at different frequencies of these samples merge into a straight line beyond 250°C and the activation energies calculated in this region are found to be 0.67 eV and 1.98 eV for K₂Zn₂(SO₄)₃ and (NH₄)₂ Mg₂(SO₄)₃ respectively.     

氟表面活性剂C_8F_(17)SO_2N(C_2H_5)C_2H_4(OC_2H_4)的合成与性能

以全氟辛基磺酰氟为原料,与乙胺在异丙醚中加热反应制得N 乙基全氟辛基磺酰胺,再与2 氯乙醇在加热回流下反应得到N 乙基N 乙醇全氟辛基磺酰胺,随后在碱性条件,加热和带压下与环氧乙烷进行聚合反应,得到表面活性剂C8F17SO2N(C2H5)C2H4(OC2H4)nOH,n=8～9。该活性剂在质量浓度为0.05%时就可将表面张力降至19.2mN/m以下,具有良好的表面活性。运用IR,NMR,DSC,TG等技术对该表面活性剂进行了表征和研究。     

双水相体系萃取分离电镀废水中镉缔合物

电镀镉废水直接排放会造成严重环境污染.利用Cd(Ⅱ)与乙基紫(EV)、KI缔合后,加入盐析剂丙醇-水双水相体系萃取分离镉.试验表明,在(NH4)2SO4存在条件下,无表面活性剂EV,在一定量碘离子的酸性条件下,Cd(Ⅱ)的萃取率只有68%,而同样条件下,加入毫克级用量的EV后,Cd(Ⅱ)被完全萃取分离.在pH值为1.0时,试验了Fe(Ⅲ)、Co(Ⅱ)、Ni(Ⅱ)、zn(Ⅱ)、Mn(Ⅱ)、Cr(Ⅲ)等离子的二元或多元离子混合干扰情况,结果表明分离完全.     

Role of U(VI) complexes in the chemiluminescent reaction U(IV) + O3 in H2SO4 solution

Data on the effect of U(VI) on the reaction U(IV) + O₃ in H₂SO₄ solution are analyzed. The chemiluminescence enhancement is caused by the formation of a complex of an excited U(VI) ion with an unexcited U(VI) ion, so-called excimer. The decomposition of the excimer to two U(V) ions and H₂O₂ is followed by the reaction of U(V) with ozone, giving rise to the excited U(VI) ion. Thus, a chain reaction develops.     

DC electrical conductivity of CoSiF6·6H2O and (NH4)2SO4

D.C. electrical conductivity of single crystals of (NH₄)₂SO₄ and CoSiF₆·6H₂O have shown conductivity jump near their respective structural transition temperature. Activation energy of (NH₄)₂SO₄ has been found to be consistent with the earlier data. However, CoSiF₆·6H₂O has given prolonged aging effect due to dipolar relaxation and formation of space charge polarisation.σ _true andP _max have been measured.P _max has shown a negative maximum at the transition point. Activation energy of ZnSiF₆·6H₂O has been found to be comparable with CoSiF₆·6H₂O.     

Low temperature synthesis and characterisation of lecontite, (NH4)Na(SO4)·2H20

Lecontite, (NH₄)Na(SO₄).2H₂O, was synthesised at room temperature in high purity compared to earlier work with a minor impurity of mascagnite, (NH₄)₂SO₄. Rietveld refinement of the XRD results confirmed the crystal structure and unit cell dimensions as published earlier. Raman and Infrared spectroscopy, in conjunction with factor group analysis, resulted in a complex pattern of overlapping sulphate, NH and OH modes. The NH modes υ₁ was observed around 2880 cm⁻¹, υ₂ around 1700 cm⁻¹ overlapping with water OH-bending modes, υ₃ around 3300 cm⁻¹ overlapping with water OH-stretching modes around 3023, 3185 and 3422 cm⁻¹, and υ₄ around 1432, 1447 and 1462 cm⁻¹. The sulphate group in the crystal structure displays a decrease in symmetry from T_d as evidenced by the activation of the ν₁ mode at 982 cm⁻¹ and the ν₂ mode around 452 cm⁻¹ in the Infrared spectrum. The υ₃ mode shows clear splitting in the infrared spectra with a strong band at 1064 cm⁻¹ accompanied by two shoulders at 1107 and 1139 cm⁻¹. The Raman spectra show three weak bands at 1068, 1109 and 1135 cm⁻¹ with a shoulder at 1155 cm⁻¹. Similar splitting was observed for the υ₄ mode around 611 and 632 cm⁻¹ in the Infrared and Raman spectra, respectively.     

Chemical etching of (100) GaAs in the (NH4)2Cr2O7-H2SO4-N H4Cl-H2O system

The etching solution containing ammonium dichromate, sulphuric acid and ammonium chloride in water solution allows for the investigation of the influence of individual active components and their concentration on the etching reaction with GaAs. The influence of these agents on etching as well as the temperature and stirring were examined. The etching rate increases with increasing Cl^– ion concentration, increases and subsequently decreases with the increasing of H⁺ ion concentration and remains constant in the wide range of oxidant anion concentration. The effect of stirring on etching rate allows us to estimate regions dominated by diffusion kinetics. The activation energy in the wide range of parameters is constant and equal to 60 kJ mol^–1. Microscopic observations reveal surfaces of various morphologies: smooth; covered with round hills; or with a network of veins. Various profiles of grooves arranged in various directions are revealed due to the preferential characteristic of etching; these profiles are also influenced by the mask material.     

Corrosion inhibition of nickel in H2SO4 solution by alanine

The effect of alanine, as a safe inhibitor, was studied by measuring the corrosion of Ni in aerated and stagnant 1 M H₂SO₄ solution (pH ～0.2). Measurements were performed under various conditions using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and the new electrochemical frequency modulation (EFM) methods. The obtained results showed that the addition of alanine alone gives a moderate inhibition and acts as an anodic-type inhibitor. The inhibition is due to physical adsorption of alanine on the metal surface. The inhibition efficiency enhances with increasing alanine concentration and immersion time but decreases with rise in temperature. The apparent activation energy, E_a, is higher in the presence than in the absence of alanine. Addition of I^? ions greatly improves the inhibition efficiency of alanine. The synergistic effect is due to enhanced adsorption of alanine cations by chemisorbed I^? anions on the metal surface. The results obtained from polarization, EIS and EFM techniques are in good agreement indicating that EFM method can be used successfully for monitoring corrosion rate of Ni in H₂SO₄ solution with and without alanine.     

Synthesis of H2SO4 doped polyaniline film by potentiometric method

H₂SO₄ doped polyaniline films were synthesized in aqueous acidic media. The polyaniline film deposited on platinum electrode exhibits highest conductivity. The conductivity of each H₂SO₄ doped polyaniline sample was determined by the four-probe technique. The current-voltage curve exhibits that polyaniline sample has an ohmic behaviour. Experiments were conducted to establish the conductivity of the sample from room temperature to 110°C. The current was set constant. It has been observed that at lower current as well as higher current conductivity of the polyaniline sample is due to the electrons transferred to the conduction band. It is observed that the concentration ratio of 0.2:1 of aniline and H₂SO₄ for synthesis of PANI film on platinum electrode shows good conductivity.     

Simulation Experiments on On-Line Isolation of Element 106 (Seaborgium,Sg) and Study of Its Chemistry in H2SO4 and H2SO4/HF Solutions

Model experiments with W and Mo were performed to simulate on-line ion-exchange isolation of element 106 (seaborgium, Sg) from H₂SO₄ and H₂SO₄/HF solutions. Short-lived isotopes of W and Mo were prepared by Sm(²⁴ xMg,xn)W nuclear reaction performed on a U-400 cyclotron. Molybdenum isotopes were prepared on an MT-25 microtron (Flerov Laboratory of Nuclear Reactions, JINR, Dubna) by fission of ²³⁵U with photoneutrons. The feasibility of isolation and chemical study of ²⁶⁵Sg in the course of its preparation and of identification of this radionuclide by long-lived daughter product, ²⁵³Fm, was demonstrated. The correlation of ion-exchange properties of W, Hf, Sr, and REE (TPE) under static and on-line conditions was revealed.     

Measurement of the Refractive Indices of H(2)SO(4)-HNO(3)-H(2)O Solutions to Stratospheric Temperatures

Refractive indices of various H(2)SO(4)-H(2)O, HNO(3)-H(2)O, and H(2)SO(4)-HNO(3)-H(2)O solutions were measured at four wavelengths in the visible (351.0, 533.5, 632.9, and 782.6 nm) over a temperature range from 30 to -60 degrees C. The temperature dependence has been determined for the first time to the authors' knowledge. This dependence is of importance for applications to atmospheric aerosols at low temperatures. In particular, it is shown that (1) the molar refractivity of the solutions is independent of temperature, whereas the temperature dependence of the refractive index arises solely through the temperature dependence of the solution's mass density, (2) the molar refractivities of H(2)SO(4) and HNO(3) in a ternary solution may be calculated as the weighted sum of the molar refractivities of two binary solutions evaluated at a concentration that corresponds to the total acid concentration, and (3) the H(2)O molar refractivity in the solutions may be taken equal to that of pure water. Although the data for the ternary system have been used for this model verification, data for binary H(2)SO(4)-H(2)O and HNO(3)-H(2)O solutions were used to improve the accuracy of the modeled refractive indices to better than 0.0017% or 0.15% for concentrations of 5-70 wt.% and wavelengths from the near ultraviolet to the near infrared (0.25-2 mum).     

Synthesis and structural study of new potassium uranyl selenates K2(H5O2)(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)4 and K3(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)5

Single crystals of new uranyl selenates K₂(H₅O₂)(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₄ (1) and K₃(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₅ (2) were prepared by isothermal evaporation at room temperature. The crystal structure of 1 was solved by the direct method [C2/c, a = 17.879(5), b = 8.152(5), c = 17.872(5) Å, β = 96.943(5)°, V = 2585.7(19) ų, Z = 4] and refined to R ₁ = 0.0449 (wR ₂ = 0.0952) for 2600 reflections with |F _o| ≥ 4σ _F . The structure of 2 was solved by the direct method [P2₁/c, a = 17.8377(5), b = 8.1478(5), c = 23.696(1) Å, β = 131.622(2)°, V = 2574.5(2) ų, Z = 4] and refined to R ₁ = 0.0516 (wR ₂ = 0.1233) for 4075 reflections with |F _o| ≥ 4σ _F . The structures of 1 and 2 are based on [(UO₂)₂(SeO₄)₄(H₂O)₂]^4? layers. The charge of the inorganic layer is compensated by potassium and oxonium ions arranged in the interlayer space. Each K ion is surrounded by seven O atoms belonging to uranyl selenate layers and water molecules, so that it binds with each other the adjacent uranyl selenate structural elements.     

Magnetic behavior of Mn(NH4)2(SO4)2 · 6H2O in its Curie region in fields directed along theb-axis

The intensity of magnetization and the isentropic magnetic susceptibility of Mn(NH₄)₂(SO₄)₂ · 6H₂O have been determined along 13 isentropes (between 0.620 and 2.825 cal mole^–1 deg^–1) in fields up to 1670 Oe directed along theb-axis of a spherical single crystal. Eleven of the isentropes originated, in zero field, within the Curie region of the salt. Field increments of 10 to 15 Oe were used below 170 Oe, with larger steps above this. All isentropes originating within the Curie region show a common (high) susceptibility at zero field. In each case the susceptibility then drops sharply at a small field characteristic of the particular entropy. The drop in susceptibility was used to define the boundaries of the Curie region (critical fieldvs entropy). The change of temperature with magnetic field was determined along the isentropes and examples are given.     

Structural properties of precipitates formed by hydrolysis of Fe3+ ions in Fe2(SO4)3 solutions

The structural properties of the solid phase, formed by the hydrolysis of Fe³⁺ ions in Fe₂(SO₄)₃ solutions at 90 or 120 °C, were investigated using X-ray diffraction,⁵⁷Fe Mössbauer spectroscopy, Fourier transform-infrared spectroscopy (FT—IR) and transmission electron microscopy. The concentration regions of Fe₂(SO₄)₃ were determined for the precipitation of goethite, -FeOOH, or hydronium jarosite, H₃OFe₃(OH)₆(SO₄)₂ as a single phase. Superparamagnetic behaviour of -FeOOH particles was observed. Hydrolysis of Fe³⁺ ions in 0.1 M Fe₂(SO₄)₃ solutions at 120 °C produced H₃OFe₃(OH)₆(SO₄)₂ and basic sulphate, Fe₄(OH)₁₀SO₄. The interpretation of⁵⁷Fe Mössbauer and FT—IR spectra is given.     

Ion-Exchange Procedure Developed for Isolation of Element 106 (Seaborgium) and Study of Its Chemistry in H2SO4 and H2SO4/HF Solutions,with W as Imitator

Ion-exchange behavior of W, Hf, Sr (homologs of elements 106, 104, and 102, respectively), U (pseudohomolog of element 106), Cm, and Eu in H₂SO₄ and H₂SO₄/HF solutions was studied. The static and dynamic ion-exchange properties of these elements were determined as influenced by the solution composition and the nature of the ion exchanger. The best conditions were found for separating element 106 (seaborgium) from daughter elements (Rf, No, and Fm) and its pseudohomolog, U, on a single cation-exchange column with the purification coefficients of 10⁵-10⁶. A possibility of using the anion exchanger for concentrating element 106 and separating it from the long-lived decay products was demonstrated. The speciation of these elements in dilute sulfuric acid solutions and in solution containing strong complexing agents was discussed.