Ni Sulfates Research Articles

Tribological properties of the FeNi alloys electrodeposited with and without external magnetic field assistance

The hereby work presents the tribological properties of the iron-nickel alloys and their dependence on the microstructure and thickness of the probes as well as the presence of an external magnetic field during the synthesis. Coatings were electroplated on the brass and copper metallic substrates using galvanostatic deposition in the same electrochemical bath condition (Fe and Ni sulfates) and the electric current density. The surface morphology of the films was observed by Scanning Electron Microscopy. The average composition of all FeNi coatings was measured using Energy Dispersive X-ray Spectroscopy. Tribo-mechanical properties such as microhardness, roughness, and friction coefficient were determined in the obtained structures. The morphology and tribologial properties of the FeNi coatings clearly depend on both the substrate (Cu, CuZn) itself and the presence of an external magnetic field (EMF) applied during the deposition process.

The Effect of Additives of Ni, Co, or Fe Sulfates in the Alkali-Silicate Electrolyte for Microarc Oxidation on the Characteristics of Coatings Formed on Titanium

The effect of nickel, cobalt, and iron sulfates’ additives in the alkali-silicate electrolyte for microarc oxidation on the element composition and electrochemical behavior of MAO-coatings formed on titanium has been studied. It has been established that these additives were incorporated into an oxide layer. The increase of the content of these components in the electrolyte resulted in the decrease of their content (along with silicon) in the coating and the increase of the titanium content. This dependence can be related to the MAO process mechanism specifics and, first of all, to changes in temperature–time characteristics of microarc discharges.

Crystal structure, stability, and electronic properties of hydrated metal sulfates MSO4(H2O)n (M=Ni, Mg; n=6, 7) and their mixed phases: A first principles study

Removal of Mg from hydrated Ni sulfates has long been a problem in the industrial purification process of hydrated Ni sulfates. In this work, we have investigated this industrial problem using state-of-the-art molecular simulations. Periodic Density Functional Theory (DFT) and cluster DFT calculations are used to study the crystal structures and phase stability of the hexahydrated and heptahydrated Ni and Mg sulfates and their mixed phases. The calculated lattice parameters of MSO4(H2O)n (M=Ni, Mg; n=6, 7) crystals are in good agreement with available experimental data. The relative energy differences of the mixed phase for both hexahydrated and heptahydrated Ni/Mg sulfates obtained from both the periodic and cluster DFT calculations are generally less than kT (25.8meV, T=300K), indicating that a continuous solid solution is formed. We also investigated the Bader charges and electronic structures of the hexahydrated and heptahydrated Ni/Mg sulfates using the periodic DFT calculations. The energy band gaps of the hexahydrated and heptahydrated Ni and Mg sulfates were predicted by first-principles calculations. Large energy band gaps of about ~5.5eV were obtained from the DFT–GGA calculations for hydrated Mg sulfates, and band gaps of about ~5.1eV were obtained by the DFT–GGA+U calculations for hydrated Ni sulfates.

Cobalt behavior during natural and technogenic oxidative leaching of Co-containing pyrites ( Letnee chalcopyrite deposit, Southern Urals)

Cobalt behavior during the oxidation of sulfide ores, unlike that during the oxidation of Co ores, is poorly known. Moreover, cobalt sulfates are rare in the world. Complex hydrous cobalt-containing and cobalt sulfates have been found in technogenic zones at the Letnee chalcopyrite deposit (Southern Urals). They have been identified at pit bottoms, in the ore stockpile, as well as directly on ore fragments and the evaporation barriers of underdump water puddles. The paper reports the first experimental data on the oxidative leaching of Co-containing sulfide ores in the laboratory. Also, parts of a thermodynamic model for Co behavior in oxidized zones are presented. Experiments have revealed an increase in acidity up to pH = 4.14, along with transport of sulfate sulfur and metals into solution. This suggests acid mine drainage during the development of the Letnee deposit. The published stability diagrams for hydrous Cu, Mg, Zn, Co, and Ni sulfates were analyzed and compared with mineralogical finds in a technogenic oxidized zone. This made it possible to explain the precipitation sequence of minerals from solutions during their concentration by evaporation. As salts of these elements are highly soluble, significant contents of toxic metals will inevitably remain in equilibrium solution, necessitating additional waste-water treatment (for example, creating sorption geochemical barriers). Therefore, the paper describes regularities in Co behavior during its sorption on solid phases.

Activity and heavy metal resistance of non-specific esterases in leaf beetle Chrysomela lapponica from polluted and unpolluted habitats

We compared the general activity and heavy metal resistance of non-specific esterases in two populations of the leaf beetle Chrysomela lapponica from habitats severely contaminated by heavy metals (mostly Ni and Cu) and two populations from unpolluted habitats. Concentrations of Ni and Cu in adult beetles from the most polluted site were 7.7 and 3.6 times higher that in beetles from unpolluted habitats. Larval esterases showed higher activity and lower susceptibility to heavy metals than esterases of adults. Larval esterase activity did not differ between populations from polluted and unpolluted sites, but adult beetles from polluted localities had lower esterase activity than beetles from unpolluted habitats. Both Cu and Ni sulfates in millimolar concentrations in vitro suppressed esterase activity of larvae from unpolluted habitats, but caused no negative effect on esterases of larvae from polluted sites. Similarly, inhibition of adult esterase activity by Ni was stronger in beetles from unpolluted localities than in beetles from polluted localities. This indicates that resistance of non-specific esterases to heavy metals is higher in leaf beetle populations from contaminated environment.

Black Nickel Coatings for Solar Collectors

Black nickel alloy coatings suitable for solar collectors were produced by electrodeposition from baths containing Ni and Zn sulfates and thiocynate. Variables having the greatest influence on optical properties of the black deposits are: pH-value, temperature, zinc and thiocyanate concentration. Of particular importance is the plating current which is related to the cathode potential that controls the composition, and alternatively, the optical properties of the deposited coatings. The mechanism of blackening of the Ni coatings was attributed to the deposition of sulfide particles with Ni-Zn alloy. It was shown that, in absence of thiocyanate, co-deposited Zn causes a degree of blackening to Ni coatings due to the deposition of Ni3Zn22 as identified by x-ray phase analysis. Considerable blackening can be achieved by sulfur, which is deposited as Ni3S2. In a modified composition it was possible to replace sulfur by phosphorous supplied to the coating by the addition of sodium hypophosphite to the plating solution. The coatings were of optimum optical properties as far as maximum absorptance and minimum emittance. Absorptance values as high as 0.93 could be obtained for selective coatings (2-3 microns thick) deposited under optimized conditions. Performance tests for coated solar water heater panels showed that the coatings are well qualified. The endurance of the coatings was evaluated in actual service conditions with regard to thermal degradation and corrosion resistance.

Recovery and Concentration of Metal Ions. III. Concentration and Temperature Effects in Multi membrane Hybrid System

Abstract The performance of the multi membrane hybrid system (MHS) made up of ion-exchange membranes and a bulk liquid membrane (D2EHPA in kerosene) has been examined. Fluxes and the separation between Zn(II), Mn(II), Cu(II), Co(II), and Ni(II) sulfates have been studied as dependent on the concentration of aqueous phases and temperature. The results show a saturation of fluxes at increased concentrations of aqueous feed or strip solutions. The total limiting fluxes are ∼1 × 10−9 mol/cm2.s whereas the limiting fluxes for specific metal ions vary in the range from 6 × 10−12 to 5 × 10−10 mol/cm2-s. The effect of temperature on MHS transport results in an activation energy of 16 to 30 kJ/mol depending on the metal species. The optimum conditions for separating metals are determined by the concentration of a feed solution in the range from 0.001 to 0.01 M and the concentration of sulfuric acid in a stripping solution in the range from 0.01 to 0.5 M. Selectivity coefficients βZn+Mn+Cu Co+Ni calculated as the ratio of stationary fluxes amount to 30–40, and are practically constant in the 298 to 328 K temperature interval.

Vibrational Spectra of Molten Salts. V. Infrared and Raman Spectra of Some Molten Sulfates

Infrared spectra of thin films of pure alkali-metal sulfates at temperatures just above their melting points have been obtained. These indicate retention of Td symmetry by the SO42− ion, though the ν1(a1) and ν3(f2) bands move to lower frequencies as the alkali metal is changed from Li to Rb, and the formally forbidden ν2(e) mode gives rise to a very weak band, indicating some interionic interactions. Much more striking changes in the spectra are produced by addition of divalent metal or silver sulfate to a K2SO4 melt. Spectra from 40 mole % solutions of Ag(I), Mg(II), Ca(II), Sr(II), Ba(II), Zn(II), Cd(II), Pb(II), Cu(II), Co(II), and Ni(II) sulfates have been obtained. These indicate the presence of perturbed SO42− ions with C3V symmetry, and full assignments of the fundamental modes of these C3V species have been made for the Zn, Cu, Co, and Ni solutions. The Raman spectra of ZnSO4 at two different concentrations in molten K2SO4 further showed small but definite frequency differences from the corresponding infrared spectra. These differences are analyzed in terms of possible metal-complex formation and the quasilattice structure of these melts.