Nickel Ammine Complex Research Articles

Liquid–liquid separation of copper and nickel ammine complexes using phenolic oxime mixture with tributyl phosphate

ABSTRACT In the present study, a complete separation of copper over nickel has been studied from an ammoniacal leach liquor of nickel laterite ore generated via the Caron process. For this purpose, a phenolic oxime (LIX 84-IC) used as the extractant molecule was mixed with tributyl phosphate (TBP) to inhibit the co-extraction of nickel with copper loading into the organic phase. The antagonistic effect of TBP was confirmed by the distribution coefficients to be D mix << D LIX 84-IC + D TBP and negative values of ∆D. The highest separation (β Cu/Ni) of >1329 was yielded using the molar ratio of organic mixture at LIX 84-IC:TBP = 0.4:0.6 at an organic-to-aqueous phase ratio of 1. The thermodynamic properties of copper extraction exhibited an endothermic nature with ΔH° value of 5.4 kJ∙mol−1, indicating the formation of inner-sphere coordination between metal ions and the organic mixture. Further, the stripping of copper from the loaded organic phase was quantitatively achieved by contacting with 1.0 mol∙L−1 H2SO4 solution at the unit phase ratio.

Nickel Ammine Complex‐derived NiO Modified g‐C3N4 Composites with Enhanced Visible‐light Photocatalytic H2 Evolution Performance

AbstractIn this paper, NiO/g‐C3N4 (NiO/CN) composites were successfully prepared by the wetness impregnation method using nickel ammine complex solution as NiO source. As photocatalysts, NiO/CN composites showed enhanced visible‐light photocatalytic hydrogen evolution activities in the presence of triethanolamine as sacrificial agent. The effects of NiO content and annealing temperature for NiO/CN composites on the photocatalytic H2 evolution activities were investigated. Furthermore, NiO/CN composite with 10.0% NiO content after annealing at 450 °C exhibited optimal photocatalytic H2 evolution rate of 90.05 μmol⋅h−1⋅g−1 which is about 17 times higher than that of pristine CN (5.22 μmol⋅h−1⋅g−1). Moreover, the experimental results demonstrated that amorphous NiO as co‐catalyst not only offered active sites for H2 evolution but also benefited the efficient separation of the photogenerated charge carries. In addition, NiO/CN composite displayed the superior photocatalytic stability during the photocatalytic process.

Definition of synthesis parameters of ultrafine nickel powder by direct electrolysis for application in superalloy production

The optimization of the synthesis method of ultrafine nickel powder for the production of superalloys, by means of direct electrolysis of the nickel ammine complex, has been conducted. The influence of electrolyte temperature and ammonia concentration on the electrolysis process and powder characteristics has been studied. It has been revealed that an increase in electrolyte temperature leads to a larger particle size of the powder and formation of compact metal particles. It has been determined that the maximum electrolyte temperature must not exceed 50 °С. By recording the polarization curves, it was established that an increase in ammonia concentration leads to increased polarization of nickel formation and formation of finer powder. Lowering of ammonia concentration leads to contamination of the powder with barely soluble hydroxyl compounds of nickel. Analysis of the anodic curves has revealed that the nickel anode is partly soluble. It has been discovered that the addition of Trilon B to the electrolyte has a positive effect on powder characteristics. The powder formed under optimal conditions was composed of coral-like particles with the size of 40–70 µm, which could be easily ground to their spherical components if no compact metal particles were present. High purity of the powder was confirmed by the EDX. The cathodic and anodic current yields were determined to be: 35–41 % and 5–8 % respectively.

Continuous Precipitation of Nickel Hydroxide by Addition of Ammonium Ions

Spherical and dense nickel hydroxide, Ni(OH)2, particles are produced by addition of ammonia or ammonium ions, NH4+, using a continuous precipitation. In this study, the nickel ion, Ni2+, concentrations and the NH4+ concentrations in a suspended solution for the continuous precipitation of Ni(OH)2 are examined, and the formation behaviors of spherical and dense Ni(OH)2 particles are discussed by the relations between the Ni2+ and NH4+ concentrations. When NH4+ was supplied into a suspended solution during the continuous precipitation of Ni(OH)2, Ni2+ was present in a steady state and the Ni2+ concentrations changed with the NH4+ concentrations in a feed solution, with the solution pH and the residence times of suspended solutions in a crystallizer. The ratios of the NH4+ concentrations to the Ni2+ in a solution at steady state were different from the coordination number of NH3 in a nickel ammine complex. Formation of Ni(OH)2 precipitates when adding NH4+ is discussed by the relations between the Ni2+ and ...

Electrochemical properties of anisotropic nickel hydroxide structures synthesized from nickel ammine complexes

Synthesis of c-axis grown β-Ni(OH)2 was attempted by rapid hydrolysis and/or direct hydrothermal treatment of the mixed solution of NiCl2, HCl and NH3. The UV–vis spectra revealed the addition of NH3 into NiCl2 solution shifted the peak position to shorter wavelength, indicating the formation of nickel ammine complex. Hydrolysis of the mixed solution containing nickel ammine complex gave β-Ni(OH)2 particles. The amount of NH3 in the mixed solution did not affect the crystallinity or morphology of the β-Ni(OH)2 particle by the conventional rapid hydrolysis. Hydrothermal treatment of the hydrolyzed β-Ni(OH)2 particles was changed the morphology from agglomerated particles to nanosheets-linked structure or hexagonal plates. However, any crystal growth or particular-axis growth was not recognized. Then, the direct hydrothermal treatment of the mixed solution was attempted. The direct treatment at certain amount of coexisting NH3 gave small amount of the precipitates, and the precipitates showed distinctive XRD pattern of c-axis grown β-Ni(OH)2. The electrochemical property of the c-axis grown β-Ni(OH)2 structures indicated that the diffusion control was the rate-determining step for the charge/discharge process.

Synthesis of nickel metal nanoparticles via a chemical reduction of nickel ammine and alkylamine complexes by hydrazine

Nickel nanoparticles were prepared from their coordination compounds, such as [Ni(NH3)6]Cl2, [Ni(N2H4)2Cl2], [Ni(HNEt2)6]Cl2, and [Ni(H2NBu)6]Cl2 in aqueous solution by chemical reduction. The reaction of nickel ammine and alkylamine complexes with hydrazine monohydrate as a reducing agent was carried out at 90 °C and pH = 10–12. Depending on the influencing parameters such as oxidizing agent, pH, and temperature, the hydrazine reaction can be carried out in different pathways. The chemical reduction method is a simple procedure and also is the best one in the controlling of composition, size, and shape of Ni powder. The reduction of nickel complexes into the metallic Ni powder occurs via the dissociation of complexes and reduction by hydrazine in alkaline solution. Therefore, complexing agents have the most effect on the reduction reaction. The results show that, when the ligands in complexes were changed from ammine to diethylamine and butylamine, respectively, the crystalline size and morphology of nickel metal nanoparticles are changed. The chemical reduction of nickel complexes into metallic nickel can be accompanied with a change in the crystalline system. The pure nickel crystalline has a face-centered cubic structure. The nickel nanoparticles were characterized using IR spectroscopy, X-ray powder diffraction, scanning electron microscopy and vibrating sample magnetometer analyses.

RF Plasma Synthesis of Nickel Nanoparticles from Liquid Precursor

Nickel nanoparticles were synthesized from liquid precursor via H-plasma reduction route. XRD patterns revealed that pure metallic nickel powders could be obtained when nickel ammine complex aqueous solution was used as precursor. FESEM showed that the products are composed of well-dispersed nanospheres with an average diameter less than 100 nm. The tap density is about 3.85g/cm3, and the sheet resistance of the conductive film prepared using the nickel particles is about 58mΩ.

Solvent extraction equilibria of nickel from ammonium nitrate solution with LIX84I

The equilibrium distribution ratios of nickel(II) ion between LIX84I (active component 2-hydroxy-5-nonylacetophenone oxime (HNAPO)), dissolved in a non-polar diluent and 3 kmol m − 3 ammonium nitrate solution are measured in the pH range 2–10 at 298 K. The effect of pH on the distribution ratio of nickel is analyzed based on the extraction equilibrium model assuming that the extracted complex has the stoichiometry of 1:2 (Ni:HNAPO). The successive aggregation of HNAPO in the organic phase and the nickel-ammine complex formation in the aqueous phase are considered, where the acid dissociation constant of ammonium ion, measured by the half-neutralization method, is used. The equilibrium constants for the extraction, successive aggregation, and distribution of the nickel extractant complex between the aqueous and organic phases are determined to be 4.90 × 10 − 5 , 9.9 (kmol m − 3 ) − 1 and 1 × 10 − 4 , respectively. These constants reproduce the experimental distribution data with good accuracy.

ChemInform Abstract: Characterization of Electrochromic Nickel Oxide Thin Films Prepared by Anodic Deposition.

Nickel oxide (NiOx) thin films have been prepared on transparent conducting indium tin oxide (ITO) substrates by anodic deposition from a nickel ammine complex solution. Electrochromic (EC) behaviour of these films was observed in a borate buffer solution at pH 10 in the potential range 0–1 V vs. Ag/AgCl; an as-prepared film (PF) was cathodically reduced to a colourless form (RF) and oxidized to a brown form (OF) by anodic polarization. Characterization of these films by low-angle incident X-ray diffraction and X-ray photoelectron spectroscopy with argon-ion (Ar+) etching revealed that the EC properties are based on the electrolytic transformation of the NiOx structure between β-NiOOH and β-Ni(OH)2, i.e. involving the redox reaction Ni3++ e ⇄ Ni2+.

NiO nanotubes assembled in pores of porous anodic alumina and their optical absorption properties

Nickel oxide (NiO) nanotubes, embedded in a porous anodic aluminum oxide (AAO) template, have been produced by a wet chemistry templating method using a nickel–ammine complex as a precursor. The dimensions of the nanotubes are about 60 μm in length, with an outer diameter of about 200 nm and a wall thickness of 60 nm. They possess a polycrystalline structure and the NiO nanotube arrays exhibit an optical absorption band gap of 3.90 eV, similar to that of bulk NiO.

Effectiveness of the template-ion exchange method for appearance of catalytic activity of Ni–MCM-41 for the ethene to propene reaction

Abstract The template-ion exchange (TIE) method, an equilibrium adsorption (EA) of nickel ammine complex, and a conventional impregnation (IMP) method were applied to prepare nickel ion-loaded mesoporous silica MCM-41 and silica gel and their catalytic activity was examined for the newly developed ethene to propene (ETP) reaction. When we employed TIE as the preparation method and MCM-41 as the support, the most active and stable catalyst could be prepared. The local structures of the nickel species supported on the TIE and EA samples were very similar to that of layered nickel silicate, while those on the IMP-catalysts were the same as that of NiO particles.

Preparation of Ni particles by ultrasonic spray pyrolysis of NiCl2·6H2O precursor containing ammonia

The preparation of nickel particles from nickel ammine complex was studied by ultrasonic spray pyrolysis in the presence and the absence of hydrogen. In the presence of H2 (about 9 vol.%), nickel particles were formed at 500 °C, which is much lower than that reported. Metallic nickel, together with NiO, was obtained as a major phase at 400 °C. In the absence of H2, metallic Ni was also obtained, but higher temperature (e.g. 900 °C) was needed. It is suggested that the addition of NH3·H2O and NH4HCO3 to NiCl2·6H2O precursor changes the reaction pathway of Ni formation. By careful control, spherical, solid and well-distributed Ni particles of about 0.5 μm were obtained at a residence time of 7–9 s in the aerosol reactor.

Influence of Ammonium Salts on Solvent Extraction of Nickel Using Lix 54.

Experiments have been carried out on the extraction of nickel from ammonium sulphate aqueous solutions using LIX 54 as extractant. Nickel extraction decreases with increasing ammonium sulphate concentration of the aqueous solution. This decrease can be attributable to the formation of nickel ammine complexes in the aqueous phase thus decreasing the free nickel ion concentration. From the slopes of log DNi versus equilibrium pH plots, the extracting species has been found to be NiR2, further, numerical analysis of experimental data confirmed the proposed stoichiometry and the corresponding log Kext are given. The extraction of free metal ion by LIX 54 was also confirmed by IR studies of nickel loaded organic solutions.

Further XRD characterization of electrochromic nickel oxide thin films prepared by anodic deposition

Electrochromic (EC) behaviour of nickel oxide (NiO x ) thin films, formed by potentiostatic electrodeposition in a nickel ammine complex solution (Ni(NH 3) x 2+; pH 9), were investigated using alkaline electrolyte solutions, KOH and (CH 3) 4NOH (pH 12.9). In both electrolytes, the fully oxidized composite films (F0.7/1.1), prepared by electrolysis at 1.1 V (vs. Ag/AgCl) followed by electrolysis at 0.7 V, commonly showed broadened UV–VIS spectra in the visible and near IR region compared with that prepared at 1.1 V (F1.1). Characterization of as-prepared, oxidized and reduced films in the electrolytes by low angle fixed X-ray diffraction (LAXRD) was performed to explain in detail the mechanism of the EC transformation of the films based on the conversion between two types of layered structure, α-Ni(OH) 2/γ 2-2NiO 2·NiOOH or β-Ni(OH) 2/β-NiOOH. A model according to the extraction/insertion of cations or water molecules from/into the interlayer was proposed.

XRD and XPS characterization of electrochromic nickel oxide thin films prepared by electrolysis–chemical deposition

Electrochromic (EC) behaviours of nickel oxide (NiOx) thin films, grown by chemical process in a nickel ammine complex solution [Ni(NH3)x2+] after electrolysis of this solution (EL–C method), were investigated using various alkaline electrolyte solutions; potassium borate buffer (pH 12), KOH (pH 12.9), (CH3)4NOH and (C2H5)4NOH. The fully oxidized films in all adopted electrolytes commonly showed broadened UV–VIS spectra in the visible and near IR region. However, voltammetry studies associated with photoabsorption of the films revealed an apparent difference in the EC dynamics among the electrolytes caused by the variation of cation sizes and electrolyte solution pH. Characterization of as-prepared, oxidized and reduced films in the electrolytes by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed to explain the mechanism of the films based on the conversion between layered α-Ni(OH)2 and γ2-2NiO2·NiOOH. A model according to the extraction/insertion of cations or water molecules from/into the interlayer was proposed.

Electrochromic properties of nickel oxide thin films prepared by electrolysis followed by chemical deposition

Nickel oxide (NiO x ) thin films were prepared onto transparent conductive tin oxide (NESA) substrates by chemical process in a nickel ammine complex solution following electrochemical deposition (at 1.1 V vs Ag AgCl ) from this solution. Compared with the NiO x films prepared simply by anodic deposition, the films obtained through the chemical process showed different mode of electrochromism between colorless and dark brown in a sodium borate buffer solution at pH 12; the absorption spectrum of the composite film in the colored (oxidized) state was broadened in the visible and near infrared region. Characterization of the films revealed that crystal structure of the film deposited during chemical process is assigned to α-Ni(OH) 2, and that its electrochromism is based on the reversible oxidation of γ 2-2 NiO 2 · NiOOH structure. Electrochromic switching performance of the film was investigated.

Enhanced Electrochromic Property of Nickel Hydroxide Thin Films Prepared by Anodic Deposition

Nickel hydroxide thin films were prepared onto transparent conductive tin oxide (NESA) substrates by potentiostatic electrolyses of a nickel ammine complex solution at various potentials (0.6 to 1.5 V vs. ). Nickel hydroxide thin film (F0.7) obtained at relatively lower anodic potential (0.7 V) showed enhanced electrochromism between colorless and dark brown in a sodium borate buffer solution at pH 12; the absorption spectrum in the colored (oxidized) state was broadened in the visible and near‐infrared region compared with the nickel hydroxide films prepared at the higher anodic potential (1.1 V). Characterization of the films revealed that crystal structure of F0.7 is assigned to , and that its electrochromism is based on the reversible oxidation to hexagonal structure. Composite nickel hydroxide film, i.e., by the electrolytic deposition at 1.1 V followed by that at 0.7 V, showed electrochromic property similar to F0.7 and its durability in repeated redox cycles were much improved in comparison with that of F0.7. Electrochromic properties in switching performance of this composite nickel hydroxide film were investigated.

Simultaneous determination of seven trace impurities (Al, As, Cr, Fe, Ti, V and Zr) in high-purity nickel metal and nickel oxide by coprecipitation and inductively coupled plasma-atomic emission spectrometry

Nickel is not coprecipitated with lanthanum hydroxide in ammonium hydroxide solution because it forms rapidly soluble nickel ammine complexes. This behaviour is used for the separation of Ni matrix from trace elements. These are simultaneously and quantitatively coprecipitated with lanthanum hydroxide at pH 10.0 and separated from the Ni matrix. Seven trace elements (Al, As, Cr, Fe, Ti, V and Zr) in Ni metal and 3 certified elements (Cr, Fe and Ti) in a standard reference material of nickel oxide have been simultaneously determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES).

Characterization of electrochromic nickel oxide thin films prepared by anodic deposition

Nickel oxide (NiOx) thin films have been prepared on transparent conducting indium tin oxide (ITO) substrates by anodic deposition from a nickel ammine complex solution. Electrochromic (EC) behaviour of these films was observed in a borate buffer solution at pH 10 in the potential range 0–1 V vs. Ag/AgCl; an as-prepared film (PF) was cathodically reduced to a colourless form (RF) and oxidized to a brown form (OF) by anodic polarization. Characterization of these films by low-angle incident X-ray diffraction and X-ray photoelectron spectroscopy with argon-ion (Ar+) etching revealed that the EC properties are based on the electrolytic transformation of the NiOx structure between β-NiOOH and β-Ni(OH)2, i.e. involving the redox reaction Ni3++ e ⇄ Ni2+.

Effect of zeolite support on catalytic activity of Nio clusters

Zeolite Y, partially dealuminated under hydrothermal conditions, is used as a support for nickel clusters. The effect of the zeolite structure and of the means of applying the Ni2+ cations on the reactivity of dispersed nickel in CO methanation has been studied. The highest conversion was obtained on samples with developed secondary porosity, impregnated with the nickel ammine complex, [Ni(H2O)2 (NH3)4]Cl2. The data obtained are discussed from the point of view of the effect of secondary porosity and the means of introducing the parent Ni2+ ions on the localization and thermal stability of Nio clusters.