Papers by Keyword: Cobalt

Abstract: The Ni-P and Ni-Co-P coatings were electrodeposited at the deposition current density of j_dep = -20 mA cm^-2. Thermal treatment of these coatings was conducted in air at 400^oC for 1 h. Scanning electron microscopy (SEM) was used for surface morphology characterization of the coatings. Phase composition was investigated by X-ray diffraction (XRD) method. Atomic absorption spectrometry (AAS) was applied to specify chemical composition of obtained coatings. It was found that introduction of Co into amorphous Ni matrix caused the surface development of the obtained deposit. The Ni-P coating revealed an amorphous structure. The Ni-Co-P coating was formed of the amorphous matrix and the amorphous alloy ingredient. Thermal treatment of the coatings allowed to obtain new multi-phase materials with slightly developed surface.

Abstract: Substance flow analysis (SFA) of cobalt in China was carried out to analyze cobalt flows and stocks by using static SFA. Cobalt can be widely used in industry due to its high-melting point, high-strength, and well magnetism. In this static model, the relationship among inflows, outflows and stocks throughout the whole cobalt life-cycle in China were identified. According to the static model, the amount was calculated in the form of cobalt metal, in 2012, 29784t of cobalt was produced, and 30700t of cobalt was imported, 9400t exported and domestic consumption was 31700t, 9000t stocks of cobalt was consumed and 3000t old scrap was recycled in China. The ore index and recovery scrap resource of cobalt industry were 0.318 t/t and 0.136 t/t respectively.

Abstract: Spherical and fine cobalt powders were prepared by thermal decomposition of cobalt oxalate precipitated in the presence of pulsed electromagnetic field (PEMF). The morphology and phase structure were characterized by scanning electron microscopy (SEM), atomic force microscope (AFM) and X-ray powder diffraction (XRD). The aspect ratio was calculated by image tool software and the average size of cobalt particles was measured by laser particle size analyzer. The results indicate that both products prepared from cobalt oxalate with or without PEMF give rise to the formation of β-Co. The morphology of both products is similar to that of the precursors. The presence of PEMF plays an important role in formation of spherical and fine cobalt particles.

Abstract: The structural phase transitions and electronic structures of Co are investigated by using the first-principles calculation based on density-functional theory (DFT). Our calculated equilibrium structural parameters of Co are in good agreement with the available experimental data and other theoretical results. The calculated phase transition hcp-Co → fcc-Co at ca. 125.25 GPa. The magnetic moment of hcp-Co and fcc-Co drops to zero at 155 GPa and 77 GPa, respectively.

Abstract: Nickel (Ni (II)), cobalt (Co (II)) and manganese (Mn (II)) are often encountered in wastewaters. These metals have been identified as micronutrients, at trace concentrations; however, they are microbial growth inhibitors, at relatively high concentrations. The present review discusses, in a systematic way, the individual effects of the above heavy metals to the growth of microorganisms grown under aerobic conditions, with focus on the growth of activated sludge.

Abstract: Cobalt particles were deposited on treated CNTs via the Strong Electrostatic Adsorption (SEA) method. Cobalt loading on CNTs support was varied from 5 to 20 wt%. Samples were characterized by N₂ adsorption and HRTEM. The results of TEM indicated that increasing the metal loading from 5% to 20% resulted in larger nanoparticles and also led to agglomeration.

Abstract: Noble metals, such as platinum or gold, may promote the reduction of cobalt in supported cobalt catalysts either by direct contact or indirectly via hydrogen spill-over. The synthesis go gold nano-particles using THPC in the presence of a calcined Co/TiO₂-catalyst precursor results in a broadening of the gold particle size distribution possibly due to the association of gold with Co₃O₄. This was not observed for platinum and platinum-gold alloys synthesized in the same manner. Platinum-gold alloys are less effective than platinum as a reduction promoter, possibly due to the presence of gold on the surface of the alloy particles.

Abstract: A method for determination of gold, lead, nickel, cobalt in a range of concentrations from mg/g to ng/g was developed. Method can be applied for determination of corresponding metals in ores, rocks and waste mining industry. Method consists of annealing, treatment with hydrofluoric acid and aqua regia followed by extraction (in the case of gold) di-n-octyl sulphide (DOS). Method was tested by certified reference material (8773-2006 РВ 3-8) and various rock samples Altai-Sayan folded area.

Abstract: The extraction process of cobalt using microemulsion system saponified with P₅₀₇ as extracting agent was studied. The influences of initial concentration, the concentration of P₅₀₇, initial pH, the extracting time and the volume ratio of organic phase to water phase on extraction coefficient were also studied. Experimental results show that the saponification microemulsion system using P₅₀₇ as extractant is thermodynamic stable, and it can separate cobalt better. The optimum conditions were achieved as: the initial concentration is 0.04 mol/L, pH is 2; The concentration of P₅₀₇ is 6%, extraction time is 6 min; The volume ratio of organic phase to water phase is 1.5:1.

Abstract: Cobalt electrodeposition on palladium and glassy carbon was studied at different temperatures by using voltammetric techniques. Temperature effect on the diffusion coefficient value was analyzed. The results clearly showed that cobalt electrodeposition is a diffusioncontrolled process. The temperature effect on the values of the diffusion coefficient was analyzed through the Arrhenius equation. The value of the activation energy was calculated as 21.56 kJ mol^-1 and 25.73 kJ mol¹ for palladium and glassy carbon respectively.