Papers by Keyword: Cobalt

Abstract: The article presents the influence of different nanomaterials such as nanopowders of ferrum, cobalt and cuprum, suspensions of copper and cobalt oxides nanoparticles and ultrafine humic acids on potato breed “Latona”. We have studied the influence of nanomaterials on morphological and physiological parameters of plants, the yield, its structure and chemical composition of potato as well as on vitamins C and PP in potato tubers. On the basis of investigations we have recommended introduction of biologically active nanomaterials into intensive technology of growing the crop.

Abstract: The article presents the influence of biopreparations containing nanoparticles of ferrum, cobalt and cuprum on fodder and red beets. We have investigated parameters of plants growth and development, the phytohormonic status of vegetating plants, the yield, its structure and chemical composition of fodder and red beets including vitamin C and carotene. We have proved ecological safety of nanopreparations on the basis of experiment area soil chemical composition. We have tried nanobiopraparations in the technology of the crops growing.

Abstract: A novel method for Co (II) and Pb (II) recovery from acidic solutions is presented. The extraction of Co (II) and Pb (II) ions using the bulk liquid membranes during a galvanostatic electrodialysis process accompanied by cathodic electrodeposition of the metals was studied. Solutions of di (2-ethylhexyl) phosphoric acid (D2EHPA) with admixtures of tri-n-octylamine (TOA) in 1,2-dichloroethane were used as the liquid membranes. Effects of current density, Co (II) and Pb (II) concentrations in the feed solution, sulfuric or nitric acid concentration in the feed solution, D2EHPA and TOA concentration in the liquid membrane, of the type and concentration of acid in the cathodic solution were studied, and optimal conditions were determined. It is demonstrated that a practically complete (98-99%) removal of Co (II) and Pb (II) from the feed solutions containing 0.01 mol∙L^-1 CoSO₄ or 0.01 mol∙L^-1 Pb (NO₃)₂ is achieved during 1.0 − 4.0 h of electrodialysis. A possibility of effective transfer of Pb (II) into dilute solutions of perchloric and nitric acids was demonstrated. The liquid membranes ensure the recovery of Co (II) ions into dilute solutions of perchloric, sulphuric, hydrochloric and nitric acids. Adherent, compact cobalt and lead electrodeposits with a fine-grained structure were obtained in the studied systems.

Abstract: The mesoporous silica SBA-15 molecular sieve has been widely studied due to its unidirectional mesoporous structure, its high average pore diameter, its high thermal and hydrothermal stability and its ability to absorb metal ions, allowing its use as support material for catalysts. This study aimed to synthesize the Co/SBA-15 catalyst, and characterize it through the techniques of X-ray diffraction, temperature programmed reduction (TPR) and scanning electron microscopy (SEM). The SBA-15 support was synthesized from the following molar composition of reaction mixture: 1TEOS: 0.017 P123: 5.7 HCl: 173 H2O: 40 EtOH, and after calcined at 550 °C for 6 hours. The Co/SBA-15 catalyst was prepared by incorporating 10% cobalt by wet impregnation. Through the X-ray diffractograms, it was found that the impregnation has not changed the structure of the material. RTP profiles showed the presence of peaks at different temperatures that may be caused by dispersion of the cobalt.

Abstract: Corrosion of cobalt-contained metal line is one of critical defects during post-CMP cleaning process. Thus, the understanding of inhibitors is significant to eliminate corrosion. In this paper, we discuss the learning from etching rate and electrochemical measurement for the solutions using multiple corrosion inhibitors. Furthermore, TEM of cobalt pattern wafer and cleaning results are shown to demonstrate cleaning and cobalt compatibility performance.

Abstract: Novel hybrid Co/UHMWPE biocoatings were obtained by electrochemical deposition of cobalt from a cobalt sulfate plating bath with ultra high molecular weight polyethylene (UHMWPE - particle size of 10 μm) as dispersed particles in order to provide possible biomedical coatings applications. The surface morphology and topography, roughness and chemical composition were investigated, as a function of UHMWPE particles concentration in the plating bath by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray analysis (EDX). Electrochemical corrosion resistance investigations were carried out in simulating body fluid solution (SBF), using electrochemical impedance spectroscopy (EIS) method at different exposure times. The results proved a good corrosion resistance of the obtained hybrid Co/UHMWPE coatings.

Abstract: The effects of Co additions on the evolution of γ' precipitates and topologically close-packed (TCP) phases during thermal exposure at 950 °C were investigated for two Ni-based single crystal superalloys with 7.9 wt.% Co and 9.1 wt.% Co. The results indicated that the γ′ morphology was not affected by Co content, whereas γ′ volume fraction decreased and precipitate size increased due to lower Co addition after standard heat treatment. The coarsening of γ′ precipitates in both alloys was controlled by diffusion. The γ′ coarsening rate increased, while the stability of γ′ volume fraction decreased due to lower level of Co addition during 950 °C thermal exposure because more Co addition suppressed the diffusion process. High Co addition promoted the formation of μ phase after thermal exposure at 950 °C for 1000 h due to higher γ′ volume fraction, more stable γ′ volume fraction and higher electron vacancy number. The experimental results of μ phase precipitation showed good agreement with thermodynamic calculation by JMatPro.

Abstract: In this paper one of the numerous chemical methods to obtain nanostructured powders of nickel and cobalt by reduction of mix of sparingly soluble metal carbonates with hydrazine hydrate as the reducing agent is considered. The influence of preparation conditions (concentration of the reducing agent, temperature, magnetic field) on size-characteristics of powders is studied. Size of nickel nanocrystallites varies in range 17-23 nm, the range for cobalt crystallites is 23-33 nm. It is found that the optimal temperature range is 80-95 °C to reduce carbonates of nickel and cobalt by the hydrazine hydrate. Application of magnetic field during the reduction of the crystal nickel carbonate to metal nickel helps to change the shape and size characteristics of the powders.

Abstract: In bioleaching processes, gas transfer is often considered as one of the key mechanisms that will influence the leaching efficiency and more precisely the leaching rate. Oxygen can be a limiting factor in bacterial leaching because of its low solubility. One way to overcome this phenomenon consists in increasing the oxygen partial pressure in the gas stream supplied to the leach pulp. The primary objective of this work was to investigate the use of oxygen-enriched gas in bioleaching stirred reactors and its impact on the consortium dynamics. First tests were performed at lab scale in four successive series of 2-L bioreactors alimented either with air or with oxygen enriched gas. The microbial consortium used has proven its efficiency on several ores such as cobaltiferous pyrite and polymetallic ores in former research projects (BioMine, BioShale, ProMine). The community diversity was remarkably reproducible irrespective of the type of gas supply, in each of the successive series of reactors. Only minor changes occurred after subculturing from one batch series to the next one, highlighting the high stability of the established consortium. Different oxygen partial pressures (from 20% to 50%) were then tested in a 20-L continuous reactors pilot experiment. There was no impact on the community diversity, showing the high tolerance to oxygen of the bioleaching strains and their capacity to easily survive 50% oxygen input. The bioleaching efficiency in terms of rate and metal leaching did not seem to be changed. The use of enriched oxygen gas is not detrimental to the bioleaching strains and may be used in order to improve process operation (gas transfer, heat management...).

Abstract: The magnetic and electrical properties of (Co/Ge)_nfilms are experimentally studied. It is established that at the Co/Ge interfacean intermediate magnetic layer forms. Twophases of cobalt, one is a face-centered cubic phase and the other ispresumably a Co–Ge alloy with a weakly ferromagnetic order, have been found toexist. A “dead” layer no more than 2 nm in thickness is formed at the interface.This layer affects the magnetic behavior andmagnetoresistive effect in the investigated structures.