In an attempt to gain an understanding of factors affecting the extraction of cobalt by trilaurylamine oxide, the equilibria between HX+SCN– (where X=NO
, Cl–, SO
) and benzene solutions of trilaurylamine oxide have been studied. Cobalt is quantitatively extracted by the oxide from aqueous 0.01–1M KSCN in 0.01M concentration of the acids. The extraction mechanism and the possible compositions of the extracted species are discussed. The effect of several anions on the extraction of the element from optimal aqueous solutions are reported and separation factors for a number of metal ions are given. The solvent has a potential for the group preconcentration of toxic metal ions from dilute aqueous solutions.
Authors:N. Sh. Lebedeva, N. A. Pavlycheva, V. P. Kulinich, G. P. Shaposhnokov, and E. V. Parfenyuk
Summary Processes of thermooxidizing destruction of series of oxygen containing cobalt(II)phthalocyanines were studied by thermogravimetry and IR and electronic absorption spectroscopy. These processes have several stages including dehydration, oxidation, desulphonation (decarboxylation) of peripheral substituents of cobalt(II)phthalocyanines, destruction of phthalocyanine macrocycle and oxidation until the highest oxides. The temperature of beginning of the process of thermal oxidative destruction decreases in the following order: Co(4-PhSO3H)4Pc>Co(4-COO-)4(5-SO-3)4(Ba2+)4Pc>Co(4-Br)4(5-SO3H)4Pc>Co(4-Cl)4(5-SO3H)4Pc>Co(4-COOH)4(5-SO3H)4Pc.
Authors:L. Gonsalves, S. Mojumdar, and V. Verenkar
The chemistry, structure, and properties of spinel ferrites are largely governed by the method of preparation. The metal carboxylato-hydrazinate
precursors are known to yield nanosized oxides at a comparatively lower temperature. In this study, we are reporting the synthesis
of one such precursor, cobalt nickel ferrous fumarato-hydrazinate which decomposes autocatalytically to give cobalt nickel
ferrite nanoparticles. The XRD study of this decomposed product confirms the formation of single-phase spinel, i.e., Co0.5Ni0.5Fe2O4. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric (TG), and differential scanning
calorimetric (DSC) analysis. The precursor has also been characterized by FTIR, EDX, and chemical analysis, and its chemical
composition has been determined as Co0.5Ni0.5Fe2(C4H2O4)3·6N2H4.
A study of fixation of cobalt on the crystalline matrix of titania by co-precipitation was carried out. The tracer level solid-liquid distribution of60Co over preformed hydrous titania showed an appreciable uptake of 71%. Macro amounts of Co2+ ions were precipitated along with Ti(IV) hydroxide (pH 8–9) and a maximum loading of 29 wt% was observed. The Soxhlet leachabilities of the calcined mixed mass, heated at 1000 °C, were found to be in the order of 10–1 g·m–2·d–1 and the observation of structural changes of the original host matrix of titania revealed the fixation of cobalt in the mineral assemblage of CoTiO3 (rhombohedral) and the rutile form of titania.
A series of mixed oxides and ferrites of iron and cobalt has been prepared by taking iron and cobalt in the atomic ratio 10.50, 11.33 and 13.00, respectively. These samples were prepared by calcination of the stoichiometric amount of their respective nitrate salts for 6 h in air at 500±10°C. Characterization of the samples has been carried out using Mössbauer spectroscopy. Percentage formation of -Fe2O3 and CoFe2O4 has been determined using the same technique. These results have been supplemented by X-ray diffraction studies. The particle size has been calculated using Scanning Electron Microscopy. the decomposition of 0.5% w/v hydrogen peroxide at 40°C over the catalyst has also been studied.
Authors:W. Wang, S. Luan, Y. Chen, L. Cal, Y. Jia, S. Ruan, and J. Duan
New complexes of the non-natural amino acid (p-iodo-phenylalanine) with divalent cobalt and nickel ions have been synthesized. The composition of the complexes is [M(IC6H4CH2CHNH2COO)2]2.5H2O (M=Co, Ni) and the crystal structure belongs to orthorhombic system. Infrared spectra indicate the nature of bonding in the
complex. The first stage in the thermal decomposition process of the complex shows the presence of crystal water. The thermal
decomposition process of cobalt complex differs from that of nickel. The intermediate and final residues in the thermal decomposition
process have been analyzed to check the pyrolysis reactions. Thermal analysis indicates that the iodine atom of the ligand
may coordinate to the metal ion in the lattice.
Mixed calcium-cobalt orthophosphates, of the general formula Ca3-xCOx(PO4)2 with 0≤x≤1.1, were prepared by coprecipitation. Reactions which occur during heating from room temperature to 850°C, of either
tricalcium phosphate or mixed Ca−Co phosphates, were monitored by thermogravimetry and differential thermal analysis. The
dried precipitates and the final products were characterised by X-ray diffraction and infrared spectroscopy.
The diffusion of cobalt sulphate is studied in 1% agar gel over a concentration range of 10–5 to 0.2M at 25 °C. The experimental values of the diffusion coefficient at various concentrations determined by the zone-diffusion technique are compared with the theoretical values of diffusion coefficinets computed on the basis of Onsager-Fuoss theory. The observed deviations are interpreted in terms of relative contributions of diffusion-enhancing and diffusion-retarding interactions occurring in the water-gel-electrolyte system.
Authors:J. Straszko, M. Olszak-Humienik, and J. Możejko
Thermogravimetry (TG-DTG), and differential thermal analysis (DTA) were used in the study of the kinetics of decomposition
of cobalt sulphate hexahydrate under an air atmosphere.
The kinetics of the particular stages of CoSO4 6H2 O decomposition were evaluated from the dynamic mass loss data. The values of the kinetic parameters for each stage of the
thermal decomposition were calculated from the α(T) data by using the integral method, applying the Coats-Redfern approximation.
Synergistic extraction of Co(II) with 8-hydroxyquinoline (Hq)/decanoic acid [(HR)2] solution mixtures in benzene and chloroform was carried out at 25°C. The aqueous ionic strength and the total concentration of cobalt(II) were 0.1 (NaCl) and 1·10–5–1·10–3M, respectively. The synergistic effect is interpreted by the formation of the mixed ligand ion-pair complexes: [(Coq(Hq)2(HR))+, R–] and [(Coq(Hq)2(HR)3)+, R–] in benzene and chloroform, respectively.