Showing papers on "Cobalt published in 1984"

Metal ion encapsulation: cobalt cages derived from polyamines, formaldehyde, and nitromethane

Abstract: Synthese et caracterisation de complexes cage derives de produits de reaction entre Co(sen) 3 3+ et Co(sen) 3+ (sen=(amino-4 aza-2 butyl)-5 methyl-5 diaza-3,7 nonane-diamine-1,9), avec formaldehyde et nitromethane en solution basique. Structure cristalline de [Co(diNO sar-H)]Cl 2 •4H 2 O

Cobalt catalysts for the conversion of methanol to hydrocarbons and for Fischer-Tropsch synthesis

Abstract: A rhenium promoted cobalt catalyst, especially a rhenium and thoria promoted cobalt catalyst, and process for the conversion of methanol to hydrocarbons. Methanol is contacted, preferably with added hydrogen, over said catalyst, or synthesis gas is contacted over said catalyst to produce, at reaction conditions, an admixture of C 10 + linear paraffins and olefins. These hydrocarbons can be further refined to high quality middle distillate fuels, and other valuable products such as mogas, diesel fuel, jet fuel, lubes and speciality solvents, particularly premium middle distillate fuels of carbon number ranging from about C 10 to about C 20 .

Mechanisms of transition metal interferences in hydride generation atomic-absorption spectrometry. Part 1. Influence of cobalt, copper, iron and nickel on selenium determination

Abstract: Transition metal interferences in the determination of selenium using the hydride generation AAS technique were investigated in a system in which the selenium hydride is generated in pure acid solution and comes into contact with the metal ions only in a second flask. All investigated elements interfere in the ionic form with selenium when they are present in sufficiently high concentrations. Whenever a precipitation of the metallic species occurs, however, capture and decomposition of the selenium hydride by the finely dispersed metal appear to be the predominant mechanism of interference. In addition, this solid-gas reaction occurs typically at considerably lower interferent concentrations than the liquid-gas reaction of the ionic species. A substantial increase in the range of interference-free determination of selenium can be achieved by increasing the acid concentration of the solution for measurement because of the increased solubility of the reduced metal in the strong acid.

Electroreduction of oxygen by pillared cobalt(II) cofacial diporphyrin catalysts

Abstract: Etudes de la reduction electrochimique d'oxygene, en presence d'une electrode tournante a disque et anneau de graphite, recouverte de complexes de Co(II) avec l'anthrylene-1,9-5,5' bis-porphyrine-(octaethyl octamethyl) ou la biphenylenylene-1,8-5,5' bis-porphyrine(octaethyl octamethyl)

Properties of 2,3‐dicarboxy cellulose combined with various metallic ions

Abstract: 2,3-Dicarboxy cellulose and partially oxidized 2,3-dicarboxy cellulose were prepared in good yields from the corresponding dialdehyde cellulose obtained by periodate oxidation of cellulose according to a modification of the method described by Hofreiter, Wolff, and Mehltretter [J. Am. Chem. Soc., 79, 6457 (1957)]. The 2,3-dicarboxy cellulose oxidized to nearly 100% oxidation level was completely soluble in water, but the 2,3-dicarboxy cellulose of 70% oxidation level was not. The former 2,3-dicarboxy cellulose took up various metallic ions other than alkali metals to form a precipitate or solid. The metal contents taken up corresponded to the theoretical values calculated as combined in the form of metallic salt of the carboxylic acid group. 2,3-Dicarboxy cellulose combined with metallic ions such as copper, cobalt, and nickel ions gave viscous, gel-like products, which solidified when exposed to air. The properties of products combined with such metallic ions are discussed.

Cobalt-nickel separation by solvent extraction with bis(2,4,4 trimethylpentyl)phosphinic acid

Abstract: The use of an organophosphinic acid to separate cobalt from nickel by solvent extraction is described. Comparative data indicate that the phosphinic acid is superior to analagous phosphoric and phosphonic acids in terms of cobalt-nickel selectivity and the ability to reject calcium. Important reagent properties, such as low aqueous solubility and hydrolytic stability, are discussed. The results of continuous, counter-current, mini-plant tests demonstrate the recovery of high purity cobalt from concentrated nickel sulphate solutions.

In Situ Laser Raman Spectroscopic Study of Anodic Corrosion Films on Nickel and Cobalt

Abstract: In-situ laser Raman spectra of anodic corrosion films formed on Ni and Co in 0.05M NaOH have been obtained for the first time and the composition of the surface films deduced. The Raman spectrum of the film found on Ni at about 0.6V vs. Hg/HgO corresponds closely to that of hydrated Ni/sub 2/O/sub 3/. The anodically formed film on Co at about 0.45 V appeared to consist of a mixture of CoO and Co/sub 3/O/sub 4/.

Cobalt in pore waters of marine sediments

Abstract: During early diagenesis on the sea floor, metal-recycling processes exert important controls on the preservation rates and distributions of metals in marine sediments. The elucidation of internal recycling processes, therefore, is important in understanding trace-metal mass balances in the oceans. Recent measurements of cobalt in seawater1 suggest that cobalt is scavenged from the deep sea and hence follows biogeochemical pathways similar to manganese. We present here measurements of cobalt in pore waters of marine sediments and find that cobalt was released into pore waters in the sub-oxic sediment zone during dissolution of sedimentary manganese oxides (Table 1, Fig. 1). Solid-phase cobalt concentrations in surface (oxic) sediments, above the pore water remobilization horizon, are almost double those measured in the deep (anoxic) sediment zone (Table 2, Fig. 1). The sediment and pore water distributions indicate that a large fraction of sedimentary cobalt is recycled with manganese between oxic and sub-oxic pore waters and redeposited in surface (oxic) sediments.

Oxidation and Hot Corrosion of Superalloys

Abstract: The oxidation, mixed gas corrosion and hot corrosion of nickel-, cobaltand iron-base superalloys at temperatures above about 6OOC are examined. It is shown that the superalloys develop resistance to corrosion by forming either alumina or chromia scales upon their surfaces. The times for which such oxide reaction product barriers are stable upon the surfaces of superalloys is discussed by first considering how these oxide scales are formed and then how they are destroyed in use. It is shown for oxidation environments that these oxide scales are degraded primarily via cracking and spalling. When mixed gas environments are encountered, the degradation is also affected by the other reactants in the gas phase. The most severe conditions are shown to be those inducing hot corrosion attack where the oxide scales are subjected to not only mixed gas conditions but also the fluxing action of molten deposits. The behavior of nickel-, cobalt-, and iron-base superalloys are compared and the effects of the various alloying elements are discussed.

Introduction on environmental chemistry and global cycles of chromium, nickel, cobalt beryllium, arsenic, cadmium and selenium, and their derivatives†

Abstract: Crude estimations are a basis for further discussion. Even a trial—which has to be verified—may be sufficiently exact to get a better feeling for sources of risk and for understanding pathways of redistribution, especially in industrial countries. Studies of global cycles may not be too relevant, but give valuable background information and stimuli to recognize more significant local changes and possible effects. It is extrapolated that the emissions of the heavier elements chromium, nickel and cobalt with their short atmospheric life cycle play a more dominant role in waters and soils. On the other side in the cases beryllium, arsenic, antimony, cadmium and selenium atmospheric transports are relatively more important. Biological cycles— extraction by plants from soil—correspond in general to about one‐third of the total emissions, but are relatively more important in the cases of cobalt and cadmium, and less in the case of chromium. Natural weathering of rocks and soils is in the order of one‐sixth of t...

The binding of metal salts and corrosion products to cells and proteins in vitro.

Abstract: The binding of metal ions from salts and from corrosion products of 316 LVM stainless steel and MP-35 to blood cells and serum proteins was studied in vitro. In the first series of experiments, metal salts were added to whole blood and then the blood separated into red cells, white cells, and serum. Nickel from nickel chloride or corrosion products of stainless steel bound in very small quantities to blood cells. Cobalt from cobalt chloride bound to both red cells and white cells. Chromium from chromic chloride (Cr3+) bound to cells in very small quantities whereas chromium from potassium dichromate (Cr6+) and corrosion products showed very high to binding to red cells and some binding to white cells. In a second series of experiments the blood was separated into its components and then the metal salts were added and the binding pattern was identical. In a third series of experiments serum which had interacted with the metal salts or corrosion products was separated into its components by isoelectric focusing on polyacrylamide gels. Almost all of the metal, whatever the source, was detected in the albumin region of the gels indicating strong binding to albumin. These studies on the cell and protein binding of the metals help to explain the dissemination of corrosion products from the site of the implant and subsequent systemic responses by some individuals.