Manganese-cobalt ratios

The laterites can be divided into three general classifications (/) iron nickeliferrous limonite which contains approximately 0.8—1.5 wt % nickel. The nickel to cobalt ratios for these ores are typically 10 1 (2) high siUcon serpentinous ores that contain more than 1.5 wt % nickel and (J) a transition ore between type 1 and type 2 containing about 0.7—0.2 wt % nickel and a nickel to cobalt ratio of approximately 50 1. Laterites found in the United States (8) contain 0.5—1.2 wt % nickel and the nickel occurs as the mineral goethite. Cobalt occurs in the lateritic ore with manganese oxide at an estimated wt % of 0.06 to 0.25 (9). 

X-ray diffraction, surface area, and cation exchange determinations were accomplished in the manner reported previously (24,25). The bulk cobalt to manganese atomic ratios were determined by dissolving the birnessite-treated samples in acidic solutions, typically 1.0 M HNO, and measuring the... 

We have investigated the Li/(Mn + Co + Ni) ratio dependence on the electrochemical properties of LSM. The raw material of manganese-cobalt-nickel mixed hydroxide was prepared by the co-precipitation technique. The hydroxide was mixed thoroughly with lithium carbonate by ball milling. The Li/(Mn + Co h- Ni) ratio was varied as 1.00, 1.05, 1.10, 1.15, and 1.20. The mixed powders were heat treated at 900°C for 20 h in air. The heat-treated samples were subjected to XRD measurement, and no other components than the layered materials were observed. 

The recovery ratios indicate that the added traces of cadmium, cerium, copper, lanthanum, manganese, scandium, and zinc are quantitatively recovered. The recoveries of barium, cobalt, bromium, iron, uranium, and vanadium were also satisfactory. 

The reaction of ions with peroxyl radicals appears also in the composition of the oxidation products, especially at the early stages of oxidation. For example, the only primary oxidation product of cyclohexane autoxidation is hydroperoxide the other products, in particular, alcohol and ketone, appear later as the decomposition products of hydroperoxide. In the presence of stearates of metals such as cobalt, iron, and manganese, all three products (ROOH, ROH, and ketone) appear immediately with the beginning of oxidation, and in the initial period (when ROOH decomposition is insignificant) they are formed in parallel with a constant rate [5,6]. The ratio of the rates of their formation is determined by the catalyst. The reason for this behavior is evidently related to the fast reaction of R02 with the... 

Reduction lowers the charge to radius ratio of transition metal ions, promoting higher rates of ligand substitution. Reduced, divalent oxidation states of manganese, iron, cobalt, and nickel are also quite soluble (Table II). 

The XPS results for cobalt at pH 4, particularly the Co 2p splitting (15 eV) and the absence of shake-up satellite structure, are indicative of cobalt(III). However, the N(amine)/Co atomic ratio of 2.7 indicates that some ammonia ligands have been displaced. Since it is known (22) that hydrolysis rates for cobalt(III) complexes are very slow, the presence of cobalt with a low number of coordinated amines, suggests that hydrolysis is induced via an interaction with the birnessite surface. The cobalt to manganese ratios for bulk and surface measurements are equivalent within experimental error, a result which is consistent with a reaction process occurring primarily at the surface. It is... 

Metal-ion catalysis has been extensively reviewed (Martell, 1968 Bender, 1971). It appears that metal ions will not affect ester hydrolysis reactions unless there is a second co-ordination site in the molecule in addition to the carbonyl group. Hence, hydrolysis of the usual types of esters is not catadysed by metal ions, but hydrolysis of amino-acid esters is subject to catalysis, presumably by polarization of the carbonyl group (KroU, 1952). Cobalt (II), copper (II), and manganese (II) ions promote hydrolysis of glycine ethyl ester at pH 7-3-7-9 and 25°, conditions under which it is otherwise quite stable (Kroll, 1952). The rate constants have maximum values when the ratio of metal ion to ester concentration is unity. Consequently, the most active species is a 1 1 complex. The rate constant increases with the ability of the metal ion to complex with 2unines. The scheme of equation (30) was postulated. The rate of hydrolysis of glycine ethyl... 

The quality of Mo03 combinations with iron, cobalt and manganese oxides has been investigated by Mazzocchia et al. [213], Table 9 presents some results, obtained with a flow reactor at 300—430° C using a C3H6/02 ratio of 0.22—0.28. The best catalyst is MnMo04. The addition of small amounts of water (up to 2.5%) further increases the selectivity, but larger amounts cause rapid deactivation. 

Salem et al. [48] reported simple and accurate methods for the quantitative determination of flufenamic, mefenamic and tranexamic acids utilizing precipitation reactions with cobalt, cadmium and manganese. The acidic drugs were precipitated from their neutral alcoholic solutions with cobalt sulfate, cadmium nitrate or manganese chloride standard solutions followed by direct determination of the ions in the precipitate or indirect determination of the ions in the filtrate by atomic absorption spectroscopy (AAS). The optimum conditions for precipitation were carefully studied. The molar ratio of the reactants was ascertained. Statistical analysis of the results compared to the results of the official methods revealed equal precision and accuracy. The suggested procedures were applied for determining flufenamic, mefenamic and... 

Soluble cobalt salts (acetate or naphthenate) are used as catalysts, most often together with manganese and bromide ions. Particularly in the presence of bromide source (as HBr, sodium bromide, or even organic bromides), the rate of the oxidation of methylbenzenes increases by up to 400 x. None of the other halogens approaches bromide in its promoting activity. The maximum effect is achieved with a 1 1 cobaltrbromine atomic ratio. 

It is likely that some of the mechanisms that we discussed are operational in parallel, and there are data that confirm this view. It is experimentally observed that the primary alkene alkane molar ratio seems to be in the range between 2 and 4. A value of 4 has been found for reaction on an iron-manganese catalyst operating at 550 K (107), on a precipitated cobalt catalyst operating at 463 K (108), and on a Ru/Si02 catalyst operating at 483 K (109). 

Bautista and Hard (B8) made a comparative study of the extractability of. several of the first-transition metals from thiocyanate solutions using methyl isobutyl ketone as the organic solvent. The transition metals readily extracted were scandium (III), iron (III), and cobalt (II) while chromium (II) and manganese (II) were not. The principal extractable species were found to be the neutral scandium and iron trithiocyanate complexes, while the extractable cobalt complex was the negatively charged tetrathiocyanate radial Co(SCN)4 . The distribution ratio for scandium, iron, and cobalt decreased with increase in metal ion concentrar tion but increased with increasing ionic strength of the solutions. 

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