Zinc additives, nickel hydroxides

As mentioned previously, one type of niekel hydroxide is by far the most common—a high density spherieal type for use in pasted electrodes which became commercial around 1990. - " High density spherieal niekel hydroxide is made in a precipitation process where metal salts sueh as nickel sulfate are reaeted with caustic such as NaOH in the presence of ammonia. The niekel source may have additives such as cobalt and zinc to enhance per-formanee. The important physieal parameters within this type of nickel hydroxide are ... 

Pocket Plate Electrode. This is the same type of electrode used in pocket plate nickel-cadmium and nickel-iron batteries. Electrodes are prepared by loading nickel hydroxide hydrate active material and a conductive additive (graphite and/or nickel flake) into tubular flat pockets which are then assembled into electrodes. Little interest currently exists in using this type of electrode in nickel-zinc cells since modern cells attempt to utilize lightweight electrode construction. 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

Cr(OH)2, manganic and manganous, ferric and ferrous, cobaltous and nickelous in short, from all elements which form basic hydroxides. And from almost all these the oxides may be obtained by heating the hydrates to redness. Excess of the precipitant, however, must be avoided in many cases, for some of these hydroxides display acid properties if in presence of excess of alkali. Thus, for example, if excess of sodium hydroxide or potassium hydroxide be added to the solution of a soluble salt of zinc, such as the chloride, nitrate, or sulphate, the first change, as already shown, is the precipitation of the hydroxide but on addition of excess of alkali, the precipitate redissolves, forming the... 

In the reduction of nitrobenzene in a 2% aqueous sodium-hydroxide solution, according to previous publications, azoxy-benzene is formed at platinum and nickel electrodes, azobenzeno at lead, tin, and zinc cathodes, and aniline at copper cathodes especially in the presence of copper powder. It was found that, in an unchangeable experimental arrangement, a cathodo potential of 1.8 volts, as measured in connection with the deci-normal electrode, could be carried out with all the chosen cathodes and additions. At this constant potential, by using different metals and adding various metallic hydroxides, the whole reduction was carried out and the nature and quantity of the reduction products determined in each case. It turned out that the emphasized differences in the results disappeared and that, with an equal potential of all cathodes, similar yields of azoxybenzene and aniline and traces of azobenzene resulted. The cathodes were of platinum, copper, copper and copper powder, tin, platinum with addition of stannous hydroxide zinc, platinum with addition of zinc hydroxide, lead, platinum with addition of lead hydroxide, and nickel. The yields of azoxybenzene varied from 41-65% of aniline 23-53%. 

Antimony, zinc, and aluminium salts do not interfere aluminium should, however, be kept in solution by the addition of sufficient sodium hydroxide the influence of copper, nickel, and cobalt salts can be eliminated by the addition of potassium cyanide solution iron salts are masked by the addition of a tartrate but if aluminium salts are also present a red colour is produced. Magnesium salts give a similar blue colour, but beryllium can be detected in the presence of this element by utilizing the fact that in ammoniacal solution the magnesium colour alone is completely destroyed by bromine water. 

The nickel-cobalt sulfides as a suspension in dilute sulfuric acid are oxidized in agitated, spherical autoclaves at 350°F in the presence of air at 500 psig and excess sulfides. The unleached solids in the thickener overflow are recycled back to the autoclave and the liquor, containing 50 gm/liter Ni, 5 gm/liter Co as sulfates and small amounts of iron, aluminum, chromium, copper, zinc, and lead, is purified. The iron, aluminum, and chromium are precipitated as the hydroxides by adjusting the pH to 5.5 with ammonia and the copper, lead, and most of the zinc are removed by subsequent addition of sulfuric acid to lower the pH to 1.5 and precipitation of the metals with hydrogen sulfide. 

Precipitation-deposition can be used to produce catalysts with a variety of supports, not only those that are formed from coprecipitated precursors. It has been employed to prepare nickel deposited on silica, alumina, magnesia, titania, thoria, ceria, zinc oxide and chromium oxide.36 It has also been used to make supported precious metal catalysts. For example, palladium hydroxide was precipitated onto carbon by the addition of lithium hydroxide to a suspension of... 

The equipment used for the recycling of waste water in a Hungarian chemical plant has been designed on the basis of the above experimental results. Contamination in the waste water of this plant exceeded the permissible limit for zinc, chromium, barium, aluminum, nickel, lead and nitrate. Based on above experiments, the metal ions present in toxic concentrations were first precipitated by the addition of lime hydrate and sedimented as hydroxide in the pH range 8.5-9.0 (. After readjustment to pH 7.5, the very diluted metal ions (about 1 ppm) in the supernate were transferred into a biological reactor and then removed with or without nitrate by... 

Buldini et al. ° developed a procedure for the ion chromatographic determination of total chlorine, phosphorus, and sulfur, and of iron, copper, nickel, zinc, cobalt, lead, and cadmium in edible vegetable oils and fats after the complete removal of the organic matrix by saponification followed by oxidative UV photolysis. The method was simple and required fewer reagents compared with other sample pre-treatment procedures. Saponification lasted for half an hour since the addition of ethanol and potassium hydroxide. 

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