Nickel trivalent

A manufacturer of painted and plated store and office fixtures, located in the Midwest conducts plating operations involving nickel, trivalent chromium and zinc. 

When nickel hydroxide is oxidized at the nickel electrode in alkaline storage batteries the black trivalent gelatinous nickel hydroxide oxide [12026-04-9], Ni(0H)0, is formed. In nickel battery technology, nickel hydroxide oxide is known as the nickel active mass (see Batteries, secondary cells). Nickel hydroxide nitrate [56171-41-6], Ni(0H)N02, and nickel chloride hydroxide [25965-88-2], NiCl(OH), are frequently mentioned as intermediates for the production of nickel powder in aqueous solution. The binding energies for these compounds have been studied (55). 

Decorative plating primarily over bright nickel is estimated to consume about 2270 t worldwide. Some 60% of this is used in North America, and about 900 t in Europe. A relatively new method in decorative chromium plating is based on trivalent instead of hexavalent chromium, and this is estimated to total about 10% of the decorative market and is expected to increase. Chromic acid, which cost about 2.76/kg in early 1993, is the hexavalent... 

R indicates the organic portion of the resin and SO3 is the immobile portion of the ion active group. Two resin sites are needed for nickel ions with a plus 2 valence (Ni ). Trivalent ferric ions would require three resin sites. As shown, the ion exchange reaction is reversible. The degree the reaction proceeds to the right will depend on the resins preference, or selectivity, for nickel ions compared with its preference for hydrogen ions. The selectivity of a resin for a given ion is measured by the selectivity coefficient. K. which in its simplest form for the reaction... 

Concern over the health hazards of the hexavalent chromium solutions used to form the top coat of conventional nickel plus chromium coatings have encouraged research into trivalent chromium plating solutions. A process with better throwing power and improved covering power than those of hexavalent chromium has been described by Smart etal". A process for depositing a chromium-iron, or chromium-nickel-iron alloy, has been outlined by Law. ... 

Allmann found that when suitable trivalent ions were introduced during the precipitation of the hydroxides of Mg, Zn, Mn, Fe, Co, and Ni, these were incorporated in the lattice and the structure changed from the brucite (Mg(OH)2) to the pyroaurite ([Mg6Fe2(OH)l6] [CO,- 4H20]) type of structure [68], One of the nickel materials he prepared was an Ni/Al hydroxide. Axmann et al. [69-71] have given the nickel compounds the general formula... 

Electrochemical Processes The charged positive electrodes of these batteries contain NiOOH, an oxide hydroxide of trivalent nickel, and the negative electrodes contain metallic cadmium or iron (M). As a rule, KOH solution serves as the electrolyte. The main current-producing reactions on the electrodes and in the cell in general can be written as... 

Cobaltites with spinel stractnre have compositions MC02O4, where M is a metal forming divalent cations, snch as zinc, cadminm, magnesinm, nickel, manganese, and divalent cobalt. In contrast to the perovskites, the cobaltites have a rather high catalytic activity already at room temperatnre. Experiments show that the activity increases with increasing spinel structure content (i.e., increasing number of Co ions) of the catalyst snrface. The trivalent cobalt ions promote the withdrawal of... 

A slight excess of base may be titrated in the previous reactions to shift the pH to a slight basic condition. This is important for the precipitation of certain metal salts (such as nickel, iron, and trivalent chromium) as hydroxides. 

As a practical example, following the reduction of hexavalent chromium, sodium hydroxide, lime, or sodium hydroxide can be added to the wastewater to neutralize the pH and precipitate the trivalent chromium, nickel, iron, divalent, and other heavy metals. If lime is used, lime will react with heavy metals and with any residual sodium sulfate, sulfurous acid, or sodium bisulfite. The following reactions apply ... 

Ferrous sulfide acts as a reducing agent at pH 8 to 9 for reduction of hexavalent chromium and then precipitates the trivalent chromium as a hydroxide in one step without pH adjustment.5162 So, the hexavalent chromium in the nickel-chromium plating wastewater does not have to be isolated and pretreated by reduction to the trivalent form. The new process is applicable for removal of all heavy metals. All heavy metals other than chromium are removed as insoluble metal sulfides, M(II)S. 

Hexavalent chromium and metals such as zinc and nickel that are present as impurities in the chromites ore are predominant pollutants associated with the sodium dichromate plant. They are generally removed through alkaline precipitation, clarification, filtration, and settling processes. The wastewater is treated with sodium sulfide to reduce hexavalent chromium to trivalent chromium,... 

This small class of blue copper-complex dyes has made a significant contribution to the acid and reactive ranges in recent years (sections 5.4.2, 5.4-3 and 7.5.8). The essential chromogen is the bicyclic 1 1 chelated grouping illustrated (1.20). Trivalent metals such as chromium, nickel or cobalt will give tetracyclic 1 2 complexes with a central metal atom, analogous to conventional 1 2 metal-complex azo dyes. 

The sluggish substitution properties of copper(III) and nickel(III) peptide complexes have permitted the isolation of complexes with these oxidation states (14, 15). Thus, the tri-valent peptide complexes pass through a cation exchange resin which readily strips copper(II) or nickel(II) from the corresponding complexes. We now have a little more information about the substitution characteristics of the trivalent metal complexes. 

In studies of the concentrations of arsenic, bromine, chromium, copper, mercury, lead and zinc in south-eastern Lake Michigan, it was shown that these elements concentrated near the sediment water interface of the fine-grained sediments. The concentration of these elements was related to the amount of organic carbon present in the sediments (161). However, it was not possible to correlate the concentration of boron, berylium, copper, lanthanum, nickel, scandium and vanadium with organic carbon levels. The difficulty in predicting the behaviour of cations in freshwater is exemplified in this study for there is no apparent reason immediately obvious why chromium and copper on the one hand and cobalt and nickel on the other exhibit such variations. However, it must be presumed that lanthanium might typify the behaviour of the trivalent actinides and tetravalent plutonium. 

For metallic iron and nickel electrodes, the transpassive dissolution causes no change in the valence of metal ions during anodic transfer of metal ions across the film/solution interface (non-oxidative dissolution). However, there are some metals in which transpassive dissolution proceeds by an oxidative mode of film dissolution (Sefer to Sec. 9.2.). For example, in the case of chromium electrodes, on whidi the passive film is trivalent chromium oxide (CrgOj), the transpassive dissolution proceeds via soluble hexavalent chromate ions. This process can be... 

In the presence of redox mediators, the Nia-C state can be further reduced to an EPR-silent state (by increasing the H2 partial pressure) in a reaction requiring one electron and one proton. Assuming trivalent nickel in the Nig-C " state, this reaction can be most simply interpreted as... 

Kruger, H.-J. and Holm, R. H. (1990) Stabilization of trivalent nickel in tetragonal NiS4N2 and NiNg environments Synhesis, structures, redox potentials and observations related to [Ni-Fe]-Hydrogenases./. Am. Chem. Soc., 112, 2955-63. 

LDHs containing nickel with trivalent cations such as aluminum, chro-miiun, manganese and iron, have been synthesized electrochemically [173]. The electrosynthesized LDHs have similar structural features to both the chemically synthesized LDHs and a-nickel hydroxide. A new Fe(II)/Fe(III)-... 

There have been a number of studies of the physical and bonding behavior of these mixed transition-metal oxides, which conclude that in the fully lithiated compounds the cobalt is trivalent, the nickel predominantly divalent, and the manganese tetra-valent. Thus, the electrochemically active species is predominantly nickel with the cobalt playing an... 

More severe respiratory effects (increased lung weight, increase in the accumulation of alveolar macrophages, increase in the density of type II cell volumes) were observed in rabbits exposed by inhalation to both nickel and trivalent chromium than in rabbits exposed to nickel only (Johansson et al. 1988b). 

Johansson A, Curstedt T, Robertson B, et al. 1989. Lung lesions after experimental combined exposure to nickel and trivalent chromium. Environ Res 50 103-119. 

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