Cadmium hydroxides

Almost all the methods described for the nickel electrode have been used to fabricate cadmium electrodes. However, because cadmium, cadmium oxide [1306-19-0], CdO, and cadmium hydroxide [21041-95-2], Cd(OH)2, are more electrically conductive than the nickel hydroxides, it is possible to make simple pressed cadmium electrodes using less substrate (see Cadmium and cadmium alloys Cadmium compounds). These are commonly used in button cells. 

The process by which porous sintered plaques are filled with active material is called impregnation. The plaques are submerged in an aqueous solution, which is sometimes a hot melt in a compound s own water of hydration, consisting of a suitable nickel or cadmium salt and subjected to a chemical, electrochemical, or thermal process to precipitate nickel hydroxide or cadmium hydroxide. The electrochemical (46) and general (47) methods of impregnating nickel plaques have been reviewed. 

Cadmium is rapidly oxidized by hot dilute nitric acid with the simultaneous generation of various oxides of nitrogen. Unlike the ziac ion, the cadmium ion is not markedly amphoteric, and therefore cadmium hydroxide [21041-95-2] Cd(OH)2, is virtually iasoluble ia alkaline media. However, the cadmium ion forms stable complexes with ammonia as well as with cyanide and haUde ions. The metal is not attacked by aqueous solutions of alkaU hydroxide. 

Cadmium hydroxide is the anode material of Ag—Cd and Ni—Cd rechargeable storage batteries (see Batteries, secondary cells). Cadmium sulfide, selenide, and especially teUuride find utiUty in solar cells (see Solarenergy). Cadmium sulfide, Hthopone, and sulfoselenide are used as colorants (orange, yellow, red) for plastics, glass, glazes, mbber, and fireworks (see Colorants for ceramics Colorants forplastics Pigments). 

Cadmium Hydroxide. Cd(OH)2 [21041-95-2] is best prepared by addition of cadmium nitrate solution to a boiling solution of sodium or potassium hydroxide. The crystals adopt the layered stmcture of Cdl2 there is contact between hydroxide ions of adjacent layers. Cd(OH)2 can be dehydrated to the oxide by gende heating to 200°C it absorbs CO2 from the air forming the basic carbonate. It is soluble ia dilute acids and solutions of ammonium ions, ferric chloride, alkah haUdes, cyanides, and thiocyanates forming complex ions. 

Cadmium nitrate is the preferred starting material for Cd(OH)2 for use as the anode ia alkaline batteries. The siatered anode matrix of such batteries is saturated with cadmium nitrate (480—500 g/L Cd) and cadmium hydroxide is formed thereia by standardized electrolysis and dryiag (37). The tetrahydrate sells for 29.10/kg ia 20 kg lots. Other uses iaclude photographic emulsions and as a colorant ia glass and ceramics. 

Unlike the cells above, which are all primary cells, this is a secondary (i.e. rechargeable) cell, and the two poles are composed in the uncharged condition of nickel and cadmium hydroxides respectively. These are each supported on microporous nickel, made by a sintering process, and separated by an absorbent impregnated with electrolyte. The charging reactions are ... 

Kadmium-jodid. n. cadmium iodide, -legie-rung. /. cadniium alloy, -oxydhydrat, n. cadmium hydroxide. 

The nickel-cadmium battery was invented by Jungner in 1899. The battery used nickel hydroxide for the positive electrode, cadmium hydroxide for the negative electrode, and an alkaline solution for the electrolyte. Jungner s nickel-cadmium battery has undergone various forms of the development using improved materials and manufacturing processes to achieve a superior level of performance. 

Although one of the most common storage batteries is called the nickel/cadmium system ( NiCad ), correctly written (-)Cd/KOH/NiO(OH)(+), cadmium is not usually applied as a metal to form a battery anode. The same can be said with regard to the silver/cadmium [(-) Cd / KOH / AgO (+)] and the MerCad battery [(-)Cd/KOH/HgO(+)]. The metallic negative in these cases may be formed starting with cadmium hydroxide, incorporated in the pore system of a sintered nickel plate or pressed upon a nickel-plated steel current collector (pocket plates), which is subsequently converted to cadmium metal by electrochemical reduction inside the cell (type AB2C2). This operation is done by the customers when they start the application of these (storage)... 

Seif-Test 12.10B Use the tables in Appendix 2B to calculate the solubility product of cadmium hydroxide, Cd(OH)2. 

Cadmium is an extremely toxic metal that finds its way into the aqueous environment as a result of some human activities. A major cause of cadmium pollution is zinc mining and processing, because natural deposits of ZnS ores usually also contain CdS. During the processing of these ores, highly insoluble cadmium sulfide ( sp = 7.9 X 10 ) maybe converted into considerably less insoluble cadmium hydroxide (.E p — 7.2 X 10" ). What mass of Cd (OH)2 will dissolve in l.OOx lO L of an aqueous solution ... 

Nickel-cadmium batteries are rechargeable because the nickel and cadmium hydroxides products adhere tightly to the electrodes. More than 1.5 billion Ni-Cd batteries are produced every year. These batteries are not without drawbacks, however. Cadmium is a toxic heavy metal that adds weight to the battery. Moreover, even rechargeable batteries degrade eventually and must be recycled or disposed of in a benign way. 

A cadmium hydroxide complex of composition [TpMe2]Cd0H-H20, obtained as an intractable material from the reactions of both (Et2NCH2CH2NEt2)CdCl2 and (Ph3P)2CdCl2 with K[TpMe2] in acetone, has been reported (89). However, the complex is not well characterized. 

Trace elements can be precipitated as carbonates, sulfates, phosphates and hydroxides in arid and semi-arid environments. But most carbonates are more stable in arid and semi-arid soils than other solid phases. Cadmium hydroxide (Cd(OH)2), sulfate (CdS04) and phosphates (Cd3(P04)2) are more soluble than carbonate (CdC03, octavite), therefore the former minerals are not stable in arid soils. In calcareous soils, CdC03 (octavite) is the main Cd mineral to control Cd2+ activity in soil solution. At high C02... 

Cadmium Iodide (ideal), Cdl2, Cadmium Hydroxide, Cd(0H)2... 

The first fractionation of urinary ampholytes in this way was carried out by Boulanger et al. (BIO) in 1952 with the use of ion-exchange resins. They had designed this procedure previously for the fractionation of ampholytes in blood serum (B8). According to this method, deproteinized urine was subjected to a double initial procedure aiming at the separation of low-molecular weight substances from macro-molecular ones. One of the methods consisted of the fractionation of urinary constituents by means of dialysis, the second was based on the selective precipitation of urinary ampholytes with cadmium hydroxide, which, as had previously been demonstrated, permits separation of the bulk of amino acids from polypeptides precipitated under these circumstances. Three fractions, i.e., the undialyzable part of urine, the dialyzed fraction, and the so-called cadmium precipitate were analyzed subsequently. 

Tri-ethylene diamine cadmium hydroxide [Cd(en)3](OH)2 Cadoxen and Cden3) Good solvating properties, slight oxidative degradation, clear, stable and colourless... 

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