Copper/ions/salts adsorption

A film became saturated with respect to aluminium ions when there was one of these in the film for every 12 stearic acid molecules, although photographs of the skim showed that appreciable adsorption could occur if the underlying solution contained only one part of aluminium in 2 X 10 parts of water Under these conditions, even if all the aluminium in the solution were concentrated in the interface, there would be only one atom of metal to every 31 molecules of stearic acid. Copper ions likewise form salts very readily, being effective from bulk concentrations as low as 1 part in 300,000,000. 

Some polystyrene resins (cross-linked with DVB) are specially modified to have chelating functional groups bound to the matrix so as to make them selective towards certain ions. Such resins with iminodiacetic acid groups are marketed under the trade names Dowex A-1 (Dow Chemical) and Chelex 100 (Bio-Rad Laboratories). The complex (XXVI) formation constants with metal ions of the chelating resin are so large that the resin absorbs metal ions equivalent to the iminodiacetic acid groups (used in sodium salt form), i.e., the efficiency of metal ion adsorption is near 100%. A particular metal ion can be removed by controlling the pH of aqueous solution. For example, at pH 2, mercury and copper ions are... 

In the 2nd period ranging from the 1930s to the 1950s, basic research on flotation was conducted widely in order to understand the principles of the flotation process. Taggart and co-workers (1930, 1945) proposed a chemical reaction hypothesis, based on which the flotation of sulphide minerals was explained by the solubility product of the metal-collector salts involved. It was plausible at that time that the floatability of copper, lead, and zinc sulphide minerals using xanthate as a collector decreased in the order of increase of the solubility product of their metal xanthate (Karkovsky, 1957). Sutherland and Wark (1955) paid attention to the fact that this model was not always consistent with the established values of the solubility products of the species involved. They believed that the interaction of thio-collectors with sulphides should be considered as adsorption and proposed a mechanism of competitive adsorption between xanthate and hydroxide ions, which explained the Barsky empirical relationship between the upper pH limit of flotation and collector concentration. Gaudin (1957) concurred with Wark s explanation of this phenomenon. Du Rietz... 

After an extensive study of the adsorption of arsenious oxide by metallic hydroxides,3 Sen concluded that this type of adsorption resembles that of cations by manganese dioxide, and that the chemical affinity between the adsorbent and the substance adsorbed plays an important part, thus differing from adsorption by charcoal. It has been observed that soils having a high absorption capacity for bases also absorb the arsenite ion from solutions of 0-001 to 0-01X concentration.4 The absorption increases with time, without reaching an end-point, and the process follows the normal adsorption equation C1=kC1Jn. The addition of ferric oxide or calcium carbonate to the soil considerably increases the capacity for absorption, but such salts as calcium sulphate or copper sulphate have no effect. 

Activators are used for anhancing flotation of the minerals that mey not possess any notability in their absence. Flotation of quartz using calcium salts and of sphalerite using copper sulfate (see Fig. 16.4-2) are typical examples of activation. In the case of oleate flotation of quartz in the preseace of calcium, activation can be attributed to electrostatic adsorption of the calcium ions on tbe nageiively charged quartz... 

In freshwater, the solubility of copper salts is decreased under reducing conditions and is further modified by water pH, temperature, and hardness size and density of suspended materials rates of coagulation and sedimentation of particulates and concentration of dissolved organics. The chemical form of copper in freshwater is important in controlling geochemical and biological processes. But the lack of knowledge on the adsorption characteristics of most cupric (Cu+ ) ion complexes contributes... 

The color is probably due to adsorption complexes (lakes). Cadmium hydroxide precipitated in the presence of (I) is brown. On standing for some time, the color changes to green-blue, because the carbazide is oxidized to the carbazone (II). The color change is accelerated by formaldehyde the reason is as yet not known. This fact can be used to test for cadmium, even when copper is present. It is necessary to provide conditions which will permit the precipitation of cadmium hydroxide, but not of copper hydroxide. The diverse behavior of the complex cyanides toward formaldehyde can be utilized. Alkali cyanides react with formaldehyde to produce the alkali salt of glycolic nitrile, whereby cyanide ions are consumed ... 

Qiu et al. [22] have demonstrated a technique for removal of Lead, Copper, Nickel, Cobalt, and Zinc from water by application of a Cancrinite type zeolite synthesized from fly ash, by employing molten salt method. The degree of heavy metal adsorption has been reported to vary with the type of ion exchange... 

---