Nickel cation exchange resins

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

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. 

Catalytic reduction, with Adams platinum oxide catalyst, 470 with copper-chromium oxide, 873 with Raney nickel, 566 Cation exchange resin, for esterification, 381, 387, 388 Cellosolve, 170, 265, 444 butyl, 170, 444 methyl, 170, 444 Cellulose, 458 ... 

A secondary, more subtle, effect that can be utilized in the achievement of selectivity in cation exchange is the selective complexation of certain metal ions with anionic ligands. This reduces the net positive charge of those ions and decreases their extraction by the resin. In certain instances, where stable anionic complexes form, extraction is suppressed completely. This technique has been utilized in the separation of cobalt and nickel from iron, by masking of the iron as a neutral or anionic complex with citrate350 or tartrate.351 Similarly, a high chloride concentration would complex the cobalt and the iron as anionic complexes and allow nickel, which does not form anionic chloro complexes, to be extracted selectively by a cation-exchange resin. 

In 40 parts by volume of water is dissolved 0.6 part of 2, 3 -epimino-2 -deamino-3 -deoxykanamycin B, and in the presence of 9 parts by volume of Raney nickel the mixture is stirred while introducing hydrogen gas at a pressure of 100 kg/cm2 at 60°C for 6 h. After the reaction Raney nickel is separated by filtration. The Raney nickel is washed well with 300 parts by volume of 1 N-aqueous ammonia and the washing is added to the filtrate. The whole is concentrated to about 100 parts by volume. The precipitated insolubles are removed by filtration, and the pH of the supernatant is adjusted to about 5.0 with hydrochloric acid. The mixture is run onto a column of 50 ml of cation-exchange resin [Amberlite CG-50, NH4+-form]. 

After preconcentration, these samples can then be back-extracted into a similar solvent or into a matrix that is more compatible with the detection system. The use of SIA with bead injection was demonstrated for the preconcentration of nickel and bismuth on a cation-exchange resin prior to detection by electrothermal atomic absorption spectrometry (ETAAS) or ICP-MS. 

All eight inositol isomers have been separated on a Ca " -form cation-exchange resin eluted under pressure with water. The method was applied to the separation of the six inositols and the range of other unknown products formed on reaction of myo-inositol with Raney nickel. " ... 

The adsorption by ion exchange resins of metallic ions removed by dissolution of magnetite layer of the coupon specimens in the decontamination formulations was studied in the glass loop experiments. Inactive metal ions of iron, nickel and activated corrosion products Co-60, Co-58, Mn-54 and fission products Cs-137, Ce-141, Ce-144, Pr-144 were also effectively removed by the cation exchange resins. Ru-103, Sb-125 were taken up by anion exchange resins. Ru-106, Zr-95 and Nb-95 were taken up by bodi the ion exchange resins. 

The successful use of chelating ion exchange resins to treat metal plating baths depends upon the selective sorption properties of the resins for the ions present in the plating baths. The selectivity of the sorption can depend upon a number of factors, including the temperature, pH, and upon the type and concentration of other anions and cations present in the solution. Various competing ion effects have been noted for metals such as copper, nickel, cobalt, iron, zinc and others (4 - 8). 

Due to the anionic nature of rhamnolipids, they are able to remove metals from soil and ions such as cadmium, copper, lanthanum, lead and zinc due to their complexation ability [57-59], More information is required to establish the nature of the biosurfactant-metal complexes. Stability constants were established by an ion exchange resin technique [60], Cations of lowest to highest affinity for rhamnolipid were K+ < Mg + < Mn + < Ni " " < Co " < Ca2+ < Hg2+ < Fe + < Zn2+ < Cd2+ < Pb2+ < Cu2+ < M +. These affinities were approximately the same or higher than those with the organic acids, acetic, citric, fulvic and oxalic acids. This indicated the potential of the rhamnolipid for metal remediation. Molar ratios of the rhamnolipid to metal for selected metals were 2.31 for copper, 2.37 for lead, 1.91 for cadmium, 1.58 for zinc and 0.93 for nickel. Common soil cations, magnesium and potassium, had low molar ratios, 0.84 and 0.57, respectively. 

A more direct synthesis was then devised in which the required metal, as a suitable salt or complex in solution, is reacted with either an anionic or cationic cellulose ion exchange resin. The metal-cellulose material was then charred and activated as before to give a dispersion of metal particles in a porous carbon matrix. The method has the immediate advantage of extending the range of metals which can be incorporated to include those more electropositive than copper eg nickel. 

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