Chelating functional group

Heavy metals Cation Polystyrene matrix Chelating functional groups Mineral acids... 

The subject of the separation and purification of metals with the aid of chitosan has been reviewed by Inoue (1998) who collected data relevant to chitosans modified with chelating functional groups as well [111]. 

Resins can also be prepared with chelating functional groups which show selective affinities for certain metals. Iminodiacetic acid, vinylacetylacetone, glyoxal-thiophenol and 8-hydroxy quinoline have all been used to produce these so-called chelating resins. Their selectivities are similar to those of the free reagent. 

The introduction of chelating functional groups (e.g. amino diacetate) into polymer beads yields a product with a high affinity for metal ions, but also capable of excluding large molecules and colloidal particles from the inner pores (i.e. in some situations the column can act as a size differentiation medium) (Florence, 1977). Compared with other techniques (such as dialysis, ultra-filtration and solvent extraction), chelating column separations can be claimed to be faster and simpler, with the equipment being relatively less expensive. 

Zhang, A., Uchiyama, G., and Asakura, T., The adsorption property and kinetics of uraniumfVI) with a novel fibrous and pol3mieric adsorbent containing amidoxime chelating functional group from sea water. Sep. Sci. Tech., 2003, 38 1829-1849. 

Humic substances and LMW organic ligands share common chelating functional groups, and it is likely that isolated segments of humate molecules... 

Chelators - functional groups that bind a metal ion to form a heterocycle that incorporates the metal ion - are useful in the diagnosis and treatment of Al intoxication. Chelation can increase Al clearance into dialy-sate, urine and bile. Desferrioxamine (DFO) has been most extensively used, and a 5 mg kg DFO injection has been used to assess Al body burden, as evidenced by an increase in serum Al, and urinary Al in those with adequate renal function (Yokel... 

Ruthenium and rhodium complexes have maintained the best track record as ketone hydrogenation catalysts. For high enantioselectivities, additional chelating functional groups are often needed. Typical substrates are represented by ketones (3.01) to (3.03), where esters, halides and phosphonates provide an additional donor group on the substrate. BlNAP/ruthenium combinations, such as complex (3.07), have given consistently high enantioselectivities with such... 

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... 

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