Purification chelating resins

Many attempts have been made to reduce the ammoniacal and sulfurous odor of the standard thioglycolate formulations. As the cosmetics market is very sensitive to the presence of impurities, odor, and color, various treatments of purification have been claimed to improve the olfactory properties of thioglycolic acid and its salts, such as distillation (33), stabilization against the formation of H2S using active ingredients (34), extraction with solvents (35), active carbon (36), and chelate resin treatments (37). 

The early development of ion exchange as a unit operation in hydrometallurgy was slow, mainly because of the lack of selectivity of the resins under operating conditions, and the limited capacities of the earlier commercial resins. Consequently, ion exchange found applications only in processes where the concentration of metal ions in solution was very low, and where the resin could be used to upgrade the solution prior to some final purification step. Recent developments, however, particularly the introduction of chelating resins, have considerably broadened the scope of resins in hydrometallurgy. 

The enzyme y3-galactosidase was purifled directly from crude cell extracts using expanded bed chromatography on another second generation matrix, Ni + loaded streamline chelating resin. The natural histidine content of the enzyme permitted the enzjune to be recovered in almost 90% jdeld and 5.95-fold purification from a crude unclarified cell extract (67). 

Donia, A. M., Atia, A. A., El-Boraey, H. A., and Mabrouk, D. (2006a). Uptake studies of copper(II) on glycidyl methacrylate chelating resin containing Fe O particles. Sep. Purif. Technol. 49, 64-70. 

Atia, A., Donia, A. M.,AbouElEnein, S. A., Yousif,A. M. Studies on uptake behavior of copper (II) and lead (II) by amine chelating resins with different textural properties. Sep Purif Technol. 2003, 33,295-301. 

Pentanedione is widely used in extraction processes for the separation and purification of metals because of its abiUty to form covalent metal chelates. It is also used as an intermediate in the production of heterocycHc substances and dyes, as a fuel additive (324), and in metal plating and resin modification. 

One of the best purification processes so far discovered is based on the coordination properties of synthetic chelating polymers containing functional thiol groups [1]. Typically, effluents rejected by industries where mercury electrodes are extensively used have been purified through resins prepared with a styrene/diyjnylbenzene copolymer functionalized with thiol groups [2]. 

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