Zinc, extraction properties

The extraction of metal ions depends on the chelating ability of 8-hydroxyquinoline. Modification of the stmcture can improve its properties, eg, higher solubility in organic solvents (91). The extraction of nickel, cobalt, copper, and zinc from acid sulfates has been accompHshed using 8-hydroxyquinohne in an immiscible solvent (92). In the presence of oximes, halo-substituted 8-hydroxyquinolines have been used to recover copper and zinc from aqueous solutions (93). Dilute solutions of heavy metals such as mercury, ca dmium, copper, lead, and zinc can be purified using quinoline-8-carboxyhc acid adsorbed on various substrates (94). 

The method has been applied to the determination of boron in river water and sewage,16 the chief sources of interference being copper(II) and zinc ions, and anionic detergents. The latter interfere by forming ion-association complexes with ferroin which are extracted by chloroform this property... 

Cadmium is close to lead and mercury as a metal of current toxicological concern.12346 Extraction of lead and zinc ores, which contain cadmium, pollutes the environment with cadmium. The use of cadmium before 1900 was infrequent however, its valuable metallurgical properties, such as resistance to corrosion, increased its use markedly, for example in the manufacture of alloys and as a coating on steel. It is also now widely used in nickel cadmium ( nicad ) batteries. Coal and other fossil fuels contain cadmium which is released into the environment on combustion. 

The extraction of zinc with the cation exchanger di(2-ethylhexyl)phosphoric acid, RH, is recommended by the EFCE as a test system for RE. Physical properties, handling, equilibrium data, etc. are documented on the internet (http // www. dechema.de/Extraction, http //www.icheme.org/leaming). 

Several carriers/extractants/ligands are available commercially for the extraction of acids, bases, elements such as copper, cobalt, nickel, zinc, iron, chromium, precious metals, and the rare earths. The physicochemical properties of the various commercial extractants available for type 2 facilitation have been previously reported by Gu et al. [46] and Cox [91], and the chemical behavior of these extractants can be broadly classified into three categories ... 

---