EXTRACTIVE SEPARATION OF TRACE AMOUNTS OF MERCURY, CADMIUM AND ZINC

A simple solvent extraction procedure is reported for the sequential s eparation of mercury(II), cadmium(II) and zinc(II). Mercury is separat ed first using 1,3-diphenyl-2-thiourea in chloroform at an overall aci dity of 0.3M HCl. Then cadmium separated using the same reagent at pH 10 into dichloromethane. The zinc which is remaining in the aqueous ph ase is then quantitatively extracted into toluene-cyclohexanol mixture using 2-mercaptobenzoxazole. Suitable stripping solutions have been p roposed for the re-extraction of these metal ions for their subsequent estimations. The method has been made highly selective by the use of appropriate masking agents and has been applied in conjunction with es timation procedures for the determination of these metal ions in city waste incineration ash (CRM 176), mercuric chloride (A. R. grade) and in magnesium alloy samples.