Separation Science and Technology, Vol.45, No.8, 1130-1138, 2010
Liquid-Liquid Extraction of Silver From Chloride Media by N,N'-Tetrasubstituted Dithiomalonamide Derivatives
N,N'-dimethyl-N,N'-diphenyldithiomalonamide (DMDPHDTMA) and N,N'-dimethyl-N,N'-dicyclohexyldithiomalonamide (DMDCHDTMA) were synthesized and tested as extractants for silver in chloride solutions. Even when relatively low concentrations are used, both compounds effectively extract Ag(I) from 2-5M chloride concentrated aqueous phases. Ag(I) is successfully stripped by a stabilized sodium thiosulfate solution. Results obtained from sequential cycles of extraction-stripping suggest that both extractants exhibit a high Ag(I) loading capacity. The effects of the equilibration time, concentrations of extractant, chloride and hydrogen ions on Ag(I) extraction have been investigated. The chemical reactions involved on Ag(I) extraction are proposed. There is no selectivity of DMDPHDTMA or DMDCHDTMA for Ag(I) when Cu(II) and Fe(III) co-exist in the chloride aqueous solution.