The solvent extraction performance of N,N’-dimethyl-N,N’-dibutylmalonamide towards platinum and palladium in chloride media

Paiva, Ana Paula; Carvalho, Gonçalo Ivo; Costa, Maria Clara; Costa, Ana M. Rosa da; Nogueira, Carlos

http://hdl.handle.net/10400.1/7389

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Separation Science and Technology, 49, 966–973, 2014.pdf		555.42 KB	Adobe PDF	Download

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Authors

Paiva, Ana Paula

Carvalho, Gonçalo Ivo

Costa, Maria Clara

Costa, Ana M. Rosa da

Nogueira, Carlos

Abstract(s)

The solvent extraction performance of N,N’-dimethyl-N,N’- dibutylmalonamide (DMDBMA) in 1,2-dichloroethane (1,2-DCE) towards platinum(IV) and palladium(II) in hydrochloric acid media was systematically evaluated. Pt(IV) extraction (%E) increases with the HCl concentration in the aqueous phases, being always higher than 72%, whereas Pd(II) extraction decreases from 65% at 1 M HCl to 22% at 8 M HCl. Several stripping agents for the two metals were tested: Pt(IV) is successfully recovered by a 1 M sodium thiosulfate solution, whereas the best result for Pd(II) was achieved with 0.1Mthiourea in 1MHCl. The loading capacity of DMDBMA for Pt(IV) is high, and data obtained from successive extraction-stripping cycles suggest a good DMDBMA stability pattern. Attempts to replace 1,2-DCE by more environmentally- friendly diluents showed, in general, worse %E for Pt(IV). The dependence of Pt(IV) distribution coefficients on DMDBMA and chloride ion concentrations, as well as on acidity, are the basis of a proposal for the composition of Pt(IV) extracted species.