Abstract

ABSTRACT In order to extract precious metals from diluted aqueous solutions, lipophilic extracting gels have been prepared by swelling lipophilic polymers - polyvinylchloride (PVC) or cross-linked polybutadiene (BR) and poly(styrene-butadiene) (SBR) rubbers-with extracting solvents. The DC 18C6-A crown-ether-CHCl3-BR gel extracts M(CN)2 anions (M = Ag, Au) from 0.1M K0H with the same extraction constant as in the conventional liquid-liquid system but the diffusion coefficient of the extracted species is decreased by the polymer. A tri-n-butyl phosphate (TBP) - PVC gel was used to extract AuCl4 from 0.5M HC1 : high aqueous-organic volume ratios (until 1500) were possible giving high concentration factors (until 10% of the gel weight).The extraction of PtCl6 2− from 0.5 M HCl with tri-n-octylamine (TOA) - toluene or CHC13, - SBR gels was limited by the poor penetration of TOA in the gels and by losses of metal-loaded organic phase outside the gels : better results were obtained with TOA-TBP-PVC gels tested ...

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