LIQUID-LIPOPHILIC GEL EXTRACTION OF PRECIOUS METALS

Publisher Website
Google Scholar
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 also as M(CN)2 extracting gels.