Liquid-liquid extraction of Au(I) by Amberlite LA2 and its application to a polymer-immobilized liquid membrane system

The liquid-liquid extraction of Au(I) by Amberlite LA2 (secondary amine) in kerosene from cyanide media has been investigated. The analysis of metal distribution data suggested the formation of R₂NH₂ ⁺Au(CN)₂-species in the organic phase with formation constant log K_ext=6.5 ± 0.03, whereas the use of mixtures of the amine with a solvation extractant (e.g. a phosphine oxide) shifted the gold-pH_1/2 extraction towards more alkaline values. The results obtained on Au(I) distribution have been implemented in a polymerimmobilized liquid membrane system, using NaOH solutions (e.g. 0.01 mol/L) to strip the metal from the organic phase.