Phosphine oxide mediate transport: modelling of mass transfer in supportedliquid membrane transport of gold (III) using Cyanex 923

The permeation of gold (III) through a supported liquid membrane impregnate d with the phosphine oxide Cyanex 923 in n-decane has been investigated. A model is reported describing the transport mechanism which consists of: dif fusion process through the feed aqueous diffusion layer, fast interfacial c hemical reaction and diffusion through the membrane. The experimental data are quantitatively explained by mathematical equations describing the rate of transport. Different rate-controlling processes take place as long as th e metal transport occurs. High selectivity in the separation of gold (III) with respect to the platinum group metals is achieved. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.