Comparative study of hybrid and activated composite membranes containing Aliquat 336 for the transport of Pt(IV)

This paper describes a comparative study of activated composite (ACM) and hybrid membranes (HM), both incorporating the commercial anion exchanger Aliquat 336 as a carrier, for the transport of Pt(IV) ions in chloride media. The incorporation of the carrier molecules in the polymeric network of both types of membranes is one of the approaches to overcome supported liquid membrane (SLM) instability. ACM are membranes with a bilayer structure: a porous lower polymeric support prepared by phase inversion (polysulfone) and a dense upper layer made by interfacial polymerisation (polyamide). HM are plasticized membranes consisting of a polymeric matrix of cellulose triacetate with a plasticizer and modified by the incorporation of an inorganic material (silanes) prepared by a sol-gel route. The efficiency of both types of membrane for the transport of Pt(IV) ions has been investigated, and several parameters affecting metal transport have been evaluated, such as the composition of the stripping phase and the selectivity of the membranes in the presence of Pd(II) ions. Moreover, comparative studies for both ACM and HM systems have been made by contacting the same feed solution in a triple-compartment cell. Finally, the results of these membrane systems are compared with those previously reported using polymer inclusion membranes (PIM) and SLM for the transport of Pt(IV) under similar experimental conditions. (c) 2007 Elsevier B.V. All rights reserved.