Transport and separation properties of poly(oxypropylene) bisphosphates as macroionophores of alkali, alkaline-earth and transient metal cations in a hybrid liquid membrane system Romuald Wo ´ dzki a, * , Marek S ´ wia ˛ tkowski a , Grzegorz Łapienis b a Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun ´ , Poland b Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Lodz ´, Poland Received 11 February 2004; received in revised form 20 October 2004; accepted 1 November 2004 Available online 22 December 2004 Abstract Poly(oxypropylene) bisphosphates (POPBPs) have been synthesized by modification of polypropylene glycols (PPG400, 1200, 2000) and used as macroionophores of metal cations in a multimembrane hybrid system comprising a flowing liquid membrane unit, cation exchange, and pervaporation polymer membranes. POPBPs ability to mediate the selective pertraction of some cations from a multication mixture containing alkali (K + , Na + ), alkaline earth (Ca 2+ , Mg 2+ ) and transient metal cations (Zn 2+ , Cu 2+ ) has been studied and compared with the properties of respective PPGs. POPBPs, after dissolving in 1,2-dichloroethane (liquid membrane phase), have been observed to transport and separate cations in the following order: Zn 2+ > Cu 2+  Ca 2+ , Mg 2+ ,K + , Na + . An increase in the molecular mass of POP chain changes the position of K + cations in the order from Zn 2+ > Cu 2+ >K + P Na + , Ca 2+ > Mg 2+ to Zn + ,K + > Na + > Ca 2+ > Cu 2+ , Mg 2+ as observed for PPG400 and PPG2000, respectively. High ionic fluxes and separation properties of POPBs are dependent mainly on the presence of ionisable phosphoric acid end-groups. These groups, in cooperation with poly(oxypropylene) chains, mediate the proton-coupled transport of cations (counter-transport) resulting in the effective up-hill transport of Zn 2+ cations. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Poly(oxypropylene) bisphosphate; Macroionophore; Pertraction; Liquid membrane; Cations separation 1. Introduction Extensive theoretical and experimental studies have been devoted to the carrier mediated trans- ports occurring in liquid membranes, and various achievements in this area have been reviewed in 1381-5148/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.reactfunctpolym.2004.11.001 * Corresponding author. Tel.: +48 566 114513; fax: +48 566 542477. E-mail address: wodzki@chem.uni.torun.pl (R. Wo ´ dzki). Reactive & Functional Polymers 62 (2005) 195–208 REACTIVE & FUNCTIONAL POLYMERS www.elsevier.com/locate/react