Mobile macromolecular carriers of ionic substances, 2 - Transport rates and separation of some divalent cations by poly(oxyethylene) phosphates

The permeation of Cu(II), Zn(II), Mn(II), Co(II), Ni(II) as facilitated by soluble macromolecular carriers (macroionophores) was investigated in a mul timembrane hybrid system (MHS). The system was composed of two cation-excha nge polymer membranes and an agitated bulk liquid membrane containing one o f the following polymers as the transport activating component: omega -meth oxy-poly(oxyethylene) phosphate (MPOEP, 1), a,omega -poly(oxyethylene) bisp hosphate (POEBP, 2), and a,omega -poly(oxyethylene) bis(dimethyl phosphate) (POEBMP, 3) of various molecular mass. For comparative studies, poly(ethyl ene glycol)s (PEG, 4) of equivalent molecular mass (1500-6000), were also s tudied. The results have been analysed by comparing the overall metal catio n fluxes, facilitation factors, and separation coefficients. It was found t hat compound 2 exhibits favourable carrier properties represented by the io nic fluxes as high as 2 .10-(11) mol/(cm(2).s). This macromolecular carrier allows the achievement of transport facilitation factors ranging from 10 t o 100 with respect to the system without any carrier and from 6 to 34 with respect to the system containing an equivalent amount of PEG. The specific values depend on molecular mass of POE in 2, with a maximum at POE 2000. Th e mechanism of transport when mediated by the ionic macromolecular carriers 1 and 2 is probably influenced by their bifunctional character involving t he cooperation between ion exchange processes and ion binding by pseudocycl ic structures of poly(oxyethylene) moieties.