Grzegorz Łapienis

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 multimembrane hybrid system (MHS). The system was composed of two cation-exchange polymer membranes and an agitated bulk liquid membrane containing one of the following polymers as the transport activating component: ω-methoxy-poly(oxyethylene) phosphate (MPOEP, 1), α,ω-poly(oxyethylene) bisphosphate (POEBP, 2), and α,ω-poly(oxyethylene) bis(dimethyl phosphate) (POEBMP, 3) of various molecular mass. For comparative studies, poly(ethylene glycol)s (PEG, 4) of equivalent molecular mass (1500-6000), were also studied. The results have been analysed by comparing the overall metal cation fluxes, facilitation factors, and separation coefficients. It was found that compound 2 exhibits favourable carrier properties represented by the ionic fluxes as high as 2-10 -11 mol/(cm 2 .s). This macromolecular carrier allows the achievement of trasnport facilitation factors ranging from 10 to 100 with respect to the system without anly 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. THe mechanism of transport when mediated by the ionic macromolecular carriers 1 and 2 is probably influenced by their bifunctional character involving the cooperation between ion exchange processes and ion binding by pseudocyclic structures of poly(oxyethylene) moieties.

Properties of star-shaped polymer with poly(oxyethylene) branches and monoesters of phosphoric acid end groups in pertraction of alkali, alkaline earth, and transient metal cations

Abstract A functionalized star-shaped polymer [CH3O(CH2CH2O)n]x–[DGEEG]–[(CH2CH2O)mP(O)(ONa)2]x, (MPOE–[DGEEG]–POEP), with the overall molecular mass approx. 2×105 and more than 40 side-arms, was used as the macroionophore of metal cations in a complex membrane system MHS[FLM-PV]. The system comprised a hybrid membrane system (MHS) with a liquid membrane (FLM) flowing between two cation-exchange membranes. Additionally, the FLM was continuously dehydrated by applying the pervaporation method (PV). The macroionophore, after dissolving in 1,2-dichloroethane, has been observed to mediate selective pertraction (liquid membrane transport) of Zn2+ and K+ cations from a multication feed solution containing alkali (K+, Na+), alkaline earth (Mg2+, Ca2+) and transition metal cations (Cu2+, Zn2+). In parallel experiments it was found that poly(ethylene glycol)s (PEG4000 and 6000) transports selectively only K+ cations. The following selectivity sequences have been established from the values of separation coefficients and ionic fluxes. MPOE-DGEEG-POEP: Zn2+>K+>Na+>Cu2+, Mg2+, Ca2+; PEG4000: K+≫Na+>Zn2+, Cu2+, Ca2+, Mg2+; PEG6000: K+≫Zn2+, Ca2+, Na+, Cu2+, Mg2+.

Selenized polysaccharides – Biosynthesis and structural analysis

The main objective of our research was to analyze the structure of the Se-containing polysaccharides and to examine how the selenium is bound to the polysaccharide molecule. During investigation of the biosynthesis of new immunomodulators, we isolated a selenium (Se)-containing polysaccharide-protein fraction containing proteoglycans of molecular weights of 3.9 × 106 Da and 2.6 × 105 Da, composed of glucose or mannose, nearly 8% of protein and 190 μg Se/g dry weight. X-ray absorption spectroscopy (XAS) data analysis in the near edge region (XANES) confirmed that selenium in the Se-polysaccharides structure is present at the -II oxidation state and that Se is organically bound. The simulation analysis in the EXAFS (extended X-ray absorption fine structure) region suggested that selenium is most likely bound by a glycosidic-link in a β-1,3 or α-1,4-glycosidic bond or substituted for oxygen in a pyranosidic ring. Calculations performed with Gaussian 03 software predicted deformations in the polysaccharide structure caused by the incorporation of the selenium atom including change in bond lengths and torsion angles and, as a result, disappearance of hydrogen bonds in the vicinity of the selenium atoms.