a b s t r a c tThe recovery of Zn(II) ions from chloride and sulfate solutions by the transport of a binary Zn(II)-Ni(II) and a quaternary Zn(II)-Cd(II)-Ni(II)-Pb(II) mixture ions through polymer inclusion membranes (PIMs) doped with 1-octyl-4-methylimidazole as an ion carrier was studied (c M(II) = 0.001 M; pH 6.0). The membranes were also used for the separation of metal ions from galvanic tailings. After 24 h, the separation efficiency of the ions from the tailings was higher than 95%, whereas that from the model chloride and sulfate solutions were 96% and 83%, respectively. The selectivity coefficients of Zn(II)/Ni(II) in the transport across PIMs doped with the imidazole derivative were higher for the o-nitrophenyloctyl ether (o-NPOE) than for the o-nitrophenylpentyl ether (o-NPPE) as plasticizers, due to an increased viscosity of the former. Membranes based on the o-NPOE plasticizer are characterized by higher porosity (23%) and lower roughness (7.7 nm), compared with those based on o-NPPE. Irrespective of the plasticizer used, the PIMs with 1-octyl-4-methylimidazole were characterized by high strengths and high thermal resistances (up to 200°C).

No abstract

No abstract

The facilitated transport of Zn(II), Cd(II), Co(II), and Ni(II) ions from different aqueous chloride source phases (c Me = 0.001 mol/dm 3 , pH = 6.0) across supported (SLMs) and polymer inclusion membranes (PIMs) doped with 1-decyl-4-methylimidazole as ion carrier was reported. The membrane is characterized by means of atomic force microscopy (AFM). The results show that Zn(II) can be separated very effectively from other transition metal cations as Cd(II), Co(II), and Ni(II) from different equimolar mixtures of such ions. The higher initial fluxes for Zn(II) were found for PIM (3.62-4.10 µmol/m 2 .s), while the lower values were observed for SLM. However, after taking into account the morphology (porosity, tortuosity) of the membranes, the values of the initial flux of Zn(II) transport across the PIM are lower than those across the SLM. The recovery factor of Zn(II) ions during transport across PIM and SLM from different mixtures of cations is above 95% after 24 hrs. PIM containing 1-decyl-4-methylimidazole are stable for 120 hrs.Keywords polymer inclusion membrane (PIM); supported liquid membrane (SLM); separation of metal ions; imidazole derivatives INTRODUCTIONSupported liquid membranes (SLM) and polymer inclusion membranes (PIM) represent an attractive liquid-to-liquid extraction for the selective removal and concentration of nonferrous metal ions (Zn(II), Co(II), Ni(II), Cd(II), Cu(II), and Pb(II)) from aqueous solutions. The transport of such metal ions across SLM and PIM can be described as the simultaneous extraction and back-extraction operations combined in

No abstract

No abstract

Polymer cellulose triacetate membranes doped with 1-alkylimidazole as fixed carriers were applied for the investigation of the facilitated transport of Zn(II) and Mn(II) ions from an aqueous sulphate feed phase (cM = 0.001 mol/dm3). For the polymer inclusion membranes (PIMs) doped with 1-alkylimidazole (alkyl – from hexyl up to decyl), the following patterns of transport selectivity were found: Zn(II) > Mn(II). The highest initial flux of Zn(II) ions (2.65 µmol/m2·s) was found for PIMs doped with 1-decyl-imidazole, whereas the best Zn(II)/Mn(II) selectivity coefficients equal to 19.7 were found for 1-hexyl-imidazole. Permeability coefficients for Zn(II) and Mn(II) ions transported across PIMs increase with an increase in the pKa values of 1-alkylimidazole. The polymer membranes of cellulose triacetate-o-NPPE with 1-alkylimidazole were characterised by scanning electron microscopy, non-contact atomic force microscopy and thermal analysis techniques. The influence of membrane morphology on the Zn(II) and Mn(II) transport process was discussed.

The study involved the transport of zinc(II), cadmium(II), and nickel(II) ions from acidic aqueous solutions using polymer inclusion membranes (PIMs). PIMs consisted of cellulose triacetate (CTA) as a support; o-nitrophenyl pentyl ether (o-NPPE) as a plasticizer; and 1-octylimidazole (1), 1-octyl-2-methylimidazole (2), 1-octyl-4-methylimidazole (3), or 1-octyl-2,4-dimethylimidazole (4) as ion carriers. The membranes were characterized by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results show that Zn(II) and Cd(II) are effectively transported across PIMs, while Ni(II) transport is not effective. The rate of transport of metal ions across PIMs is determined by the diffusion rate of the M(II)–carrier complex across the membrane. The best result achieved for Zn(II) removal after 24 h was 95.5% for the ternary Zn(II)–Cd(II)–Ni(II) solution for PIM doped (4). For this membrane, the separation coefficients for Zn(II)/Cd(II), Zn(II)/Ni(II), and Cd(II)/Ni(II) were 2.8, 104.5, and 23.5, respectively. Additionally, the influence of basicity and structure of carrier molecules on transport kinetics was discussed.