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Facilitated transport of Cr(VI) ions from aqueous chromate donor phase (2.10–4 kmol/m3) through polymer inclusion membranes (PIMs) using a new synthesized 5,17-di-tert-butyl-11-piperidinomethyl-25,26,27,28-tetrahydroxycalix[4]arene (carrier), as ion carrier, has been investigated. The Cr(VI) passed through a PIM comprised of cellulose triacetate (CTA) as a support and 2-NPOE as a plasticizer. The prepared PIM was characterized with Fourier transform infrared (FT-IR) spectroscopy and the atomic force microscopy (AFM) techniques as well as with contact angle measurements. The efficiency of Cr(VI) transport through the PIM was investigated by studying the effects of carrier concentration on the donor phase as well as by measuring the amount of plasticizer in the membrane, the pH in the acceptor phase, the effect of acid type in donor phase, and the membrane’s stability and thickness. The kinetic parameters were calculated as permeability coefficient (P), flux (J), and diffusion coefficient (D). The transport efficiency of Cr(VI) was observed to be 99.38% after 6 h under optimized conditions. These results indicated that PIMs can be used in the long term for the removal of Cr(VI) from industrial waste waters.

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The kinetics of transport of mercury (II) ions through a bulk liquid membrane (chloroform) containing calix[4]arene nitrile derivatives as a carrier was examined at different temperatures and different stirring rates. The kinetics of mercury (II) transport could be analyzed in the formalism of two, consecutive, irreversible first-order reactions. The influence of temperature and stirring rate on kinetic parameters also have been investigated. The membrane entrance rate, k 1 , and the membrane exit rate, k 2 , increased with increasing temperature and increasing stirring rate. For maximum membrane exit fluxes, J max a ; the activation energies were found as 1.923^0.15 and 2.112^0.2 kj/mol, for ligand carrier 1 and 2, respectively. The values for the found activation energy indicate that the process is controlled by species diffusion.

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