Transport kinetics of chromium(VI) ions through a bulk liquid membrane containing p-tert-butyl calix[4]arene 3-morpholino propyl diamide derivative

The transport of chromate ions (Cr2O72-) from an aqueous solution into an aqueous receiving solution through a bulk liquid membrane containing p-tert-butyl calix[4]arene 3-morpholino propyl diamide as a carrier was examined. The influence of pH on donor and acceptor phase, effect of chromate and carrier concentration, type of solvent, stirring speed and temperature were investigated. The kinetic parameters (k(1), k(2), t(max) R-m(max), J(d)(max), J(a)(max)) were calculated for the interface reactions assuming two consecutive, irreversible first order reactions. The activation energy values are 24.83 kJ mol(-1) for extraction and 5.14kJ mol(-1) for reextraction. These values indicate that the process is diffusionally controlled by chromate ions. The experiments demonstrated that calix[4]arene diamide derivative is a good carrier for Cr(VI) transport through liquid membranes in this study. (c) 2006 Elsevier B.V. All rights reserved.