Kinetic study of mercury (II) transport through a liquid membrane containing calix[4]arene nitrile derivatives as a carrier in chloroform

In this study, the kinetics studies of mercury (II) ion transport through a bulk liquid membrane system which contains calix[4]arene nitrile derivatives (5,11,17,23-Tetra-tert-butyl-25,27-bis-(2-cyanobenzyloxy)-26,28-dihydroxycalix-[4]arene (membrane I) and 25,27-bis-(2-cyanomethoxy)-26,28-dihydroxycalix-[4]arene (membrane II) as a membrane were investigated at different temperatures and stirring rates. The kinetics was analyzed by means of a kinetic model involving two consecutive irreversible first order reactions. The parameters such as transport rate constants, membrane entrance rate, k1, and the membrane exit rate, k2, and the maximum values for membrane entrance and exit values Jdmax and Jamax were determined for the experimental data. It was found that both membrane entrance and exit rate constants increase with temperature. The activation energies were found as 6.96 ± 0.15 and 6.91 ± 0.15 kcal/mol, for ligand membranes I and II, respectively. These activation values indicate that the transport process for both membranes is controlled by species diffusion.