Transport of Hg(II) through bulk liquid membrane containing calix[4]arene thioalkyl derivative as a carrier

In this study effectiveness of 5,11,17,23 tetrakis[(propylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (1) towards Hg(II) across bulk liquid membrane has been examined. The effect of the fundamental parameters influencing the transport process, e.g. carrier concentration, type of solvent used, effect of temperature and time dependency of the process have been investigated. The mass transfer of Hg(II) was analyzed on the basis of kinetic laws of two consecutive irreversible first order reactions. Thus, the kinetic parameters (k(1), k(2), R-m(max), t(max), J(d)(max), J(a)(max)) for the transport of Hg(II) were studied. The activation energy values for the extraction and re-extraction were found as 19.59 and 27.57 kJ mol(-1), respectively. These values demonstrate that the process is diffusionally controlled by Hg(II). Observations show that the membrane entrance and exit rate constants (k(1), k(2)) increase with increasing stirring speed, carrier concentration and temperature. The effect of solvent on k(1) and k(2) was found to be in the order of CH2Cl2>CHCl3>CCl4. The effectiveness and reproducibility of Hg(II) transport has proved that 1 is an efficient carrier of Hg(II) in ELM process. (C) 2010 Elsevier B.V. All rights reserved.