Selectivity study of derivate 15-crown-5 for heavy metals extraction.

The capability of benzo-15-crown-5 ether to form complexes with some heavy metals cation (Cd2+, Hg2+, and Pb2+) has been investigated by the density functional theory method (DFT) using the Gaussian system. The DFT calculations were performed using 6-311G(d,p) with LANL2DZ ECP basis set at the B3LYP level of theory. The interaction energies were used to evaluate the metal binding capability of the crown ethers. The influence of adding substituents was also studied. This calculation showed that the number of ion charge transfers is proportional to the increase of the interaction energy. Furthermore, the existence of the electron donating group (EDG) affected the crown ether's ability to bind heavy metals cation. In addition, based on the extraction interaction energy, charge transfer, and the electron distribution at the HOMO-LUMO orbitals, the selectivity order of derivate 15-crown-5 is Cd2+>Hg2+>Pb2+. [ABSTRACT FROM AUTHOR]