Title: Computational spectroscopic study of copper, cadmium, lead and zinc interactions in the environment

Authors: Medhat Ibrahim, Hanan El-Haes

Addresses: Spectroscopy Department, National Research Center, NRC. Dokki, Cairo, Egypt. ' Physics Department, II. Physikalisches Institut A, RWTH Aachen Huyskensweg, Turm 28A, D-52056 Aachen, Germany

Abstract: Molecular modelling has been used to investigate the interactions of various heavy metals, in order to understand and possibly to control the nature and behaviour of metals, especially in the aquatic environment. The interactions of copper, cadmium, lead and zinc with organic acids were studied using density functional theory (DFT) calculations. Carboxylic acid was used as a model molecule. The structure of each metal carboxylate was optimized and the vibrational spectrum calculated. The results indicate that there is a shift in the calculated v_S(C=O) of metal carboxylates compared with that of carboxylic acid. It was also found that hexaaqua structures of both cadmium and zinc are stable whereas those of copper and lead are not. Furthermore, dipole moment calculations indicate that cadmium carboxylate dihydrate is more representative of cadmium interactions in the aquatic environment. Moreover, hexaaquo cadmium could further interact with surrounding molecules in the aquatic environment.

Keywords: carboxylic group; heavy metals; total dipole moment; vibrational spectra; copper; cadmium; lead; zinc; molecular modelling; organic acids; aquatic environment; water pollution.

DOI: 10.1504/IJEP.2005.007604

International Journal of Environment and Pollution, 2005 Vol.23 No.4, pp.417 - 424

Published online: 19 Aug 2005 *

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