NMR and Thermodynamic Studies of Pb2+ Removal by α-Keratin Nano-Structure in the Environment
Leila Mahdavian *
Department of Chemistry, Doroud Branch, Islamic Azad University, P.O. Box: 133. Doroud. Iran.
*Author to whom correspondence should be addressed.
Abstract
Aims: In this study is simulated removal of lead ions by human hair. Human hair that has formed of keratin and 14% of keratin is cystine. The approached of Pb2+ to cystine is simulated and calculated by Gaussian program package.
Study Design: Density functional methods use for the simulated of keratin and investigation of lead ions removal by keratin. A large number of computational physicists use these methods merely as a recipe, not reflecting too much upon their logical basis.
Methodology: The density functional theory (DFT) method with B3LYP/6-31G is used for calculation energy, chemical shift nucleus magnetic resonance (NMR) and thermodynamics properties for cystine in α-keratin of Human hair in the absence and the presence of heavy metal ions.
Results: Natural hair can be considered as an amphoteric gel containing alkaline and acidic groups with nearly equal and reciprocal strengths. Partial preference of alkaline group accounts for creation of a cation resin quality for hair. When a cation compound gets in touch with a hair having numerous contact sites, an electrochemical bond is formed between the hair and the positive charge.
Conclusion: The results shown, the active site of cystine in this interaction is -S-S- bond and NMR parameters have sharp peak in 2.91nm of ions related to cystine. The thermodynamics properties shown, this interaction is exothermic and spontaneous.
Keywords: Pb2 ions, keratin fibers, human hair, nucleus magnetic resonance (NMR) study, density functional theory (DFT) methods.