DFT: B3LYP/ LANL2DZ Study for the Removal of Fe, Ni, Cu, As, Cd and Pb with Chitosan

Human activities are responsible for the existence of heavy metals in the environment. The accumulation of these metals in the environment causes several risks, such as toxicological, mutagenic, and carcinogenic effects. Chitosan (Cs) based materials have been explored its competitive efficacy in heavy metals removal from contaminated water. In this study, an attempt is presented to develop a natural, reliable, and cost-effective biopolymer structure of Cs with a high ability to entrap some heavy metals, which can be found in polluted water. The correlation between Cs-heavy metals and its stability was studied by density functional theory (DFT) using B3LYP together with the basis set LANL2DZ. The observed results revealed that the bandgap energy values for Cs, Cs- Fe, Cs-Ni, Cs-Cu, Cs-As, Cs-Cd and Cs-Pb were 2.571, 0.6147, 0.7176, 0.3396, 0.6648, 1.5007 and 0.4128 eV, respectively. The later showed that Cs structure has high selectivity and binding affinity to Cu and Pb hydrated metals, respectively rather than Fe, Ni, As and Cd. The examined correlation between Cu and Pb with Cs revealed that Cs could be applied for sensing and removing of Cu and Pb from wastewater.