A DFT-based analysis of adsorption of Cd, Cr, Cu, Hg, Pb, and Zn, on vanillin monomer: a study of the removal of metal ions from effluents.

The density functional theory was used to understand the adsorption process of Cd(II), Cr(III), Cu(II), Hg(II), Pb(II), and Zn(II) ions with the methacrylate monomer derived of vanillin (VMA). Different analyses were carried out: Conformational analysis, molecular electrostatic potential (MEP), adsorption energy, frontier orbitals, hardness, and softness, all of which are necessary to predict the formation of complexes. By means of the molecular electrostatic potential and frontier molecular orbital (FMOs), the best region for adsorption was found, so each metallic ion of the study was placed close to the nitrogen and oxygen atoms of the imine and carboxyl groups of vanillin monomer, respectively.