Separation of heavy metals by amino acid functionalized polymer: Experimental and theoretical insights

A chloromethylated polystyrene resin was chemically functionalized with glycine molecules to introduce metal ions chelating sites. The functionalized resin (PsGly) was loaded in a glass column and successfully used for the extraction of heavy metal ions. Several experimental parameters like solution pH, sample flow rate, adsorbent dose and breakthrough volume was studied and optimized. The adsorption capacity observed for Ni(II), Cu(II) and Zn(II) were 0.72, 0.68 and 0.60 mmol g⁻¹, respectively. The chelating mechanism for metal ion adsorption was studied by density functional theory. The metal-ligand interaction energy, entropy, and Gibbs energy were estimated by employing the B3LYP basis set of density functional theory and suggest that the studied metal ions form strong complexes with the adsorbent. The column procedure was employed for the extraction of heavy metal ions from wastewater with detection limit of 0.2 μg L⁻¹.