Unraveling the influence of biomaterial’s functional groups in Cd biosorption: a density functional theory calculation

Several biomass wastes, including forest wastes, bagasse, algae, and others, have been studied to determine their biosorption capability for adsorbing different ranges of heavy metals in the literature. Most experimental studies have not clearly shown the impact of functional groups in biomaterials discovered by FTIR analysis on the investigated biosorption processes. Because of this, the findings of this study indicate that it is necessary to theoretically investigate the influence of identified functional groups (as determined by FTIR analysis) on the biosorption activities of the sorbent or biomaterial prepared for the removal of cadmium metal from an effluent. Using the most geometrical structure for cadmium (Cd) metal, a series of identified functional groups for the sorbent were analyzed using FTIR to determine their mode and intensity of interaction to computationally understand better how they each influence the biosorption of cadmium. This was done to determine how each functional group contributes to the intensity of the cadmium biosorption, using a ground-state B3LYP density functional theory calculation performed in a Spartan 20 simulation package utilizing the 6-31G* and LANL2DZ > Kr basis sets. According to the study’s findings, carboxylate (–COO*) had the most significant effect on cadmium biosorption activity of all the functional groups studied due to the stronger binding strength obtained for it. Therefore, this research suggests exploring biomaterials with greater intensity for carboxylate function, which would aid cadmium sorption efficiency in an effluent treatment process.