A DFT study on removal of Mn and V from wastewater using chitosan/graphene oxide composite as adsorbent

Metals tend to accumulate in the environment, leading to carcinogenic effects. Chitosan (Cs) has gathered significant research interest for its exceptional metal-binding properties and cost-effectiveness in heavy metal removal. To enhance chitosan adsorption capacity, it has been combined with graphene oxide, forming a chitosan-graphene oxide composite through hydrogen bonding. Various biopolymers have interacted with these metals, effectively removing them from wastewater via adsorption processes. In this study, the Cs/GO composite has been utilized for extracting metals from aquatic environments. The Cs/GO-M interaction and complex stability have been analyzed using ground-level DFT at the B3LYP/LANL2DZ level of theory. The study has demonstrated the selectivity of both Mn and V towards the composite, successfully extracting them from wastewater. Analyses of band gap energy, adsorption energy, electrophilicity, and reactivity indices have revealed that vanadium exhibited higher adsorption affinity towards Cs/GO than Manganese. Furthermore, in interactions with metals Mn and V have reduced the band gap to 0.1986 ​eV and 0.1940 ​eV, respectively. The Cs/GO composite has displayed substantial stability in aqueous media, suggesting its potential as a promising adsorbent for effluent and toxic metal removal.