Removal of Pb-based compounds mediated by graphene oxide-like materials obtained from Sargassum: unravelling key features of their interaction using density functional theory and spectroscopic methods

Abstract

Graphene oxide obtained from biomass possesses a rich variety of properties and applications. Sargassum, a macroalgae abundant in the Caribbean Sea, has been proposed as a viable and cost-effective biomass. Graphene oxide derived from Sargassum has an unprecedented selectivity for Pb capture in the hydrocerussite phase. This study presents exhaustive theoretical and experimental efforts to understand the interaction between Pb-based molecules (Pb, Pb(CO₃)₃, and Pb(OH)₂) with representative models of the functional groups present in graphene oxide (COOH, OOH, OH, and O). Our results demonstrate that CO₃ enhances the Pb adsorption on the graphene oxide surface. Hydrogen bonds and van der Waals interactions between CO₃ of the Pb(CO₃)₃ with the GO surface are the driving forces to improve the Pb capturing process and further hydrocerussite formation on GOs. Although Pb and Pb(OH)₂ can also be trapped by graphene oxide, it is less probable from an energetic point of view. Here, we demonstrate that low-cost graphene oxide obtained from Sargassum can be useful in environmental remediation.