Emerging role of graphene oxide as sorbent for pesticides adsorption: Experimental observations analyzed by molecular modeling

Abstract The accumulation of pesticide residues in the environment due to their persistence and stability is causing increasing health concern. Indeed, researchers have rekindled their interest in eliminating pesticides from the environment by a range of biological and chemical approaches. In particular, graphene oxide (GO) has drawn great attention because it impressively enhances adsorption of pesticides in aqueous solutions, which provides promising environmental applications on water purification to remove pesticide residuals. However, although multiple studies have highlighted the adsorption of environmental contaminants by GO, the underlining molecular mechanisms remain limited. Consequently, we further delved into the knowledge regarding their adsorption molecular mechanism that is of both practical and theoretical importance. It was revealed that the π-π stacking and van der Waals interactions accounted for the major adsorption interactions between GO and its removing pesticides through integrating both density functional theory (DFT) calculation, fully atomistic molecular dynamics (MD) simulation, and binding free energy calculation. These findings not only bridged the theoretical gap of the adsorption mechanisms of GO, but also provided a venue for visualizing the adsorption process, which were essential for guiding its future adsorption applications.