Synergistic effects of FeNPs@GO on arsenic adsorption: Insights from experimental and theoretical studies

Arsenic contamination in drinking water is a serious environmental and public health issue. In this study, we investigate the synergistic effects of iron nanoparticles immobilized on graphene oxide (FeNPs@GO) for arsenic removal through a combined theoretical and experimental approach. FeNPs@GO was synthesized and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), confirming the successful anchoring of FeNPs on GO. Adsorption studies revealed that FeNPs@GO exhibited a significantly higher arsenic removal capacity (32.8 mg g⁻¹) compared to FeNPs (10.96 mg g⁻¹) and GO (0.48 mg g⁻¹). Kinetic analysis followed a pseudo-second-order model, indicating that chemisorption is the dominant interaction mechanism. Isotherm studies fit the Freundlich model, indicating a multilayer adsorption process. Density Functional Theory (DFT) calculations were performed to gain a deeper understanding of the interfacial interactions between the adsorbent material and arsenic species. These atomic-level simulations revealed that arsenic binding is significantly enhanced in the presence of Fe and O anchoring sites, particularly in graphene oxide structures containing carbon vacancies. Among the configurations studied, the system featuring three carbon vacancies coordinated with Fe-O sites exhibited the highest adsorption energy (5.230 eV), highlighting the critical role of defect engineering and functionalization in optimizing arsenic adsorption at the interface. These findings provide a foundation for optimizing FeNPs@GO-based materials, opening the door to more efficient and scalable arsenic remediation technologies. Future studies should focus on stability, regeneration, and performance under various environmental conditions to assess the real-world applicability of these systems.