Nanoscale Zerovalent Iron Grafted with Graphene Oxide: A Dye Adsorption Study

Abstract Methylene blue (MB) removal from aqueous solutions were studied using nanoscale zero valent iron/graphene oxide (nZVI/GO) composites, which were synthesized. Nanoscale zero valent iron (nZVI) and graphene oxide (GO) were used for comparison. It was followed by Fourier‐transform infrared spectroscopy (FTIR) analysis and followed by Scanning electron microscope analysis (SEM), X‐ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis for sample characterization. The variable in this case included the initial concentration of MB, which was varied from 200, 250, and 300 mg/L and the contact time, which was varied between 0–90 min. The pH and mass of adsorbent was kept constant at 7 and 0.5 g respectively. Outcomes were indicative that the highest removal of MB was at 92.75% for nZVI/GO composite at 200 mg/L of MB. The experimental data was fitted on to the Langmuir, Freundlich and BET adsorption isotherm models which gave R 2 > 0.95. This can be attributed to high favorability of adsorption taking place in many layers. The nZVI/GO adsorbent would follow the pseudo‐first‐order kinetic model showing an R 2 value of 0.99, 0.94, and 0.93 for from 200, 250, and 300 mg/L of MB, respectively. Furthermore, Boyd's external diffusion equation model was applied to calculate the external diffusion. The finding indicated high external diffusion with R 2 > 0.99. The results from this paper are attributed to the simplistic generation of nZVI/GO composite and its effect on the removal of MB from aqueous solution. The significance of this study would be that nZVI/GO composites have been only recently being experimented for dye removal and are proving to be an extremely efficient form of adsorption according to recent studies.