Sulfanilic acid-functionalized magnetic GO as a robust adsorbent for the efficient adsorption of methylene blue from aqueous solution

In this work, a superior magnetic graphene oxide (GO) functionalized with sulfanilic acid (Fe3O4@GO@SA) was successfully fabricated by an in-situ precipitation approach and amidation reaction as a robust material for methylene blue dye (MB) removal. The obtained material was investigated by different techniques, such as XRD, FTIR, TGA, SEM, zeta potential analysis, and BET analysis. The surface areas of GO, MGO, and the Fe3O4@GO@SA nanocomposite were measured to be 3.30, 95.2, and 112 m2/g, respectively. The particle size of Fe3O4@GO@SA was found to be 12.8 nm. The adsorption of MB dye under various adsorption parameters, namely, contact time, temperature, dose, pH, and initial concentration of MB was investigated. The findings revealed that Fe3O4@GO@SA possessed good adsorption performance for MB dye under optimal conditions (30.0 mg/dose, 240 min/contact time, pH 8, 298 K/T, and 100 rpm/shaking speed). The adsorption kinetics of Fe3O4@GO@SA obeyed pseudo first-order kinetics, and the Langmuir model was the best matched model for MB removal. The highest uptake capacity (qm) at 298 K was reported to be 317 mg/g. The thermodynamic variables (ΔH°, ΔS°, and ΔG°) suggest that the removal of MB dye using the Fe3O4@GO@SA adsorbent is a feasible, exothermic and physical process. Fe3O4@GO@SA adsorbs MB molecules via three mechanisms including π-π stacking, columbic attraction, and hydrogen bonding. The Fe3O4@GO@SA nanocomposite exhibited good reusability. All the experimental results show that the Fe3O4@GO@SA nanocomposite has potential applications in future environmental management.