Adsorptive performance of aminonaphthalenesulfonic acid modified magnetic-graphene oxide for methylene blue dye: Mechanism, isotherm and thermodynamic studies

In this research, a new aminonaphthalenesulfonic acid modified magnetic-graphene oxide (Fe3O4@GO@AHSA) was fabricated via in situ co-precipitation process followed by a covalent functionalization of Fe3O4@GO with aminonaphthalenesulfonic acid (AHSA) via amidation reaction. Fe3O4@GO@AHSA was featured by Zeta po- tential, FTIR, SEM, XRD, and TGA, then utilized in methylene blue (MB) adsorption from an aquatic media. The optimum removal efficiency of Fe3O4@GO@AHSA was assessed by batch method at different variables such as adsorbent dose (0.01–0.05 g), pH (2–8), adsorption time (1–1440 min), initial concentration of MB (25–300 mg/ L), and temperature (25–45 ◦C). Accordingly, 0.03 g Fe3O4@GO@AHSA dose, pH: 7, contact time: 240 min at 25 ◦C were found to be the best optimal conditions, and a maximum experimental adsorption capacity of Fe3O4@GO@AHSA toward was 220.1 mg/g. Three nonlinear isotherm and kinetic models were utilized to assess the equilibrium experimental adsorption data. The findings show that the removal performance fits a Longmire isotherm and pseudo-second-order kinetic models. Besides, the result revealed that the maximum monolayer adsorption of MB on Fe3O4@GO@AHSA was 286.4 m/g. Based on thermodynamic results, the MB adsorption on Fe3O4@GO@AHSA nanocomposite was exothermic and a feasible process. The reusability tests displayed that the Fe3O4@GO@AHSA nanocomposite can be regenerated and reused up to the fourth cycle successfully for the uptake of MB pigment. Finally, this research indicates that the Fe3O4@GO@AHSA nanocomposite has a robust adsorption performance for MB dye from an aqueous medium.