Methylene blue (a cationic dye) adsorption performance of graphene oxide fabricated Fe-Al bimetal oxide composite from water

Graphene oxide (GO) fabricated iron-aluminium oxide (GO@IAO) nanocomposite was synthesized with one-spot chemical reaction from emulsification of GO (1.0 g) in 0.2 L of 1.0 M mixed metal solution, which was characterized with some of the latest analytical tools aiming to assess methylene blue (MB) adsorption performance from aqueous solutions. Adsorption of MB on GO@IAO surfaces shows a steep increase from pH 3.0 to 5.0, but steepness declines at pH >5.0. The closeness of fitted kinetic data with the pseudo-second order (PSO) equation (R2 = 0.9845) compared to the pseudo-first order equation (R2 = 0.9527) confirms the adsorption process is of the PSO type. The MB adsorption equilibrium data can be described better by the Langmuir isotherm (R2 = 0.99) than the Freundlich isotherm (R2 = 0.96–0.97), inclining to the monolayer adsorption process. The Langmuir adsorption capacity of GO@IAO has been estimated to be 330.35 mg/g at 303 K. The MB adsorption is established to be spontaneous (–ΔG0 = 26.31–26.61 kJ/mol) owing to favourable enthalpy and entropy changes (ΔH0 = –23.38 kJ/mol; ΔS0= 0.01 kJ/mol/K). Both absolute and aqueous (1/1, v/v) alcohols regenerate the MB adsorbed GO@IAO up to 80–85%, indicating recyclability of composite.