Polyvinyl alcohol cross-linked graphene oxide with grafted glutamic acid aerogels for enhanced methylene blue adsorption

Abstract In this study, glutamic acid modified graphene oxide (GG-PVA) aerogels were fabricated through a simplistic sol gel and freeze-drying process utilizing polyvinyl alcohol (PVA) as a cross-linker. The aerogels were extensively explored in the abatement of methylene blue (MB) dye from aqueous solutions. Successful synthesis of the aerogels was confirmed by field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR) and Thermogravimetric analysis (TGA), Yielding relatively homogeneous honeycomb and porous surfaces, with 3.4326 m 2 g −1 surface area and high thermal stability. The MB removal followed monolayer adsorption on the homogeneous surfaces of the GG-PVA, thus defined by the Langmuir Isotherm model, with a maximum adsorption capacity (q max ) of 121.95 mg g −1 . Maximum adsorption of the MB was favored by near neutral to alkaline conditions, reaching 88.4% efficiency and equilibrium reached in the first 30 min of the adsorption process. The kinetics of the MB removal followed the pseudo-second order model. Furthermore, thermodynamic studies revealed endothermic (ΔH o = 80.598 kJ mol −1 ) and spontaneous (ΔG o = -8.219 kJ mol −1 ) nature of the adsorption process. The overall adsorption process was principally influenced by the charge and size of the MB molecule, as well as the surface-active sites, porosity, and charge of aerogels among other factors. This study underscores the facile synthesis and effective application of GG-PVA aerogels in MB dye removal, highlighting their potential as effective materials for textile wastewater remediation. Graphical abstract