Synthesis and characterization of grapheme-chitosan hydrogel as adsorbent for methyl orange

Using formaldehyde as crosslinking agent, the graphene-chitosan composite hydrogel was formed. FT-IR, Raman, XRD, XPS, TGA, and SEM-EDX were used to analyze the structure of composite hydrogel. The produced hydrogel had remarkable adsorption capabilities for the anionic dye methyl orange (MO). UV-vis was used to investigate the adsorption properties of hydrogel (dye content, effect of contact time, temperature, and pH). The investigation of the adsorption behavior revealed that the Dubinin-Radushkevich model was well matched by the isotherm analysis with maximum adsorption capacity of 102.84 mg g-1, while kinetic studies revealed that the adsorption adheres to the pseudo-first order and intraparticle diffusion models. The thermodynamic analysis revealed that at high temperatures, the MO adsorption process onto hydrogel was more feasible and spontaneous. It was discovered that the adsorption was not pH dependent, demonstrating that acidic or alkaline circumstances were ideal for the adsorption process. Additionally, three different sorption-desorption investigations have been carried out to look into the reusability of hydrogel. The hydrogel is an effective adsorbent for MO removal from the aqueous solution due to its simple manufacture, low cost, high removal efficiency (nearly 100%), quick recovery, and steady performance.