Abstract
In this paper, chitosan/Fe3O4/graphene oxide hydrogel was synthesized then modified with 2,6-pyridinedicarbonyl dichloride to obtain a novel composite hydrogel. The modified hydrogel formed via interfacial polymerization crosslinking of amino groups of chitosan in chitosan/Fe3O4/graphene oxide hydrogel with acyl groups of 2,6-pyridinedicarbonyl dichloride. The synthesized hydrogels were characterized using different tools such as FT-IR, XRD, TGA, VSM, BET, HR-TEM, and FE-SEM instruments. The successful modification was demonstrated through FE-SEM where sphere and rod shapes were noticed due to the presence of Fe3O4/graphene oxide. The XRD diffraction peaks of the modified hydrogel were close to that of Fe3O4 without any changes in its structure. Also, there are no distinguishing XRD diffraction peaks due to the graphene oxide owing to the disorders that happen in graphene during the formation of the composite. The modified hydrogel was efficiently utilized for removing eriochrome black T and methylene blue dyes from aqueous media. The optimum pH for removing eriochrome black-T and methylene blue dyes is 2 and 8, respectively. Also, the optimum contact time and temperature for removing eriochrome black-T and methylene blue dyes are 140 min and 318 K, respectively. The maximum adsorption capacity of the modified hydrogel toward eriochrome black T and methylene blue dyes is 289.85 and 261.78 mg/g, respectively. The equilibrium and kinetic results were best fitted to the Langmuir isotherm and pseudo-second-order. The thermodynamic results confirmed that the adsorption process was spontaneous and endothermic.