Design and physicochemical characterization of a novel polymer nanocomposite based on biopolymer dextran–magnetic‐graphene as efficient adsorbent for methyl orange removal from wastewater

In this research, a novel Fe 3 O 4 /functionalized graphene/dextran nanocomposite was designed for adsorbing methyl orange dye from aqueous media. For this purpose, a modified Hummers‐based oxidation followed by amine functionalization using para‐phenylenediamine was used for preparing amine‐functionalized graphene nanoplatelets. Next, a modified co‐precipitation approach was used for synthesis of amine‐functionalized graphene/Fe 3 O 4 /dextran nanocomposite as the adsorbent. The prepared nanocomposite was studied by Fourier transform IR spectroscopy, XRD, TGA, SEM, TEM, vibrating sample magnetometry and the Brunauer–Emmett–Teller method. The role of different factors like pH, adsorbent dosage, adsorption time and temperature in the process was analyzed using UV–visible spectroscopy. The kinetic investigations showed a pseudo‐second‐order trend. Methyl orange adsorption onto the nanocomposite was demonstrated to fit favorably with the Langmuir isotherm model, indicating a homogeneous process, showing the maximum adsorption capacity of approximately 370 mg g –1 . Aminated graphene/Fe 3 O 4 /dextran nanocomposite exhibits better adsorption for methyl orange dye than aminated graphene/Fe 3 O 4 . The thermodynamics of the adsorption were studied, demonstrating that the adsorption of the dye on the functionalized graphene/Fe 3 O 4 /dextran adsorbent was thermodynamically favorable and exothermic in nature. The composite showed excellent reusability after five adsorption–desorption cycles with minimal iron leaching. These results demonstrate that the prepared nanocomposite is a promising adsorbent for removal of methyl orange from wastewater.