Modification of graphene oxide with poly (ethylene glycol) –cysteine, synthesis of gold colloidal nanoparticles on the surface of reduced modified graphene oxide and their behavior in the removal of methylene blue

In this study, poly (ethylene glycol)-cysteine from the reaction of poly (ethylene glycol) with L-cysteine in the presence of N, N-dicyclohexylcarbohydramide (DCC) and graphene oxide by the improved Hummer method were synthesized. Then, graphene oxide was mixed with poly (ethylene glycol)-cysteine in aqueous solvent at room temperature to form biocompatible functionalized graphene oxide (MGO). Finally, the gold salt was loaded on the surface of functionalized graphene oxide under ultrasonic waves and reduced by NaBH4 under constant stirring at room temperature to form a gold colloidal nanoparticles- modified reduced graphene oxide composite. The synthesized compounds were characterized using different techniques: SEM, UV-Vis, XRD, Potential-Zeta, FT-IR, Raman and TEM. The results showed the formation of stable gold colloidal nanoparticles with an average size of 2.5 to 6 nm on the surface of functionalized reduced graphene oxide (rMGO-Au). Finally, synthesized MGO and rMGO-Au nanocomposite were investigated as adsorbents to remove methylene blue dye. According to the obtained results, functionalized graphene oxide and synthesized nanocomposite can be used in the treatment of industrial effluents and polluted waters.