Functionalized graphene oxide decorated with Au nanoparticles as a designed catalyst for reduction of organic dyes

The accumulation of organic dyes in the water bodies causes eutrophication, reduces the reoxygenation capacity and makes severe damage to the aquatic organisms by hindering the infiltration of sunlight [1]. The superiority of photocatalytic degradation by nanocatalyts in wastewater treatment is due to its advantages over the conventional methods, such as quick oxidation, no formation of polycyclic products and oxidation of pollutants. It is an effective and rapid technique in the removal of pollutants from wastewater. In this research, Graphene oxide (GO) was first synthesized from natural graphite flakes by a modified Hummers method [1]. In the following, the surface of GO functionalized during several steps. First, carboxilation of GO via reaction with bromoacetic acid and formed GO-COOH. In the other step, the GO-COOH converted to GO-COOCl in the presence of thionylchlorid. The obtained GO from previous step reacted with 4-aminothiophenol which nucleic reaction easily done and SH functional group coordinated with Au (III) ions. Finally Au NPs synthesized by reduction with sodium citrate as a mild and green reducing agent. The synthesized catalyst have been used for the rapid reduction of 4-nitrophenol (4-NP), methyl orange (MO) and methylene blue (MB) in the presence of NaBH4 and shown high catalytic activity.