Highly efficient dye adsorption and removal: a functional hybrid of reduced graphene oxide-Fe3O4 nanoparticles as an easily regenerative adsorbent

A functional hybrid of reduced graphene oxide (RGO)-Fe3O4 nanoparticles (NPs) has been chemically synthesized with exceptionally high yield and tunable RGO/Fe3O4 ratio. The adsorption behaviors of a series of dyes using this hybrid as the adsorbent are systematically investigated in aqueous solutions through real-time monitoring of the fingerprint spectral changes of the dyes. The results show that, benefiting both from the surface property of RGO and from the magnetic property of Fe3O4, the hybrid possesses quite a good (although unoptimized) and versatile adsorption capacity to the dyes under investigation, and can be easily and rapidly extracted from water by magnetic attraction. Most importantly, it is found that by simply annealing in moderate conditions, this hybrid adsorbent can be easily and efficiently regenerated for reuse with hardly any compromise of the adsorption capacity. Furthermore, the adsorbability of this hybrid shows satisfactory tolerance against the variations in both pH environment and dye concentration. Even when exposed to a multi dye cocktail, the hybrid can work well without suppressing the adsorption capacity for each of the dyes, as compared with that measured separately. The inherent advantages of this nanostructured adsorbent, such as non-compromised adsorption capacity, low cost, easy, rapid extraction and regeneration, good tolerance, multiplex adsorbability, and handy operation, may pave a new, efficient and sustainable way towards highly-efficient dye pollutant removal in Earth's water environments.