Thermal regeneration of recyclable reduced graphene oxide/Fe3O4 composites with improved adsorption properties

BACKGROUNDGraphene was chosen as magnetic adsorbent because of its unique size and structure. Much effort has been made to prepare magnetic graphene-based composite materials with Fe3O4, however, regeneration of the magnetic adsorbent has been ignored. In this study, a simple thermal regeneration method was proposed with the advantages of low cost, environment-friendly and no secondary pollution. The effectiveness of thermal recovery in reduced graphene oxide (RGO)-Fe3O4 recyclable composites (RGFs) was tested. The evolution of structure, morphologies, magnetic properties, and recyclability of RGFs were characterized. RESULTSThe results show that equilibrium data were best described by the Sips isotherm model, with a maximum monolayer adsorption capacity of 228.64 mg g(-1) at 25 degrees C. Adsorbed methylene blue was removed from contaminated RGFs through a simple thermal recovery method (calcination at approximate to 300 degrees C in air). Meanwhile, RGO sheets remained stable, and the Fe3O4 transformed to magnetic -Fe2O3, rather than nonmagnetic -Fe2O3, which enables magnetic separation of RGFs. CONCLUSIONCompared with other similar reported adsorbents, RGFs exhibited excellent adsorbability and recyclability without obvious performance degradation using the proposed thermal regeneration procedure. (c) 2013 Society of Chemical Industry