Adsorption and photocatalysis removal of fulvic acid by TiO₂–graphene composites

The adsorption and photocatalysis of natural organic matter, fulvic acid (FA), by TiO₂–graphene (T–G) composites under UV₂₅₄ was investigated in this study. A one-step solvothermal reaction of graphene oxide (GO) and titanium(IV) butoxide (Ti(OBu)₄) in an ethanol solvent was used to prepare T–G composites. During the solvothermal process, both of the reduction of GO and depositing of T nanoparticles were achieved. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were applied to investigate the morphologies and structures of the as-prepared samples. Results from this study indicated that the as-prepared T–G composites exhibited great adsorptivity and photocatalytic activity of FA. Two removal mechanisms have been identified as significant for FA aqueous interacting with T–G composites: surface adsorption and photocatalytic degradation. It is revealed that the photocatalytic degradation of FA is correlated to surface adsorption, an effective surface adsorption resulting in a quick degradation.