Preparation of Polydopamine-Modified Graphene Oxide/Chitosan Aerogel for Uranium(VI) Adsorption

The relatively low density of functional groups of graphene oxide (GO) and the difficulty to completely recover after adsorption limit its application in uranium (U(VI)) removal from aqueous solution. Inspired by a special chemical property, polydopamine (PDA) was first used as a surface modifying agent for GO, and then the as-formed GO@PDA cross-linked with chitosan (CS) to assemble a three-dimensional (3D) porous GO@PDA/CS aerogel for U(VI) adsorption. Morphology and structure of the aerogel were characterized by TEM, SEM, FTIR, XPS, XRD, Raman, and TGA. The results show that compared to GO/CS, the GO@PDA/CS aerogel possesses a more homogeneous and well-organized 3D porous structure as well as the enhanced active sites, which are beneficial for U(VI) removal. According to batch experiments, the adsorption rate of the GO@PDA/CS aerogel was very fast, and the adsorption equilibrium could be reached in 15 min at pH = 6.0. Its maximum adsorption capacity for U(VI) is as high as 415.9 mg g–1 at 298 K calculated from the Langmuir model. In addition, the as-prepared GO@PDA/CS aerogel exhibits satisfactory thermal and mechanical stability and could be recycled six times without an apparent decrease in removal efficiency.