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.