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

Abstract

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