Simple synthesis of graphene oxide-supported and phosphorylated chitosan gel bead to uptake uranium from wastewater

With the development of the nuclear industry, the direct discharge of uranium-containing wastewater has become increasingly harmful to the environment. A novel graphene oxide-supported and phosphoric-crosslinked chitosan gel bead (C-PGCB) with excellent uranium uptake capability was successfully fabricated to treat uranium-containing wastewater. The experimental results showed that the introduction of PO and CO bonds through phosphoric acid crosslinking could greatly improve the capturing ability of chitosan-based materials, which could reach 97.1 % and 460.9 mg g^-1 within 20 min, respectively. In the presence of multiple coexisting ions, the adsorbent still maintained high uranium adsorption efficiency. After 5 cycles, the uptake efficiency of C-PGCB with good cycle stability remained above 90 %. The fitting both the dynamic model and the isotherm model showed that the uranium uptake of C-PGCB was a uniform single-layer chemisorption process. Furthermore, the excellent dynamic separation properties proved the great potential value in the uranium-containing wastewater treatment. The uptake of C-PGCB for uranium could be owed to synergistic complexation and electrostatic interaction between uranium and multifunctional groups on C-PGCB. This work offered a chitosan-based adsorbent to effectively remove uranium from wastewater and gave a novel and effective way for the construction of chitosan-based adsorbents to enhance capture performance.