Efficient cooperative extraction uranium(VI) from aqueous solution and seawater by a novel phosphate/amidoxime chitosan-based adsorbent

Herein, a novel chitosan-based porous adsorbent (CS-AO-AMP) with multifunctional efficient cooperation groups, such as amidoxime and phosphate groups, was synthesized to enhance U(VI) sorption . The optimal pH for U(VI) sorption is 7–9, which is beneficial for extraction U(VI) from seawater . The maximum U(VI) sorption of CS-AO-AMP is up to 620 mg/g at 298 K and pH 8.0. In simulated seawater, the salts of high concentration, such as Na 3 PO 4 , NaCl, NaClO 4 and Na 2 SO 4 , have little influence on U(VI) sorption capacity. Whereas in 0.1 M Na 2 CO 3 solution, the uranium sorption capacity is only 13.5 mg/g. The selective sorption capacity of U(VI) can reach 72.9 mg/g in five mixed-metal solutions. After one week static sorption in 100 mL natural seawater, the U(VI) sorption capacity can reach 266.6 μg/g. After four sorption-desorption cycles, CS-AO-AMP shows excellent recovery performance and maintains 90 % of the initial sorption capacity. The sorption process follows pseudo-second-order kinetic model, Langmuir, Sips and Freundlich isotherm models, indicating that sorption is dominated by chemisorption , together with monolayer and multilayer sorption. All in all, the CS-AO-AMP has a very high application prospect of extracting U(VI) from aqueous solution and seawater.