Synergistic and efficient sorption of uranium by amidoxime-based chitosan with multiple functional groups

A novel amidoxime-modified chitosan (CS-AO) containing amidoxime, amino and Schiff base was prepared, by introducing diaminomaleonitrile (DAMN) which contains both amino and nitrile groups into chitosan. CS-AO has a very good synergistic uranium sorption property with high efficiency, with the maximum uranium sorption capacity up to 596 mg/g, and 243.2 μg/g in seawater; besides, after four cycles of sorption-desorption, more than 90 % of its initial uranium sorption capacity is still left. In addition, the uranium sorption of the adsorbent is mainly carried out through the coordination of amidoxime with uranium, followed by amino and Schiff base. The sorption process is fitted by pseudo-second-order kinetics, Langmuir and Sips isothermal models. It is controlled primarily by chemisorption, as well as monolayer sorption and multilayer sorption, which is a spontaneous endothermic process.