Efficient adsorbent for recovering uranium from seawater prepared by grafting amidoxime groups on chloromethylated MIL-101(Cr) via diaminomaleonitrile intermediate

Here, reaction of a chloromethylated metal-organic framework (MOF) MIL-101 with diaminomaleonitrile (DAMN) following with an amidoximation reaction successfully produced a novel amidoxime functionalized porous material (MIL-101-AO). The chelation of amidoxime group to uranium and the large specific surface area afforded MIL-101-AO excellent selective adsorption ability for U (VI) in aqueous solutions (586 mg·g−1). Furthermore, MIL-101-AO showed much stronger selective adsorption for U (VI) than other co-existing metallic ions in the artificial seawater (removal rate reached 96%). The influence factors on the adsorption process were evaluated by batch adsorption experiments under different condition. The process of adsorbing uranium on MIL-101-AO fitted with the Langmuir model and the pseudo-second-order kinetic model. The △H° and △G° values of uranium adsorption indicated that it was an endothermic heat process; a higher adsorption temperature could promote the adsorption on MIL-101-AO. All the experimental results indicated that MIL-101-AO was an adsorbent with the application value of extracting uranium in seawater.