A modified freezing-casted conductive hierarchical porous polymer composite electrode for electrochemical extraction of uranium from water

Efficient extraction of uranium from aqueous media not only protects environment from uranium radiation, but also recover the uranium resource. Herein, we have successfully constructed a hierarchical porous electrode material with a (super)macro-mesoporous-structure by a modified freezing-cast method, for the electrochemical extraction of uranium from aqueous solution. The prepared porous composite electrode (AGMM) is composed of melamine sponge as the supporting skeleton, amidoxime and glutaroimide-dioxime as the functional co-groups for uranium capture, and hydroxylated multi-walled carbon nanotube as the conductive medium. It shows excellent electrochemical uranium extraction performance, hydrophilicity and antimicrobial activity. During the electrochemical extraction process, the maximum extract mass of uranium reached 831.5 mg/g at 3 h, and has considerable selectivity for uranium and cyclic elution performance. Results of characterization and DFT calculation showed that uranyl ions migrated to the electrode surface and rapidly diffused in the pore structure of the electrode. Then, under the action of adsorption groups, electrosorption and electrochemical reduction occurred, the amidoxime and glutaroimide-dioxime undergo a variety of potent complexations with uranyl ions, with latter complexation effect being stronger.