Amidoxime-modified hypercrosslinked porous poly(styrene-co-acrylonitrile) adsorbent with tunable porous structure for extracting uranium efficiently from seawater

To efficiently and economically extract uranium from seawater, novel amidoxime-modified hypercrosslinked poly(styrene-co-acrylonitrile) (SAN) adsorbents with tunable porous structure were synthesized via simple Friedel-Crafts reaction followed by amidoximation. The adsorbent HCPSAN-B-AO obtained by using biphenyl dichlorobenzyl (BCMBP) as an additional crosslinking agent, possessed a larger pore size and higher surface area due to the longer and more rigid molecular structure of BCMBP compared to the original crosslinking agent 1,2-dichloroethane (DCE), resulting in the higher uranium adsorption capacity of HCPSAN-B-AO. Investigations on the adsorption performance in real seawater containing a large amount of interfering ions showed that the adsorbent owned excellent selectivity for uranyl ions, and the removal percentage of uranium could reach 84.4%. Furthermore, the adsorbent maintained good adsorption performance even after 5 adsorption–desorption cycles, indicating a good recyclability. Investigations on adsorption kinetics, thermodynamics, adsorption isotherms and adsorption mechanism manifested that the adsorption was a rapid (adsorption equilibrium within 30 min), spontaneous and chemical adsorption process (maximum adsorption capacity was 228 mg g −1 ), and the mechanism was mainly the interaction between uranyl ions and amidoxime groups. In summary, the as-prepared adsorbent was a feasible adsorbent for uranium extraction from seawater.