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

•Amidoxime-modified hypercrosslinked SAN uranium adsorbent was developed.•The adsorbent possessed a high specific surface area and tunable porous structure.•The adsorbent exhibited a high adsorption capacity, recyclability and selectivity.•The adsorbent showed a high removal percentage of uranium in real seawater.