Synthesis of amidoximated polyacrylonitrile nanoparticle/graphene composite hydrogel for selective uranium sorption from saline lake brine

•PAO/GH is prepared to enhance the uranium selectivity of graphene hydrogel .•PAO/GH is characterized by different methods.•The uranium selectivity and sorption capacity of PAO/GH increased obviously.•Uranium sorption mechanism by PAO/GH is revealed by various characterizations.•PAO/GH has relative high uranium sorption capacity in natural slain lake brine.