“…234 Various types of adsorbents such as biosorbent, organic and inorganic sorbents and carbonbased materials have been developed for uranium recovery. 234 In aqueous solutions, uranium can be present in both tetravalent and hexavalent stable forms, uranous U 1 and uranyl UO 2 21 ions. 240 For adsorption studies, uranyl nitrate hexahydrate is always used to prepare the uranium-containing solution, meaning that the UO 2 21 ion constitutes the main adsorbate.…”