Microwave-assisted preparation of Mn3O4@sepiolite nanocomposite for highly efficient removal of uranium

Nuclear energy is an important alternative energy source to non-renewable fossil fuels. Nevertheless, the nuclear contamination associated with nuclear activities and wastes is a formidable concern worldwide. Uranium is one of the most commonly used and discharged radionuclides, and hexavalent uranium [U(VI)] has significant mobility owing to its good solubility in water, leading to serious environmental and health risks. However, facile and economical solutions to effectively treating U(VI)-contaminated water are still limited. Herein, Mn ₃O ₄ nanoparticles were dispersedly anchored on sepiolite nanofibers via a facile microwave-assisted method for adsorbing U(VI) from aqueous solutions. Batch adsorption experiments showed that the nanocomposite possessed faster removal kinetics and greater removal capacity than the individual sepiolite and Mn ₃O ₄ , as well as better removal performance than many reported inorganic and organic adsorbents. The nanocomposite can also reduce the U(VI) concentrations to far less than the standard of drinking water. Furthermore, a systematic investigation of the adsorption mechanism revealed that the nanocomponents Mn ₃O ₄ and sepiolite were responsible for the high-affinity U(VI) capture through the bonding of ≡Mn–O–U(VI) and ≡Si/Mg–O–U(VI), respectively, but the loaded Mn ₃O ₄ nanoparticles dominated the adsorption. Given that the simple synthesis and excellent U(VI) removal performance, the Mn ₃O ₄@sepiolite nanocomposite holds great promise for practical applications in radioactive uranium treatment.