Fabrication of novel carboxyl and amidoxime groups modified luffa fiber for highly efficient removal of uranium(VI) from uranium mine water

Novel luffa cylindrica adsorbent modified with carboxyl and amidoxime groups is successfully prepared by a simple water bath method for effective U(VI) uptake from uranium-containing wastewater and real uranium mine water. The critical factors affecting U(VI) adsorption are explored, such as grafting time of carboxyl and amidoxime groups, solution pH, initial concentration of U(VI) and contact time. The results show that LC-CA(2)-AO(4) obtained under optimal condition possesses outstanding adsorption performance to U(VI) (q(max), 399.1 mg g(-1)). Repeated adsorption/desorption experiments display that LC-CA(2)-AO(4) can be efficiently regenerated by 0.50 mol L-1 HCl solution and reused for uranium adsorption. Adsorption capacity and desorption efficiency of LC-CA(2)-AO(4) to U(VI) drop slightly after eight cycles of regeneration test. The accordance of kinetic data with pseudo-second-order kinetics model suggests that the adsorption reaction is controlled by chemical process. Moreover, LC-CA(2)-AO(4) displays high removal rate to U(VI) in real uranium mine water. Based on this work, it is demonstrated that LC-CA(2)-AO(4) would be a promising candidate for potential application in field of uranium adsorption.