Synthesis of flexible cross-linked cryptomelane-type manganese oxide nanowire membranes and their application for U(VI) and Eu(III) elimination from solutions

The efficient elimination of radionuclides from aqueous solutions is crucial for environmental protection from radionuclides’ pollution. The construction of octahedral molecular sieve (OMS-2) nanoporous membranes is of great technical importance for different kinds of applications like purification filter, catalysts, oil separation, seawater desalination and pollutant elimination. The facile synthesis of freestanding materials demonstrated uniform and monodispersed nanostructures and a cross-sectional pattern of the membranes, which is easily recycled in the process of adsorption and separation of pollutants from aqueous solutions. The OMS-2 exhibited rapid adsorption kinetics and high adsorption capacities of U(VI) (348 mg/g) and Eu(III) (106 mg/g) at pH = 5.0 ± 0.1 and T = 298 K. The paper-like membranes still retained the original filiform morphologies and showed extraordinary stability after 6 adsorption cycles. The surface complexation and ion exchange were the main mechanisms for the uptake of radionuclides, and the change of water environment had little influence on radionuclide adsorption efficiency. Based on the high adsorption capacity and excellent recycle ability, the OMS-2 membranes are considered as superior adsorbents for the efficient elimination of metal ions in the decontamination of polluted water.