Nickel-metal-organic framework nanobelt based composite membranes for efficient Sr²⁺ removal from aqueous solution

The sorption removal of radionuclides Sr²⁺ using a freestanding functional membrane is an interesting and significant research area in the remediation of radioactive wastes. Herein, a novel self-assembled membrane consisting of metal-organic framework (MOF) nanobelts and graphene oxides (GOs) are synthesized through a simple and facile filtration method. The membrane possesses a unique interwove morphology as evidenced from SEM images. Batch experiments suggest that the GO/Ni-MOF composite membrane could remove Sr²⁺ ions from aqueous solutions and the Sr²⁺ adsorption capacity and efficiency of the GO/Ni-MOF composite membrane is relevant to the MOF content in the composite. Thus, the dominant interaction mechanism was interface or surface complexation, electrostatic interaction as well as ion substitution. The maximum effective sorption of Sr²⁺ over GO/Ni-MOF membrane is 32.99% with 2 mg composite membrane containing a high content of Ni-MOF at 299 K in 100 mg/L Sr²⁺ aqueous solution. The FT-IR and XPS results suggest that the synergistic effect between GO and Ni-MOF is determinant in the sorption Sr²⁺ process. The GO/Ni-MOF composite membrane is demonstrated to have the advantages of efficient removal of Sr²⁺, low cost and simple synthesis route, which is promising in the elimination of radionuclide contamination.