Self-assembly of 2D-metal-organic framework/graphene oxide membranes as highly efficient adsorbents for the removal of Cs⁺ from aqueous solutions

The potential toxicity and irreversibility of radionuclide Cs place severe pressure on the natural environment, which has become one of the most forefront pollution problems in nuclear energy utilization. To solve this problem, novel self-assembled membranes consisting of two-dimensional (2D) metal-organic frameworks (MOFs) and graphene oxide (GO) were prepared by a facile filtration method, which can efficiently absorb Cs⁺ from aqueous solutions. The batch experimental results showed that the sorption of Cs⁺ on the GO/Co-MOF composite membrane was strongly dependent on the addition mass and the membrane compositions. Thus, the dominant interaction mechanism was interface or surface complexation and electrostatic interaction. The maximum sorption efficiency of Cs⁺ on GO/Co-MOF was 88.4% with 8 mg addition mass at pH = 7.0 and 299 K. Detailed FT-IR and XPS analyses suggested that the efficient synergistic effects in the unique architectures of GO/Co-MOF play an important role in the high sorption capacity of Cs⁺. The facile preparation method and the highly-efficient Cs⁺ removal behaviour of GO/Co-MOF make the novel membrane a promising candidate for the elimination of radionuclide contamination.