Metal-Organic Framework-Intercalated Graphene Oxide Membranes for Selective Separation of Uranium

Design and construction of a membrane that can achieve selective separation of uranium from spent fuel or seawater is a big challenge in the field of separation science. In this work, 1,3,5-benzenetricarboxylic acid (BTC) and three different nitrates (Zn/Ni/Cu) were used to prepare metal-organic frameworks (BTC-MOFs) with different pore sizes, and then, BTC-MOFs were intercalated into the interlayers of graphene oxide (GO) for preparing the composite membranes which presented selective separation of uranium with strong acid resistance. Composite membranes prepared by Zn/Ni/Cu-BTC-MOFs and GO can achieve the separation between ions of different valence states, and their permeability and selectivity depend on the membrane thickness, the acidity of driving solution, and the pore sizes of MOFs. Importantly, Cu-BTC-MOF-intercalated GO membranes can not only achieve the selective separation of Th⁴⁺ and UO₂²⁺ with a selectivity of ≈6 but also induce the ultra-high selectively separation of UO₂²⁺ and Ce³⁺ because the rejection rate of Ce³⁺ is about 100%. Moreover, the Zn-BTC-MOF-intercalated GO membrane shows an excellent selectivity of Th⁴⁺ and UO₂²⁺ with a selectivity of ≈25, and it may also achieve selective separation of uranium from seawater.