Radioactive strontium ions sieving through reduced graphene oxide membrane

Partitioning of 90Sr from other radionuclides in radioactive liquid waste is crucial for treating high-level liquid waste (HLLW) generated during spent fuel reprocessing, as the unique high heat-generating and long half-life of 90Sr pose a significant challenge for the long-term storage of nuclear waste. However, it remains difficult to sieve 90Sr for membrane based on size-selective effect, as the radioactive liquid waste contains numerous typical divalent ions, such as 60Co, 63Ni, and 65Zn, which have the same valence and similar hydration diameters to 90Sr. Here, we experimentally demonstrate a rapid and efficient separation of radioactive 90Sr from other radioactive ions by a reduced graphene oxide membrane, which prepared by the amino-hydrothermal method from graphene oxide suspensions. For SrCl2/CoCl2, SrCl2/NiCl2, and SrCl2/ZnCl2 binary mixed solutions, SrCl2 can pass through efficiently, while the rejection rates for CoCl2, NiCl2, and ZnCl2 reached 99.9 %. The separation factors reached 3232, 4254, and 3314, which are about one or two orders of magnitude higher than the highest reported separation factors for membranes sieving divalent ions. Our findings offer a simple avenue for the precise treatment of radioactive liquid waste, which is vital for the advancement of nuclear energy technology.