Accelerating Solid/Liquid Chemical Exchange-Based Isotope Separation by the Dissolution/Precipitation Mechanism

Isotope separation is essential for cutting-edge developments in sustainability, health, and fundamental sciences. Chemical exchange-based isotope separation (CEIS) is a scalable approach that stems from the isotope-dependent free energy of chemicals, which has already been commercialized for H/D and ^6/7Li separation. However, existing CEIS processes often involve toxic materials such as H₂S and Li_xHg amalgam. Environmentally benign and low-cost materials and techniques are urgently needed to develop scalable isotope separations. CEIS processes are often between liquids and gases. Solids are attractive due to their high concentration of the nuclide of interest and the wide tunability of free energy at low temperatures. However, isotope diffusion is sluggish in most solids, making the time for isotope exchange impractical. Here we report a new exchange strategy based on accelerated dissolution/precipitation of solids in liquids where the exchange is not limited by solid diffusion. An attractive isotope separation factor of 1.021-1.026 is achieved within 10 min between solid LiCl and LiCl solution in acetone at 2 °C, which aligns with the prediction from the first-principle simulation. These results open new possibilities for scalable isotope separation between solids and liquids.