Dual-Pathway Catalytic Proton Exchange in Water Distillation Enables Record Detritiation of Tritiated Water

Tritiated water (HTO) is a major radioactive liquid effluent from nuclear facilities and is commonly discharged into aquatic environments because of the limited availability of effective detritiation technologies. Water distillation currently remains the only practically scalable method for detritiation, yet its efficiency is fundamentally constrained by conventional packings governed solely by gas-liquid equilibrium. Here we report a distillation packing modified with an amino-functionalized metal-organic framework, NH₂-MIL-101(Cr), which achieves a record separation efficiency of 42.5 theoretical plates per meter. This corresponds to a 134-fold improvement over the best reported packing and a 6 orders of magnitude enhancement over commercial packings at an industrially relevant packed height of 10 m. The exceptional performance originates from a dual-pathway catalytic proton exchange mechanism, in which Cr-oxo clusters and amino-functionalized organic ligands provide parallel proton-transfer pathways through hydrogen-bond networks of water molecules. These dual pathways markedly strengthen liquid-solid isotope exchange and enable an efficient and continuous vapor-liquid-solid triphasic distillation process beyond the limits of conventional biphasic operation. This work provides a promising strategy for advancing detritiation technologies and mitigating tritium releases from the nuclear industry.