Catalytic proton exchange in water distillation for efficient tritiated water clean-up

Abstract

Tritiated water emissions from nuclear facilities pose significant environmental risks and threaten the sustainability of nuclear energy. However, deep detritiation remains a major challenge due to the nearly indistinguishable physicochemical properties among water isotopologues. Here we present an efficient hydrogen isotope separation process based on catalytic proton exchange. The unique catalysis-promoted proton-transfer pathway found in a metal–organic framework (MIL-101(Cr)) significantly lowers the isotope exchange energy barrier to a previously unachieved level. Incorporating MIL-101(Cr) into a water distillation (WD) system enables a solid–liquid–gas triphasic mass transfer that overcomes the thermodynamic constraints of traditional WD, which relies on a liquid–gas biphasic isotope exchange. The height equivalent to the theoretical plate of the established WD prototype fell by half compared to the existing WD systems, thus increasing the separation efficiency by over four orders of magnitude in a 10-m distillation tower. This work offers an industrially viable and scalable option for cleaning up tritiated water. It is extremely difficult to separate tritium from radioactively contaminated water. Here the authors introduce catalytic hydrogen isotope exchange to water distillation, realizing excellent detritiation performance.