German scientists have separated a mixture of three hydrogen isotopes for the first time using a solid porous material. Researchers used a synthetic zeolite with silver ions to separate protium, deuterium, and tritium. The technology could help future fusion power plants return unburned fuel back into reactors.
The study was conducted by specialists from the Helmholtz-Zentrum Dresden-Rossendorf, Leipzig University, and the Max Planck Institute for Solid State Research.
Future fusion reactors will likely operate on a mixture of deuterium and tritium. Fuel in a reactor is not completely consumed, leaving behind a mixture of all three isotopes because ordinary hydrogen, or protium, forms when fuel interacts with reactor materials.
Isotope separation mechanism
Separating these isotopes with standard chemical methods is extremely difficult because their chemical properties are virtually identical. They differ mainly by nuclear mass: protium has no neutrons, deuterium has one, and tritium has two.
The researchers used quantum properties linked to the mass of the isotopes. Microscopic channels and cavities in the synthetic zeolite contain silver ions, which interact with the electron fields of passing hydrogen molecules.
Heavier deuterium and tritium bind to the silver centers much more strongly than light protium. Gradually heating the zeolite releases the isotopes in sequence, starting with protium, followed by deuterium, and ending with tritium, which requires the highest temperature to escape.
Separation results and durability
In the starting mixture, the three isotopes were present in equal proportions of 1:1:1. After a single separation step, the ratio changed to approximately 1:41:175 for protium, deuterium, and tritium respectively.
Tritium is radioactive, extremely rare in nature, and represents one of the most valuable components of fusion reactor fuel. Efficiently separating tritium reduces fuel loss and supports a closed fuel cycle.
The material retained its structure and separation ability after several hours of exposure to tritium. However, scientists noted that industrial application remains far off because a short laboratory test does not show if the material can endure years inside an operating power plant.
Next steps include studying the separation mechanism further, finding more effective materials, and testing long-term durability.
