Producing nuclear fusion fuel is banned in the US for being too toxic: Researchers find an alternative

Lithium-6 is crucial for producing nuclear fusion gas, however isolating it from the rather more widespread isotope, lithium-7, often requires liquid mercury, which is extraordinarily poisonous. Now, researchers have developed a mercury-free technique to isolate lithium-6 that’s as efficient as the traditional technique. The new method is offered within the journal Chem.

“This is a step towards addressing a major roadblock to nuclear energy,” says chemist and senior writer Sarbajit Banerjee of ETH Zürich and Texas A&M College. “Lithium-6 is a critical material for the renaissance of nuclear energy, and this method could represent a viable approach to isotope separation.”

The standard technique used to isolate lithium-6, referred to as the COLEX course of, entails liquid mercury and has been banned in the USA since 1963 resulting from air pollution considerations.

Since then, nearly all lithium-6 utilized in US analysis has relied on a diminishing stockpile maintained at Oak Ridge Nationwide Laboratory in Tennessee. Having a secure technique of isolating lithium-6 will likely be key to unlocking nuclear fusion as a sustainable vitality supply.

The researchers stumbled upon their technique of isolating lithium-6 isolation whereas creating membranes for cleansing “produced water”—groundwater that is dropped at the floor throughout oil and fuel drilling and that have to be cleaned earlier than it may be pumped again underground. They seen that their cleansing membrane captured disproportionate portions of lithium within the water.

“We saw that we could extract lithium quite selectively given that there was a lot more salt than lithium present in the water,” says Banerjee. “That led us to wonder whether this material might also have some selectivity for the 6-lithium isotope.”

The membrane’s lithium-binding properties are resulting from a cloth referred to as zeta-vanadium oxide (ζ-V₂O₅), a lab-synthesized inorganic compound that accommodates a framework of tunnels working in a single dimension.

“Zeta-V₂O₅ has some pretty incredible properties—it’s an amazing battery material, and now we’re finding that it can trap lithium very selectively, even with isotopic selectivity,” says Banerjee.

To check whether or not the fabric might separate lithium-6 from lithium-7, the group arrange an electrochemical cell with a zeta-V₂O₅ cathode.

After they pumped an aqueous resolution containing lithium ions via the cell whereas making use of a voltage, the positively charged lithium ions had been drawn in the direction of the negatively charged zeta-V₂O₅ matrix and into its tunnels. As a result of lithium-6 and lithium-7 ions transfer in a different way, the zeta-V₂O₅ tunnels preferentially captured lithium-6 ions whereas the extra cell lithium-7 ions escaped seize.

“Lithium-6 ions stick a lot stronger to the tunnels, which is the mechanism of selectivity,” says co-first writer Andrew Ezazi of Texas A&M. “If you think of the bonds between V₂O₅ and lithium as a spring, you can imagine that lithium-7 is heavier and more likely to break that bond, whereas lithium-6, because it’s lighter, reverberates less and makes a tighter bond.”

As lithium ions are built-in into the zeta-V₂O₅the compound regularly adjustments shade from brilliant yellow to darkish olive inexperienced, which permits the diploma of lithium isolation to be simply monitored.

The group exhibits {that a} single electrochemical cycle enriched lithium-6 by 5.7%. To acquire fusion-grade lithium, which requires a minimal of 30% lithium-6, the method must be repeated 25 instances, and 90% lithium-6 will be obtained in about 45 sequential cycles.

“This level of enrichment is very competitive with the COLEX process, without the mercury,” says Ezazi.

“Of course, we’re not doing industrial production yet, and there are some engineering problems to overcome in terms of how to design the flow loop, but within a bunch of flow cycles, you can get fusion-grade lithium for quite cheap,” says Banerjee.

The researchers say that their outcomes counsel that supplies like zeta-V₂O₅ could possibly be used to isolate different substances, for instance, to separate radioactive from non-radioactive isotopes.

Now, the group is taking steps to scale their technique as much as an industrial degree.

“I feel there’s a variety of curiosity in nuclear fusion as the last word resolution for clear vitality,” says Banerjee. “We’re hoping to get some support to build this into a practicable solution.”