No more nuclear waste and metals healing themselves? These are the findings of two studies published last week. Sounds unbelievable? These two scientific breakthroughs might be a great sign for our future on planet Earth! So let me explain these studies and why they matter.
Can we still save ourselves or is our time on this planet over? This question has frequently crossed my mind these past few weeks, especially because natural disasters and extreme temperatures around the world have been part of my background noise. Some days, I feel like we are all doomed and that it is too late to change anything. But sometimes, I stumble upon great ideas or scientific research that make me believe otherwise. Last week, two studies have caught my eye. The first one, published last Tuesday, offers a solution to nuclear waste. The second one was published last Wednesday and discovered that metals can heal themselves. I know it sounds too good to be true but let me explain these findings first!
The first study from a team at Houston University in Texas has discovered molecular crystals capable of capturing iodine: one of the most common radioactive fission products. What does that mean?
The material used to produce heat to power turbines is called nuclear fuel. Once nuclear fuel has been used, it is placed in water to cool it down and contain radiation. After 6 to 10 years, the fuel can be transferred to a dry storage facility in reinforced concrete containers. According to the World Nuclear Association, some countries such as France, Japan, Germany, Belgium and Russia recycle the used nuclear fuel. And yet, the International Atomic Energy Agency (IAEA), in 2022, reported 146 incidents. "In recent years, a growing number of incidents involved detections at metal recycling chains and the detection of manufactured goods contaminated with radioactive material. This indicates a persistent problem for some countries in securing and detecting the unauthorized disposal of radioactive sources. […]The resulting contaminated metal, if used to manufacture household goods, could pose a potential health problem to unsuspecting consumers" reports the IAEA.
On top of the safety issues with the recycled materials, some of the by-products of nuclear fuel – mainly the fission products – still need to be placed in a repository. In Canada, there are 4 nuclear power plants and 16 different sites for radioactive waste management. So even if the radioactive waste is immobilised it is still dangerous and that is precisely why the findings of the Houston research team are interesting.
The study shows that crystals made of carbon, hydrogen and oxygen atoms can capture iodine in aqueous and organic solutions, and on the interface between the two. "This last point is particularly salient because iodine captured on interfaces could prevent the iodine from reaching and damaging the specialized paint coatings used in nuclear reactors and waste containment vessels" explains Ognjen Miljanic, professor of chemistry and corresponding author of the paper detailing the breakthrough in Cell Reports Physical Science. "When the material is deposited between the organic and aqueous layer, it essentially stops the transfer of iodine from one layer to another" he adds. Furthermore, the captured iodine can potentially be moved from one area to another. "The idea here is that you capture it at a place where it's difficult to manage, and then you release it at a place where it's easy to manage" says the professor.
Of course, all of these great potentials still need to be tested in practical applications, which has Ognjen Miljanic thinking of the next steps. "The crystals are quite easy to make and can be produced at a large scale from relatively inexpensive materials without any special protective atmosphere" he says. They can also capture other molecules such as carbon dioxide, which would be another great step towards a cleaner and more sustainable world. The next goal is to find a partner who will help the scientists explore different commercial aspects. Until then, the team is planning to further explore the kinetics and behaviours of the crystal structures to make them even better.
In the second study, a research team from Sandia National Laboratories and Texas A&M University witnessed pieces of metal crack, then fuse back together without any human intervention. But why does it matter?
Metals wear out and eventually break: it is called fatigue damage. Repeated stress or motion causes microscopic cracks to form and, over time, these cracks grow and spread until the whole device breaks. Although scientists have created some self-healing materials (mostly plastics) the notion of a self-healing metal has largely been the domain of science fiction.
But in 2013, Michael Demkowicz, a professor at Texas A&M, published a new theory, based on findings in computer simulations, that under certain conditions metal should be able to weld cracks formed by wear and tear. This year, his theory became true in Sandia laboratories when a team of researchers was evaluating how cracks formed and spread through a nanoscale piece of platinum. Surprisingly, about 40 minutes into the experiment, the damage reversed course. One end of the crack fused back together as if it was retracing its steps, leaving no trace of the former injury.
Although a lot remains unknown about the self-healing process, including whether it will become a practical tool in a manufacturing setting, "the extent to which these findings are generalizable will likely become a subject of extensive research" explains Brad Boyce, one of the scientists in the team. "We show this happening in nanocrystalline metals in vacuum. But we don't know if this can also be induced in conventional metals in air" he adds.
If the newly discovered phenomenon can be harnessed, it could make engines, bridges or airplanes safer and longer-lasting and, in the long run, could lead to less extraction of metals, less production and less waste. This is fundamental because the extraction and production of metals is not only associated with negative environmental effects including deforestation and pollution but also with social negative impacts such as violence, child labour, escalation of gender and health inequalities.
Overall, these two studies not only give me hope for a more sustainable life, they also show that we still have a lot to learn from minerals, plants and animals on our planet.
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