Researchers at the University of Waterloo have found that a special type of charcoal, known as biochar, can remove toxic chromium from water and turn it into a safer form.
This discovery could lead to a natural and effective way to clean up industrial pollution.
Why is chromium dangerous?
Chromium is a heavy metal that exists in two forms:
- Chromium(III) (Cr(III)) – A safe and essential nutrient for humans.
- Chromium(VI) (Cr(VI)) – A highly toxic chemical that can cause cancer and reproductive problems.
Chromium(VI) is often released during industrial activities such as leather tanning, stainless steel production, and mining. It can also form naturally when manganese minerals are present.
Since this toxic form can contaminate water sources, scientists have been searching for ways to remove it safely and efficiently.
How biochar cleans up chromium
Biochar is a special kind of charcoal made by heating agricultural waste without oxygen. It has been studied as a natural filter that can trap pollutants and improve soil and water quality.
Filip Budimir, a Ph.D. researcher at the University of Waterloo, wanted to test whether oak-based biochar could absorb chromium(VI) from water and convert it into the safer chromium(III). His study was published in the journal Chemosphere.
Using advanced X-ray technology at the Canadian Light Source, Budimir examined how chromium interacted with biochar over time. His results were exciting:
After 120 hours (5 days), about 85% of the toxic chromium(VI) had turned into the safe chromium(III).
The biochar was not just trapping chromium—it was actively transforming it into a harmless form.
“We were happy to see that the majority of what we were finding on the biochar grains was chromium-3 and not chromium-6,” Budimir said.
In addition to removing chromium from water, Budimir’s study revealed another useful discovery. He found that lighter chromium isotopes were removed and converted to Cr(III) faster than heavier isotopes.
This means that scientists can track isotope changes to monitor how well biochar is working in cleaning groundwater.
“Things are happening underground, but we’re not sure what,” Budimir explained. “Testing the isotopes can give us an idea of what is happening and if the process is working.”
This research suggests that biochar could be a natural, low-cost solution for cleaning up polluted water—especially near industrial sites where chromium contamination is common.
With further research, this method could help protect drinking water sources, ecosystems, and public health, making the environment safer for future generations.
