Mercury pollution is a global problem in the water, air and soil near gold mines, cement and some metal productions, and other heavy industries burning fossil fuels – with a disposal too costly or difficult in some of the world’s poorest countries.
Now experts at Flinders University have extended testing of a sustainable extraction material that can absorb almost all the mercury from polluted water in minutes – itself made entirely from waste low cost from oil, citrus and agricultural production.
In fact, tests have shown almost complete uptake of mercury within minutes under test conditions, lead author Professor Justin Chalker and fellow scientists explain in a new paper published by the Royal Society of Chemistry.
“It is clear from the study that this mercury-binding material, invented at Flinders University, is ultra-fast in its ability to remove mercury from water. In some cases, more than 99% of the mercury is captured in just a few minutes,” says Professor Chalker.
Chalker Lab co-author Dr. Max Worthington explains that tests were performed on a new material created by coating silica with sulfur and limonene — a new chemical combination that effectively absorbs mercury waste.
“This silica coated with an ultra-thin layer of poly(S-r-limonene), using sulfur left over from petroleum production and orange oil from orange peel discarded by the citrus industry, has been extensively tested at various pH and salt concentrations,” says -he.
“Not only is this new mercury sorbent capable of rapidly binding mercury in water, but it is also selective in absorbing mercury, but not other metal contaminants such as iron, copper, cadmium , lead, zinc and aluminum.”
Importantly, this means that only mercury binds to the orange-sulfur sorbent, which helps post-capture safety of inorganic mercury, adds co-author Dr. Max Mann of Flinders University Chalker Lab.
“The particles in just 27g of this free-flowing orange powder have an approximate surface area of a football field, and they can be quickly produced in volumes large enough to accommodate contamination levels,” he says.
Alfrets Tikoalu, a PhD student at the Chalker Lab, says silica from agricultural waste, such as wheat or rice production, could also be used to make the material even more sustainable.
“This mercury remediation technology can be a circular economy solution for a more sustainable world because this value-added material is made entirely from waste,” he said.
To support the results, mathematical modeling was used to qualitatively understand the rate of mercury uptake – essential data for measuring and optimizing the new sorbent in the real world.
“This is an exciting new development in producing renewable and accessible solutions to the major environmental problems facing the world today,” says applied mathematician Dr Tony Miller, another co-author of the publication in Physics Chemistry Physical Chemistry.
The project is a “great example of the chemical and physical sciences and mathematics working together to understand the rate of uptake of mercury by our innovative new sorbent”, Prof Chalker said.
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