Putri Fraser

Combining iron with natural silicates can create a safer, easier method for removing nitrate pollution from waterways, PhD graduate Putri has discovered.

“Previous research shows that nano-sized iron can remove pollutants from soil and waterways, but it’s not a perfect solution,” Putri says. “The iron is magnetic, so these nano-sized particles can clump up, reducing their reactivity and also making them difficult to work with. This clumping can also occur if they are ingested by fish, potentially harming wildlife.”

Putri needed to find a way of making the nano-sized iron less likely to clump, but still maintain its reactivity towards pollutants. She tested several different products, but the solution came in the form of a micro-silicate product she first encountered while working as a Summer Research Scholar at Callaghan Innovation in 2012.

“This micro-silicate product is cheap to produce and is a by-product of thermal power generation,” Putri says. “My supervisor, Dr Robin Fulton, and I thought it was very fitting to use another waste product to deal with nitrate waste.”

Putri says they were able to coat the micro-silicate with the nano-sized iron, effectively increasing the size of the nano-iron while maintaining its reactivity.

“Coating the silicate with the iron makes it easier to distribute the iron in a solution, so the soil gets better coverage,” Putri says. “Also, as the silicate-coated nanoparticles can’t clump, we don’t have to worry about any potential negative interactions with fish.”

“Putri’s research is significant,” says Dr Fulton, “as not only has she made new materials for removing nitrate from waterways, but she has also discovered that the ability of the nano-sized iron to remove nitrates is strongly influenced by the minerals around it. This discovery has implications for determining the best strategies for using nano-sized iron to address many environmental pollution issues.”

Using chemistry to remediate environmental pollutants was what excited Putri about her research. She is currently assisting her secondary supervisor, Professor Jim Johnston, in a research project on enhancing geothermal energy recovery through nano-technology. "In the future, I would like to take my PhD project to completion and apply it to real-world solutions."