Representational image: The team used electrified membrane for faster conversion.
Yale researchers have developed a promising new method to electrochemically convert nitrate, a common water pollutant, into ammonia.
This development offers two main benefits: cleaning contaminated water and producing a valuable resource that can be used for fertilizer and carbon-free fuels.
Nitrate is a prevalent contaminant in wastewater. Although nitrates are crucial for plant growth, their abundance can severely degrade water quality.
The idea of converting nitrate into ammonia is not novel, but doing it efficiently and affordably has been a huge challenge.
Researchers face a dilemma: how to convert nitrate to ammonia with minimal unwanted byproducts – what scientists call selectivity – and how to do it quickly – that’s activity.
Typically, scientists have focused on expensive, complex materials to boost these conversion rates. Researchers often try to improve the conversion of pollutants by developing better electrocatalysts.
However, as Professor Lea Winter from Yale explains, “When you’re using expensive materials and complicated synthesis techniques to make these fine-tuned nanostructured materials, then you add a lot of cost.” Especially when trying to tackle wastewater on a large scale.
However, the Yale team, led by Professor Winter, has unveiled a “two-pronged solution” that could change everything.
First, they introduced an ionophore into their system. It is like a magnet designed to hold onto nitrite, a tricky byproduct formed during the conversion.
This ensures the nitrite stays put long enough to be fully converted into ammonia, dramatically increasing the amount of usable ammonia produced.
“So our trick here was to incorporate the ionophore, which keeps nitrite nearby, allowing it to convert to ammonia before it gets released into water. And that’s our key to getting the very high ammonia selectivity,” the researchers noted.
And the second innovation is an electrified membrane, which serves as an “electrochemical conversion” platform.
The membrane is composed of copper and carbon nanotubes.
This platform rapidly pushes the conversion forward. The challenge was that its speed sometimes created too much nitrite.
By combining the ionophore with the electrified membrane, they achieved both high activity and high selectivity.
“Part of the challenge is that, because the membrane works so quickly, you get a lot of nitrite,” Winter said.
“But when we combine the electrified membrane with the ionophore, we get both the very high activity and the high ammonia selectivity without compromising one or the other,” the lead researcher explained.
Yale’s new system dramatically outperforms others, converting nitrate to ammonia in just “six seconds” – a process that typically takes hours.
Moreover, it achieves an impressive 92 percent conversion rate of nitrate into ammonia.
They even tested their system on real water from a lake and a wastewater treatment plant. The system remained stable for hours, proving its real-world potential.
With flexible membranes and impressive stability, the researchers believe this technology has the potential to scale up to conventional water treatment processes.
The new development holds the potential to create a future with cleaner water and reduced pollution, while also providing a new, sustainable source for fertilizers and fuels.
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