Removing heavy metal pollutants from water will soon be easier than ever, thanks to an experimental new sponge. With just one treatment, the device is able to reduce contaminated water to safe drinking levels.
The technique was developed by scientists at Northwestern University in Illinois, based on two previous studies.
The researchers started with an inexpensive, commercially available cellulose sponge and dropped it into a slurry of manganese-doped goethite nanoparticles. Then they took it off, let it dry, and rinsed off any loose particles with water.
The result is a sponge with a high-surface-area coating of nanoparticles that is only tens of nanometers thick.Manganese-doped goethite particles were chosen not only because they absorb Lead ions, also because they are cheap and non-toxic to humans.
When the sponge is immersed in tap water containing more than one part per million of lead, it sequesters the lead ions so they are no longer detectable in the water… making the water safe to drink.
What’s more, the lead can subsequently be removed by rinsing the sponge in mildly acidic water. The recycled lead could then conceivably be used in products like batteries, and the rinsed sponge repurposed to treat more contaminated water – it wouldn’t work as well in later cycles, although it would still be able to remove 90% Lead ions in the samples above.
The scientists have now developed a platform called Sponge Coating of Heavy Metal Nanomaterials (Nano-SCHeMe) to guide other teams in selecting different types of nanoparticles to sequester different types of heavy metals.
“The presence of heavy metals in water supplies is a huge global public health challenge,” said Professor Vinayak Dravid, senior author of the research paper. “This is a multi-gigascale problem that requires solutions that can be deployed easily, efficiently and cheaply. That’s where our sponge comes in. It removes pollution and then uses it again and again.”
The paper was recently published in the journal ACS ES&T Water.
source: Northwest University