Italian scientists have incorporated spent coffee grounds into a foam filter that can remove lead and mercury from water.

Cuppa Joe skinny, hold the lead.Restaurants, beverage shops and consumers produce millions of tons of used coffee grounds every year worldwide, says researcher Despina Fragouli, team leader of the Smart Materials Lab at the Italian Institute of Technology's Center of Biomolecular Nanotechnologies. While some of this is applied as fertilizer and some is used as a biodiesel source or mixed into animal feed, much of the used grounds wind up in landfills.

Scientists are now studying it as a possible material for water remediation. Experiments show that powder made from spent coffee grounds can rid water of heavy metal ions, which can cause health problems. But an additional step is needed to separate the powder from the purified water, so Fragouli and colleagues sought to simplify this process.

The researchers fixed spent coffee powder in a bioelastomeric foam, which acts as a filter. In still water, the foam removed up to 99% of lead and mercury ions over the course of 30 hours. In a more practical test, in which lead-contaminated water flowed through the foam, it scrubbed the water of as much as 67% of the lead ions.

Because the coffee is immobilized, it is easy to handle and discard after use without any additional steps, the researchers say.