Each year, coffee drinkers across the globe create six million pounds of waste in the form of spent coffee grounds. Some of us chuck it in our compost pile, but most of it becomes just another garbage disposal challenge.
It turns out that there is a surprising use for used coffee—one that solves another environmental problem, too. Coffee can remove heavy metals such as lead and mercury from water.
In the past, researchers have experimented with placing coffee grounds in water contaminated with heavy metals. The coffee was effective at binding to the heavy metal ions, but it was extremely difficult, says researcher Despina Fragouli, to get the coffee out of the water afterwards.
She and a team of researchers from Italy have found a novel solution to this problem.
“By introducing the spent coffee grounds into a polymeric foam, we formed a solid composite system…that is easy to manipulate…[and that] can be used as a filter,” she says…
…Next, the researchers will need to determine whether the coffee filter still works in water that also contains organic pollutants. Fragouli believes that if they are successful, the filter could used at industrial sites and in urban waste water processing plants. They are also in the process of studying whether it can remove enough heavy metals from water to make it safe for human consumption.
Source: Chavan AA et al. Spent Coffee Bioelastomeric Composite Foams for the Removal of Pb2+ and Hg2+ from Water. ACS Sustainable Chemistry and Engineering. 2016.
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