Microplastics have been found in every marine habitat where scientists have looked, according to a fact sheet from Ocean Conservancy.
With countless marine animals — and us humans — ingesting these tiny particles regularly, the scientific community has forged ahead to create solutions. And according to researchers from George Mason University, one such solution could be found right in our kitchens.
At least 6 million tons of spent coffee grounds — or, the byproduct that comes from brewing coffee — are produced annually, but they don’t have to go to waste.
In fact, we already know that coffee grounds are capable of removing toxins from the environment, having been used to curb pollutants from agriculture and clean up oil spills.
But a trio of scientists — including GMU assistant professor Jeff Moran, post-doctoral researcher Amit Kumar Singh, and high school lab assistant Tarini Basireddy — have mobilized the power of coffee grounds to create “CoffeeBots,” an invention that can remove oil, microplastics, and methylene blue from seawater.
Coffee grounds work to clean up pollution because they have a “porous, irregular surface,” allowing pollutants to bind to the surface area. But Moran posited that this could be even more effective if the coffee grounds were coated with much smaller iron oxide nanoparticles.
So, the researchers made their coffee byproduct “rusty” by adding those iron oxide particles. This also made the substance magnetic, allowing a simple handheld magnet to drive the CoffeeBots through polluted water.
“While using coffee grounds to clean up oil spills is not entirely new, this team is the first to show that moving CoffeeBots outperform stationary ones at removing pollutants, since moving CoffeeBots encounter pollutant molecules more often than stationary coffee grounds do,” a press release from GMU explained.
“Making the coffee grounds magnetic has another benefit: Once the CoffeeBots are recovered, they can be reused several times with little loss in water-cleaning efficacy.”
The team’s research, recently published in Nanoscale, concluded that this approach was effective in removing methylene blue — a dye commonly used in textile production — from water.
Methylene blue is a carcinogen that can have adverse effects on both humans and marine life.
“It can cause skin irritation, if there’s too much in the water,” Basireddy said. “It can cause a lot of digestive problems… nausea, fever, lots of symptoms.”
The CoffeeBots cleaned the dye from the water samples and were especially effective when loaded with ascorbic acid, which helps break down the dye. Basireddy was especially eager about these findings, considering the implications of the invention in practical use.
“It’s cool because the countries that are big textile producers also happen to be the countries that are big in coffee production,” she said, pointing to Brazil, Colombia, Ethiopia, India, Peru, and Vietnam as countries that produce both dyed textiles and coffee and struggle with water pollution.
Most excitingly, however, is the CoffeeBots’ ability to clean oil and microplastics from water samples. Just like oil clings to coffee grounds, so do microplastics.
“One reason why microplastics and nanoplastics are such a tricky environmental problem is that they’re so small, and that makes it difficult to locate them just to remove them,” said Moran.
“By driving the CoffeeBots through the water, the hydrophobic interactions cause the microplastic particles to build up and accumulate on the surface of the coffee grounds.”
Certainly, there are other techniques to confront oil spills and clean microplastics from water, but using a byproduct from something as ubiquitous as coffee offers a more affordable and sustainable solution.
For now, the team has applied to patent their CoffeeBots technology. As Basireddy now studies at John Hopkins University, Singh and Moran will further explore this research.
Their future plans include attempting to make the CoffeeBots solar powered, further investigating the range of pollutants that can be removed by this technology, and characterizing the efficacy of different types of coffee grounds.
Ultimately, they want to make the simplest procedure to help the most people access clean water.
“Growing up, I always thought science was complicated,” Basireddy told WUSA9 News.
“But here we have coffee grounds with rust on them and we’re able to remove a whole slick of oil. You can do science with very simple starting materials, and you can do some amazing things with it.”