Five Things to Know about George Mason’s Mobile CoffeeBots

Sometimes the most elegant solutions are the simplest, like using one waste product to eliminate another, such as used coffee grounds, called CoffeeBots, engineered in a George Mason University laboratory.

1. CoffeeBots can remove pollutants from seawater. By combining spent coffee grounds with iron oxide (rust), George Mason engineers have created CoffeeBots in the laboratory of College of Engineering and Computing professor Jeff Moran using the remains of Moran’s morning brew. Moran’s lab focuses on developing self-propelled microparticles for medical and environmental applications. 
    
2. A CoffeeBot can move through water by using a magnet. Coffee grounds have an irregular, porous surface to which pollutants can bind, even with the much smaller iron oxide nanoparticles attached. Since iron oxide is magnetic, a simple handheld magnet can drive CoffeeBots through polluted water and remove them.
    
3. CoffeeBots are reusable. While using coffee grounds to clean up oil spills is not entirely new, this team is the first to show that mobile CoffeeBots outperform stationary ones since moving particles encounter more pollutant molecules. Making the coffee grounds magnetic has another benefit: Once the CoffeeBots are recovered, they can be reused several times before losing their efficacy.  
    
4. Students discovered the use of coffee grounds. Postdoctoral research fellow Amit Kumar Singh in Moran’s lab originally proposed the project as a way for then-Thomas Jefferson High School student Tarini Basireddy to gain hands-on experience in the laboratory without having to interact with dangerous chemicals.
    
5. CoffeeBots can be used against three types of seawater pollutants: methylene blue, oil, and microplastics. The team found that the particles can be an effective solution for cleaning methylene blue, a carcinogenic dye commonly used in textile production, especially when they are first loaded with ascorbic acid, which helps break down the dye and render it nontoxic. And microplastics, like oil, cling to coffee grounds because they are hydrophobic.