When most of us think of plastic waste in the ocean, we likely think of pieces of trash that can be seen floating on the surface. In fact, though, the plastic microbeads that give products like toothpaste, sunscreen and hair gel a smooth texture are also a big problem. They're small enough that they don't get caught by sewage filtration systems, and can be ingested by wildlife once in the sea. With that in mind, scientists from the University of Bath have developed biodegradable microbeads.
Instead of the usual petroleum-based polyethylene or polypropylene, which can last for hundreds of years, the new beads are made from plant-derived cellulose. This means that they not only come from a renewable source – it's possible that agricultural waste or paper-manufacturing byproducts could be used – but they also break down into harmless sugars once exposed to microbes in sewage treatment plants or even in the aquatic environment.
They're made by forcing a cellulose solution through tiny holes in a tubular membrane, causing that solution to form into spherical droplets. Using vegetable oil, those droplets are washed away from the membrane and collected together. They're then separated from the oil, and left to cure into solid microbeads.
According to the university, the process could be easily scaled up to support commercial production.
The research was led by Dr. Janet Scott and James Coombs OBrien, and is described in a paper recently published in the journal ACS Sustainable Chemistry and Engineering.
Source: University of Bath
