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Spotted: By now, many people are familiar with microplastics – tiny pieces of plastic less than 5 millimetres long that appear to be just about everywhere. One study has estimated there are between 15 to 51 trillion microplastic particles floating on the surface of the oceans. Fewer people, however, are aware of nanoplastics – particles less than 100 nanometres in size that are formed when microplastics break down. These microscopic particles are even more difficult to remove from water.

Researchers at Shinshu University have now developed a method for removing nanoplastics from water using a biopolymer made from apples. The researchers began by noting that microplastics can be captured during the sewage treatment process by binding them to biopolymers – causing them to sink to the bottom of treatment tanks, where they can be easily removed.

Building on this observation, the research team developed a method for binding a biopolymer to nanoplastics with the help of pectin and Fe(III). Pectin is a fibre found in fruits such as apples whereas Fe(III) is a form of iron. The team’s use of pectin was inspired by the abundance of apples in the prefecture of Nagano where Shinshu University is located.

The research was published in the Journal of Environmental Chemical Engineering. In the study, the team applied the pectin and Fe(III) to polystyrene nanoplastics dissolved in liquid. The mixture was then left for two days, after which the researchers found that 95 per cent of the nanoplastics had been removed.

Microplastics and nanoplastics have been found everywhere on Earth where researchers have looked – including in our bodies and in the food we eat. Removing these particles from water and air is extremely difficult, but that has not stopped innovators from trying. Some of the methods Springwise has recently covered include a system that allows ships’ scrubbers to remove plastic particles on the go, and a method that uses okra instead of chemicals. 

Written By: Lisa Magloff