While no one likes seeing plastic waste floating in our waterways, tiny unseen "microplastic" particles are also a threat to the aquatic environment – and to human health. A new study now suggests that a material known as nanocellulose could be used to remove them from the water.

Nanocellulose is a porous "pseudo-plastic" material, made by processing minuscule cellulose fibers. Cellulose is in turn the most abundant organic compound on the planet, found (among many other places) in the cell walls of plants.

Microplastics, on the other hand, come from sources such as chunks of plastic waste that have broken down into smaller pieces, microbeads that are used in products such as toothpaste, and even small fibers shed by synthetic clothing while it's being washed.

Because the particles are by definition smaller than 5 millimeters each – and often even microscopic – they're difficult to see, and to filter out of waterways. As a result, they frequently end up being eaten by fish, and subsequently passed along to people who consume those fish. Depending on how toxic the particles are, there's a risk that ingesting them could harm both fish and humans alike.

Seeking to address the problem, scientists at the VTT Technical Research Centre of Finland recently tried using nanocellulose films and hydrogels to remove microplastics from water. They were successful, thanks mainly to the mesh-like internal structure of the material. When placed in the water, this structure generated capillary forces that drew the particles into the mesh, then held them there.

In the immediate future, the technology could be used to sample the water in different regions, determining the concentration and types of microplastic particles present. Once developed further, though, it could be scaled up to inexpensively filter microplastics out of the water at their source.

"New filtration solutions would allow particles to be captured where they are generated," says the lead scientist, Prof. Tekla Tammelin. "The solutions could be utilized, for example, in laundry, where microplastic particles are released from fleece clothing and other synthetic fibers. Similarly, we could develop filtration methods for any industry where there is a risk of microplastics being generated and released into waterways."

Source: VTT Technical Research Centre of Finland

