Adding compounds known as tannins to wood dust creates a filter that traps microplastic particles in water.
Microplastic pollution is one of the gravest environmental challenges facing us, and a solution as to how to tackle it could come from an unlikely source: plants.
By adding natural plant compounds known as tannins to a layer of wood dust, scientists have created a filter that traps nearly all microplastic particles in water.
“Most solutions proposed so far are costly or difficult to scale up. We’re proposing a solution that could potentially be scaled down for home use or scaled up for municipal treatment systems,” says Orlando Rojas, a scientific director at the University of British Columbia who led the research.
“Our filter, unlike plastic filters, does not contribute to further pollution as it uses renewable and biodegradable materials: tannic acids from plants, bark, wood and leaves, and wood sawdust: a forestry byproduct that is both widely available and renewable,” explains Rojas, who is a professor at the university’s departments of wood science, chemical and biological engineering, and chemistry.
Microplastics have permeated freshwater and seawater globally. For instance, another team of scientists has recently found that all lakes they studied worldwide have been polluted by these tiny plastic particles. Even tap water has been contaminated by microplastics, which is worrying as these particles can breach the blood-brain barrier and accumulate in our organs.
Worse still, by 2025 more than 10 billion tons of mismanaged plastic waste will be dispersed in the environment, scientists estimate. Research is underway to try and remove these particles from the environment as they are posing a threat to marine and aquatic life as well as to our health.
The scientists in Canada analyzed microparticles released from popular tea bags made of polypropylene and found that their so-called bioCap method trapped up to 99.9% of plastic particles in a column of water. “When tested in mouse models, the process was proved to prevent the accumulation of microplastics in the organs,” the scientists report in a study.
“There are microfibres from clothing, microbeads from cleansers and soaps, and foams and pellets from utensils, containers and packaging,” Prof. Rojas says. “By taking advantage of the different molecular interactions around tannic acids, our bioCap solution was able to remove virtually all of these different microplastic types.”
Although the technique has only been tested in a laboratory setting, it can be scaled up and deployed in nature given sufficient investment in it, according to the scientists.
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