We have a plastic problem. As it turns out, the novel invention that was supposed to make our lives easier has turned into an ecological nightmare. The real problem is that we consume an enormous amount of microplastics every year. We’ve found them in archeological remains, blood, breast milk, and even human testicles.
Eliminating microplastics has become a priority for many scientists, and it looks like the key might be in a filter called “Ct-Cel” that claims to eliminate up to 99.9% of these microplastics. So, what’s it made of? Squid bone and cotton, more or less.
The filter. The filter was presented in a recent study in Science from researchers at Wuhan University in China. According to the study, Ct-Cel is a fibrous filter made of supramolecular biomass made of a combination of chitin, a byproduct of squid bone, and cellulose derived from cotton.
“This biomass fibrous framework (Ct-Cel) showcases an excellent adsorption performance for polystyrene, polymethyl methacrylate, polypropylene, and polyethylene terephthalate,” the researchers write in their study.
Efficiency. The most interesting thing about the filter is that it acts as if it were a living organism. As explained by the researchers: “The affinity for diverse microplastics is attributed to the transformation of multiple intermolecular interactions between different microplastics and Ct-Cel.”
This means that the filter has a great variety of linked reactions between its parts, allowing it to adapt to better “trap” these microplastics that can range from 100 nanometers to 3 microns.
The scientists point out that the filter was able to eliminate between 98% and 99.9% of these types of microplastics in real tests carried out in water samples from agriculture irrigation, lakes, still water, and coastal water. It maintained a high removal efficiency of between 95.1% to 98.1% after five capture cycles. Notably, the team mentioned that the presence of some chemicals in the water reduced its absorption capacity.
What kinds of mechanisms does the filter use to trap the microplastics? There are several of them, including van der Waals force and the electrostatic attraction between particles. The simplest one is the physical interception of the microplastics.
Scientists note that the filter's efficiency decreases by the fourth cycle. However, the amount of microplastics trapped by it is still very high.
Next steps. While both chitin and cellulose had already been proposed as possible methods to filter and eliminate contaminants from water, the real challenge was combining them. This required researchers to deconstruct the internal structure of each component and then reconstruct them into a singular combined one.
Importantly, the authors point out that their filter is at an early development stage. Despite the potential exhibited by Ct-Cel, researchers must conduct more tests at a larger scale before carrying out another study to determine whether it’s viable to produce at a commercial level.
Promising. Although the filter’s efficiency at capturing microplastics is impressive, perhaps the biggest takeaway is that both cellulose and chitin are components that can be found easily in nature at a low cost. As such, this solution would allow us to be respectful of the environment.
We’ll have to wait and see how future tests pan out, but any glimmer of hope that could help us face off against the millions of tons of plastic we have lying around is welcome news.
Image | Jack Van Hel
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