New Microplastics Water Filter Made With Cotton and Squid Bone Could Be 99.9% Effective, Scientists Report

In a new study led by researchers at Wuhan University, scientists have developed a filter, made with cotton and squid bone, that can be used to adsorb certain microplastics in aquatic environments. Further, they determined the filter was about 98% to 99.9% effective in filtering microplastics.

The study, published in the journal Science Advances, explored the development of a foam filter made with cellulose, from cotton plants, and chitin, a type of natural biopolymer found in the exoskeletons of arthropods and mollusks, as well as in some cell walls of fungi and algae, according to Science Direct. Both cellulose and chitin are considered “two of the most abundant polysaccharides found in nature,” according to the study, and they are already used frequently for removing larger pollutants from wastewater.

The researchers are applying the use of cellulose and chitin in a novel way to tackle microplastic pollution in water, which has typically been addressed with magnets, surface-engineered adsorption methods or coagulation methods, all of which can be difficult and expensive to scale.

However, the researchers noted that using cellulose and chitin, which for this study they sourced from cotton and squid bone, respectively, would result in a cost-effective and scalable foam known as Ct-Cel that could effectively filter out microplastics such as polystyrene, polymethyl methacrylate, polypropylene and polyethylene terephthalate, according to the study. The foam can also be produced in a readily available way using freeze dryers or mechanical stirrers, The Guardian reported.

As Phys.org reported, the resulting filter was effective on several different types of plastics, including 100-nanometer polystyrene particles to microplastics spanning about 3 microns in size.

In addition to the impressive 98% to 99.9% adsorption rate, the scientists were also surprised by the reusability of the filters. After going through five filtration cycles, the filters were still effectively adsorbing microplastics in irrigation waters, lake water, still water and coastal waters at a rate of 95.1% to 98.1%.

“The favorable recycling ability of biomass foams in organic solvents can further reduce the cost of feedstock and disposal of waste biomass, thereby enhancing their potential for dealing with microplastic contamination on a large scale,” the authors wrote in the study. “Moreover, the recycling process could prevent microplastics from re-entering the environment during the natural degradation of biomass foam.”

According to The Guardian, an industrial-scale model of the Ct-Cel filter could be ready within several years. After testing that model, the filter could be designed and scaled for filtering microplastics for residential and municipal water systems.