Cotton-and-squid-bone sponge can soak up 99.9% of microplastics, scientists say

A sponge made of cotton and squid bone that has absorbed about 99.9% of microplastics in water samples in China could provide an elusive answer to ubiquitous microplastic pollution in water across the globe, a new report suggests.

Just as importantly, the filter’s production appears to be scalable, the University of Wuhan study authors said in the paper, which was peer-reviewed and published in the journal Science Advances. That would address a problem that has stymied the use of previous microplastic filtration systems that were successful in controlled settings, but could not be scaled up.

If it is successfully deployed on a larger scale in forthcoming research, the filter could change the course of one of the world’s most serious public health crises.

“Microplastic remediation in aquatic bodies is essential for the entire ecosystem, but is challenging to achieve with a universal and efficient strategy,” the study’ authors wrote in the paper.

Microplastics have been detected in water samples around the world at levels that are increasingly worrying researchers as the substance’s health threats become clearer. By one estimate, the average person ingests about 4,000 plastic particles in drinking water annually, while the substance has been found in clouds above Mount Fuji and in the ocean’s deepest trench.

Microplastic pollution can contain any number of 16,000 plastic chemicals, and often is attached to highly toxic compounds – like PFAS, bisphenol and phthalates – linked to cancer, neurotoxicity, hormone disruption or developmental toxicity. Microplastics can cross the brain and placental barriers, and those who have it in their heart tissue are twice as likely to have a heart attack or stroke during the next several years.

The study tested the material in an irrigation ditch, a lake, seawater and a pond, where it removed up to 99.9% of plastic. It addressed 95%-98% of plastic after five cycles, which the authors say is remarkable reusability.

The sponge is made from chitin extracted from squid bone and cotton cellulose, materials that are often used to address pollution. Cost, secondary pollution and technological complexities have stymied many other filtration systems, but large-scale production of the new material is possible because it is cheap, and raw materials are easy to obtain, the authors say.

The equipment for the material’s production, such as freeze dryers and mechanical stirrers, is also widely available, while the absorption capacity was not significantly affected by other pollutants, another common problem researchers have previously encountered.

Others have had some success with a biomass sponge – different Chinese researchers previously developed a similar sponge that removed about 90% of plastic.

The authors say they could have an industrial scale model ready within several years, if larger-scale testing proves successful, and it could be used in home or municipal filtration systems. A sponge could also be used in clothes washing machines, dishwashers and other source of microplastic pollution.