Sponges developed that absorb microplastics

Scientists in China have developed a sponge that absorbs the microplastics that wreak havoc in our water systems.

Humans have used sponges for aeons – for cleaning, painting, and even as contraceptive devices. Now, scientists at a Chinese university have developed a new use for sponges that could address one of the world’s gravest pollution problems.

Scientists at the Ocean University of China’s College of Food Science and Engineering have developed a sponge that can absorb microplastics in our water.

The microplastics problem – pollution and health risks

Microplastics are tiny fragments of plastic, less than five millimetres long. They come from a variety of sources, including larger plastics, health and beauty products (think exfoliating microbeads), and clothing made from synthetic fibres like polyester.

Microplastics are so small that they easily pass through many water filtration systems and end up in our oceans, lakes, and rivers. They have been found in the deepest depths of our oceans and even in Antarctic sea ice.

Marine animals often mistake microplastics for food, which in turn puts fish eaters at risk of ingesting microplastics. Humans also risk ingestion through untreated drinking water and even sea salt.

One study suggests that total microplastic ingestion amounts to the equivalent of 50 plastic bags per year. Others link microplastic ingestion to various health problems, including cancer and poor foetal development.

The sponge – absorbing microplastics

Scientists at the Ocean University of China’s College of Food Science and Engineering developed the sponge from cornstarch and gelatine.

The result, according to their study in the Journal of Hazardous Materials, was an “ultralight porous sponge” that “affords capture of micro- and nano-scale plastics into its pores by simple pressing in an efficiency up to 90% while preserving excellent mechanical strength”.

They then tested the sponge’s performance in tap water, seawater, soil surfactant, and even takeaway food. The study found that the sponge had a high “removal efficiency” of between 60% and 70%.

What this means for the future – tackling the microplastics problem

Made using simple materials, this sponge immediately tackles one of the main problems that limit the current tools for tackling the microplastics problem: cost. A 2019 study in the Marine Pollution Bulletin revealed that marine plastic pollution costs the world up to $2.5 trillion annually.

In terms of physically addressing the problem, Alice Horton at the United Kingdom’s National Oceanography Centre argues that attempts to remove plastic from the ocean are futile and that attentions should be focused on “[stopping] it getting there in the first place”.

Christian Adlhart of Zurich University of Applied Sciences agrees, suggesting that the sponges would be best used in washing machines.

“You could place such a sponge inside the drum,” Adlhart told Hakai Magazine. “I think it would absorb a large fraction of the fibres”.