Materials that replace plastic biodegrade in the ocean

Sep. 23 () –

UC San Diego scientists have developed new biodegradable materials designed to replace conventional plastic and counteract the increase of garbage with this origin.

After proving that their polyurethane foams biodegrade in land-based fertilizers, the researchers have now shown that the material biodegrades in seawater within weeks. The results are published in the journal Science of the Total Environment.

Researchers are working to tackle a plastic pollution problem now being described as a global environmental crisis. In 2010, researchers estimated that 8 billion kilograms of plastic enter the ocean in a single year, with a strong escalation expected by 2025.

Upon entering the ocean, plastic debris disrupts marine ecosystems, migrating to central locations and forming garbage gyres such as the Great Pacific Garbage Patch, which covers an area of ​​more than 1.6 million square kilometers. These plastics never degrade, but instead break down into smaller and smaller particles, eventually becoming microplastics that persist in the environment for centuries.

The researchers conducted a series of tests of their biodegradable polyurethane materials, currently used as foams in the first commercially available biodegradable shoes (sold by a spin-off company called Blueview) in a marine aquarium at the Scripps Institution of Oceanography. The location gave scientists access and a unique opportunity to test materials in the natural ecosystem near the coast, which is the exact environment where discarded plastics are most likely to end up.

The team discovered that a variety of marine organisms colonize the polyurethane foam and biodegrade the material to its initial chemicals, which are consumed as nutrients by these microorganisms, in the marine environment. The study data suggests that microorganisms, a mixture of bacteria and fungi, live throughout the natural marine environment.

“Improper disposal of plastic in the ocean breaks down into microplastics and has become a huge environmental problem,” he said. it’s a statement biologist and study author Stephen Mayfield, a professor in the College of Biological Sciences and director of the California Center for Algal Biotechnology. “We have shown that it is absolutely possible to make high-performance plastic products that can also degrade in the ocean. Plastics shouldn’t go into the ocean in the first place, but if they do, This material becomes food for microorganisms and not garbage and microplastics that harm aquatic life.”

Shoes, including flip-flops, the world’s most popular shoe, make up a large percentage of the plastic waste that ends up in the world’s oceans and landfills. To fully test and analyze its polyurethane materials, developed at UC San Diego over the past eight years, the study brought together experts in biology, polymer and synthetic chemistry, and marine science. Foam samples were exposed to tidal and wave dynamics and molecular and physical changes were tracked using Fourier transform infrared spectroscopy and scanning electron microscopy. The results showed that the material began to degrade in just four weeks. The researchers then identified microorganisms from six marine sites around San Diego. that are able to break down and consume the polyurethane material.

“No single discipline can address these universal environmental problems, but we’ve developed an integrated solution that works on land, and now we know it also biodegrades in the ocean,” Mayfield said. “I was surprised to see how many organisms colonize these foams in the ocean. It becomes something like a microbial reef.”