Hopes that breakthrough could signal a new age of eco-friendly materials
Plant-based polymers can fully biodegrade at the microplastic level in less than seven months, according to a new US study.
Researchers from the University of California, San Diego – in conjunction with a company called Algenesis – found that the biodegradable plastic tested was fully digested by microbes when placed in a compost.
With microplastics becoming more pervasive, finding viable alternatives to traditional fossil-fuel based plastics has never been more important, but the authors of this new research paper believe they can give people hope.
“We’re just starting to understand the implications of microplastics,” said Michael Burkart, Professor of Chemistry and Biochemistry, one of the paper’s authors and a co-founder of Algenesis.
“We’ve only scratched the surface of knowing the environmental and health impacts. We’re trying to find replacements for materials that already exist, and make sure these replacements will biodegrade at the end of their useful life instead of collecting in the environment. That’s not easy.”
Fellow paper author Prof. Robert Pomeroy, who is also an Algenesis co-founder, said: “When we first created these algae-based polymers about six years ago, our intention was always that it be completely biodegradable.
“We had plenty of data to suggest that our material was disappearing in the compost, but this is the first time we’ve measured it at the microparticle level.”
Testing biodegradability
To assess the biodegradability of the plant-based polymer, the research team ground their product into fine microparticles and performed three tests on the material to confirm that, when placed in a compost, it was being digested by microbes. These were:
- CO2 levels – using a respirometer, the researchers measured how much carbon dioxide (CO2) was released by the composted material. When compared to the breakdown of cellulose – considered the industry standard of biodegradability – the plant-based polymer matched this at almost 100%.
- Water floatation – 200 days after placing microplastics in water, only 3% of the algae-based microplastics were recovered from its surface, indicating that 97% of it had biodegraded. By contrast, almost 100% of the petroleum-based microplastics were recovered (0% biodegradation).
- Chemical analysis – gas chromatography/mass spectrometry (GCMS) – which detects the presence of the monomers used to make the plastic – indicated that the polymer was being broken to its starting plant materials. Further study through scanning-electron microscopy demonstrated further how microorganisms colonise the algae-based microplastics during the composting process.
A breakthrough for the packaging industry?
Biodegradable polymers have, for some time, been used to create more sustainable packaging that can be disposed of in a composting environment.
Products such as compostable mailing bags and compostable waste sacks are becoming increasingly popular with consumers.
But with the contribution of microplastics to pollution levels and associated risks to human health, opportunites to use a range of polymers that do not create microplastics would no doubt be welcomed across the industry.
“This material is the first plastic demonstrated to not create microplastics as we use it,” said Professor Stephen Mayfield, another of the paper’s co-authors and co-founder of Algenesis.
“This is more than just a sustainable solution for the end-of-product life cycle and our crowded landfills. This is actually plastic that is not going to make us sick.”
Many challenges remain for companies such as Algenesis looking to create eco-friendly polymers – and the creation of a suitable material itself is just one of them.
For any new material to become a viable alternative to traditional fossil-fuel-based plastics, one significant challenge is being able to use that material on pre-existing manufacturing equipment originally built for traditional plastic.
Algenesis has already partnered with several companies to make products such as cell phone cases using the plant-based polymers developed in the laboratory, and the research team from UC San Diego believe they are making progress.
“When we started this work, we were told it was impossible,” added Burkart. “Now we see a different reality. There’s a lot of work to be done, but we want to give people hope. It is possible.”
The full research paper can be found in Nature Scientific Reports, volume 14, article number 6036 (2024).
