Researchers in the US have developed plant-based polymers that biodegrade—even at the microplastic level—in under seven months.
- They first ground their product into fine microparticles, and then used three different measurement tools to confirm that, when placed in a compost, the material was being digested by microbes.
THE RESEARCH: The project was conducted by scientists at the University of California San Diego and materials-science company Algenesis.
- The paper, whose authors are all UC San Diego professors, alumni or former research scientists, has appeared in Nature Scientific Reports.
- The authors of the paper are Robert S Pomeroy, Michael D Burkart, Steven P Mayfield (all UC San Diego), Marco N Allemann, Marissa Tessman, Jaysen Reindel, Gordon B Scofield, Payton Evans, Ryan Simkovsky (all Algenesis).
- Burkart, Mayfield and Pomeroy are co-founders of and hold equity positions in Algenesis Corporation.
THE PROCESS: The first tool was a respirometer. When the microbes break down compost material, they release carbon dioxide (CO2), which the respirometer measures. These results were compared to the breakdown of cellulose, which is considered the industry standard of 100% biodegradability. The plant-based polymer matched the cellulose at almost one hundred percent.
- Next, the team used water floatation. Since plastics are not water soluble and they float, they can easily be scooped off the surface of water. At intervals of 90 and 200 days, almost 100% of the petroleum-based microplastics were recovered, meaning none of it had biodegraded.
- On the other hand, after 90 days, only 32% of the algae-based microplastics were recovered, showing that more than two-thirds of it had biodegraded. After 200 days, only 3% was recovered indicating that 97% of it had disappeared.
- The last measurement involved chemical analysis via gas chromatography/mass spectrometry (GCMS), which detected the presence of the monomers used to make the plastic, indicating that the polymer was being broken to its starting plant materials.
- Scanning-electron microscopy further showed how microorganisms colonise the biodegradable microplastics during composting.
FURTHER STUDIES: Creating an eco-friendly alternative to petroleum-based plastics is only one part of the long road to viability. The ongoing challenge is to be able to use the new material on pre-existing manufacturing equipment that was originally built for traditional plastic, and here Algenesis is making progress.
- They have partnered with several companies to make products that use the plant-based polymers developed at UC San Diego, including Trelleborg for use in coated fabrics and RhinoShield for use in the production of cell phone cases.
WHAT THEY SAID:
We're just starting to understand the implications of microplastics. 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.
— Michael Burkart
Professor of Chemistry and Biochemistry / Co-Founder
UC San Diego / Algenesis
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.
— Robert Pomeroy
Professor of Chemistry and Biochemistry / Co-Founder
UC San Diego / Algenesis
This material is the first plastic demonstrated to not create microplastics as we use it. 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.
— Stephen Mayfield
Professor, School of Biological Sciences / Co-Founder
UC San Diego / Algenesis
