The University of California, San Diego, and materials science company Algenesis have developed biodegradable microplastics that break down in under seven months, presenting a significant step towards finding alternatives to traditional petroleum-based plastics and microplastics.
The team stress the limited understanding of microplastics' impacts and the challenge of finding biodegradable replacements for current materials. They emphasize the intended full biodegradability of their algae-based polymers, supported by recent measurements at the microplastic level.
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Biodegradable Microplastics: A Step Towards Sustainable Solutions
In the study, titled "Rapid biodegradation of microplastics generated from bio-based thermoplastic polyurethane" published in Nature Scientific Reports, the team conducted a series of tests to evaluate the biodegradability of their product, pulverizing it into fine microparticles and employing three measurement techniques to confirm its breakdown by microbes when placed in compost.
Firstly, they utilized a respirometer to monitor the release of carbon dioxide, finding a close match between their plant-based polymer and cellulose, which is considered 100% biodegradable.
Secondly, water flotation tests revealed that while nearly 100% of petroleum-based microplastics were recovered after 90 and 200 days, only 32% and 3% of algae-based microplastics were retrieved, indicating significant degradation.
Lastly, chemical analysis using gas chromatography/mass spectrometry (GCMS) detected the presence of monomers used in plastic production, indicating the breakdown of the polymer into its initial plant components, while scanning-electron microscopy showed microbial colonization during composting.
According to coauthor Stephen Mayfield, their material stands out as the first plastic to demonstrate no microplastic generation during use, underscoring its health and environmental benefits.
Continued work is required to address compatibility challenges with manufacturing equipment, with Algenesis teaming up with companies like Trelleborg and RhinoShield to integrate plant-based polymers into items such as coated fabrics and cell phone cases. Professor Burkart, despite initial doubts, underscores the practicality of their inventive approach, providing optimism for a more sustainable tomorrow.
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How Long Do Microplastics Break Down?
The gradual deterioration of larger plastic items, like bottles and packaging, in the sea or on land, occurs due to factors such as sunlight exposure, oxidation, and interaction with animals. This process leads to their fragmentation into smaller pieces, ultimately transforming them into microplastics and nanoplastics, which are nearly undetectable even with advanced microscopes.
As a result, beaches often display not just visible large plastic debris but also numerous faded or colored fragments, some of which resemble grains of sand.
Although non-biodegradable plastic can disintegrate into millions of particles, micro- and nanoplastic accumulation exponentially increases, altering the composition of marine environments, leading to widespread distribution across water, soil, and air.
Microplastics, predominantly smaller than 5 mm, constitute the majority of plastic fragments in the ocean, with most remaining far from shorelines, undergoing gradual fragmentation over periods ranging from 100 to 1,000 years.
These minute plastic particles, resistant to complete decomposition, pervade water, soil, and air, propelled over vast distances by their lightweight nature. Recent discoveries reveal the widespread presence of microplastics in polar ice, indicating their dispersion through ocean currents and atmospheric transport, even reaching the remotest corners of the globe and penetrating the deepest ocean depths.
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