New Material: It Is Found That The Algal Based Plastic That Will Not Produce Microplastics Has Passed The Test

In recent years, the discussion and research on microplastics emerge in endlessly. Microplastics are tiny, almost indestructible fragments that fall off from daily plastic products. Most studies have focused on designing methods for collecting and removing microplastics from the environment to prevent their possible health problems.

In a new study, the University of California San Diego and the materials science company Algenesis The researchers of have solved this problem from another point of view. They have developed a plant based polymer, which can complete biodegradation within 7 months even if it is ground into microplastics.

Michael Burkart, professor of chemistry and biochemistry at the University of California, San Diego, co-founder of Algenesis and one of the authors of the study Says: "We are just beginning to understand the impact of microplastics. We are trying to find alternatives for existing materials and ensure that these alternatives can be biodegradable after the end of their service life, instead of accumulating in the environment. This is not easy."

Biodegradation is a process in which microorganisms break down polymers into simpler molecules. It requires that the polymer contains chemical bonds that can be contacted by plastic degrading enzymes produced by microorganisms, and these microorganisms can consume the molecules released from polymer decomposition. Note: All plastics are polymers, but not all polymers are plastics.

Robert, professor of chemistry and biochemistry, co-founder of Algensis and author of research report Pomeroy) said: "About six years ago, when we first created this kind of algal polymer, our original intention has always been to hope that it can be fully biodegradable. We have a large number of data indicating that our materials are disappearing in composting, but this is the first time we measured it on the particle level."

Many years ago, Pomeroy, Burkart and Stephen Mayfield, professor of molecular biology Mayfield's project of converting algae into fuel has evolved into the exploration of developing high-performance biodegradable polyurethane. Since plastic comes from oil and oil comes from algae, researchers began to make plastic directly from algae oil. The resulting algal polymer is called TPU-FC1 is used to make the world's first pair of biodegradable shoes. Pomeroy even wrote a book about his algae based materials.

In the current study, the researchers used the abrasive belt machine with 80 # abrasive paper to generate the TPU-FC1 Including various materials of microplastics. Different belt sanders are used for each material to prevent cross contamination. They used different methods to test whether microorganisms digested the microplastics.

First, under the same conditions as domestic compost, micro plastics are put into the compost containing natural microorganisms. After 90 days, the inspection results of compost samples showed that TPU-FC1 microparticles decreased by 68%, while The number of EVA microparticles has hardly changed. After 200 days, the number of microplastics particles in TPU-FC1 sample decreased by 97% compared with that at the beginning (the number of EVA particles did not change).

The particle count of petroleum based (EVA) and plant based (TPU-FC1) microplastics shows that over time, EVA has almost no biodegradation, while TPU reaches 200 The weather has basically disappeared. Figure/SC Santiago

The researchers used the same set of microplastics and compost samples to track carbon dioxide (CO2) And measured with a breathmeter. When microorganisms decompose compost, they release carbon dioxide gas. Pure cellulose samples are used as internal controls to monitor the background "carbon dioxide evolution", which is a measurement method of microbial activity in compost. Cellulose in 75% of carbon dioxide evolution amount was reached within 45 days, indicating that the compost had sufficient activity. As expected for non biodegradable materials, EVA microparticles are There is no carbon dioxide evolution in the experiment of days. The biodegradation effect of TPU-FC1 microplastics is significant. At the time point of 200 days, the evolution of carbon dioxide reaches 76%. Therefore, respirometry confirmed that TPU-FC1 is biodegradable, and it is proved that one of the results of biodegradation is to convert the carbon in the microplastics into carbon dioxide.

Since the plastic is insoluble in water and will float on the water surface, it is easy to be scooped out of the water surface, so the research team will next add the micro plastic to the water for testing. Almost 100% EVA every 90 and 200 days Micro plastics are recycled, which means they are not biodegradable. In contrast, after 90 days, only 32% of TPU-FC1 microparticles were recycled, and after 200 days, only 3% % of the microparticles were recycled, which indicates that 97% of the microparticles have been biodegradable.

Chemical analysis of the algal plastic detected the monomer used to make the plastic, indicating that the polymer had been decomposed into the original plant material. Further analysis found that bacteria could transform TPU-FC1 It is used as a carbon source and proved that they can decompose it.

Stephen Mayfield, another author of the study Mayfield) said: "This material is the first plastic that will not produce microplastics during use. This is not just a sustainable solution for the end of the product life cycle and our crowded landfill. This is actually a plastic that will not make us sick."

Manufacturing biodegradable plastics using traditional manufacturing equipment is challenging, but Algenesis The company is making progress. The company has cooperated with Trelleborg to produce coated fabrics, and with RhinoShield to produce mobile phone protective cases.

"When we started this work, someone told us that it was impossible. Now we see a different reality. There is still a lot of work to do, but we hope to bring hope to people. It is possible."

The study was published in the journal Science Report.