polymer

Removing microplastics from water

April 23, 2025 By EarthWise Leave a Comment

Microplastics come from the breakdown of larger plastics in the environment as well as from direct use in various products such as certain cosmetics. They are found everywhere, from oceans and mountain peaks to the air and water, and alarmingly, in our bodies. They are ingested by all sorts of organisms, from tiny plankton to fish and marine mammals. Microplastics just don’t go away. They don’t biodegrade so they simply accumulate in the environment.

Researchers at North Carolina State University have recently demonstrated proof of concept for a system that actively removes microplastics from water. Such a system has the potential for helping to cleanse oceans and other bodies of water from the tiny plastic particles.

The system makes use of soft dendritic colloids, which are tiny particles that have the ability to stick to just about any surface. These sticky particles can attract microplastics and grab them, even in wet and salty conditions. The colloids are made from chitosan, a harmless and biodegradable polymer made from processed shellfish waste.

The researchers produced small pellets of the colloids that also contain small amounts of magnesium, which makes them bubble up and rise to the surface of water. The pellets are coated with a gelatin layer, which blocks the magnesium. As the gelatin gradually dissolves away, the pellets collect microplastics. Eventually, the result is a microplastic-laden scum that rises to the surface where it can be skimmed away.

The scum itself can be bioprocessed into more chitosan that can create more of these microcleaner pellets to then capture more microplastics. The researchers are investigating how the process can be scaled up to become a valuable tool in dealing with the microplastics problem.

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New Water Microcleaners Self-Disperse, Capture Microplastics and Float Up for Removal

Photo, posted January 17, 2018, courtesy of Bo Eide via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Seashells inspire better concrete

July 10, 2024 By EarthWise Leave a Comment

Mother of pearl – also known as nacre – is a natural material found in certain seashells such as those of oysters and abalone. On the microscopic level, it consists of hexagonal tablets of the hard mineral aragonite glued together by a soft biopolymer. The aragonite gives nacre its strength, and the biopolymer adds flexibility and crack resistance.

Scientists at Princeton University have developed innovative composite materials inspired by nacre by utilizing conventional construction materials like Portland cement paste combined with a limited amount of polymer. The new material consists of alternating layers of cement paste sheets with the highly stretchable polymer polyvinyl siloxane.

The materials were subjected to bending tests to evaluate crack resistance or fracture toughness. Three different versions of the material were tested that used different ways of interposing the polymer layers. The new materials were compared with similar structures composed entirely of cement.

The concrete-only samples were brittle, breaking suddenly and completely upon reaching their failure point. The samples with alternating cement and polymer layers demonstrated increased ductility and resistance to cracking.

By fully mimicking the structure of nacre – using completely separated hexagonal cement tablets – the researchers demonstrated materials with 19 times the ductility and 17 times the fracture toughness of cement while retaining nearly the same strength as solid cement samples.

Engineered materials inspired by nature could eventually help increase the durability of a wide range of brittle ceramic materials, from concrete to porcelain.

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From seashells to cement, nature inspires tougher building material

Photo, posted January 2, 2016, courtesy of Yantra via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Bio-based products on the rise

January 30, 2024 By EarthWise Leave a Comment

There is a growing global movement working towards replacing conventional synthetic products – ones that are toxic to make or use, difficult to recycle, and have large carbon footprints – with products made from plants, trees, or fungi that can be safely returned to the earth at the end of their useful life. This so-called bioeconomy is in its infant stages, but there is increasing interest in turning successful research into manufactured products.

One example is nylon. Nylon was created in the 1930s by DuPont. It has been used and continues to be used in a wide range of products. The problem with it is that it is made from petroleum, it doesn’t biodegrade, and producing it generates nitrous oxide, which is a problematic greenhouse gas.

A San Diego-based company called Genomatica has developed a plant-based nylon using biosynthesis, a process in which a genetically engineered microorganism ferments plant sugars to create a chemical intermediate that can be turned into the nylon-6 polymer, and then into textiles.

The impetus for developing bio-based products includes the growing public disgust at the mounting environmental toll of plastic, not the least of which is that people and animals are increasingly ingesting it. Coupled with this, there is a rapidly-growing torrent of funding, especially in the US and Europe, aimed at accelerating the transition away from products that are non-biodegradable, toxic, and that produce carbon emissions. Last September saw the launch of the National Biotechnology and Biomanufacturing Initiative which will support research and development on such topics as the use of sustainable biomass and waste resources to make non-toxic, bio-based fuels, chemicals, and fertilizers.

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From Lab to Market: Bio-Based Products Are Gaining Momentum

Photo, posted May 27, 2010, courtesy of André C via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ending plastic separation anxiety

December 27, 2023 By EarthWise Leave a Comment

Petroleum-based plastics are one of the biggest environmental problems we face. They mostly end up in landfills – or worse, in the oceans and elsewhere in the environment – and they basically don’t decompose over time. Bio-based plastics were invented to help solve the plastic waste crisis. These materials do break down in the environment providing a potential solution to the problem. But it turns out that they can actually make plastic waste management even more challenging.

The problem is that bioplastics look and feel so similar to conventional plastics that they get mixed in with the petroleum-based plastics rather than ending up in composters, where they can break down as designed.

Mixtures of conventional and bioplastics end up in recycling streams where they get shredded and melted down, resulting in materials that are of very poor quality for making functional products. The only solution is to try to separate the different plastics at recycling facilities, which is difficult and expensive to do.

Scientists at Lawrence Berkeley National Laboratory, the Joint BioEnergy Institute, and the incubator company X have invented a simple “one pot” process to break down mixtures of different types of plastic using naturally derived salt solutions and specialized microbes and then produce a new type of biodegradable polymer that can be made into fresh commodity products.

The team is experimenting with various catalysts to find the optimum way to break down polymers at the lowest cost and are modeling how their processes can work at the large scales of real-world recycling facilities. Chemical recycling of plastics is a hot topic but has been difficult to make happen economically at the commercial scale.

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Putting an End to Plastic Separation Anxiety

Photo, posted November 28, 2016, courtesy of Leonard J Matthews via Flickr.

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A Better Way To Recycle Plastics | Earth Wise

November 10, 2022 By EarthWise Leave a Comment

The global accumulation of plastic waste is an ever-growing problem. At least five billion tons of the stuff has accumulated on land and sea and is even showing up in the bodies of animals and humans. Recycling plastic instead of making even more of it seems like an essential thing to do but it has proven to be extremely challenging.

The main problem is that plastics come in many different varieties and the ways of breaking them down into a form that can be reused are very specific to each type of plastic. Sorting plastic waste by plastic type is extremely impractical at large scale. Certainly, most consumers can’t do it themselves. As a result, most plastic gathered in recycling programs ends up in landfills.

New research at MIT has developed a chemical process using a catalyst based on cobalt that is very effective at breaking down a variety of plastics, including polyethylene and polypropylene, which are the two most widely produced plastics. The MIT process breaks plastics down into propane. Propane can be used as a fuel or as a feedstock for making many different products, including new plastics.

Plastics are hard to recycle because their long-chain molecules are very stable and difficult to break apart. Most chemical methods for breaking their chemical bonds produce a random mix of different molecules which would somehow have to be sorted out in order to be useful for anything.

The new process uses a catalyst called a zeolite that contains cobalt nanoparticles. The catalyst selectively breaks down various plastic polymer molecules and turns more than 80% of them into propane.

The researchers are still studying the economics and logistics of the method, but it looks quite promising.

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New process could enable more efficient plastics recycling

Photo, posted April 25, 2016, courtesy of NOAA Coral Reef Ecosystem Program via Flickr.

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A Cheap Material For Carbon Capture | Earth Wise

September 12, 2022 By EarthWise Leave a Comment

The recently passed Inflation Reduction Act includes significant support for carbon capture technologies. Eliminating fossil fuel burning is essential for halting climate change, but in the interim, methods for capturing emissions of carbon dioxide and either storing it or turning it into usable products are increasingly necessary.

There are a variety of techniques being developed for carbon capture but at this point, none of them are commercially viable. The best technique in use today involves piping flue gases through chemicals called liquid amines, which bind CO2. The process requires large amounts of energy to release the bound carbon dioxide so it can be concentrated and stored. As a result, it is complicated and expensive.

Researchers at UC Berkeley, Stanford, and Texas A&M University have developed a carbon capture method using melamine, which is an inexpensive polymer used to make Formica, as well as low-cost dinnerware, industrial coatings, and other plastics. Porous melamine itself adsorbs CO2 to a limited extent. But the researchers discovered that adsorption could be much improved by adding the chemical DETA (diethylenetriamine) to bind the CO2. In addition, adding cyanuric acid increased the melamine pore size and radically improved CO2 capture efficiency even more.

The result is a material that is more efficient even than exotic carbon capture materials like metalorganic frameworks and is much cheaper and easier to make. The researchers aim to design equipment that can used in industrial facilities, attached to buildings and other structures, or even to the tailpipes of gas-powered vehicles.

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A simple, cheap material for carbon capture, perhaps from tailpipes

Photo, posted June 10, 2006, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Plastic-Eating Bugs | Earth Wise

February 3, 2022 By EarthWise Leave a Comment

27-year-old Miley Cyrus and 30-year-old Liam Hemsworth divorced exactly one year ago, but still continue to remember each other quite often in conversations with reporters. Recently, Miley indulged in nostalgia once again. During a recording Miley Cyrus boyfriend list of the podcast Barstool Call Her Daddy, the singer said that her ex-husband was her first man. It happened almost 10 years before they got married. I didn’t have that with men until I was 16, but I ended up marrying this guy,

According to a new study, microbes in oceans and soils around the world are evolving to eat plastic. The study by Chalmers University in Sweden was published recently in the journal Microbial Ecology.

The study is the first large-scale assessment of the plastic-degrading potential of bacteria. There are 95 microbial enzymes already known to degrade plastic.

The researchers looked for similar enzymes in environmental DNA samples taken from bacteria from 236 different locations around the world. They found that one in four of the organisms analyzed carried suitable enzymes. Overall, they found many thousands of new enzymes.

The explosion of plastic production in the past 70 years has given microbes time to evolve to make use of plastic. About 12,000 new enzymes were found in ocean samples and 18,000 in soil samples. Nearly 60% of the new enzymes did not fit into any known enzyme classes, suggesting that these molecules degrade plastics in ways that were previously unknown. The large number of enzymes in such a wide range of habitats is an indication of the scale of the problem of plastics in the environment.

The first bacterium that eats plastic was discovered in a Japanese waste dump in 2016. Scientists tweaked that microbe in 2018 and managed to create an enzyme that was even better at breaking down plastic bottles.

The next step in research is to test the most promising enzyme candidates in the laboratory to investigate their properties and see how effective they can be in plastic degradation. The hope is to be able to engineer microbial communities with targeted degrading functions for specific polymer types.

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Bugs across globe are evolving to eat plastic, study finds

Photo, posted June 19, 2013, courtesy of Alan Levine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Better Ways To Make Bioplastics | Earth Wise

August 27, 2021 By EarthWise Leave a Comment

The world produces over 300 million tons of plastics each year, mostly produced from petroleum. The environmental consequences are substantial and there is a critical need to replace as much of that plastic production with biodegradable plastics as possible. Thus, there is global research aimed at making bioplastics more economical and as environmentally friendly as possible.

Researchers at Texas A&M University have developed an improved approach for making bioplastics from corn stubble, grasses, and mesquite agricultural production. Apart from the obvious environmental benefits of having biodegradable plastics, producing bioplastics from common agricultural waste would create new revenue streams for farmers as well as the people who transport harvested feedstock and byproduct crops to refinery operations.

The key to bioplastic production is the efficient extraction and use of lignin, the organic polymer that is the primary structural support material in most plants. The new research takes five conventional pretreatment technologies for plant materials and modifies them to produce both biofuel and plastics together at a lower cost. The new method is called “plug-in preconditioning processes of lignin” and it can be directly and economically added into current biorefineries. The process is designed to integrate dissolving, conditioning, and fermenting lignin, extracting energy from it and making it easily adaptable to biorefinery designs.

The so-called bioeconomy currently supports some 286,000 jobs. Innovation is the key to achieving more widespread use of biodegradable plastic. With improved economics of so-called lignocellulosic biorefineries, there can be new avenues to use agricultural waste to produce biodegradable plastics.

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‘Plugging in’ to produce environmentally friendly bioplastics

Photo, posted November 5, 2015, courtesy of Kathryn Faith via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Transparent Wood | Earth Wise

June 14, 2021 By EarthWise Leave a Comment

In recent years, there have been efforts to change the nature of wood to give it new properties. People have demonstrated so-called augmented wood with integrated electronics, energy storage capabilities, and other properties. Several different groups of researchers have developed wood that is actually transparent.

In 2016, researchers at KTH Royal Institute of Technology in Stockholm demonstrated transparent wood made by selectively extracting lignin – the substance that makes up the cell walls of wood -and replacing it with a polymer. The result is a new material that is weatherproof, fairly fire resistant, stronger than wood, lighter than wood, and transparent.

When the lignin is removed from wood, the empty pores left behind need to be filled with something that restores the wood’s strength. The early versions of transparent wood used polymethyl methacrylate – essentially acrylic plastic – for this purpose. But that material is made from petroleum, so it is not an environmentally desirable approach.

Recently, the KTH researchers have successfully tested an eco-friendly alternative: limonene acrylate, which is a monomer made from renewable citrus, such as peel waste that can be recycled from the orange juice industry.

There are many potential applications for transparent wood as a structural material. These include load-bearing windows, skylights, and semi-transparent facades that are strong and thermally insulating and yet permit light to enter.

Transparent wood would be a very attractive material for many applications in that it comes from renewable sources and offers excellent mechanical properties including strength, toughness, low density, and low thermal conductivity.

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Citrus derivative makes transparent wood 100 percent renewable

Photo, posted October 12, 2018, courtesy of Mussi Katz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Sustainable Polymer From Wood | Earth Wise

February 24, 2021 By EarthWise Leave a Comment

Scientists from the University of Bath in the UK have developed a sustainable polymer using xylose, a sugar found in wood.

The new polymer is a member of the polyether family. It could be used in a variety of applications, including being a building block for polyurethane, used for example in mattresses and shoe soles. It could also be a bio-derived alternative to polyethylene glycol, a chemical widely used in biomedicine, or in polyethylene oxide, which is sometimes used as an electrolyte in batteries.

Xylose, also known as wood sugar, is one of the most abundant carbohydrates on earth, second only to glucose. Apart from comprising 5-20% of hardwoods, xylose is a major component of straw, corncobs, and many other plant materials.

The new polymer could reduce reliance on crude oil products and its properties can be easily controlled to make the material flexible or crystalline. Added functionality could be added to it by binding other chemical groups such as fluorescent probes or dyes to the sugar molecule for biological or chemical sensing applications.

Tweaking the physical and chemical properties of bio-derived polymers has previously been a very difficult thing to do. The Bath researchers discovered that combining two mirror-image chemical forms of xylose results in a stronger and more adaptable material. They have filed a patent for their technology and are seeking industrial collaborators for further development.

The reliance of plastics and polymers on fossil fuels is a major problem. Bio-derived polymers, such as this new one, are an important part of the effort to make plastics sustainable.

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Scientists make sustainable polymer from sugars in wood

Photo, posted January 25, 2017, courtesy of Keith Double via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sustainable Plastics

January 28, 2019 By EarthWise Leave a Comment

According to the United Nations, plastic accounts for up to 90% of all the pollutants in the ocean. Conventional plastics take hundreds of years to decay, so all the plastic that gets into the oceans piles up and endangers marine life and pollutes the environment. Unfortunately, there are few comparable, environmentally friendly alternatives.

An often-proposed solution is bioplastics, which are not made from petroleum and degrade quickly. The downside of bioplastics is that growing the plants or bacteria used to make the plastic requires fertile soil and fresh water, which are scarce commodities in many places.

One such place is Israel. So, researchers there at Tel Aviv University have developed a process to make a bioplastic polymer that doesn’t require land or fresh water. The new polymer is derived from microorganisms that feed on seaweed. It is biodegradable, produces zero toxic waste and recycles into organic waste.

The polymer is called polyhydroxyalkanoate, or PHA for short. The raw material is multicellular seaweed, cultivated in the ocean. These algae are eaten by single-celled microorganisms, which also grow in salty seawater and produce a polymer that can be used to make bioplastic. PHA is already produced in commercial quantities, but it is currently made from plants that require agricultural land and fresh water. The new process would enable countries with limited fresh water, such as Israel, China and India, to switch from petroleum-based plastics to biodegradable plastics.

Plastics from fossil sources are one of the world’s biggest pollution problems. The new study shows that it is possible to produce bioplastic completely based on marine resources in an environmentally-friendly process.

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Sustainable ‘plastics’ are on the horizon

Photo, posted March 14, 2015, courtesy of Flickr.

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Infinitely Recyclable Plastic

June 8, 2018 By EarthWise Leave a Comment

Less than 10% of discarded plastic is recycled. This is one of the major reasons that plastic waste is such a threat to the environment. There are many challenges to recycling plastics. For one thing, there are many different types of plastic and if they are melted together, they tend to phase-separate like oil and water and the resultant substance is structurally weak. Sorting plastics by type is not a simple task. More generally, it is very difficult to produce plastic with its original properties from recycled feedstock. So recycled plastics generally end up being useful in only more limited applications.