northwestern university

Researchers at Northwestern University have developed a new method for recycling plastic that is safer, cleaner, cheaper, and more sustainable than those currently in use. The U.S. is the world’s largest plastic polluter per capita, and we only recycle 5% of our plastics. There is a pressing need for better technologies for processing different types of plastic waste.

The Northwestern method is designed to break down polyethylene terephthalate or PET, which is the most common type of polyester plastic. PET plastic is used in food packaging and beverage bottles and represents 12% of total plastics used globally. It does not break down easily and is therefore a major contributor to plastic pollution. It mostly either ends up in landfills or, over time, degrades into tiny microplastics or nanoplastics that end up almost everywhere.

The non-toxic, environmentally friendly, solvent-free Northwestern process first uses an inexpensive molybdenum catalyst to break apart the bonds in PET. Then the broken plastic is exposed to ambient air. Just from the trace amounts of moisture in air, the broken-down PET is converted into monomers, which are the building blocks of plastic. The monomers could then be recycled back into PET products or used to make other valuable materials.

The process is fast and effective and takes just a few hours. The catalyst is durable and recyclable, meaning it can be used over and over again. It only works on polyesters, which means it can be used for recycling mixed plastics without sorting them since it will select only the PET from its inputs.

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Plastic recycling gets a breath of fresh air

Photo, posted August 10, 2013, courtesy of Lisa Risager via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Every year, 380 million tons of plastic are created worldwide, and that number continues to grow. Furthermore, more than 75% of these materials are discarded after one use. Much of it ends up in oceans and waterways, harming wildlife and spreading toxins.

Recycling most plastics is difficult because while they can be melted and reprocessed, the resultant material is not as structurally strong as the original material. Thus, plastics are often down-cycled such as turning plastic bottles into molded park benches.

Researchers at Northwestern University, Argonne National Laboratory, and Ames Laboratory have developed a new method for upcycling abundant, seemingly low-value plastics into high-quality liquid products, such as motor oils, lubricants, detergents, and even cosmetics. The catalytic method could remove plastic pollution from the environment and contribute to a circular economy.

Plastics don’t degrade when disposed of because they have very strong carbon-carbon bonds. Instead they just break into smaller bits, known as microplastics. The researchers viewed these strong bonds as an opportunity rather than a problem.

The new technique actually recoups the high energy that holds these bonds together by catalytically converting polyethylene molecules into value-added commercial products. The catalyst consists of platinum nanoparticles deposited onto perovskite nanocubes. Under moderate pressure and temperature, the catalyst cleaves the carbon-carbon bonds in plastic to produce high-quality liquid hydrocarbons.

The researchers believe these findings could lead to a future in which we can continue to benefit from plastic materials but do so in a way that is sustainable and less harmful to the environment.

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Turning plastic trash into treasure

Photo, posted August 15, 2012, courtesy of Emilian Robert Vicol via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A new way to recycle plastic

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Turning Trash Into Treasure

Every year, 380 million tons of plastic are created worldwide, and that number continues to grow. Furthermore, more than 75% of these materials are discarded after one use. Much of it ends up in oceans and waterways, harming wildlife and spreading toxins.

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