How Chemical Recycling Technology Could Help Fix Plastic Pollution

How Chemical Recycling Technology Could Help Fix Plastic Pollution Mountains of plastic. Shutterstock/MOHAMED ABDULRAHEEM

It’s impossible to imagine everyday life without plastics. Lightweight, durable and cheap, these materials outperform many others in a diverse range of applications.

Plastics have brought about positive change in ways we often overlook. For example, the development of plastic components in electronic devices, such as the one you’re using to read this article, means we’ve never been more connected to the world around us.

 Get The Latest By Email

Weekly Magazine Daily Inspiration

But our love of plastics has come at an environmental cost. It’s been estimated that of the 8.3 billion tonnes of plastic made between 1950 to 2015, over 75% is now waste, with 79% accumulating in either landfill or the natural environment.

For scale, that’s more than all living things on Earth, and our oceans are drowning in plastic. Because of this, recent research efforts have focused on addressing these mounting environmental concerns. One of these is chemical recycling.

The value of plastic

To overcome the huge environmental concerns created by plastic we need to start valuing plastic waste as a resource. After all, plastic waste contains value in the form of stable chemical bonds, so at the very least we should try to recover that energy. In fact, the stability of these bonds is why plastics linger for so long in the environment.

Beyond burning plastic to recover this energy, we can also recycle plastic. The world currently relies on mechanical recycling, where plastics are sorted, melted and remoulded to create mainly lower-grade plastic products. But this process is limited. The harsh conditions involved mean each time a piece of plastic is recycled, its performance properties are negatively affected. This limits the number of times a piece of plastic can be recycled.

To make sure plastic keeps its value in the long term, we need alternative recycling strategies. Chemical recycling provides the potential for infinite recyclability. But the challenge lies in achieving it in a sustainable and economic way at scale. Traditional methods are usually costly and energy or resource intensive, which has limited their widespread use.

Chemical recycling

Plastics are made up of long-chain molecules known as polymers, which consist of smaller repeating building blocks called monomers. These monomers come in different shapes and sizes, and the bonding between them determines the plastic’s material properties – such as melting temperature and toughness – which affects the way it is used.

While mechanical recycling involves melting, chemical recycling relies on a chemical transformation and thus breaking the links between monomers. Chemical recycling breaks the plastic down at a molecular level. This means the monomer can be recovered in what’s called closed-loop recycling or the plastic waste can be transformed into other higher-value chemicals in open-loop recycling. For many types of plastic, it’s possible to recover monomers or other useful materials.

Some plastics, such as polyolefins – the material in a polyethylene plastic bag – don’t have weak monomer links, making it harder to chemically recycle them. In such cases, a process called pyrolysis is used, a different process to burning, which relies on high reaction temperatures to typically produce fuels and waxes.

How Chemical Recycling Technology Could Help Fix Plastic Pollution Sorting plastic. Shutterstock/Peryn22


Catalysts are used in around 90% of industrial chemical processes. They make the process more efficient by providing the reaction with an alternative route, much like the way Google maps optimises your journey. They can also allow us to be selective about what product is created and reduce waste. Such benefits are central to ensuring chemical recycling can be performed both sustainably and economically at an industrial scale.

The enzymes that were working tirelessly during your last meal are naturally occurring catalysts that play an important role in digestion. Enzymes that can even break down plastics have been reported.

However, these processes are limited by their productivity and require specific process conditions – such as the right temperature and pH – to keep the enzyme active. But given how rapidly the field is advancing, using naturally occurring catalysts may be commercially viable in the future.

We’ve developed highly efficient metal-based catalysts for the chemical recycling of polylactic acid (PLA), a plastic made from plant starch. This work used cheap and abundant metals – such as zinc or magnesium – targeting chemicals called lactate esters, which are a potential green alternative to petroleum-based solvents.

This area remains in its infancy, but we expect significant developments, particularly in process optimisation, to be made as the field gathers momentum. This is in fact a general endeavour of the field because traditional methods typically use harsh chemicals, and can be resource and energy intensive.

Beyond PLA, there is the potential to “up-cycle” other plastics, such as polyethylene terephthalate (PET), which is used for plastic bottles. Recent examples include building blocks for high-performance materials and antibiotics and corrosion inhibitors from PET waste.

Our recent work has also investigated the chemical recycling of PET, which is used far more extensively. PET is used more widely in plastic bottles and food containers, while PLA takes up a much smaller share of the market, used mostly for 3D printing, biomedical devices and certain packaging applications.

Looking ahead

Given societies diverse plastic use, a one-solution-fits-all approach is not feasible. Diverse and tailored recycling strategies are needed for both existing and new emerging plastics. However, commercial-scale chemical recycling operations are underway.

In the future, we expect chemical recycling to complement its mechanical counterpart, especially for difficult to recycle materials such as thin-films. One thing is for certain, plastics are here to stay. With production expected to exceed one billion tonnes by 2050, chemical recycling promises to be an exciting space to watch.The Conversation

About The Author

Matthew Jones, Professor, Department of Chemistry, University of Bath, University of Bath and Jack Payne, PhD Candidate, Centre for Sustainable and Circular Technologies, University of Bath

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Recommended books:

Capital in the Twenty-First Century
by Thomas Piketty. (Translated by Arthur Goldhammer)

Capital in the Twenty-First Century Hardcover by Thomas Piketty.In Capital in the Twenty-First Century, Thomas Piketty analyzes a unique collection of data from twenty countries, ranging as far back as the eighteenth century, to uncover key economic and social patterns. But economic trends are not acts of God. Political action has curbed dangerous inequalities in the past, says Thomas Piketty, and may do so again. A work of extraordinary ambition, originality, and rigor, Capital in the Twenty-First Century reorients our understanding of economic history and confronts us with sobering lessons for today. His findings will transform debate and set the agenda for the next generation of thought about wealth and inequality.

Click here for more info and/or to order this book on Amazon.

Nature's Fortune: How Business and Society Thrive by Investing in Nature
by Mark R. Tercek and Jonathan S. Adams.

Nature's Fortune: How Business and Society Thrive by Investing in Nature by Mark R. Tercek and Jonathan S. Adams.What is nature worth? The answer to this question—which traditionally has been framed in environmental terms—is revolutionizing the way we do business. In Nature’s Fortune, Mark Tercek, CEO of The Nature Conservancy and former investment banker, and science writer Jonathan Adams argue that nature is not only the foundation of human well-being, but also the smartest commercial investment any business or government can make. The forests, floodplains, and oyster reefs often seen simply as raw materials or as obstacles to be cleared in the name of progress are, in fact as important to our future prosperity as technology or law or business innovation. Nature’s Fortune offers an essential guide to the world’s economic—and environmental—well-being.

Click here for more info and/or to order this book on Amazon.

Beyond Outrage: What has gone wrong with our economy and our democracy, and how to fix it -- by Robert B. Reich

Beyond OutrageIn this timely book, Robert B. Reich argues that nothing good happens in Washington unless citizens are energized and organized to make sure Washington acts in the public good. The first step is to see the big picture. Beyond Outrage connects the dots, showing why the increasing share of income and wealth going to the top has hobbled jobs and growth for everyone else, undermining our democracy; caused Americans to become increasingly cynical about public life; and turned many Americans against one another. He also explains why the proposals of the “regressive right” are dead wrong and provides a clear roadmap of what must be done instead. Here’s a plan for action for everyone who cares about the future of America.

Click here for more info or to order this book on Amazon.

This Changes Everything: Occupy Wall Street and the 99% Movement
by Sarah van Gelder and staff of YES! Magazine.

This Changes Everything: Occupy Wall Street and the 99% Movement by Sarah van Gelder and staff of YES! Magazine.This Changes Everything shows how the Occupy movement is shifting the way people view themselves and the world, the kind of society they believe is possible, and their own involvement in creating a society that works for the 99% rather than just the 1%. Attempts to pigeonhole this decentralized, fast-evolving movement have led to confusion and misperception. In this volume, the editors of YES! Magazine bring together voices from inside and outside the protests to convey the issues, possibilities, and personalities associated with the Occupy Wall Street movement. This book features contributions from Naomi Klein, David Korten, Rebecca Solnit, Ralph Nader, and others, as well as Occupy activists who were there from the beginning.

Click here for more info and/or to order this book on Amazon.

You May Also Like

English French Spanish

follow InnerSelf on

facebook icontwitter iconyoutube iconinstagram iconpintrest iconrss icon

 Get The Latest By Email

Weekly Magazine Daily Inspiration

New Attitudes - New Possibilities | | | InnerSelf Market
Copyright ©1985 - 2021 InnerSelf Publications. All Rights Reserved.