From Linear to Circular: Chemistry’s Pathway to Sustainability

It is a decade since the UN adopted the 2030 Sustainable Development Goals and the Panel Discussion on Sustainability on Thursday, 3 July 2025, starting 10:25 CEST, in occasion of the 74^th Lindau Nobel Laureate Meeting, will focus on this key theme.

Chemistry and industry have been intertwined since the 19^th century and are still mostly based on the use of finite resources (water, air, minerals, fossil fuels). The lifecycle of chemical processes and products is linear, using a “take-make-use-dispose” model, where resources are used and lost throughout the process, and more and more waste is produced. This approach has long been viewed as unsustainable. A well-known example is the massive disposal of plastic waste: in 2015, it was estimated that only 9% of plastic waste was recycled, while 12% was incinerated, and 79% ended up in landfills.

The repurposing of chemical products into new materials has been practiced for decades, yet various errors in the processes have taken place, such as recycling products containing hazardous chemicals into food packaging, kitchen utensils or toys. The advent of green chemistry and sustainable chemistry in the 1990s set the stage for today’s concept of circular chemistry – new materials should generate as little waste as possible, including atoms at the molecular scale, chemical processes should be less toxic and should generate less pollution, renewable starting materials (such as bio-sourced materials) should be prioritized over fossil fuels, and chemicals, as well as products, should ideally degrade after use.

The Principles of Green Chemistry

But the principles of green chemistry are also mostly linear; for example, biopolymers still contain toxic chemicals and micro(nano)plastics, which leach into the soil and water. It’s a good alternative to traditional plastics, but not a viable solution to the problem.

In circular chemistry, waste becomes a resource, and the use of resources and energy are minimized at the onset of production. In 2019, Keijer et al. introduced the 12 principles of circular chemistry:

1. Collect and use waste: looking at waste as a valuable resource and recirculating molecules and materials
2. Maximize atom circulation: ensuring that all atoms in a molecule are used, which starts with appropriate molecule design
3. Optimize resource efficiency: reuse of materials, which limits the use of finite resources
4. Strive for energy persistence: capturing the energy output when reusing waste material
5. Enhance process efficiency: maximizing the reuse and recycling of materials during and after the chemical process
6. No out-of-plant toxicity: reducing the release of toxic chemicals into the environment as much as possible
7. Target optimal design: designing products in the most sustainable way regarding their end-of-life
8. Assess sustainability: determining the sustainability of chemical products throughout their life cycle
9. Apply the ladder of circularity: reject, reduce, reuse, redistribute, repair, refurbish, repurpose, remanufacture, recycle, recover, return – in chemical processes
10. Sell service, not product: centering on companies that manufacture chemical products and know how to repurpose them, limiting waste
11. Reject lock-in: helping businesses adapt to changes in how their products are made – incentivizing innovation despite longer production times and higher costs
12. Unify industry and provide a coherent policy framework: industry and policymakers should work together to ensure the development of circular chemistry.

Innovation Is the Basis of Circular Chemistry

As we can see from these principles, innovation is the foundation of circular chemistry, as both new and existing products will have to be designed or redesigned, even at the molecular level, to ensure their sustainability and circularity. Many dependable and even simple chemical processes will have to go back to the drawing board for optimization. It is anticipated that basic science may again become an important part of chemistry. Already, new journals focusing on circular chemistry are being established and may serve as an outlet for breakthroughs in this new field.

It is critical for various industries and companies to work together, to enable the optimization of chemical processes and new technologies from start to finish. Also, policy will play a vital role in bringing together chemists, engineers, and business leaders to develop and adopt the principles of circular chemistry in a wide range of areas – the production of food, polymers, pharmaceuticals, and energy, among many others.

Many scientists see circular chemistry as a revolution in science. It may take many years to adapt research and industry to this new reality but upholding the status quo in the wasteful practices of today’s chemical industry may with time become unaffordable as well as unsustainable.

Don’t miss the livestream of the referring Panel Discussion on 3 July 2025!

Panel Discussion on Sustainability Livestream