Designing a safer circular economy of chemicals

Sustainability, chemical safety, and circular economy represent holistic frameworks that support chemical synthesis, design, manufacturing, use, reuse, recycling, and disposal to create a closed-loop economic production system. Also, these frameworks target minimizing waste generation, energy consumption, and fresh raw material needs, maximizing resource efficiency, and economic, social, and environmental benefits. Therefore, designing a safer economy for chemicals includes the contribution of all chemical life cycle stages, starting from utilizing safer renewable feedstocks, developing safer chemical products, implementing sustainable chemical manufacturing systems, effective regulatory foundations, and non-destructive end-of-life management systems.

Safer and renewable chemical feedstocks

Safer and renewable chemical raw materials support a more sustainable chemical industry. Renewable and abundant feedstocks like plant biomass and agricultural organic end-of-life (EoL) materials offer a sustainable alternative to non-renewable fossil-based resources, substantially reducing the environmental footprint of chemical manufacturing (Lamolinara et al. 2022; Takkellapati et al. 2018). For example, lignocellulosic biomass (cellulose, hemicellulose, and lignin) can be a feedstock for manufacturing biofuels, chemical commodities, and polymers without competing with food security (Isikgor and Becer 2015). Also, safer chemical feedstocks facilitate the synthesis of valuable products while generating less hazardous by-product substances (Sheldon 2020). Therefore, employing renewable and safer feedstocks promotes resource efficiency while minimizing environmental and human health impacts and EoL hazardous material generation. Moreover, continuous progress in the synthesis of biocatalysts, metabolic engineering, and synthetic biology expands the efficiency and synthesis routes for manufacturing high-value fine chemicals from renewable feedstocks in more sustainable chemical/biochemical processes (García-Granados et al. 2019).

Synthesizing safer chemical products

Design and synthesis of environmentally benign chemicals are the core of a safer circular economy for chemicals. Green chemistry principles play a crucial role as the foundational guidelines to chemists on designing chemical reactions that minimize the use and generation of hazardous substances, yield commercial products degrading naturally after their use stage, employ safer solvents, and run under safer reaction conditions (Anastas and Eghbali 2010). However, chemical product designers need to ensure a safer circular economy when developing persistent chemicals that can be durable, reused, and recycled. In addition, it is necessary to evaluate and ensure that any environmental releases from any chemical life cycle stage do not persist and bioaccumulate to minimize the likelihood of long-term exposure. Therefore, safer sustainable chemicals should supply a service and fulfill commercial needs, but they should also fundamentally include sustainability and hazard minimization (van Dijk et al. 2022).

Sustainable chemical manufacturing systems

Chemical manufacturing systems provide products and services that significantly enhance human quality of life. However, converting feedstocks into valuable chemical products requires environmental resources and managing the impact of environmental releases. Therefore, sustainable chemical manufacturing systems are imperative to minimize adverse environmental and human health impacts. To do so, stakeholders need to assess sustainability, find the most effective path to achieve enhanced sustainability performance, and evaluate the progress toward a more sustainable position. Sustainability indicators can evaluate chemical manufacturing sustainability within the environmental, efficiency, energy, and economic domains to ease the development of the most sustainable processes within existing constraints. Sustainability assessment tools such as GREENSCOPE enable stakeholders to make informed decisions, find safer and more sustainable chemical manufacturing systems, and compare alternatives at various decision-making levels, thus contributing to the advancement of sustainability goals (Ruiz-Mercado et al. 2012a, b; 2013).

In addition, industrial symbiosis can aid sustainable manufacturing systems in transitioning into circular economy paths by incentivizing different chemical facilities to collaborate and use each other’s EoL streams as raw materials instead of generating environmental releases.

Effective regulatory foundations

The Frank R. Lautenberg Chemical Safety for the 21st Century Act, an amendment to the Toxic Substances Control Act (TSCA), mandates the US Environmental Protection Agency (EPA) to undertake risk assessments of high-priority chemicals currently in use (Hernandez-Betancur et al. 2023). Also, the European Union’s registration, evaluation, authorization, and restriction of chemicals (REACH) is another notable example aiming to support the safety and sustainability of chemicals within a circular economy perspective (European Chemicals Agency 2020). The primary objective of such regulatory frameworks is to ascertain whether a chemical substance in the market presents an unreasonable risk of harm to human health and the environment at various stages of its life cycle, including manufacturing, use, and EoL. These evaluations facilitate developing and selecting safer chemicals and materials and promote sustainable circular economy practices such as recycling, reusing, and recovery. It is important to note that the inventory of registered chemicals used in global commerce is continuously expanding.

In addition to regulatory frameworks, collaboration between industry, academia, and non-governmental organizations is essential to promote partnerships and adopt voluntary initiatives to develop and implement sustainable practices and safer chemicals. For instance, the green chemistry and commerce council (GC3) constitutes an alliance between businesses, government agencies, and non-governmental organizations to promote, develop, and use green chemistry solutions (GC3 2021).

Non-destructive EoL management systems

Non-destructive EoL methods, like reuse and recycling, are crucial components of a safer circular economy of chemicals. The aim is to minimize EoL environmental releases and ensure the harmless management, recycling, and reuse of chemicals to efficiently link their EoL and manufacturing stages (Perez et al. 2024). Also, incentivizing and implementing extended producer responsibility (ERP) programs encourage chemical producers to develop chemical products while considering their EoL stage to achieve greater reuse and recyclability (Chea et al. 2024). For example, advancing recycling paths for plastics, like chemical processing (alcoholysis, aminolysis, hydrolysis, glycolysis, catalytic, and methanolysis), can potentially support more sustainable alternatives in managing EoL plastics (Qian and Ren 2024). Chemical processing of plastics breaks down polymers into their monomers, enabling the production of new high-value chemicals, reducing the need for fresh feedstocks, and decreasing the overall impact of plastic life cycle footprint.

Conclusions

Designing a safer economy for chemical products needs a synergistic comprehensive approach that integrates safer and renewable chemical feedstocks, green chemistry principles to synthesize safer chemicals, sustainable chemical manufacturing systems, regulatory foundations, and non-destructive EoL management systems. Safer chemicals and sustainable practices prevent and control environmental and health impacts from chemical production and use. Transitioning to a circular economy of chemicals is challenging but, at the same time, offers opportunities for innovation, economic benefits, and environmental stewardship.