Green Chemistry: Where Scientific Principles meet Moral Principles

In my blog, we talk a lot about what it means to be bioinspired and its important new developments. But today, I want to zoom out a little bit to an overarching concept of sustainability that helps to govern and inform developments in chemical and bioinspired engineering: Green Chemistry. This post will look at the birth of Green Chemistry, explain what it means, and explore how Green Chemistry and bioinspiration are interrelated. 

Introducing Green Chemistry: 

Green Chemistry’s official definition is the “design of chemical products and processes to reduce or eliminate the use and generation of hazardous substances.”¹ The concept of Green Chemistry was founded in the 1990s by Paul Anastas—commonly acknowledged as the “Father of Green Chemistry” for coining the term when he worked for the EPA—and also John Warner. Together, in 1998, they published the book Green Chemistry: Theory and Practice.

To summarize the most important points of understanding for Green Chemistry, who better to quote than the Father of Green Chemistry himself: 

“The three main points about the Green Chemistry framework can be summarized as: 

1. Green Chemistry designs across all stages of the chemical life-cycle. 

2. Green Chemistry seeks to design the inherent nature of the chemical products and processes to reduce their intrinsic hazard. 

3. Green Chemistry works as a cohesive system of principles or design criteria.”¹ 

In order to maximize these goals for the design of new materials or chemical processes, there is a framework of 12 sustainability principles to follow (check out the pocket guide from ACS below!).² 

These principles would make a good parody to the song “The Twelve Days of Christmas”... just saying.

American Chemical Society (ACS): Poster for the 12 principles of Green Chemistry https://www.acs.org/green-chemistry-sustainability/principles/12-principles-of-green-chemistry.html

Here I’ll go down the list to briefly give the official definitions for each principle and explain what each one means:² 

1] Waste Prevention

This first principle states that it is more favorable to prevent the generation of byproducts/waste than to clean up after the fact. Waste prevention concerns both efficiency and cost by eliminating the need for extra waste management processes, while also ensuring environmental responsibility for potentially toxic, non-biodegradable, contaminated materials generated from manufacturing processes.

2] The Atom Economy 

The concept of the Atom Economy (also atom efficiency) is premised on maximizing chemical interactions at the molecular level so that the number of atoms in the reactants is the same as the number in the products, or more simply put, no raw materials are wasted. If you think about it, the term “Atom Economy” is actually pretty perfect! Scientists and engineers are visualizing and thinking about atomic interactions from an economic standpoint to “maximize profits,” where the profits are the atoms in the products themselves.

3] Less Hazardous Synthesis 

This principle urges chemists to think about not just the safety and sustainability of the final product of their experiment, but also the design of the chemical processes used along the way to make reactions happen. In order to get reactions that are kinetically and thermodynamically favorable, many chemists end up using typical synthetic protocols that utilize toxic materials. Creating fully “green” experiments requires us to find new safe materials and catalysts to use for reaction mechanisms.

4] Designing Safer Chemicals

Move away from chemicals known to be toxic and minimize toxicity by embracing new solutions directly through molecular design. A good example is trading out current plastics for PHA and PLA.

5] Safer Solvents and Auxiliaries Solvents are, in fact, one of the most well-researched areas in the field of emerging green chemistry, as most of the beloved, versatile solvents that are traditionally used are volatile, flammable, corrosive, toxic, etc. Reducing steps that require additional auxiliaries and solvents should also be a priority to limit the amount of waste generated for a given experiment. Some examples of greener solvent ideas include ionic liquids, water, supercritical fluids, and completely solventless systems.

6] Design for Energy Efficiency Going back to the very first principle, overconsumption of energy can also be considered waste. Energy-intensive equipment in laboratories for heating, cooling, or pressured vacuum systems all require lots of energy in order to operate. Using sustainable alternatives to power these sources—such as solar cells or hydrogen fuel cells—are all ways to mitigate this issue.

7] Renewable Feedstocks 

Feedstocks refer to the raw materials we extract to fuel industrial processes—think CO₂, oil, coal, etc. Green Chemistry aims to create bioenergy from renewable feedstock materials in order to address the sustainability crisis at its root, as well as to produce more efficient products that are safer for consumers and perform better. Examples of recent innovations using renewable feedstocks in the past decade include biodiesel from algae, cellulosic ethanol, and bio-based hydrocarbons.

8] Reduce Derivatives 

In chemistry, reducing derivatization steps refers to avoiding the use of protecting groups (temporary groups added to molecules to prevent specific portions from reacting) and unnecessary modifications in multi-step synthesis reactions in order to avoid generating excess toxic waste. Instead, Green Chemistry promotes finding ways to achieve direct synthesis or to use enzymes in chemical reactions, thereby reducing the number of steps and reagents required. You can think of Principle 8 as the “baby” of Principles 1 and 2—waste prevention and Atom Economy.

9] Catalysis 

Use catalytic reagents—substances that speed up chemical processes, are not consumed in the reaction, and can be used repeatedly— as opposed to stoichiometric reagents, which can only be used once. Keeping in mind the Atom Economy, the usage of catalysts should be as purposeful and selective as possible. 

10] Design for innocuous degradation 

Products should be designed with forward-thinking intent—so that they are able to undergo safe, non-toxic degradation in the environment and do not persist indefinitely in the future. Examples of safe degradation include biodegradable plastics, as well as other types of environmentally friendly breakdown processes such as photodegradation, and enzymatic degradation.

11] Real-Time Analysis for Pollution Prevention 

We already understand the need to limit pollution and environmental waste as outlined in some of the previous principles, but what is key about the 11th principle is the word “real-time.” In the same way that weather forecasters use real-time data sets to predict weather patterns, or traffic-route apps perform real-time analysis to give you the optimal road, Green Chemistry suggests that in order to properly control the generation of hazardous waste, real-time analytical methods must be developed to monitor experiments as they happen.

12] Safer Chemistry for Accident Prevention 

The twelfth and final principle is also commonly regarded as the “Safety Principle.” It urges chemical engineers to design chemicals—and their different physical states (solid, liquid, or gas)—to reduce their potential for accidents, such as lab explosions, fires, and harmful environmental releases.

Green Chemistry & Bioinspiration: How do they connect?

To preface, Green Chemistry and bioinspiration are distinct ideas and cannot be used interchangeably: Green Chemistry is a regulatory framework that emphasizes safety and sustainability, while bioinspiration is a type of engineering technique that draws on inspiration from nature. However, both Green Chemistry and bioinspired innovations are united by a common interest—in proving that new innovations, ones that are sustainable and better for the environment, can also be more efficient and improve on incumbent technologies.

You can think of bioinspiration as one avenue that scientists are exploring to achieve goals outlined in the 12 principles of Green Chemistry. For instance, take Principle 3, Less Hazardous Synthesis: bioinspired synthesis routes are being explored for the assembly of nanomaterials. This approach looks at bioinspired modifications to surfactants (compounds that lower surface tension), which offer a green alternative to the commercial single-use templates in mesoporous material synthesis, improving efficiency in nanomaterials research.³ 

In combination, Green Chemistry and bioinspiration help to pave a future where science doesn’t have to mean compromising on sustainability and ethics, but rather, there is a powerful synergy that comes when science is guided by them.

Citations + Additional Sources to check out!

1] Anastas, Paul T., and Nicolas Eghbali. "Green Chemistry: Principles and Practice." Chemical Society Reviews, vol. 39, no. 1, 2010, pp. 301–312. Royal Society of Chemistry, https://doi.org/10.1039/B918763B. 

2] American Chemical Society. “12 Principles of Green Chemistry.” ACS Green Chemistry & Sustainability, American Chemical Society. https://www.acs.org/green-chemistry-sustainability/principles/12-principles-of-green-chemistry.html 

3] Patwardhan, Siddharth V., Joseph R.H. Manning, and Mauro Chiacchia. "Bioinspired Synthesis as a Potential Green Method for the Preparation of Nanomaterials: Opportunities and Challenges." Current Opinion in Green and Sustainable Chemistry, vol. 12, 2018, pp. 110–116. Elsevier, https://doi.org/10.1016/j.cogsc.2018.08.004.

4] Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice; Oxford University Press; New York, 1998.

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