Green chemistry, also known as sustainable chemistry, was born out of the Pollution Prevention Act of 1990. The Act focuses on industry, government and public attention to reduce the amount of pollution through changes in production, operation and raw material use. And that is basically the definition of green chemistry. The Environmental Protection Agency (EPA) defines it as the design of chemical products and processes that reduce or eliminate the generation of hazardous substances.
The green design of these products is meant to cover its entire lifecycle, from the chemicals used, to the creation, the use, and the ultimate disposal of the product. There are a total of 12 green chemistry principals that must be followed:
- Prevent waste: Design chemical syntheses to prevent waste. Leave no waste to treat or clean up.
- Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. Waste few or no atoms.
- Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to either humans or the environment.
- Design safer chemicals and products: Design chemical products that are fully effective yet have little or no toxicity.
- Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If you must use these chemicals, use safer ones.
- Increase energy efficiency: Run chemical reactions at room temperature and pressure whenever possible.
- Use renewable feedstocks: Use starting materials (also known as feedstocks) that are renewable rather than depletable. The source of renewable feedstocks is often agricultural products or the wastes of other processes; the source of depletable feedstocks is often fossil fuels (petroleum, natural gas, or coal) or mining operations.
- Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
- Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are effective in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and carry out a reaction only once.
- Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.
- Analyze in real-time to prevent pollution: Include in-process, real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.
- Minimize the potential for accidents: Design chemicals and their physical forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.
Right now, the EPA is calling for nominees for the 2021 Green Chemistry Challenge Awards. These awards recognize U.S. businesses and researchers that have followed the above principals while creating new products. Nominations must be in by December 4, and the winners will be announced next June. Past award winners are responsible for:
- 826 million pounds of hazardous chemicals and solvents eliminated each year—enough to fill almost 3,800 railroad tank cars or a train nearly 47 miles long.
- 21 billion gallons of water saved each year—the amount used by 820,000 people annually.
- 7.8 billion pounds of carbon dioxide equivalents released to air eliminated each year—equal to taking 810,000 automobiles off the road.