Green Chemistry and Sustainable Design

The twenty-first century presents us with many interrelated challenges. Among them is the relationship between human industry and natural systems. Industrial activities have traditionally gone hand-in-hand with material processes that endanger the health of people and other living beings, both in the immediate present (e.g. toxic pollutants, habitat destruction) and in the future (e.g. persistent toxicants, resource depletion, climate change). Broadly, this has been the result of a tendency to neglect the context of industrial operations within the larger systems of ecology and society. Increasingly, we are realizing that this design philosophy must be improved. Rather than attempting to remedy or lessen the impacts of hazardous practices, we should avoid undertaking them in the first place.

As chemists, we are uniquely equipped to address this problem. The science of chemistry stands to contribute critical tools for redesigning production, and for putting into practice a philosophy of sustainability. New materials and technologies for industrial and consumer uses are already routinely developed on the molecular level by chemists. The next step is to learn how to simultaneously consider toxicity, safety, environmental fate and lifecycle along with function, use and cost when developing new substances and technologies; to learn how to eliminate waste before it is generated, by developing materials that are integrated into material cycles by design. With common consumer products increasingly being implicated as health hazards, and with global chemical production occurring on the scale of billions of tons per year, green chemistry and sustainable design are highly relevant research areas that have a great potential for beneficial impact.


What is Green Chemistry?

Green chemistry, as first defined by Paul Anastas and John Warner in their book Green Chemistry: Theory and Practice, is:

The utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products.
 

Twelve Principles of Green Chemistry

  1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.
  2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.
  3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.
  4. Use renewable feedstock: Use raw materials and feedstock that are renewable rather than depleting. Renewable feedstock are often made from agricultural products or are the wastes of other processes; depleting feedstock are made from fossil fuels (petroleum, natural gas, or coal) or are mined.
  5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.
  6. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
  7. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.
  8. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. If a solvent is necessary, water is a good medium as well as certain eco-friendly solvents that do not contribute to smog formation or destroy the ozone.
  9. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.
  10. 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.
  11. 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.
  12. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.
 

References

  1. Paul T. Anastas and John C. Warner, Green Chemistry: Theory and Practice. Oxford University Press, 2000.
  2. William McDonough and Michael Braungart, Cradle to Cradle: Remaking the Way We Make Things. New York: North Point Press, 2002.
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