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Green Chemistry & Green Engineering Defined

Green Chemistry

Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances.

12 Principles of Green Chemistry

  1. Prevention
    It is better to prevent waste than to treat or clean up waste after it has been created.
  2. Atom Economy
    Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.
  3. Less Hazardous Chemical Syntheses
    Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
  4. Designing Safer Chemicals
    Chemical products should be designed to effect their desired function while minimizing their toxicity.
  5. Safer Solvents and Auxiliaries
    The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.
  6. Design for Energy Efficiency
    Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure.
  7. Use of Renewable Feedstocks
    A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.
  8. Reduce Derivatives
    Unnecessary derivatization (use of blocking groups, protection/ deprotection, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste.
  9. Catalysis
    Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
  10. Design for Degradation
    Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.
  11. Real-time analysis for Pollution Prevention
    Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.
  12. Inherently Safer Chemistry for Accident Prevention
    Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires.

Anastas, P. T. and Warner, J. C. Green Chemistry: Theory and Practice. Oxford University Press: New York, 1998, p. 30. By permission of Oxford University Press.

Green Engineering

Green Engineering is the development and commercialization of industrial processes that are economically feasible and reduce the risk to human health and the environment.

12 Principles of Green Engineering

  1. Inherent Rather Than Circumstantial
    Designers need to strive to ensure that all materials and energy inputs and outputs are as inherently nonhazardous as possible.
  2. Prevention Instead of Treatment
    It is better to prevent waste than to treat or clean up waste after it is formed.
  3. Design for Separation
    Separation and purification operations should be designed to minimize energy consumption and materials use.
  4. Maximize Efficiency
    Products, processes, and systems should be designed to maximize mass, energy, space, and time efficiency.
  5. Output-Pulled Versus Input-Pushed
    Products, processes, and systems should be "output pulled" rather than "input pushed" through the use of energy and materials.
  6. Conserve Complexity
    Embedded entropy and complexity must be viewed as an investment when making design choices on recycle, reuse, or beneficial disposition.
  7. Durability Rather Than Immortality
    Targeted durability, not immortality, should be a design goal.
  8. Meet Need, Minimize Excess
    Design for unnecessary capacity or capability (e.g., "one size fits all") solutions should be considered a design flaw.
  9. Minimize Material Diversity
    Material diversity in multicomponent products should be minimized to promote disassembly and value retention.
  10. Integrate Material and Energy Flows
    Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows.
  11. Design for Commercial "Afterlife"
    Products, processes, and systems should be designed for performance in a commercial "afterlife."
  12. Renewable Rather Than Depleting
    Material and energy inputs should be renewable rather than depleting.

*Anastas, P.T., and Zimmerman, J.B., "Design through the Twelve Principles of Green Engineering", Env. Sci. Tech. 2003, 37(5), 94A-101A.