Green Chemistry
Definition
of green chemistry
Green
chemistry is the design of chemical products and processes that reduce or
eliminate the use or generation of hazardous substances.
Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal. Green chemistry is also known as sustainable chemistry.
Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal. Green chemistry is also known as sustainable chemistry.
Green
chemistry's 12 principles
These
principles demonstrate the breadth of the concept of green chemistry:
1.
Prevent
waste: Design chemical syntheses to
prevent waste. Leave no waste to treat or clean up.
2. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. Waste few or no atoms.
3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to either humans or the environment.
4. Design safer chemicals and products: Design chemical products that are fully effective yet have little or no toxicity.
5. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If you must use these chemicals, use safer ones.
6. Increase energy efficiency: Run chemical reactions at room temperature and pressure whenever possible.
7. 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.
8. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
9. 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.
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 physical forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.
Green chemistry aims to design and produce cost-competitive chemical products and processes that attain the highest level of the pollution-prevention hierarchy by reducing pollution at its source.
Benefits of Green Chemistry
Human health:
Ø Cleaner air: Less release of
hazardous chemicals to air leading to less damage to lungs
Ø Cleaner water: less release of
hazardous chemical wastes to water leading to cleaner drinking and recreational
water
Ø Increased safety
for workers in the chemical industry; less use of toxic materials; less
personal protective equipment required; less potential for accidents (e.g.,
fires or explosions)
Ø Safer consumer
products
of all types: new, safer products will become available for purchase; some
products (e.g., drugs) will be made with less waste; some products (i.e.,
pesticides, cleaning products) will be replacements for less safe products
Ø Safer food: elimination of
persistent toxic chemicals that can enter the food chain; safer pesticides that
are toxic only to specific pests and degrade rapidly after use
Ø Less exposure to
such toxic chemicals
as endocrine disruptors
Environment:
Ø Many chemicals
end up in the environment by intentional release during use (e.g., pesticides),
by unintended releases (including emissions during manufacturing), or by
disposal. Green chemicals either degrade to innocuous products or are
recovered for further use
Ø Plants and
animals suffer less harm from toxic chemicals in the environment
Ø Lower potential
for global warming,
ozone depletion, and smog formation
Ø
Less chemical disruption of ecosystems
Ø Less use of
landfills,
especially hazardous waste landfills
Economy and business:
Ø Higher yields
for chemical reactions, consuming smaller amounts of feedstock to obtain
the same amount of product
Ø Fewer synthetic
steps,
often allowing faster manufacturing of products, increasing plant capacity, and
saving energy and water
Ø Reduced waste, eliminating
costly remediation, hazardous waste disposal, and end-of-the-pipe treatments
Ø Allow replacement
of a purchased feedstock by a waste product
Ø Better
performance so
that less product is needed to achieve the same function
Ø Reduced use of
petroleum products,
slowing their depletion and avoiding their hazards and price fluctuations
Ø Reduced
manufacturing plant size or footprint through increased throughput
Ø
Increased consumer sales by earning and
displaying a safer-product label (e.g., Safer Choice labeling)
Ø Improved
competitiveness
of chemical manufacturers and their customers
Sources
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