Green chemistry is chemistry for the environment, including the production and use of less hazardous substances. Green chemistry is a creating new methods of thinking and creating, environmentally.
2. What is Green Chemistry?
Green chemistry is chemistry for the
environment, including the production
and use of less hazardous substances.
Green chemistry is a creating new
methods of thinking and creating,
environmentally. Green chemistry was
first introduced in the 20th Century
and is the combining together of tools,
techniques and technologies that
enables chemists all over the world to
develop more environmental and
efficient goods and procedures.
3. What’s The Purpose Of Green
Chemistry?
The purpose of green chemistry is to
discover new ways to make the best
chemical products and processes that
need less reagents, smaller amounts
of solvent, and fewer energy to make;
also being safer, producing less waste,
and increasing productivity.
There are 12 principles of green
chemistry that industries today
work around. These principles were
developed to assist reviewing how
environmentally benign [harmless]
a chemical reaction or process is.
5. As human beings --- we are part of the environment
The way in which we interact with our environment influences
the quality of our lives
Green
Chemistry
A tool
Industrial
ecology
Sustainable
development
the goal
Green chemistry, lies at the heart of the industrial ecology
7. Prevention
Atom
Economy
Less Hazardous
Chemical Synthesis
Designing Safer
Chemicals
Safer Solvents &
Auxiliaries
Design for Energy
Efficiency
Use of Renewable
Feedstocks
Reduce
Derivatives
Catalysis
Design for
Degradation
Safer Chemistry for
Accident Prevention
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Real time analysis for
Pollution Prevention
8. 1. Waste prevention
It is better to prevent the formation of
waste than to treat or clean up the waste.
Chemical wastes are undesirable products
from chemical reactions. They are usually
hazardous to the environment.
Industrial processes should be designed
to minimize the generation of waste.
9. 2. Maximizing atom economy
Traditionally, the success of a chemical
reaction is judged by the percentage
yield of product.
It is possible to achieve 100% yield but
the reaction may generate waste that is
far greater in mass and volume than that
of the desired product.
10. 3. Using less hazardous chemical
syntheses
Chemical syntheses should be designed to
use or generate substances that possess
little or no toxicity to humans and the
environment.
11. 4. Producing safer chemical
products
The chemical products synthesized
should be safe to use.
For example, chemicals called organotin
compounds(Anti-biofouling agent) were
used in large ships to prevent
accumulation of barnacles(藤壺) and
marine plants traditionally.
12. 5. Using safer solvents and
auxiliaries
The solvents and auxiliaries (e.g.
drying agent, blowing agent, etc.) used
in chemical syntheses will become part
of the wastes.
They may cause environmental pollution
and health hazard.
13. 6. Designing for energy efficiency
Chemical syntheses should be designed
to minimize the use of energy.
heat liquid mixtures for separating
and purifying products by distillation.
Energy is used to
raise the temperature of reactants
so that a reaction starts or goes on.
14. Using catalysts
- reactions at lower T & P
Using microwave heating
- more efficient
Using biosynthetic pathways
- reaction at ambient T & P
Ways to conserve energy:
15. 7. Using renewable raw materials
They are often made from agricultural
products.
E.g. glucose for making adipic acid
and vitamin C
biodiesel for motor vehicles
Renewable raw materials
16. Shredded paper (left) and seaweed (right) can be
used as the raw materials for the production of
synthesis gas
18. 8. Reducing derivatives
We should avoid unnecessary use of
synthetic steps in order to reduce the
derivatives of the desired product.
Otherwise, more reagents are needed
and more waste will be generated.
19. 9. Using catalysts
TAMLTM catalysts can be used to clean up
wastewater streams in the pulp and paper industry
Environmental benefits of using TAMLTM catalysts in
wastewater treatment
Decrease in
energy requirements
Elimination of chlorinated
organic substancesReduction in
water usage
Degradable
catalysts
20. 10. Designing degradable chemical
products
Many chemical products persist in the
environment after use.
They should be designed so that they
can be broken down into harmless
substances.
22. 11. Developing real-time analysis
for pollution prevention
When coal is burnt in industrial boilers, SO2 (a pollutant)
is formed.
Real-time monitoring system for
monitoring sulphur dioxide (SO2) level
If the temperature of the boilers is too high, a large
amount of SO2 will be generated.
Once it reaches an unacceptable level, an alarming signal
will be generated. Then the temperature will be lowered
immediately.
Using real-time monitoring, the amount of SO2
generated can be measured all the time.
23. 12. Minimizing the potential for
chemical accidents
Chemical accidents include leakages,
explosions and fires.
Minimize the use of volatile liquids or
gases which are associated with the
majority of chemical accidents.
If possible, allow reactions to proceed
under ambient T & P.
24. Examples of Green Chemistry
• New syntheses of Ibuprofen and Zoloft.
• Water based polyurethanes.
• Removing Arsenic and Chromate from
pressure treated wood.
• Many new pesticides.
• New oxidants for bleaching paper and
disinfecting water.
• Getting the lead out of automobile paints.
• Replacing VOCs and chlorinated solvents.
25. Conclusion
• Green Chemistry:
Preventing Pollution
Sustaining the Earth
Green chemistry has come a long way since its birth in 1991,
growing from a small grassroots idea into a new approach to
scientifically-based environmental protection
All over the world, governments and industries are working
with “green” chemists to transform the economy into a
sustainable enterprise
Who knows? Green chemistry may be the next social
movement that will set aside all the world’s differences and
allow for the creation of an environmentally commendable
civilization