green chemistry

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Green Chemistry
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SCH 3U- GREEN CHEMISTRY

• DEFINITION
• Green Chemistry is the utilisation 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. A manufacturing process is changed so
  it is less harmful to the environment.
• GREEN CHEMISTRY IS ABOUT
• Use of Renewable Resources
• Use of Catalysts To Increase Reaction Efficiency
• Use of Chemicals That Have Less Environmental
  Impact
• Use Less Energy
• Minimizing Waste
• 
  
  

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Green Chemistry Is About...
Waste
Materials
Hazard
Reducing
Risk
Energy
Cost
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Why do we need Green Chemistry ?

• Chemistry is undeniably a very prominent part of
  our daily lives.
• Chemical developments also bring new
  environmental problems and harmful unexpected
  side effects, which result in the need for
  greener chemical products.
• A famous example is the pesticide DDT.

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• Green chemistry looks at pollution prevention on
  the molecular scale and is an extremely important
  area of Chemistry due to the importance of
  Chemistry in our world today and the implications
  it can show on our environment.
• The Green Chemistry program supports the
  invention of more environmentally friendly
  chemical processes which reduce or even eliminate
  the generation of hazardous substances.
• This program works very closely with the main
  principles of Green Chemistry.

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The Five Major Principles of Green Chemistry

• Use Renewable Resources as Starting Materials
• Many manufacturing processes are well established
  and accepted, but it is worthwhile to look for a
  better starting material.
• The plastic industry as an example is considering
  new options. Adipic Acid which is a benzene
  derivative is a key ingredient in making plastics
  like nylon and polyurethane. Benzene is derived
  from oil, a cancer-causing substance and
  non-renewable.
• Glucose can be made from renewable resources such
  as starch from food crops. There is still concern
  about the use of land and possible increase in
  food costs.
• Use less plastic?????

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A raw material of feedstock should be
renewablerather than depleting wherever
technically andeconomically practical
Non-renewable
Renewable
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Resource Depletion

• Renewable resources can be made increasingly
  viable technologically and economically through
  green chemistry.

Carbondioxide
Biomass
Nanoscience
Solar
Waste utilization
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Poly lactic acid (PLA) for plastics production
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Polyhydroxyalkanoates (PHAs)
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The Five Major Principles of Green Chemistry

• 2. Use Chemicals With Less Environmental Impact
• Polystyrene (Styrofoam) is used for cups and
  packing materials. Liquid polystyrene is injected
  into a mould and then a gas is injected to expand
  the material to the shape of the mould.
• CFCs were used previously, but it was found that
  CFCs escape into the atmosphere and breakdown
  ozone. Wide-scale use of CFCs lead to a thinning
  of the ozone layer.
• Chemists at DOW manufacturing in the 1990s used
  carbon dioxide as the expanding agent instead of
  CFCs. It was cheaper, non-flammable (safer for
  worker) and less harmful for the environment. CO2
  is a greenhouse gas, so the process is not
  totally benign.

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The Five Major Principles of Green Chemistry

• 3. Use Catalysts To Increase Reaction Efficiency
• Catalysts make reactions go faster and are not
  consumed in the reaction, therefore it can be
  used over and over again.
• Sulfuric acid, H2SO4(aq) is an important chemical
  made with a catalyst of vanadium oxide, V2O5.
• Pure Sulfur is converted to sulfuric acid in a
  three step process.
• Sulfur is burned to produce sulfur dioxide
• Sulfur dioxide is converted to sulfur trioxide
  very slow. The vanadium catalyst is used to
  speed up this step.
• Sulfur trioxide mixes with water to produce
  sulfuric acid.

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The Five Major Principles of Green Chemistry

• 4. Use Less Energy
• - Many manufacturing industries use a lot of
  energy which is financially and environmentally
  costly. The steel industry is very energy
  intensive
• - Updating equipment like the use of more
  efficient blast furnaces reduces energy costs.
  Smaller amounts of fossil fuels are used in the
  process and less pollutants result. The initial
  cost of new equipment can be offset by greater
  production and less materials used.
• - Companies can also use less energy by changing
  the process itself or using different materials
  to result in energy savings and less pollutants.

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The Five Major Principles of Green Chemistry

• 5. Minimize Waste
• - Lead and sulfuric acid in car batteries are
  hazardous. A Canadian battery recycler has
  developed a closed loop process so that old
  batteries go in clean, recycled materials come
  out.
• - There are only a few places in the process open
  to the atmosphere, but exhaust hoods are used to
  collect dust and vapour and return it to the
  process.
• - The closed loop process prevents hazardous
  materials from escaping into the environment.
  This results in less waster, safer working
  conditions, and a cleaner environment. Worker
  productivity increases and waste clean-up cost
  decrease.

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It is better to prevent waste than to treat or
cleanup waste after it is formed
Chemical Process
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Energy requirements should be recognized for
their environmental impacts and should be
minimized.Synthetic methods should be conducted
at ambientpressure and temperature
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The major uses of GREEN CHEMISTRY

• Energy
• Global Change
• Resource Depletion
• Food Supply
• Toxics in the Environment

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Energy

• The vast majority of the energy generated in the
  world today is from non-renewable sources that
  damage the environment.
• Carbon dioxide
• Depletion of Ozone layer
• Effects of mining, drilling, etc
• Toxics

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Energy

• Green Chemistry will be essential in
• developing the alternatives for energy
  generation (photovoltaics, hydrogen, fuel cells,
  biobased fuels, etc.) as well as
• continue the path toward energy efficiency with
  catalysis and product design at the forefront.

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Global Change

• Concerns for climate change, oceanic temperature,
  stratospheric chemistry and global distillation
  can be addressed through the development and
  implementation of green chemistry technologies.

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Resource Depletion

• Due to the over utilization of non-renewable
  resources, natural resources are being depleted
  at an unsustainable rate.
• Fossil fuels are a central issue.

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Resource Depletion

• Renewable resources can be made increasingly
  viable technologically and economically through
  green chemistry.
• Biomass
• Nanoscience technology
• Solar
• Carbon dioxide
• Chitin
• Waste utilization

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Food Supply

• While current food levels are sufficient,
  distribution is inadequate
• Agricultural methods are unsustainable
• Future food production intensity is needed.
• Green chemistry can address many food supply
  issues

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Food Supply

• Green chemistry is developing
• Pesticides which only affect target organisms
  and degrade to non-harming by-products.
• Fertilizers that are designed to minimize usage
  while maximizing effectiveness.
• Methods of using agricultural wastes for
  beneficial and profitable uses.

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Toxics in the Environment

• Substances that are toxic to humans, the
  biosphere and all that sustains it, are currently
  still being released at a cost of life, health
  and sustainability.
• One of green chemistrys greatest strengths is
  the ability to design for reduced hazard.

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Conclusion
Green chemistry Not a solution to all
environmental problems But the most fundamental
approach to preventing pollution.
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Homework - Apply the five principles of Green
Chemistry to the Pulp and Paper Industry or
another common manufacturing industry in Canada