sustainability and green chemistry

Sustainability and Green Chemistry

GREEN CHEMISTRYWhat is it? • encourages environmentally conscious behaviour

• reduces and prevents pollution• reduces the destruction of the planet

GREEN CHEMISTRY

Basics• better to prevent waste than to treat it afterwards• aim for maximum atom economy• use processes which require fewer chemicals• don’t make products that are toxic to human health • don’t make products that are toxic to the environment• reduce the energy requirements of processes• use alternative energy resources• use renewable raw materials, not finite resources• use catalysts where possible• waste products should be designed to be

biodegradable• reduce the risk of explosions and fires

The principles of Green Chemistry

The 6 key points:

Using industrial processes that reduce or eliminate hazardous chemicals and which involve the use of fewer chemicals

Designing processes with a high atom economy that minimise the production of waste materials

Using renewable resources such as plant-based substances

Seeking alternative energy sources such as solar energy, rather than consuming finite resources such as fossil fuels that will eventually be exhausted

Ensuring that any waste products produced are non-toxic, and can be recycled or biodegraded by being broken down into harmless substances in the environment

Establish international cooperation to promote the reduction of pollution levels

Using industrial processes that reduce or eliminate hazardous chemicals and which

involve the use of fewer chemicals

Example: Manufacture of Ibuprofen

Another example:

Lead has largely been eliminated from use in petrol, paints and

electrical components.

Designing processes with a high atom economy that minimise the

production of waste materials.

Example: Making ethanol

Work out the atom economy for the following processes:

• ethene + steam ethanol• glucose ethanol + carbon dioxide• chloroethane + sodium hydroxide ethanol + sodium chloride

• Comment on the results and thinking about other aspects of Green Chemistry, suggest the best method of making ethanol.

Using renewable resources such as plant-based substances

Example: Making polylactic acid (PLA)

Renewable Resources

• can be replenished by natural processes

• their rate of replenishment is equal or greater

than the rate of consumption

• often do not contribute to global warming

• often far more environmentally friendly

• lead to more sustainable use of materials;

resources can be used indefinitely

Seeking alternative energy sources such as solar energy, rather than

consuming finite resources such as fossil fuels that will eventually be

exhausted

Example: Biofuels

BIOFUELS• fuels made from a living things or the waste produced by them• renewable and potentially carbon neutral.

Carbon neutral refers to “an activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”. Ethanol is a biofuel.

GREEN CHEMISTRY – EXAMPLES



ETHANOL

GOOD




ETHANOL

GOOD • bio-ethanol is made from crops (corn and sugar cane)• takes in carbon as carbon dioxide in the atmosphere• when burnt, it returns CO2 to the atmosphere• appears to be carbon neutral




ETHANOL


BAD




ETHANOL


BAD • energy is required to - plant and harvest- convert plants to ethanol

• fertiliser and pesticides used are pollutants• crops compete for land with… crops / animals / forests• could destroy natural habitats and reduce biodiversity

Ensuring that any waste products produced are non-toxic, and can be

recycled or biodegraded by being broken down into harmless substances in the

environment

Example: New foams such as Pyrocool® FEF have been invented to put out fires

effectively without producing the toxic or ozone-depleting waste products found in other halogenated fire-fighting materials.

RECYCLING

Definition “Recovering resources by collecting, separating, and processing scrap materials and using them as raw materials for manufacturing new products.”

RECYCLING

Definition “Recovering resources by collecting, separating, andprocessing scrap materials and using them as rawmaterials for manufacturing new products.”

Why do it? • world resources are running out and are non-renewable

• we need to reduce the waste of valuable resources• reduces the expense of disposal• reduces expense of making things from raw

materials• avoids environmental problems posed by waste

- landfill sites- greenhouse gases (mainly methane)- destroying habitats- de-forestation leading to climate change

and the destruction of ecosystems

Establish international cooperation to promote the reduction of pollution

levels

e.g. Kyoto Protocol

INTERNATIONAL CO-OPERATION

KYOTO PROTOCOL (1997)• over 50 developed countries pledged to cut greenhouse gas emissions• gases included carbon dioxide CO2

methane CH4

hydrofluorocarbons HFC’sperfluorocarbons PFC’ssulphur hexafluoride SF6

• some countries agreed to make larger cuts• developing countries were not required to cut emissions• the US didn’t sign up; it would have significantly affected their economy

INTERNATIONAL CO-OPERATION

KYOTO PROTOCOL (1997)• over 50 developed countries pledged to cut greenhouse gas emissions• gases included carbon dioxide CO2

methane CH4

hydrofluorocarbons HFC’sperfluorocarbons PFC’ssulphur hexafluoride SF6

• some countries agreed to make larger cuts• developing countries were not required to cut emissions• the US didn’t sign up; it would have significantly affected their economy

But... Many experts say that the protocol is futile without US support as they are the world’s largest emitter of greenhouse gases.

Countries such as India and China are going through greatindustrial change and they do not have to cut emissions.

Cuts weren’t big enough according to many scientists, who say that a 60% cut is required to avoid the risks of global warming.

Answer the questions on the sheet