Dr. Ed Marshall

Room: M220, RCS 1

e.marshall@imperial.ac.uk

www.ch.ic.ac.uk/marshall/4I10http://webct1.imperial.ac.uk

4.I10 Green Chemistry Lecture 1 Slide 1

Module 4I10: Green Chemistry

Lecture 1: An Introduction to Green Chemistry

Imperial CollegeLondon

Lecture 1: Learning Objectives

By the end of today's lecture you should:

(i) be able to define what is meant by the term Green Chemistry;

(ii) appreciate how Green Chemistry may be beneficial to industry;

(iii)understand that Green Chemistry is not an easy subject.

"We can't solve problems by using the same kind of thinking we used to create them."

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Albert Einstein (1879-1955)

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So what is Green Chemistry?

Imagine you are at a party and you have to explain what Green Chemistry is to someone who isn't a chemist.

What would words are you going to use to tell them?

Scenario:

Imperial CollegeLondon

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Imperial CollegeLondonBrown Chemistry

Is this the public perception of the chemical industry?

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Brown Chemistry Imperial CollegeLondon

Cuyahoga River 1952 and 1969…

…major fires also happened in 1868 and 1936.

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Brown Chemistry – the UK’s worst chemical accident

Flixborough 1974

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28 fatalities

40 tonnes cyclohexane released in 1 minute (225 °C, 10 atm)

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Brown Chemistry – the world’s worst chemical accident

Bhopal 1984

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Imperial CollegeLondon

Brown Chemistry

Is this reputation deserved?

Imperial CollegeLondon

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Imperial CollegeLondonWhy does the chemical industry need Green Chemistry?

The Chemical Industry has responsibilities:

to the environment

to the public

to shareholders

As legislation becomes stricter and as petrochemical feedstocks are depleted, so green chemical processes will become more cost effective.

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Imperial CollegeLondonClass exercise: Which is greener - Disposable or Cotton Nappies?

In groups of 4, discuss whether it is better to use disposable nappies (diapers) or reusable cotton nappies.

Results of Vote:

In favour of disposable:

In favour of cotton:

Far more importantly......what factors did you consider in your answer?

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Imperial CollegeLondonThe answer

In 2004 the UK Environment Agency concluded that there is…

"no significant difference between the environmental impactsof either nappy system, although the life cycle stages are different"

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Disposable Nappies - Simplified System Outline DiagramEnvironmental Resources

Ener

gy S

uppl

y

Environment (air, land and water)

Other Production Inputs

timber polymers acrylic acid NaOH packaging

pulp and bleaching

plastic components

super absorbantpolymer

disposablenappy

landfill

electricitygeneration

retail

recycle

domestic use landfillincineration

Home Laundered Cotton Nappies - again, simplifiedEnvironmental Resources

Ener

gy S

uppl

y

Environment (air, land and water)

Other Production Inputs

fertiliser

pesticide

cottoncultivation

cottonginning

cottonspinning

cotton productionand wet processing

cotton nappyother nappyconstruction

materialspackaging

retail

domestic usesewage treatment

packagingdisposal

electricitygeneration

water

detergentmanufacture

linermanufacture

Imperial CollegeLondonSo what factors do we need to consider?

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transportation(fuels, emissions)

waste and theenvironment

energy

Green Chemistry: a cradle to grave approach

productionprocess

i.e. conditions, risks, hazards

raw materials

solvents

other chemicalse.g. additives

Imperial CollegeLondonGreen Chemistry: A reductionary approach

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Materialsincluding

plant

Energy Waste

Risk andHazards

Toxicity

Impact onenvironment

Green Chemistry reduces…

Cost

Green Chemistry is not anti-industry

Imperial CollegeLondonDefinitions of Green Chemistry

“The reduction or elimination of the use or generation of hazardous substances in the design, manufacture and application of chemical products”

Green Chemistry theory and Practice - Anastas and Warner

“Green Chemistry underlies our commitment to potentially harmful technologies by developing alternative syntheses to prevent environmental pollution.”

Green Chemistry is not anti-industry

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Imperial CollegeLondonSummary of Lecture 1

By the end of today's lecture you should:

• be able to define what is meant by the term Green Chemistry:

• appreciate how Green Chemistry may be beneficial to industry:

• understand that Green Chemistry is not an easy subject:

Green Chemistry ultimately reduces cost and increases responsibility to the environment, the public and shareholders

The reduction or elimination of the use or generation of hazardous substances in the design, manufacture and

application of chemical products

Green Chemistry is a cradle to grave approach

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Imperial CollegeLondonWhat we will cover in lectures 2-8

Lecture 2: Metrics

Lecture 3: Catalysis

Lecture 4: Green Solvents

Lecture 5: Biofuels

Lecture 6: Biomass

Lecture 7: Biotechnology

Lecture 8: Hazards

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Imperial CollegeLondonFinally, here is one part of last year’s exam question

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Green Chemistry is often said to be a 'cradle to grave' approach. Explain what this term means with specific reference to the industrial production of polyethylene.

5 marks