[5105 Chem] Chp 18 : Polymers - Plastic and Pollution

PLASTIC AND POLLUTION

-Sylvia Earle

" Only we humans make waste that nature cannot digest " 

Lesson Objectives

• describe the problem of pollution caused by disposal of plastics

• describe two methods of recycling plastics (physical and chemical method)

• discuss the social, economic and environmental issues of recycling plastics

1. Land pollution

2. Air pollution

3. Water pollution

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Problems caused by disposal of plastics

Open Ended

How does disposal of plastic contribute to :

1. Land pollution

2. 2. Water pollution

3. 3. Air pollution

Categorize

Options (3)

Non-biodegradable and do not decompose

Plastics are flammable and produces toxic gases.

Plastics thrown in sea will endanger marine lifes.

Organize these options into the right categories

Land pollution

Air pollution

Water pollution

Recycling Plastics

How can we recycle plastics

Recycling plastics can be carried out by using the
1. physical method
2. chemical method

As not all plastics can be recycled, the plastic waste need to undergo pre-treatment before recycling.

Chemical composition changed.

Converts plastic waste into raw materials via cracking to form shorter chain hydrocarbons.

Chemical method

Chemical composition remains unchanged
After pre-treatment, plastics are melted, cooled, pulled into long strands and cut into pellets.

Physical method

Methods to Recycling Plastics

Fill in the Blank

Cracking is the _______ of long-chain hydrocarbons into small chain molecules.

Multiple Choice

What can smaller chain hydrocarbon molecules be used for?

• As plastics

• As fuels

• As lubricating oil

Multiple Choice

What is the catalysts for cracking?

• uv light

• bromine liquid

• nickel

• aluminium oxide / silicon dioxide

Multiple Choice

What is the temperature needed for cracking?

• 500 $$^o$$ C

• 150 $$^o$$ C

• 200 $$^o$$ C

Issues with recycling plastics

Environmental Issues

Wastewater from recycling plastics can contaminate water bodies if not treated properly before discharging them.

Issues with recycling plastics

Economic Issues

Costly : Transporting of plastic wastes to processing plant, pre-treatment of plastics, recycling using the two methods as it require more manpower, machines and energy.
Therefore, it may not economically viable to recycle plastic waste if the cost is higher than the value of the plastic.

Issues with recycling plastics

Social Issues

Many people
1. find it more convenient to throw away plastic wastes.
2. are not aware the proper way to recycle plastics.

Thus it require time and effort to for people to adipt recycling habits.

Open Ended

How can we address the issues related to recycling plastics?

Addressing recycling issues

1. Stricter measures and laws to minimise environmental pollution.

2. Educate the public on the correct way to recycle plastic waste.

3. Introduce creative ways to encourage people to recycle such as the Reverse Vending Machines.

Open Ended

State two economical issues related to recycling plastics.