GCSE OCR Gateway Chemistry C6.1k-n Recycling
C6.1k To be able to describe the basic
principles in carrying out a life-cycle assessment of a material or product
C6.1l To be able to interpret data
from a life-cycle assessment of a material or product
C6.1m To be able to describe a process where a
material or product is recycled for a different use, and explain why this is
viable
C6.1n To evaluate factors that
affect decisions on recycling
What is Life Cycle Assessment (LCA)?
Life Cycle
Assessment (LCA) is the detailed
analysis that provides the information you need to make the most
environmentally friendly decisions throughout product design.
The analysis looks at a
product’s entire life, which encompasses
ore extraction,
material production,
manufacturing,
product use,
end-of-life disposal,
and all of the
transportation that occurs between these stages.
A typical
life cycle assessment of a chemical product
Life cycle of a plastic bottle
Take as an
example the life cycle of a plastic bottle.
This example
of life cycle analysis particularly focuses on the product use and end of life
disposal.
Here is the problem with plastic bottles 480 billion were sold in 2016 worldwide a million bottles a minute and 110billion were made by Coca Cola.
What do we do with the bottle once we have drunk the coke? you seethe plastic bottle hangs around for a long time if you just chuck it into a ditch.
What better use can we make of the valuable resources contained in all those billions of bottles thrown away each year across the world? What can we do to prevent them ending up in the sea.
Here is the problem with plastic bottles 480 billion were sold in 2016 worldwide a million bottles a minute and 110billion were made by Coca Cola.
What do we do with the bottle once we have drunk the coke? you seethe plastic bottle hangs around for a long time if you just chuck it into a ditch.
What better use can we make of the valuable resources contained in all those billions of bottles thrown away each year across the world? What can we do to prevent them ending up in the sea.
You can see
from the illustration above how the life cycle of the plastic bottle pans out.
After
manufacture of the plastic bottles from PET (polyester), their distribution and
use what happens to the plastic waste is the crucial question being asked
today.
A) Bottles
can be chipped and incinerated leading to production of further Carbon dioxide (CO2)
and toxic oxides of nitrogen (NOx)
B) Bottles
can be taken to land fill where they take ages to decompose to residue creating
volumes of methane (CH4)
C) If
bottles are recycled by being melted down (Bottles made of PET are
thermoplastic) and remoulded then energy can be conserved.
D) Most PET
bottles cannot be reused as bottles but must be melted down and then remoulded
into some other product.
E) Finally,
and this is not shown on the chart above, the plastic polyesters can be
hydrolysed back to their respective monomers and then these monomers purified
and reused to make new plastic product.
This approach is energy intensive however and not commercially viable at
present.
Viable recycling
Viable
recycling involves collecting, cleaning and melting down the product plastic
into a melt form where it can be remoulded into a new different product.
This is
viable if the new product has a profitable market and can be produced at a
lower energy cost than an equivalent product made from scratch and at a price
that is also competitive in the market.
It is these
factors of energy cost and marketability that determine whether the product is
recyclable not just reusable.
Other
factors also come into play such as the extent to which the recycling process
contaminates the environment with toxic materials.
You can find out more about plastic bottle recycling here:
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