GCSE OCR Gateway Chemistry C6.1k-n Recycling

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.  

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: