Biodegradability & Disposal of Polymers (Oxford AQA International A Level Chemistry)
Revision Note
Written by: Philippa Platt
Reviewed by: Stewart Hird
Biodegradability
Both polyesters and polyamides can be broken down using hydrolysis reactions
This is a major advantage over the polymers produced using alkene monomers (polyalkenes)
When polyesters and polyamides are taken to landfill sites, they can be broken down easily and their products used for other applications
Hydrolysis of polyesters and polyamides
Simple esters and amides can be hydrolysed by reaction with either aqueous acids or bases into carboxylic acids and alcohols (in the case of esters) or amines (in the case of amides)
Condensation polymers are linked by ester or amide linkages and so can undergo hydrolysis
Under the action of acid catalysts or biological enzymes the amide and ester links in polyamides and polyesters can be hydrolysed into smaller fragments
Polyalkenes are inert and non biodegradable as a result of the C-C bonds between the monomers in addition polymers
Examiner Tips and Tricks
The conditions present in different environments can influence the rate of hydrolysis and therefore the rate of biodegradation. Be mindful that some environments may have a different moisture content, oxygen levels, bacterial content and access to UV light. All of which can influence the rate of hydrolysis of biodegradable polymers.
Disposal of Polymers
There are three main ways of disposing of polymers; landfill, incineration and recycling and you need to know some advantages and disadvantages of each process
Method of disposal | Advantages | Disadvantages |
|---|---|---|
Landfill | Buried at specific contained site Biodegradable polymers (polyesters and polyamides) will slowly degrade | Less space than landfill Energy released from burning can generate electricity |
Incineration | Less space than landfill Energy released from burning can generate electricity Prevents build up of polymers in the environment | Increase in CO2 Toxic gas emissions and particulates released into atmosphere |
Recycling | Reuse and conservation of finite hydrocarbon resources Reduction of waste going to landfill | Collection, sorting, separating, remoulding all require energy Time consuming Expensive |
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