Polymer disposal
In a nutshell
There are different types of polymers, each with their own unique property, making them ideal for their use. Many polymers are non-biodegradable or they biodegrade at a very slow rate. This has led to the deployment of different methods to dispose polymers. Polymers may be dumped in a landfill site, reused or burned.
Polymers
There are different types of polymers which occur naturally and are man-made. The table summarises two types of polymers which are synthesised and their properties.
polymer
| property
| advantage
| disadvantage
|
| Addition polymers
[poly(alkenes)] | - Non-polar carbon backbone
- Chemically inert
| Durable
| Non-biodegradable |
| Condensation polymers | - Polar bonds
- Subject to nucleophilic attack
| Can undergo hydrolysis and are biodegradable | Process of biodegrading is slow |
Disposing polymers
There are a few ways to dispose polymers, although not every method is environmentally friendly.
Landfill
Plastics are dumped in the landfill when the quantity of plastic is not economically viable to separate the plastic out from other waste materials or it is difficult to recycle. Burying waste in landfill is amongst the cheapest and easiest method to dispose polymers, however land is needed and there is a finite amount of space available for areas to be used as a landfill site. Furthermore, leaks may occur in landfills which may contaminate water supplies. This is in addition to the release of methane gas which contributes to global warming.
In recent years, there has been a significant increase in the quantity of waste. This must be reduced soon to prevent adverse effects to the environment and the ecosystem. Alternative methods are being employed to decrease the waste diverted to landfills.
Reuse
Plastics may be reused usually in one of two ways:
- Via cracking - the polymers are cracked into smaller monomers or smaller molecules which are then repurposed.
- Via recycling - the polymers are melted then remoulded into a new item.
The table summarises advantages and disadvantages of reusing plastics.
advantage
| disadvantage
|
| Less waste dumped into a landfill. | Reusing plastics is difficult. |
| Lower emissions of carbon dioxide produced compared to burning polymers. | Plastics can be contaminated during the recycling process. |
| Oil fractions are non-renewable. Reusing plastics reserves this raw material for where it is required the most and for future generations. | Recycling is more expensive than using a landfill site or burning them. The whole process of collecting, separating and processing plastics consumes a lot of time and energy. |
| Recycling plastics is cheaper than producing plastics from raw materials. |
|
Burning
Plastics may be incinerated to generate heat electricity. However, this needs to be moderated as some plastics produce toxic fumes. Scrubbers can be used to neutralise the gases.
Example
PVC contains chlorine which produces hydrogen chloride when burned. When hydrogen chloride is passed through scrubbers it is neutralised by a base.
