The chemistry and ecology underlining plastics recycling options

1. 21/02/2021
Source: M.G. Davidson, R.A. Furlong and M.C. McManus Journal of Cleaner Production 293 (2021) 126163
Definitions of plastic waste management options
• Mechanical recycling
The use of separation techniques, crushing, heat and extrusion to melt used plastic waste down and
produce recycled plastic pellets.
• Chemical/feedstock recycling
The use of thermo and/or chemical techniques to break down plastic waste into its consistent parts such
as monomers, oligomers or liquid, solid and gaseous hydrocarbon mixes.
1. Pyrolysis
The use of heat in an oxygen deficient atmosphere to breakdown
the hydrocarbon bonds in plastic waste to produce a range of solid, liquid and gaseous hydrocarbon
products.
2. Gasification
The use of heat and controlled steam, oxygen and/or air content to breakdown plastic waste to produce
syngas, a hydrogen and carbon monoxide rich gaseous mixture.
3. Hydrocracking
The use of heat and pressure in an inert, hydrogen rich atmo- sphere to break the carbon to carbon
bonds in plastic waste and add hydrogen to produce solid, liquid and gaseous hydrocarbons.
4. Depolymerization
The use of polymer chemistry to reverse polymerization re- actions to yield the component monomers
and oligomers of plastic, which can then be used in further polymerization reactions.
5. Incineration
The process of burning plastic waste to derive heat. This heat is captured and either used directly to
heat buildings or used indi- rectly to produce electricity. Sometimes called Waste to Energy (WTE).

2. 21/02/2021
Source: M.G. Davidson, R.A. Furlong and M.C. McManus Journal of Cleaner Production 293 (2021) 126163

3. Source: M.G. Davidson, R.A. Furlong and M.C. McManus Journal of Cleaner Production 293 (2021) 126163

4. Source: M.G. Davidson, R.A. Furlong and M.C. McManus Journal of Cleaner Production 293 (2021) 126163