Recycling Plastics

• Pre-treatment of Plastic Waste

  
  

  • Pre-treatment of plastic waste is necessary before recycling it
  • Pre-treatment includes sorting out suitable plastics for recycling, washing the plastics to remove contaminants from them, and shredding or grinding the plastics
• Physical Method (Recycling Plastics)

  • also known as mechanical recycling
  • chemical composition of plastics remain unchanged
  • small pieces of plastics are heated until they melt, the melted plastic is cooled and pulled into long strands that can be easily cut into pellets. The pellets are used for making new plastic products
• Chemical Method - Cracking (Recycling Plastics)


  • plastics undergo cracking to form short chains of alkanes and alkenes
  • cracking is essential in order to meet demands for short chain hydrocarbons such as alkanes and alkenes
  • short chain alkenes (e.g. ethene) can be used to make chemical feedstock and other chemical substances
  • short chain alkanes are used as fuel
• Chemical Method - Depolymerisation (Recycling Plastics)



  • process in which a polymer is converted back into its monomers (reverse reaction of polymerisation)
  • polymers can be depolymerised by breaking the ester linkages using water in the presence of an acid catalyst, which is known as acid hydrolysis
  • the products of depolymerisation are the monomers of the polymer (dicarboxylic acids and diols)
• Environmental Issues Related to Recycling Plastics

  • Recycling plastics generates wastewater. Untreated waste water contaminates and pollutes water bodies
• Economic Issues Related to Recycling Plastics


  • recycling plastics is expensive as costs are incurred to collect, transport, sort, clean and recycle plastic waste.
  • It can be challenging for companies to sustain their businesses as recycled plastic products are sold at a lower price compared to virgin plastics (plastics made from crude oil without adding recycled materials)
• Social Issues Related to Recycling Plastics


  • Plastic waste is only recycled if placed in designated recycling bins, most plastic waste is disposed of.
  • Plastic waste may also be contaminated with leftover food or are not recyclable
  • Time and effort is needed for communities to practise recycling as a lifestyle
• Measures to address Issues of Recycling plastics

  • introduce strict measures and regulations to minimise potential environmental issues
  • educate the public on the importance of recycling plastics and the correct way of recycling plastic waste
  • give incentives to encourage recycling effort. E.g. users may be rewarded with discount vouchers for recycling a number of plastic containers