What Solutions Does Chemical Recycling Provide?
Many people, countries and experts agree that global waste generation is a problem, and it in fact goes further than just that: it is a necessity that we must deal with efficiently.
This is how the recycling initiative was born a long time ago, but the current type of recycling is not able to cope with the high need for reuse of materials.
Chemical recycling was born as another alternative, thus establishing new uses for the technology, which would replace and address the chemical processes that were being wasted, in order to take advantage of the materials that were being discarded in their entirety.
What is Chemical Recycling?
This is a depolymerisation process applied in the recycling of plastics which results in the decomposition into monomers and hydrocarbons that can be used again in the production of polymers of a similar quality to the depolymerised virgin material.
Chemical recycling consists of the decomposition of plastic elements as polymers, and seeks to more efficiently complement the shortcomings of mechanical recycling by obtaining the original components of the formation, better known as monomers.
This type of recycling is a much more viable approach to polymer recycling as it allows the creation of other new elements or materials, reducing production and raw material collection costs.
Difference with Mechanical Recycling
Chemical recycling, although much less developed and centralised at the industrial level, was born as a response to a need that mechanical recycling could not adress. Chemical recycling complements the decomposition processes that were not previously possible.
Mechanical recycling does not allow for efficient recovery of all the chemicals that make up the recycled material.
Chemical recycling breaks down polymers into hydrocarbons such as oils, and these can be used in many other chemical compositions. In addition, they can also be broken down into monomers that are used as raw materials to make new polymers of a similar quality to the first product created.
Some of the elements or products that mechanical recycling, unlike chemical recycling, could not break down are:
- Products with high organic contamination.
- One-coat products with high colouring.
- Multi-layer products.
Material Decomposition Processes Used in Chemical Recycling
Thermal depolymerisation (pyrolysis)
It is a chemical process in which, by means of technological equipment, the transformation and decomposition of complex polymers into monomers is achieved through the supply of heat, without the use of external reactive agents that may be pollutants.
Dissolution
This chemical process allows for the efficient recovery of purified polymers from recycled materials, eliminating contaminating components from them. This process does not modify the molecular composition of the polymers, leaving them free of impurities for the production of new products.
Solvolysis
This is a process in which solvents are used as a reagent for the decomposition of polymers into raw material. These solvents are distinguished into different processes depending on the composition of the material to be dissolved, and are as follows:
- Hydrolysis: this dissolution process allows the treatment of highly dyed and mixed wastes to obtain usable monomers.
- Methanolysis: is a process by which methanol is used in materials such as polyester, thus breaking it down into basic molecules, which can be used again in the polymerisation process of new products.
Glycolysis: the reagent used is ethylene glycol, and is usually less severe than the two processes mentioned above, thus reducing process costs, but this method is less effective with highly coloured materials.
