Resource Recirculation and Circular economy : Chemical Recycling of Waste Plasticsby Pranav Gaba | 20-01-2023 22:45 |
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.png) [JANUARY THEMATIC REPORT] In a circular economy, useful plastic materials are kept in circulation as opposed to being incinerated, or leaked into the natural environment. By converting previously unrecyclable plastic wastes into petrochemical feedstock which can then be utilised as building blocks for fresh, virgin-quality polymers, chemical recycling adds value to previously unrecyclable plastic waste. Traditionally, plastic waste has been recycled manually. But with emerging technologies and the onset of 'chemical recycling industry', we have reached one step further in recycling plastic waste which is difficult or uneconomic to recycle mechanically. Chemical recycling is the broad term used to describe a range of emerging technologies in the waste management industry which allows above mentioned plastics to be recycled. Chemical recycling methods have the potential to significantly increase recycling rates and divert plastic waste from landfill or incineration by converting plastic trash back into base chemicals and chemical feedstocks. Chemical recycling support mechanical recycling methods by allowing for the further value extraction of polymers after their economic viability for mechanical processing has been reached. In the case of formerly difficult-to-recycle plastic items including films, multi-layered plastics, and laminated plastics, chemical recycling offers an option over simply incineration and burning. The supply chain for plastics also receives virgin-quality raw materials through chemical recycling. This makes it possible to make food-grade polymers out of leftover consumer goods. Chemical recycling is best suited for hard to recycle, multilayered or heavily contaminated plastics. The main benefit of a chemical recycling process is that it is more tolerant of contamination, and it yields polymers that are identical to the original, eliminating downcycling. Any technology that employs procedures or chemical substances that directly impact the chemistry of the polymers is referred to as chemical recycling. Based on where the technologies' outputs are located in the supply chain for plastics, the technologies can be divided into three different groups. These groups include: Purification - A number of purification procedures are carried out to remove the polymer from additives and pollutants during the solvent-based purification process, which involves dissolving plastic in a suitable solvent (or solvents). Depolymerisation - Sometimes referred to as chemolysis, it is the reverse of polymerisation and yields either single-monomer molecules or shorter polymer fragments known as oligomers. Feedstock Recycling - Any thermal process that breaks down polymers into smaller molecules in order to create the feedstock for petrochemical-style processing is referred to as "feedstock (thermal conversion) recycling." Pyrolysis and gasification are the two basic processes involved in this. Contrary to mechanical recycling, which employs processes to make used polymers ready for reuse without significantly altering the material's chemical composition, chemical recycling uses processes to prepare discarded polymers for reuse by changing their chemical structure. Mechanical recycling processes the separated, single-polymer stream, which is washed, granulated and then re-extruded to make recycled pellets that are ready for moulding applications. Chemical recycling processes based on depolymerisation and feedstock recycling, breaks down the long hydrocarbon chains in plastics into shorter hydrocarbon fractions or into monomers using chemical, thermal or catalytic processes. References:- 1. Chemical Recycling 101. (n.d.). British Plastics Federation. https://www.bpf.co.uk/plastipedia/chemical-recycling-101.aspx 2. Chemical Recycling | Circular Economy Asia. (n.d.). https://www.circulareconomyasia.org/chemical-recycling/ Other Helpful Resource(s):-
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