Dissolution recycling processes leave a polymer structure intact, and belong in the physical recycling category along with mechanical recycling, Plastics Recyclers Europe said. | Rene Notenbomer/Shutterstock
Industry association Plastics Recyclers Europe is looking to raise the profile of dissolution recycling, an often-overlooked process that doesn’t quite fit into common recycling categories.
“As the European Union intensifies its push toward a circular economy, dissolution recycling emerges as a promising solution that bridges the gap between mechanical and chemical recycling,” according to a new white paper from Brussels-based PRE, which comprises more than 200 EU companies.
Dissolution uses a solvent to dissolve an intended polymer, most commonly PE and PP but also polystyrene, nylon, PET, PVC, polycarbonate and ABS. Other substances, such as inks, additives and barrier layers, do not dissolve and then can be removed, leaving the purified polymer to be collected from the solvent and processed into virgin-quality resin.
The process keeps a polymer’s chemical structure intact, while chemical recycling techniques such as pyrolysis and gasification break down a polymer’s complex chemical structure into new, smaller compounds. As such, dissolution recycling processes belong in the physical recycling category, along with mechanical recycling, PRE asserts.
Along these lines, the Association of Plastic Recyclers in the US says physical recycling is also known as dissolution, and is a “process in which a plastic is subjected to a series of purification steps to separate the target polymer/polymers from other polymers, additives and other added materials such as fibers, fillers, colorants and contaminants, resulting in recovered polymers, which remain largely unaffected by the process and can be reformulated into plastics.”
APR owns Resource Recycling, Inc., publisher of Plastics Recycling Update.
Christian Bruey, director of communications and government relations at US-based PureCycle, told Plastics Recycling Update that the concerns the EU white paper raises are also evident in the US, particularly the lack of regulatory consistency. “There needs to be harmonization. We see New Jersey’s got this rule for recycled content, we see Oregon lumping dissolution with mechanical, we see Washington differentiating chemical and physical and mechanical. So I think the key takeaway from the white paper is harmonization.”
He added that dissolution and mechanical recycling processes also provide traceability of a polymer, whereas chemical recycling does not. “So lumping them together makes more sense than putting dissolution with chemical processes.”
Another advantage of dissolution recycling PRE highlighted is its compatibility with existing supply chains, polymer processing facilities and waste collection systems, as it is a polymer-to-polymer recycling method.
However, the group emphasized that “as the EU moves towards more sustainable waste management, all recycling technologies, mechanical, dissolution, and chemical, will play complementary roles in addressing different types of plastic waste and achieving different quality standards of recycled materials.”
In April, PRE set up the Dissolution Taskforce to complement its collaboration with the Dissolution Recycling of Plastics Initiative (DROP-IN). At least 40 stakeholders in the EU have joined DROP-IN, including US-based PureCycle and LyondellBasell, which acquired German solvent-based recycler APK last fall.
“Currently, dissolution recycling operates within a regulatory and definitional grey zone, both in the European Union and globally,” according to a recent DROP-IN post on LinkedIn. The group also describes the process as “the overlooked third option between mechanical and chemical recycling.”
Dissolution technologies produce a high-yield resin of quality that is suitable for demanding applications such as food-contact packaging, automotive and electronics.
Solvent-based techniques also could enable reuse of hard-to-recycle materials, PRE added. For example, plastics used in electronics have posed challenges when discarded, due to such substances as flame retardants or metals, commonly present in plastics from end-of-life electronics.
PRE also urged the EU to harmonize standards throughout its member countries, adding that the lack of regulatory clarity and consistency are hindering adoption of dissolution technologies as well as investment in infrastructure.
However, PRE noted that an International Standards Organization technical committee “is effectively reviewing ISO 15270, with a new focus group ISO 15270 3a, Physical Recycling. This group of experts aims to formally define all known physical polymer recycling processes additional to mechanical recycling, including dissolution recycling (based on the well-known ‘extraction’ separation method, also called dissolution purification).”
More stories about chemical recycling