Polyamide recycling by selective dissolution approach: Life Cycle Assessment study and environmental impacts comparison with different recycling technologies

Polyamide 6 (PA6) is a material extensively utilized thanks to its high mechanical and thermal properties, but its widespread use has raised concerns about its environmental impact, especially because polyamides are often coupled with other materials that hinder recyclability. Recycling techniques currently at industrial scale are mechanical and chemical recycling, but the high temperatures and harsh chemicals involved generate impurities that complicate the process, leading the waste materials to disposal. Solvent-based recycling may offer a solution allowing non-nylon-coupled material separation at milder process conditions, but no industrial data and few studies concerning its environmental impacts are available. This work reports the Life Cycle Assessment of polyamide selective dissolution recycling, analyzing different process configuration scenarios, where the precipitation of PA6 is induced either by the addition of an antisolvent or by solvent evaporation, also exploring the possibility to valorize the non-nylon-coupled material. A comparison between mechanical, chemical, and solvent-based recycling is made in terms of applicability and environmental impacts, all calculated considering renewable energy sources. Solvent-based recycling approach from an environmental point of view resulted as industrially feasible, where best environmental performing process configuration results in solvent evaporation-induced PA6 precipitation, with a global warming potential between chemical and mechanical recycling. Highlights: Dissolution recycling is an innovative process to treat mixed plastic waste. Life Cycle Assessment (LCA) analysis is useful to evaluate the industrial feasibility of a new process. LCA of dissolution recycling considering different configurations was evaluated. Comparative LCA analysis of current PA6 recycling methods with solvent-based one. Dissolution recycling can be considered a valid alternative for PA6 recycling.