Selective recovery of pyrolyzates of biodegradable (PLA, PHBH) and common plastics (HDPE, PP, PS) during co-pyrolysis under slow heating.

Pyrolytic synergistic interactions, in which the production of pyrolyzates is enhanced or inhibited, commonly occur during the co-pyrolysis of different polymeric materials, such as plastics and biomass. Although these interactions can increase the yield of desired pyrolysis products under controlled degradation conditions, the desired compounds must be separated from complex pyrolyzates and further purified. To balance these dual effects, this study was aimed at examining pyrolytic synergistic interactions during slow heating co-pyrolysis of biodegradable plastics including polylactic acid (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexaoate) (PHBH) and petroleum-based plastics including high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). Comprehensive investigations based on thermogravimetric analysis, pyrolysis-gas chromatography/mass spectrometry, and evolved gas analysis-mass spectrometry revealed that PLA and PHBH decompose at lower temperatures (273-378 °C) than HDPE, PP, and PS (386-499 °C), with each polymer undergoing independent decomposition without any pyrolytic interactions. Thus, the independent pyrolysis of biodegradable plastics, such as PLA and PHBH, with common plastics, such as HDPE, PP, and PS, can theoretically be realized through temperature control, enabling the selective recovery of their pyrolyzates in different temperature ranges. Thus, pyrolytic approaches can facilitate the treatment of mixed biodegradable and common plastics.

Recent Advancements in Pyrolysis of Halogen-Containing Plastics for Resource Recovery and Halogen Upcycling: A State-of-the-Art Review.

Plastic waste has emerged as a serious issue due to its impact on environmental degradation and resource scarcity. Plastic recycling, especially of halogen-containing plastics, presents challenges due to potential secondary pollution and lower-value implementations. Chemical recycling via pyrolysis is the most versatile and robust approach for combating plastic waste. In this Review, we present recent advancements in halogen-plastic pyrolysis for resource utilization and the potential pathways from "reducing to recycling to upcycling" halogens. We emphasize the advanced management of halogen-plastics through copyrolysis with solid wastes (waste polymers, biomass, coal, etc.), which is an efficient method for dealing with mixed wastes to obtain high-value products while reducing undesirable substances. Innovations in catalyst design and reaction configurations for catalytic pyrolysis are comprehensively evaluated. In particular, a tandem catalysis system is a promising route for halogen removal and selective conversion of targeted products. Furthermore, we propose novel insights regarding the utilization and upcycling of halogens from halogen-plastics. This includes the preparation of halogen-based sorbents for elemental mercury removal, the halogenation-vaporization process for metal recovery, and the development of halogen-doped functional materials for new materials and energy applications. The reutilization of halogens facilitates the upcycling of halogen-plastics, but many efforts are needed for mutually beneficial outcomes. Overall, future investigations in the development of copyrolysis and catalyst-driven technologies for upcycling halogen-plastics are highlighted.

Latest trends and challenges in PVC and copper recovery technologies for End-of-Life thin cables.

This review investigates the latest trends in separation technologies regarding hard-to-recycle thin cables, specifically in the form of end-of-life wire harnesses (WHs). The cables in WHs mainly contain copper (Cu) and poly(vinyl chloride) (PVC), which is commonly used to insulate and sheath cables. This review reveals that most separation technologies prioritize the recovery of Cu and overlook that of PVC. The recovery of high-purity PVC is very important because of its incompatibility with other plastics or Cu during recycling treatments. Through this investigation, we confirm that physical treatments, such as stripping and chopping, are insufficient to recover high-purity PVC from thin cables. Instead, a combination of chemical (e.g., swelling of PVC insulation or sheathing of cables under a suitable solvent) and physical (e.g., ball or rod milling and mechanical agitation of swollen cables) treatments can be used to achieve the recovery of high-purity PVC and Cu both for recycling. We believe that recovering metals and plastics from end-of-life cables is vital for sustainable waste management, offering several environmental and economic benefits.