In the face of current global environmental challenges, plastic pollution has become a critical issue. To address this challenge, researchers from the State Key Laboratory of High Field Laser Physics at the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, and UiT the Arctic University of Norway have recently proposed a novel method for plastic recycling using laser technology and reviewed the hypothetical approach. This innovative approach is based on Laser-Induced Breakdown (LIB) and has the potential to bring revolutionary changes to the plastic recycling industry. The results were published in Sustainable Materials and Technologies on August 2, 2024.

In the traditional plastic recycling industry, LIB spectroscopy (LIBS) has been widely used for plastic classification, separation, identification, and elemental analysis. However, to achieve breakthroughs in plastic recycling systems, it is crucial to gain a deeper understanding of the molecular-level dynamics, thermodynamic interactions, bond-breaking, and the influence of process parameters during plastic degradation. Currently, the application of LIB in plastic pyrolysis remains an unexplored area, which urgently requires in-depth investigation.

In this work, the challenges of commercial-scale plastic recycling are addressed by focusing on the complex response mechanisms that are essential for effective processes. The use of lasers to analyze the molecular breakdown behavior of plastics, expanding beyond traditional uses such as classification, sorting, composition, and elemental analysis are reviewed and discussed. The importance of understanding the kinetics and thermodynamics of laser interactions with plastics at the molecular level is emphasized. The insights into the pathways of formation, bond cleavage behaviors, and the effects of process parameters on necessary structural modifications for improved recycling efficiency are presented. The structure of high-density polyethylene (HDPE) is analyzed, with a focus on carbon-carbon (C-C) and carbon-hydrogen (C-H) bonds. Why certain bonds are resistant to breaking and how lasers can be used under controlled conditions to enhance recycling methods are explored. According to the theoretical hypotheses explored in this review, a detailed understanding of bond-breaking processes could lead to innovative applications of lasers not only for bond disruption but also for the pyrolysis of HDPE. The research roadmap of laser-induced HDPE pyrolysis is proposed (Fig.1). This insight has the potential to advance research and the development of laser-induced pyrolysis reactors, contributing to more efficient recycling techniques.

This work was in part supported by NSAF joint fund, the Shanghai Science and Technology Program, the International Partnership Program of the Chinese Academy of Sciences and the CSC Scholarship for International Students.

For more information, please refer to the published article.

https://doi.org/10.1016/j.susmat.2024.e01074