Advancements and future directions in waste plastics recycling: From mechanical methods to innovative chemical processes

Abstract

The rapid escalation in plastic production, predominantly from non-renewable sources, has precipitated a critical environmental challenge due to ineffective end-of-life management and low recycling rates. This review article comprehensively examines the array of methodologies currently employed in plastic waste recycling, including mechanical recycling, pyrolysis, solvolysis, gasification, hydrocracking, photocatalysis, biotechnology, and electrochemistry. While mechanical recycling remains the predominant approach, contributing over 90% to waste plastic recycling, it faces significant limitations such as degradation in mechanical properties and insufficient processing of contaminated waste, inspiring intensive efforts to develop new techniques. Chemical recycling approaches, such as pyrolysis and solvolysis, have been widely explored, achieving near practical implementation at an industrial scale. Innovative processes, such as photocatalysis, biotechnology, and electrochemistry, show promise for eco-friendly and efficient recycling. Future research directions are identified with emphasis on the recycling of CC-containing polymers, depolymerization into monomers, understanding the mechanisms of waste plastic conversion, processing real-world plastic waste, and developing biodegradable plastics from biological feedstocks. This article aims to provide a holistic view of the current landscape of plastic recycling and its potential evolution, underscoring the importance of innovative recycling strategies in achieving a sustainable plastics economy.