Polymer and plastic waste recycling: Challenges and prospects towards a circular economy

• Continuous use of plastics is damaging the ecosystem and threatening human health • Conventional chemical recycling techniques such as oxidation have not been sustainable • Developing advanced multifaceted catalysts that can handle different plastic feed • Techno-economic analysis will assess the economic viability of valorisation process • Life cycle assessment will evaluate environmental impacts towards safe technologies The annual global production and consumption of plastics have continued to rise due to their favourable characteristics such as high versatility and durability. However, the extensive usage of these plastics and their low recovery rates are causing damage to the ecosystem and threatening human health. Of the different recycling methods which consists of primary, mechanical, chemical, and tertiary methods, chemical recycling is the most desirable as it helps to generate new products that are more valuable than the original plastic. Unfortunately, the existing conventional chemical recycling methods such as oxidation and pyrolysis have not been sustainable and requires improvements as it typically requires high-temperature requirements, usage of unfriendly chemicals, and formation of coke which eventually leads to a wide range of product distribution. In this review, the different degradation approaches and catalytic strategies employed to address plastic waste upcycling towards sustainability and high product selectivity are highlighted. The advanced techniques such as tandem catalytic technologies and microwave-assisted pyrolysis that are currently employed to overcome the challenges in conventional approaches are summarised. The application of techno-economic analysis and life-cycle assessment studies to study the economic and environmental potentials of the developed products and processes, which are fast gaining attention, are summarised with some case studies. The future outlooks and perspectives towards rapid advancement to achieve a circular plastic economy are also discussed. It is expected that this review will provide researchers a better understanding of the advanced chemical recycling methods, bridge innovative findings with real-world environmental applications, and provide actionable insights towards the development of safe and sustainable waste valorisation technologies.