On the potential of microwave heating to convert waste into added-value chemicals and materials: a review

Microwave (MW) heating represents a superior alternative to conventional heating techniques due to its unique ability for rapid, selective, uniform and volumetric heating. However, challenges such as temperature non-uniformity, especially in certain materials and processing conditions, can limit its widespread application. Nevertheless, this heating method can enhance the physicochemical properties and performance of materials produced, making it a vital tool in sustainable material processing to produce valuable porous carbons for CO₂ capture, essential for climate change mitigation through carbon capture, utilization and storage (CCUS) strategies. MW heating significantly reduces processing time, energy consumption and operational costs, providing an efficient, green and cost-effective processing option. In this review we explore the use of MW heating in converting biomass, plastics and materials such as tyres and electronic waste into biofuels, bioenergy and hydrogen through biological and thermochemical processes. We highlight MW heating for producing solid adsorbents such as activated carbons from waste, their role in carbon capture and regeneration after CO₂ exposure. We also examine the principles of MW heating, its unique processing advantages and diverse applications across fields. In addition, we emphasize the life cycle assessment (LCA) of MW-assisted treatment for biomass and plastics while addressing the limitations of MW processing in material applications.This article is part of the discussion meeting issue 'Microwave science in sustainability'.