Harnessing Ash for Sustainable CO₂ Absorption: Current Strategies and Future Prospects

This review explores the potential of using different types of ash, namely fly ash, biomass ash, and coal ash etc., as mediums for CO₂ capture and sequestration. The diverse origins of these ash types - municipal waste, organic biomass, and coal combustion - impart unique physicochemical properties that influence their suitability and efficiency in CO₂ absorption. This review first discusses the environmental and economic implications of using ash wastes, emphasizing the reduction in landfill usage and the transformation of waste into value-added products. Then the chemical/physical treatments of ash wastes and their inherent capabilities in binding or reacting with CO₂ are introduced, along with current methodologies utilize these ashes for CO₂ sequestration, including mineral carbonation and direct air capture techniques. The application of using ash wastes for CO₂ capture are highlighted, followed by the discussion regarding challenges associated with ash-based CO₂ absorption approach. Finally, the article projects into the future, proposing innovative approaches and technological advancements needed to enhance the efficacy of ash in combating the increasing CO₂ levels. By providing a comprehensive analysis of current strategies and envisioning future prospects, this review aims to contribute to the field of sustainable CO₂ absorption and environmental management.