Application of red mud in carbon capture, utilization and storage (CCUS) technology

Global warming is continually growing, and CO2 is the biggest contributor among all greenhouse gas emissions. Carbon capture, utilization and storage (CCUS) technologies are applied to reduce greenhouse gas emissions and mitigate climate change. Meanwhile, red mud is a byproduct produced in the aluminium industry and its accumulation has resulted in extensive land occupation. The complex composition and high alkalinity of red mud would threaten ecological balance and human health. The application of red mud in CCUS not only absorbs large amounts of CO2 and neutralizes the alkalinity of red mud but also reduces the accumulation of excess solid waste. This review provides a comprehensive overview of recent advances in red mud for CCUS, including carbon capture sorbents, direct gas-solid carbonation, direct aqueous carbonation, indirect carbonation and carbonation curing. The effects of various reaction conditions, the physical and chemical properties of red mud, and the addition of calcium and magnesium-containing substances on the carbon sequestration of red mud were investigated. The mechanism of red mud in CCUS is discussed, and the advantages and disadvantages of various methods are also analyzed. The carbon uptake of red mud is 5–175 g CO2/kg red mud, depending on the composition and carbonation pathway of red mud. Finally, challenges and prospects for future research in the field of red mud for CCUS are proposed, emphasizing the energy consumption and economics of the red mud-based sorbents. This research is beneficial for promoting the application of alkaline solid waste such as red mud in CCUS.