CO2 Capture Using Red Mud: A Review of Process Variables, Mechanisms, and Post-Carbonation Challenges

Abstract

The rise in greenhouse gas emissions, mainly anthropogenic CO₂, is causing global warming that leads to climate change and has become a matter of global concern. This review investigates the use of red mud in CO₂ capture and highlights recent advancements over the past 25 years. The bauxite ore is digested with sodium hydroxide to form sodium aluminate using Bayer's process, leaving behind a highly alkaline residue known as red mud. This residue is a well-suited feedstock material for CO₂ capture processes and its subsequent neutralization. This article discusses the fundamentals of red mud and various pathways for carbonation. Then, the chemical and mineralogical components of red mud that contribute to the adsorption of CO₂ are investigated. It then focuses on research progress and provides an up-to-date review of recent advances in CO₂ capture using red mud. This article reviews the mechanism and critically evaluates the process variables that influence the adsorption of CO₂ in red mud. It also provides insight into recent activation methods to improve its capacity. It then discusses the associated post-carbonation challenges with red mud, concluding that further research is needed in reshaping red mud's perception from industrial waste to a valuable feedstock material for key carbon-emitting industries. This review serves as a comprehensive reference in the emerging area of CO₂ capture using red mud and addresses the distinct gap of process variables, mechanisms, and post-carbonation challenges. The ultimate aim is to resolve the CO₂ emitted into the atmosphere and its simultaneous neutralization.