A review on the application of the red mud-based adsorbents for industrial and municipal pollutants remediation

Red mud is the residue produced from the alumina manufacturing process, which is one of the largest volume industrial solid wastes worldwide. The large-scale annual accumulation of the red mud not only occupies valuable land resources but also leads to soil alkalization, which also poses significant environmental risks. Therefore, it is crucial to explore feasible methods to effectively utilize red mud. This work outlines the preparation methods of the red mud-based adsorbents and their adsorption performance for pollutants is also investigated. It also provides a detailed overview of utilizing red mud-based adsorbents for pollutants treatment, including removal of heavy metal ions (Pb 2+ and Cd 2+ adsorption amount :730.16 and 215.37 mg/g), non-metal ions (phosphorus adsorption amount: 200 mg/g), and organic pollutants (methylene blue adsorption amount: 47.9 mg/g), as well as for gas adsorption such as CO 2 and SO 2 . Adsorption mechanisms of pollutants removal are comprehensively analyzed, and the regeneration process of the red mud-based adsorbents after use is also investigated. Furthermore, a preliminary economic analysis of the red mud-based adsorbents is conducted with the production cost of the $4.90 per kg. Finally, the future research directions for advancing red mud-based adsorbents development are proposed.