Adsorption performance of amine-functionalized red mud-based adsorbent for CO2 capture

Abstract

In this work, an industrial solid waste red mud was resourcefully processed to prepare a red mud-based solid amine adsorbent for efficient CO₂ capture. Nitrogen adsorption-desorption isotherms, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy measurement were performed, suggesting that the organic amine was successfully loaded onto the red mud. The results obtained from the CO₂ adsorption tests showed that the red mud-based solid amine adsorbent obtained a significantly higher CO₂ capacity in comparison to the pristine red mud. Moreover, the type of the organic amine and the loading had a significant impact on the adsorption performance. By comparing the adsorption performance of different organic amine types and loadings, MRM-20-TETA was finally selected as the most effective adsorbent (23.94 mg/g), with only 0.8 mg/g adsorption to the pristine red mud. In parallel, the improved adsorption performance was nearly 29 times higher. In addition, cyclic stability tests were conducted on MRM-20-TETA. It was demonstrated that the adsorption capacity decreased by only 9.9 % after the application of five adsorption–desorption cycles, indicating its wide application potential. The kinetics analysis showed that the Avrami model provided the best fit for the kinetics of the amine-functionalized red mud adsorbent, signifying a combination of physical and chemical adsorption mechanisms. Our work provided valuable insights for efficient CO₂ capture and provided a novel technique for the resource utilization of red mud.