Amine-incorporated adsorbents with reversible sites and high amine efficiency for CO2 capture in wet environment

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

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.