Comparative Analysis of the Efficiencies of Two Low Cost Adsorbents for Carbon Dioxide Capture

Abstract

Global warming, climate change and associated threats have motivated research to look for cost effective adsorbents for Carbon dioxide (CO₂) capture at source. This study focused on CO₂ adsorption using a polymer- and a mineral-based adsorbent (chitosan and zeolite, respectively) modified with monoethanolamine (MEA). Chitosan beads were prepared by insolubilisation in NaOH whereas hollow zeolites were prepared by hydrothermal synthesis. Both adsorbents were successfully impregnated with MEA in different weight percent. Various physicochemical properties were studied using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Fourier Transform Infrared spectroscopic (FTIR) techniques confirming the successful formation of the designed adsorbents. Both the sorbents were studied for CO₂ adsorption from a simulated flue gas mixture comprising nitrogen and CO₂ using a fixed-bed flow reactor. Observations showed that the CO₂ adsorption capacity enhanced with amine loading for both the adsorbents. The adsorbents were found to be very active and promising, and the maximum adsorption found was 19 mg/g of modified chitosan. Compared to hollow zeolites, the modified chitosan beads showed better adsorption. The stability of the adsorbents was tested and observed that the same material can be recycled for three adsorption-desorption cycles and no significant change in CO₂ adsorption capabilities.