科研之友
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摘要
Carbon nanotubes (CNTs) possess unique electronic, mechanical, and structural properties. They were shown to be effective and stable low temperature adsorbent materials that could make them potentially useful for gas storage and separation of various gas mixtures. Carbon dioxide (CO2) is a greenhouse gas and CO2 levels in the atmosphere have been steadily increasing due to human activity. Hence, capturing CO2 is an active research area. Previous studies on CO2 adsorption using CNTs focused on low concentration CO2 environments; however, capturing CO2 at the source (coal plants, automobile emissions, etc.) is a more realistic solution, therefore, in the current study, the potential use of CNTs as CO2 adsorbents at high concentration CO2 environments is reported. The effects of single walled carbon nanotube diameter and length, and CO2 concentration were studied using molecular dynamics simulations at 300 and 320 K. Results showed that CO2 molecules were selectively adsorbed by the single walled carbon nanotubes (SWNTs), and adsorption was dependent on both the internal volume of the nanotube and the cross-sectional area of the tube entrance. Temperature increase had a substantial impact on the location of CO2 molecules in and around the nanotube, i.e., at 300 K, CO2 molecules were located both inside and on the nanotube surface; whereas at 320 K, the CO2 molecules were mostly inside the nanotube. This result suggests that the mechanism of CO2 adsorption and retention can be controlled by temperature. Finally, our results showed that although the amount of adsorbed CO2 increased with increasing CO2 concentration, the efficiency of adsorption increased with decreasing CO2 concentration.
- 出版日期2012-10
