Amine-functionalization of multi-walled carbon nanotubes for adsorption of carbon dioxide

Carbon nanotubes (CNTs) have emerged as one of the potential support materials for adsorption of carbon dioxide (CO₂) because of their specific surface morphology and unique chemical characteristics. CNTs are well known with their large surface area, porous structure and excellent chemical and thermal stability. They can be effectively used as support materials in the development of high efficient adsorbents to capture CO₂ from the emission sources, which are normally present in relatively high temperature. In this study, adsorbents for capturing CO₂ were prepared from the modification of multi-walled carbon nanotubes (MWCNTs) with 3(aminopropyl)- triethoxysilane. The modification of MWCNTs was performed in various conditions to study the key factors affecting the quality of the adsorbents, including the presence of solvent, thermal treatment and functionalization duration. The effects of solvent, functionalization duration and thermal treatment were found to be significant in the functionalization process. High quality amine-functionalized MWCNTs were obtained in the presence of toluene with thermal treatment. A maximum CO₂ uptake of 74 mg/g adsorbent was achieved from the adsorbent developed in this study.