Functionalization of multi-walled carbon nanotubes with diamine precursor to increase CO2 Adsorption

فاقد چكيده فارسي

The aim of this project is to modify multi-walled carbon nanotubes with amines to increase the carbon dioxide adsorption capacity. To achieve this goal, pristine multi-walled carbon nanotubes were functionalized in a two-step process. In the first step, multi-walled carbon nanotubes, oxidized with a mixture of diluted sulfuric acid and diluted nitric acid (5 molars HNO3/5 molar H2SO4 with a volume ratio of 1:3). This was done with the aim of removing metal catalysts impurities and introducing carboxyl groups on the surface of multi-walled carbon nanotubes. In the second step, to enhance the performance of multi-walled carbon nanotubes in carbon dioxide adsorption, oxidized carbon nanotubes were functionalized with the 1,3-diaminopropane (DAP) solution. Specifications and characteristics of raw and modified carbon nanotubes were determined by using Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The CO2 adsorption capacity was measured at the temperature range of 303-323 K and pressures up to 17.3 bar using volumetric method. At 303 K and 17.3 bar, 71.9 mg/g of CO2 were adsorbed on MWCNT/DAP, While the CO2 uptake of raw MWCNT in the similar conditions was only 48 mg/g. These results showed that amine groups that were attached to the carbonaceous surfaces during the functionalization process, causing the formation of carbon dioxide-adsorption sites on multi-wall carbon nanotubes which increased the adsorption capacity of MWCNTs.