Hybrid Clay Nanomaterials with Improved Affinity for Carbon Dioxide through Chemical Grafting of Amino Groups
International Journal of Environmental Pollution and Remediation
triethoxysilane on Na-montmorillonite in ethanol-water mixture or ethylene glycol as solvent resulted in two organoclays (NaMt-S-EW and NaMt-S-EG, respectively). The latter were characterized through X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis, differential scanning calorimetry and 29 Si solid-state nuclear magnetic resonance (NMR). Nitrogen adsorption isotherms measurements revealed lower specific surface area as compared to the starting clay mineral. This was
... mineral. This was explained by the formation of compact lamella stacks bound by silylation at the edges of the clay sheets. Thermal programmed desorption analyses (TPD) revealed an improved affinity towards carbon dioxide (CO2) as compared to the starting clay mineral. NaMt-S-EW displayed higher affinity towards CO2 than NaMt-S-EG, with retention efficiency factor exceeding 16 µmol.m -2 for high amine content. Differential scanning calorimetry gave desorption enthalpy ranging from 148 to 467 kcal.mol -1 , suggesting that only chemical interactions are involved between the amino groups grafted and CO2. CO2 retention capacity exceeding 1.0 mmol.g -1 with efficiency factor higher than 16 micromol.m -2 can be obtained for higher amine content, in optimum content, when no CO2 removal through forced convection takes place.