High Efficiency and Eco-Friendly TEPA-Functionalized Adsorbent with Enhanced Porosity for CO2 Capture

In this study, the goal is to design a new CO2 capture platform along with an emerging nan-adsorbent development. Surface property changes occurred in the two-step preparation of halloysite nanotubes (HNTs) resulted in an enhanced mesoporous silica nanotubes (EMSNTs) with a more than 8.5-fold increase in the specific surface area to 382.23 m2/g and 3.2-fold increase in the pore volume to 0.66 m3/g compared to HNTs. It has been the highest possible value of surface properties of halloysite achieved so far. Also for the first time, EMSNTs was prepared by functionalizing Tetraethylenepentamine (TEPA). Because of its lack of the space barrier structure of TEPA in loading on nanotubes and its low viscosity, more amine content and more active sites for CO2 uptake were provided which resulted in exceptional adsorption efficiency and an increase in the capture rate by about 20–40% compared to polyethyleneimine functionalization. The optimum amount of adsorption capacity was for EMSNTs/TEPA30% (EM-TE-30) specimen and the maximum CO2 adsorption capacity of adsorbents was 9.3 mmol/g at 20 °C and 9 bar. For characterization of physiochemical traits of nanocomposites, the test methods such as scanning electron microscopy, X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, Brunauer–Emmett–Teller, and N2 adsorption/desorption, were carried out after treatment. Also during the 12 cycles of adsorption–desorption, the as-prepared nanocomposite adsorbents illustrated the good reversibility and stability accompanied by great thermal stability.