Tailoring the pore structure of amine-functionalized KCC fibrous nanosilica for efficient CO₂ adsorption

Controlling the emission of greenhouse gases such as CO₂ by adsorption has been extensively investigated over various solid adsorbents to achieve effectual capture. The present work studied the fabrication of mesoporous nanosilica materials, KCC-1, KCC-2, KCC-3, and their corresponding amine-functionalized NH₂-KCC, as potential adsorbents for CO₂ capture. The KCC-1, KCC-2, and KCC-3 silica were prepared using the hydrothermal and reflux methods under various parameters. The NH₂-functionalized materials were obtained by grafting the KCC materials with 3-aminopropyltriethoxysilane (APTES). The synthesized materials were characterized by XRD, FTIR, N₂-sorption, CHN elemental analysis, SEM-EDX, TEM, and TGA techniques. Results showed that the NH₂-KCC materials retained the original KCC structure. Adsorption experiments revealed that the maximum CO₂ capture capacity was 0.997 mmol g^-1 at 1 bar (60 °C) and 0.715 mmol g^-1 at 1 bar (25 °C) by NH₂-KCC fibrous nanosilica. Furthermore, the CO₂/N₂ selectivity of KCC-3-APTES was 36 at 50 mbar (25 °C). The pores and surface silanol groups of the mesoporous silica, with NH₂ functionalities, possess unique textural and binding properties that assess the efficient adsorption of CO₂. The adsorption data were fitted using Langmuir and Freundlich models. Moreover, the NH₂-KCC material was recycled and reused for five cycles and retained 99% adsorption efficiency. The results suggest that the synthesized functional porous silica (NH₂-KCC) materials are potential adsorbents for advanced adsorption and CO₂ capture processes.