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

Abstract

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.