Rice husk derived Aminated Silica for the efficient adsorption of different gases

Abstract

Abstract In this present work, we successfully prepared aminated silica (ASiO2) from rice husk ash (RHA) and functionalized with 3-aminopropyltriethoxysilane (APTES). Physical and chemical properties of the synthesized material were investigated by various techniques SEM–EDX, XPS, FTIR, TGA. The surface area of RHA was 223 m2/g, while for ASiO2 was 101 m2/g. Molecular level DFT calculations revealed that the functionalization of ASiO2 resulted in a significant decrease in the HOMO–LUMO energy gap, a reduction in hardness, and a consequent increase in charge transfer characteristics. The adsorption behavior at low pressure (1 atm.) of aminated silica on different gases CO2, CH4, H2, and N2 at temperatures 77, 273, 298 K was studied. The adsorption of hydrogen was reported for the first time on aminated silica with an excellent adsorption capacity of 1.2 mmol/g. The ASiO2 exhibited excellent performance in terms of gas separation in binary mixtures of CO2/CH4, CO2/N2 and CO2/H2 at 273, and 298 K, respectively. The catalyst further exhibits high stability during three cycles with less than 10% variation in the separation capacity.