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

Rashed S Bakdash,Isam H Aljundi,Ismail Abdulazeez,Chanbasha Basheer

doi:10.1038/s41598-020-76460-0

Rashed S Bakdash, Isam H Aljundi + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-76460-0

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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.

Highlights

The flexibility of silica-based mesoporous materials enables their functionalization with other materials, such as metal nanoparticles, or rare-earth e lements[1]
There is no significant difference in the morphology of the surface before (Fig. 1A) and after the functionalization of rice husk ash (RHA) with APTES (Fig. 1B)
The functionalization of RHA with APTES was confirmed by EDX analysis (Fig. 1D) and showed a content of C, O, Si, and N of 27.4%, 38.3%, 31.1%, and 3.2%; respectively

Summary

Introduction

The flexibility of silica-based mesoporous materials enables their functionalization with other materials, such as metal nanoparticles, or rare-earth e lements[1]. Mesoporous silica has an advantage of high surface area and pore volume, high stability, unique pore structure characteristics, and uniform pore size distributions. It has been widely used in wastewater treatment, air purification, thermal insulation systems, oxygen, and humidity sensors and battery electrodes a pplications[2]. The development of mesoporous materials have attracted more attentions in recent years for CO2 adsorption due to their high porosity, high gas diffusibility, and large pore volumes. Amine functionalization results in highly efficient C O2 capture at low temperature due to the strong interaction between the CO2 molecules and the porous structure, resulting in high gas diffusion through the a dsorbent[18]. Zeng and Bai have reported a low-cost mesoporous silica with large pore volume impregnated with tetraethylenepentamine for efficient C O2 adsorption with a maximum C O2 uptake up to 173 mg/g22

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