A silica aerogel synthesized from olivine and its application as a photocatalytic support

Y.X Chen,Y Hendrix,K Schollbach,H.J.H Brouwers

doi:10.1016/j.conbuildmat.2020.118709

Y.X Chen, Y Hendrix + Show 2 more

Open Access

https://doi.org/10.1016/j.conbuildmat.2020.118709

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Abstract

This study investigates the performance of a silica aerogel-based air purifying coating to functionalize building materials. The air-purifying function comes from an increased photocatalytic activity when the photocatalyst is supported on a silica network with a large specific surface area like silica aerogels. In this study, silica aerogel was first synthesized with a low energy-consumption method from olivine via ambient pressure drying and was applied as a support to load photocatalytic anatase crystals. The silica aerogel production includes sol-gel synthesis, ion-exchange, surface modification and ambient pressure drying. The produced silica aerogel obtained a high specific surface area (694 m2/g) and pore volume (2.99 cm3/g), with a uniform pore size distribution and mesoporous structure. Titania was loaded onto the prepared silica aerogel through a precipitation method. The resulting samples were characterized by measuring the conversion efficiency to oxidize nitric oxide under UV-light irradiation, nitrogen physisorption and FTIR. The silica aerogel coating with titania crystals had a photocatalytic activity of 99.6%, showing it to be a promising photocatalyst in the built environment.

Highlights

Air pollution in large urban cities is becoming a big threat to human health, especially for the harmful gases such as nitrogen oxides (NOx)
All the silica aerogel obtained a porosity beyond 93.6% and density below 0.134 g/cm3
This research shows that coating silica aerogel particles with titania can result in promising photocatalysts for air purifying

Summary

Introduction

Air pollution in large urban cities is becoming a big threat to human health, especially for the harmful gases such as nitrogen oxides (NOx). Silica aerogels contain an ultra-low density (0.03–0.2 g/cm3), high specific surface area (500–900 m2/g) and ultra-high porosity (90–99%). Due to these properties of aerogels, many researchers have synthesized different kinds of silica aerogels and applied them as thermal insulation [8,9,10,11], catalytic supports [12,13] and absorbent of pollutants [14,15]. The industrial silica aerogels are mostly produced from organic silica sources like tetrathoxysilane (TEOS) and methyltrimethoxysilane (MTMS), through supercritical drying [16] These processes are energy intensive and obtain a high carbon footprint [17]. A sustainable and low energy consumption method to produce silica aerogel would be a more desirable way to produce silica aerogel and used as a green and cost-effective support for catalysts

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