Effect of the TMCS/hydrogel volume ratio on physical properties of silica aerogels based on fly ash acid sludge

Abstract

The silica aerogels based on the fly ash acid sludge were successfully synthesized using ethanol (EtOH)/trimethylchlorosilane (TMCS)/n-hexane as surface modification agent via ambient pressure drying. The surface modification of hydrogels was a crucial step during the processing which preserved mesopores structure in ambient pressure drying. It was found that the structure and physical properties of silica aerogels dependent on the TMCS/hydrogel volume ratio. The results indicated that the specific density decreased with an increase in the TMCS/hydrogel volume ratio. The silica aerogels modified with TMCS (volume ratio = 1) presented good performance with the specific surface area (830 m2/g), bulk density (0.072 g/cm3), contact angle (146°), and the average pore size (10.7 nm).