Silica based aerogel synthesis from fly ash and bottom ash: The effect of synthesis parameters on the structure

This research aims to demonstrate the synthesis of silica based hydrophobic aerogel from fly ash, bottom ash and the pure silica source, tetraethyl orthosilicate (TEOS). The silica solutions were obtained from the fly ash and bottom ash by alkali fusion reaction, and the synthesis of materials was based on the base-catalyzed sol-gel process. The unreacted materials were removed by washing with hexane and the drying step was carried out with the ambient pressure drying method, which is safer, cheaper and more environmentally friendly. The modification process for the hydrophobic aerogel was completed during the synthesis step, with no further hydrophobization being performed. Characterization of the synthesis samples was achieved by using Fourier transform infrared spectroscopy (FT-IR), contact angle and density measurements. X-ray diffractometer (XRD), differential thermal analysis and thermogravimetry (DTA-TG) and N-2 adsorption/desorption analyses were also performed for optimum samples.