Synthesis of silica aerogel with silica sand, feldspar and tetraethylortosilicate by sol-gel method and characterization

ABSTRACTDue to having high surface area, porosity and low density, silicaaerogels are used in many fields. Therefore, production of silicaaerogels is fundemantal for many technological research areas.In this study, silica aerogels were synthesized by different precursorsby using the sol-gel method. Silica sand, feldspar and TEOS were usedas precursors. Because of the fact that silica sand and feldspar areinartificial materials, silica was extracted by boiling these materials insodium hydroxide solution. Extraction process was carried out indifferent stirring times as 1, 2 and 3 hours. By evaluating datamentioned above, stirring times for silica and feldspar were selected as3 hours and 2 hours, respectively. The effect of the aging temperature(30, 40, 50, 60 and 80C) on the surface area and average pore diameterof synthesized silica aerogel was investigated. It is observed that therewere no significant effects of different aging temperatures on surfacearea and pore size of silica aerogel synthesized from TEOS. The highestsurface areas of silica aerogels synthesized from silica sand andfeldspar were obtained at 30 C. Surface areas of silica aerogels madefrom silica sand and feldspar were found as 609 m2/g and 954 m2/g, viirespectively. Pore diameters of silica aerogels produced from silicasand and feldspar were in range 20-60 Å and 15-60 Å, respectively.While silica aerogel produced from silica sand was mesoporous, silicaaerogel synthesized from feldspar was micro and mesoporous andsilica aerogel produced from TEOS was microporous.Surface modification was made to silica aerogel which was synthesizedfrom silica sand and feldspar at 50?C aging temperature. TEOS wasused during the aging for modification. It is observed that silica aerogelobtained from the modification of silica sand had hydrophobicstructure.