Synthesis and Characterization of silica Xerogel Prepared with sodium silicate and sulfuric acid

Silica xerogels are extremely porous materials with highly cross linked network of silica particles [1]. Typically, they exhibit low density (0.03 g/cm3), low thermal conductivity(*0.05 W/m K), low refractive index (1.01 to 1.1), large surface area (1600 m2/g) and high hydrophobicity. Theseextraordinary properties of silica xerogels make them as a unique material in many fields of applications [2]. It can use in Cerenkov radiation detectors, filters, membranes, collectorsfor micrometeorites, catalyst supports, thermal super insulators for solar ponds, hot-water system and so on [3].Silica xerogels are produced generally by hydrolysis and condensation of silicon alkoxides like TMOS or TEOS in the presence of an acidic or basic catalyst followed bysupercritical drying in an autoclave [4]. Various groups of monolithic and transparent silica xerogels have been preparedby the same method. However, this method of preparation of xerogels in an autoclave is very risky and expensive. Due to the drying occurs at high temperature and pressure withevacuation of highly flammable gases. Hence, it is necessary to produce silica xerogels using cheap inorganic precursor anddrying the gels at an ambient pressure. In this work, we prepared the silica xerogels using sodium silicate as a precursor and dried the gels at an ambient pressure