Reduction in the processing time of doped sodium silicate based ambient pressure dried aerogels using shaker

Abstract

The experimental results on the “reduction in the processing time of doped sodium silicate based ambient pressure dried aerogels using shaker”, are reported. Shaking the hydrogels in the shaker in presence of distilled water helps in the removal of sodium salt and reduces the processing time of the aerogels. In addition, doping the gels enormously helps in the improvement of strength and thermal insulation property of the aerogels. Hence, the present paper deals with the study of the effects of shaking speed and shaking period of the granular gels, and doping the gels with titanium dioxide powder (TiO 2) on the physical properties of the aerogels. The aerogels have been characterized by bulk density, volume shrinkage (%), porosity (%) and thermal conductivity. The quantitative analysis of hydrophobicity was done by measuring the contact angle of water on the surface of aerogel. The microstructural and elemental analyses studies were carried out using transmission electron microscopy (TEM), energy dispersive analysis by X-ray (EDAX) and fourier transform infrared (FTIR) spectroscopy. The pore volume and surface area of the aerogels were measured using N 2 adsorption–desorption BET surface analyzer. The thermal stability of the aerogels was checked by thermogravimetric and differential thermal analyses (TGA–DTA). Silica aerogels with low density ∼0.047 g/cc and low thermal conductivity ∼0.057 W/m K have been obtained by shaking the gels at the speed of 150 RPM for 4 h using the molar ratio of Na 2SiO 3:H 2O:TiO 2:Citric acid:TMCS at 1:146.67:6 × 10 −5:0.54:9.46, respectively. The shaking of the wet gels in a shaker reduces the processing time of the aerogels from 4 to 2 days. These aerogels can be used as thermal insulating materials in ovens, refrigerators and related systems.