Abstract
Hydrophobic silica aerogels were successfully preparation by an ambient pressure drying method from sodium silicate (Na2SiO3) with different pH values (5, 6, 7, 8, 9 and 10). In this study, acidic HCl (1M), a basic NH4OH (1M) were selected as a catalyst to perform the surface modification in a TMCS (trimethylchlorosilane) solution. The surface chemical modification of the aerogels was assured by the Fourier transform infrared (FTIR) spectroscopic studies. Other physical properties, such as pore volume and pore size and specific surface area were determined by Brunauer-Emmett- Teller (BET) method. The effect of pH values on the bulk density of aerogel. The sol–gel parameter pH value in the sol, have marked effects on the physical properties of the silica aerogels produced by this technique. The density and the hydrophobic tendency of the aerogels were significantly influenced.
Highlights
Since its discovery by Kistler in1931[1], silica aerogels are advanced materials and are new in the field of materials science
Last few years, preparation hydrophobic silica aerogels by an Ambient Pressure Drying (APD) technique has been attracting great interest
There are some differences in the relative intensity of some vibration bonds. This may be due to the injection of the organic modifiers into the silica structure. This organic rout can be used as a referee factor in the determination of the hydrophobic properties of the aerogel
Summary
1931[1], silica aerogels are advanced materials and are new in the field of materials science. Silicate aerogels consist of 4% of a weak structure from the matrix of silicon dioxide, the residual 96 % is air. It is the inorganic matter that dissolves in distilled water due to the polar property of the molecules Si-O and Na ion. The polar Property of the molecule (Si–O and Na+ ion) on one hand makes it dissolve readily in water. Silica aerogels were created by supercritical drying (SCD) process so as to attain a porous structure [6, 7]. Last few years, preparation hydrophobic silica aerogels by an Ambient Pressure Drying (APD) technique has been attracting great interest. Silica aerogels could be successfully preparation by (APD), through solvent exchange and surface modification of the wet gel using trimethylchlorosilane (TMCS), ethanol (EtOH), hexane mixed solution before drying [9]. Because of the characteristic properties and the unique for hydrophobic aerogels make it an attractive material for a multiplicity of applications such as liquid propellant transporters, highly effective catalysts, and radiators in Cherenkov detectors for high energy particles, filters for automobile exhaust systems and industrial pollutants, heat storage devices for automobile, encapsulation media, hydrogen fuel storage composite and oil spilling clean-up [3, 4 and 11]
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