Preparation and adsorption property of hydrophobic SiO2 aerogels modified by methyl triethoxysilane

Abstract

The hydrophobic SiO 2 aerogels were prepared by in-situ polymerization sol-gel method and supercritical drying of ethanol method with tetraethylorthosilicate(TEOS) as silica source, methyl triethoxysilane (MTMS) as modifi er, ethanol as solvent. Moreover, the structure and adsorption property of SiO 2 aerogels were also studied. As results, the surface area of SiO 2 aerogels was 863.59 m 2 /g, the pore volume was 3.57 cm 3 /g, and the contact angle was 150 °. Adsorption intensity of silica aerogels for organic liquid (alkanes, benzene compounds, and nitro-compounds) is bigger than that of activated carbon. The mass of the liquid absorbed increased linearly with the surface tension of the liquid. The lower surface tension and boiling point are, the shorter desorption time is. After regenerating 10 times, nitromethane regeneration rate remain the same, and almost more than 94%. So SiO 2 aerogels have good absorption and regeneration property.

3D Visualization of the Radar Environment

“…In recent years, with the advancement of interactive visualization technology, researchers have explored 3D expression of the radar electromagnetic information. Based on different theories and application purposes, existing 3D methods for the expression of radar can be divided into four types: 1) Radar modeling in free space [3][4]: this method confines the radar electromagnetic environment to pure free space, which has no regard to other factors such as terrain occlusion, atmospheric effects, and earth surface's refraction; 2) Geometric model correction [5][6]: this method first calculates the radar's coverage by employing the radar equation, and then aims at specific factors that affect the radar coverage such as terrain occlusion and atmospheric effects, and thus revises the boundary to achieve 3D visualization of the radar coverage under different circumstances; 3) Pattern propagation factor estimation [7]: this method first estimate the pattern propagation factor in the radar equation and then calculate the radar coverage by the radar equation. The method has high computation complexity and is not based on actual electromotive parameters; 4) Region selection based on Advanced Propagation Model [8]: here different computational models are employed with different electromagnetism regions according to the propagation attenuation computational models.…”