Preparation Of Superhydrophobic Elastic Of SiO₂ Aerogels And Adsorption Properties

Silica aerogel is a kind of porous material with spatial structure of three- dimensional network and widely applied in adsorption, catalysis, thermal insulation, medical and other fields due to its low density, high porosity and large specific surface area. However,conventional hydrophilic silica aerogels shows the disadvantages of brittleness and low strength, its application is severely limited. Therefore, how to prepare the high mechanical properties and hydrophobic of Silica aerogel, it has important practical significance.In this paper, silica aerogel was prepared through sol-gel method with MTMS and DMSMS as the mixed precursor under normal pressure and characterized by FI-IR、SEM、XRD and TGA analysis. Effect of organic silicon source ratio, the dosage of methanol, the dosage of water, the dosage of the DMF and PH value factors on the performance of aerogel were investigated. Hydrophobicity of aerogel was modified through surface hydrophobic modification method, the effect of the concentration of the modifying agent and modifying time on hydrophobic property of the aerogel was studied. It demonstrates excellent Adsorption performance in adsorbing oily water or organic wastewater. Doping of carbon fiber and polyacrylonitrile fiber can toughen SiO2 aerogel with enhanced mechanical properties. The results show that: under atmospheric conditions, the precuso ratio(MTMS: DMDMS = 1: 0.6): methanol: water(acetic acid c = 0.01 mol / L): the ratio of the amount of DMF substance is 1: 8: 12: 0.5 and a pH of about 8.5,SiO2 aerogel with better performance was obtained, having a density of 78 kg / m3, 80% after the compression can be fully restored, with good flexibility; with TMCS as a modifier and n-hexane as a solvent, when TMCS / n-Hexane volume ratio of 0.1, and modification time of 6h, the best modification effect was achieved with the maximum contact angle of 169 °, showing superhydrophobic property;The aerogels modified show high adsorption capacity for oil and other organic substances and good recyclability; SiO2 aerogels doped with carbon fiber and polyacrylonitrile demonstrate excellent mechanical properties, Compressive strength being increased by 16.6-fold and 3.7-fold.