A rapid and low solvent/silylation agent-consumed synthesis, pore structure and property of silica aerogels from dislodged sludge
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Dislodged sludge, a kind of industrial waste, was used as raw material to prepare silica aerogels via ambient pressure drying. The effect of solvent exchange and surface silylation on the pore structure and property of the obtained materials was investigated in detail. If the ethanol and n-hexane exchange decreases to 8 h (two times, each time for 4 h) and 4 h (one time), respectively, and the volume ratio of ethanol/wet gel and n-hexane/wet gel reduces to 2 and 1, respectively, the obtained materials exhibit a desirable pore volume of 3.17 cm3/g, a water contact angle of 152.9° and a low thermal conductivity of 0.030 W/ (m·K). Further decreasing the mole ratio of silylation agent/SiO2 to 0.5 and the silylation time to 6 h results to silica aerogels with a pore volume of 3.44 cm3/g, a water contact angle of 144.5° and a low thermal conductivity of 0.032 W/ (m·K). A rapid synthesis (a total time of 50 h, from wet gel aging to ambient pressure drying) of silica aerogels has been realized and the consumption of solvent/silylation agents has been pronouncedly reduced without sacrificing the thermal insulation property of the obtained materials.
KeywordsSilica aerogels Pore structure Rapid synthesis Dislodged sludge Thermal insulation property
This research is financially supported by Scientific Research Common Program of the Beijing Municipal Commission of Education (Grant Nos. KZ201410005006, KM201210005012), National Natural Science Foundation of China (Grant Nos. 21171014, 50502002, 51402007), Beijing Natural Science Foundation of China (Grant Nos. 2141001), State Key Laboratory of Solid Waste Reuse for Building Materials (Grant Nos.SWR-2014-010), Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality, and Beijing University of technology science and technology fund (Grant Nos. ykj-2015-12356).
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Conflict of interest
The authors declare that they have no conflict of interest.