Preparation Of Silica Airgel, Characterization And Performance Studies

Silica aerogel has widely application prospects in thermology, mechanics, optics, electrics, acoustics and catalyst carriers, owning to its advantages of low density, high surface area and high porosity.In this paper, the new method of "one-step acid-base sol-gel pr ocess" was firstly explored in the synthesis of Silica aerogel, when Tetraethoxysilane was used as precusor of silica, dimethyl formamid e, glycerol and polyethylene glycol were as DCCA. ethanol/hexmeth ydisilazane/hexane were the reagents of one-step solvent exchange and surface modification process.The stability, tap density, contact angle and specific surface of aerogels were took as the main performance indexes of products. The structure and morphology of silica aerogels have been investigated by FTIR, XRD, TG-DSC, F-SEM, BET. The influence of the kinds and amounts of DCCA, EtOH/HMDZ molar ratio, HMDZ/Hexane volume ratio on the structures and properties of silica aerogels were also discussed, and the absorptivities of silica aerogels for were also investigated when took the adsorption performance of the product on methyl orange and methylene blue.The results showed that the aerogels had high surface area of 842.63m2/g when the molar ratio of DMF and TEOS was 0.2, the optimal molar ratio of ETOH and HMDZ was 0.8, and the volume ratio of HMDZ and Hexane was 0.1. the density of the aerogels with the high surface area was 130kg/m3, the diameter was about 15nm and the diameter of the pore sizes was in the range of 2～150nm, the aerogels also showed an excellent hydrophobic feature.The maximum absorptivity of product on methyl orange was 18.5% and the maximum absorptivity of products on methylene blue was 98.8% when the temperature was 45℃.Moreover, silica aerogels doped with K2Ti6O13 whiskers were also prepared, and the effects of doping amount on structure and heat-proof quality of product were also investigated. Results showed that the heat-proof quality of products was enhanced with doping amounts increasing on condition that the original microstructure of silica aerogel wasn't destroyed.In conclusion, the performance of silica aerogel prepared with one-step method was superior than that prepared with multistep method, the production cycle was cut to four days from primary six days. The energy consumption was reduced, the pollution was decreased and the cost was saved in the premise of the guaranteeing quality. It also provided important theoretical basis for solving the problems of the long cycle and complex conditions of traditional aerogel preparation technology and realizing the advantages of energy saving and emission reduction.