文摘
Hydrophobic aerogels were synthesized, characterized by IR, surface areas, relative pore size distributions and decomposition behavior. The materials were then tested for oil absorbing capacity in oil salt-water mixtures for applications to oil-spill clean up processes. Aerogels containing the CF3(CH)2-group (CF3-aerogel) were successfully synthesized using (CH3O)4Si and nominally 30, 10, 1.5 mol % CF3(CH2)2Si(OCH3)3 in CH3OH by a NH4OH catalyzed reaction followed by supercritical extraction with CH3OH. The aerogels were found to be hydrophobic based on water absorption and sessile drop experiments. By IR, the CF3(CH2)2-group was found to be intact after the gelation process and after supercritical drying. Si–OH-groups were also found in all cases, with decreasing amounts with increasing amounts of the CF3(CH2)2-group. Heating under air caused the 30 % CF3-aerogel to decompose, where the transition temperature from hydrophobic to hydrophilic appeared around 375–400 °C, which corresponded to disappearance of the CF3(CH2)2-moiety bands in the IR. Treating oil and salt-water mixtures with the aerogel at an oil to aerogel ratio of 3.5 showed that all CF3-aerogels cleanly separated the oil from the water, regardless of CF3(CH)2-group concentration. This indicates that CF3-aerogels can absorb oil as much as 237 times their weight, much more than previously determined.