Hydrophobic aerogels for oil-spill cleanup - Intrinsic absorbing properties

A hydrophobic, CF3-functionalized silica aerogel has been applied to water-oil mixtures to determine oil absorbing capacity of the solid aerogel. Preliminary tests on Prudhoe Bay crude oil mixed with salt water, using the aerogel in powder form, show three regimes for absorbing based on oil to aerogel wt ratios (O/A): 1) all oil is absorbed and the aerogel is dry, O/A 0-3.5; 2) all oil is involved in an oil-aerogel-water emulsion, O/A 4.6-14; and 3) some oil is involved in an oil-aerogel-water emulsion, but free-phase oil is seen, O/A> 16. For comparison, a silica aerogel that has not been functionalized shows maximum absorbing capacity without the appearance of free-phase oil at O/A<0.1. Separation and extraction studies showed good aerogel recovery and moderate oil recovery. Extraction studies at O/A of 2.3 showed that the aerogel could be reused at least two times. Infrared studies show that the oil recovered from the absorbing material and the starting oil are structurally similar. These results indicate that the CF3-functionalized aerogel as a powder has the potential of cleanly separating oil from oil-water mixtures up to 14 times the weight of the aerogel.