Figure 5

Oil absorption application.

(a) Photograph of superhydrophobic surface with; (b) a ca. 150° contact angle measurement with a 2 mm diameter water droplet resting on the sponge surface; (c) weight-to-weight (wt/wt) absorption capacity plot for common solvents measured with samples of density 24.3 mg/cm³ (green), 17.3 mg/cm³ (red) and 10.8 mg/cm³ (blue); (d)–(g) demonstration using CBxMWNT sponge to clean up used engine oil spill (0.26 mL) in seawater; sample (m ≈ 4.8 mg, ρ ≈17 mg/cm³); (d) photograph shows the sponge dropped into the oil at t = 0 min, inset shows sponge before use; (e) sponge sample absobing the oil at t = 2 min, inset shows t = 5 min; (f) by burning or squeezing (inset) one can salvage the oil; (g) the sponge can then be reused repetitively. By using a magnet one can track or move the oil; inset shows sponge after burning and before reuse.