Improvement of oil adsorption performance by a sponge-like natural vermiculite-carbon nanotube hybrid

Sponge-like exfoliated vermiculite (EV)/carbon nanotube (CNT) hybrids with different CNT content were prepared by intercalating aligned CNT arrays into natural vermiculite layers for oil adsorption. The intercalated growth of CNT arrays among EV layers of the EV/CNT hybrids was characterized by scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis under air atmosphere showed that CNT contents of the hybrids varied from 11.4% to 94.8% for different growth duration. Pore size distributions measured by an ex-situ Hg penetration method showed that large amount of pores can be formed in the hybrids after the intercalation of CNT arrays. N₂ adsorption results showed that the specific surface areas of all hybrids were significantly improved compared with original EV particles. Oil adsorption tests were conducted on a class of organic solvents and oils in baker and the recovery process was carried out in a syringe. It was found that the oil adsorption capacities of the as-obtained sponge-like EV/CNT hybrids were significantly improved compared with original EV particles due to the large quantity of pores produced by the intercalated growth of aligned CNT. The highest adsorption capacity of the EV/CNT hybrids was 26.7g/g for diesel oil when the CNT content reached 91.0%, which also exhibited good recycling performance. Furthermore, the adsorption capacity for diesel oil can be further increased to 70.6g/g by transforming the EV/CNT hybrids into fluffy EV/CNT cotton through high-speed shearing.