Carbon nanostructures-modified expanded vermiculites produced by chemical vapor deposition from ethanol

摘要

In this work, chemical vapor deposition using ethanol and FeMo catalysts at 600, 700, 800 and 900 ℃ was used to modify the surface of expanded vermiculite (EV). Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, Moessbauer spectra, N_2-BET surface areas, and carbon elemental analyses suggested that the FeMo catalyst promoted 2-3% growth of carbon in different forms, mainly nanofibers, on the EV surface. The amount of 2-3% carbon produced by ethanol/CVD process on EV produced a 500% increase in the absorption of soybean, diesel and engine oil, with a concomitant decrease on water absorption. These results were discussed in terms of a hydrophobization of the EV surface by the carbon structures and a "sponge-like" effect due to the entangled nanofibers structure, as it was observed by microscopy, and an increase of N_2-BET surface area from 3 m~2 g~(-1) for EV up to 21 m~2 g~(-1) for the ethanol CVD-treated EV.