Activation studies of vapor-grown carbon fibers with supercritical fluids Original Research Article

The objective of this research was to investigate the feasibility of activating vapor-grown carbon fibers (VGCFs) with supercritical fluids (SCFs). VGCFs with a mean diameter of 150 nm and a length of a few micrometres were treated using water or carbon dioxide under supercritical conditions for 10 min. Hydrochloric acid and nitric acid were utilized for the oxidation of the VGCFs prior to the treatment of the SCFs. The nitrogen adsorption results at 77 K showed that the BET surface area of the treated VGCFs can be increased from 9 m2/g to about 35 m2/g. The adsorption of benzene vapor on the VGCFs revealed that the adsorption capacity of benzene was enhanced after the activation treatments. However, in comparison with commercial activated carbon fibers (ACF), the adsorption amount of benzene is still relatively low. Based on the CHN elemental analysis and X-ray photoelectron spectroscopy (XPS), it was found that oxygen compounds were contained on/in the VGCFs after the treatment by oxidation and by SCFs.