Characteristics of Rayon-based Activated Carbon Fibers by Chemical Modification and Thermal Treatment

摘要

Activated carbon fibers (ACFs) are widely used in air pollution control because of their extended surface area, high adsorption capacity, rapid adsorption/desorption rates, microporous structure, and specific surface reactivity. Several studies have been attempted to improve the adsorption performance of ACFs. Therefore, the objective of this study is intended to understand the properties of ACFs after chemical oxidation and thermal treatment, and further to determine their adsorption capacities. One rayon-based ACF was selected in this study. The as-received ACF samples were immersed in H2O2, H3PO4 or HNO3, under room temperature or 60 °C. The followed heat treatment was operated in a tubular furnace, conducted at 400, 600 and 850 °C for 30 or 60 min. The properties of ACFs were analyzed, including the surface morphology, the specific surface area, the pore volume, the surface oxides, the total ash content and the pH value. The adsorption amounts of toluene on selected ACF samples at 25 °C were determined for evaluation of the effect of chemical modification and thermal treatment. The results show that the specific surface area and pore volume of ACFs were decreased after chemical oxidation, and the loss was proportional to the acid-treated temperature. This could be attributed to the occupation of surface oxides or the collapse of graphitic sheets. Nevertheless, it has been found that the chemical oxidation followed by thermal treatment would increase the specific surface area and the toluene adsorption of ACFs.