The Preparation Of Activated Carbon Fibers With High Specific Surface Areas And Their Adsorption Of VOCs

Volatile organic compounds(VOCs) have become one of major air pollutants in various industries, and can be harmful to the environment and human health, and the removal of VOCs have been one of the hot issues in the field of air pollution control, therefore the research on the removal of VOCs by adsorption is practically important. This thesis studied the preparation and microscopic structures of PAN-based and pitch-based porous carbon through a series of experiments and physical and chemical characterization method, and investigated their adsorption performances of toluene, n-hexane etc on the porous carbons prepared under the optimized conditions. The main experimental results are as following:(1) Porous carbon materials with high specific surface area of 1800m2/g and 3400 m2/g were obtained through CO2 activation and KOH activation, respectively based on polyacrylonitrile fiber as raw materials. Several preparation parameters including pre-oxidation temperature and time, carbonization temperature and time, activation temperature and time, alkali/cabon ratio on specific surface areas SBET and surface properties of porous carbon were found to be significant factors in the materials preparation. Further experimental results show the following adsorption performances of toluene and n-hexane on such obtained ACF materials under different adsorption conditions: Rasing adsorption temperature lead to a decrease in adsorption capacity; increasing VOC concentration and gas fluid speed velocity shortens the time of bed penetrating.(2) The activated carbons with high specific surface areas of 3340 m2/g were obtained based on an industrial pitch as raw material and KOH as activator after studying the influence of preparation conditions such alkali carbon ratio on surface area, and the materials showed the maximum adsorption capacity of ethyl acetate is 671mg/g under the optimized adsorption conditions. The adsorption equation fits well with the Bangham equation with a fitting degree as high as 99%.(3) The competitive adsorption of toluene/n-hexane and toluene/ethyl acetate on the obtained ACF materials have been investigated, and the results show that toluene has a stronger adsorption on the ACF than n-hexane and ethyl acetate; in addition, a small amount of water vapor has minor impact on toluene adsorption on the materials, while increasing the percentage of water vapor in the gas fluid will strongly affect the VOC removal(4) After modifying PAN-based ACF With melamine, polyethylene glycol 2000 and urea in the preparation process, the samples has increased their absorption capacity of volatile organic compounds.