CONVERSION OF POLYACRYLONITRILE TO NANOPOROUS CARBON FOR ENVIRONMENTAL APPLICATIONS

摘要

The nanoporous activated carbon prepared from polyacrylonitrile by a two-step physical activation process had a surface area exceeding 540 m~2/g and contains only pores of radius smaller than 3 nm. This carbon has a basic character in aqueous solutions owing to the oxygen- and, even more, the nitrogen-containing functional groups developing on the surface during the preparation. These groups were identified by XPS. The nanoporous structure may result in a kinetic hindrance in solutions. The nanoporosity and the basic surface character resulted in a fast and effective uptake of a nasal carcinogen, formaldehyde, from the gas phase at controlled relative humidity. This granular carbon was also successfully applied to the removal of phenol and 2,3,4-trichlorophenol from dilute aqueous solution at ambient temperature. A higher uptake was achieved in the case of the polychlorinated pollutant, owing to its lower water solubility. The adsorption capacity and the mechanism of the adsorption were found to depend on the pH of the contacting media, as a result both of the heterogeneity and acid/base property of the carbon surface and of the weak acidic character of the solutes to be removed.