Adsorption of aromatic compounds on CxN-coated activated carbon

CxN-coated activated carbons have been prepared by deposition of CxN on activated carbon at 600, 700 and 1000 degrees C, and the adsorption of four aromatic compounds (nitrobenzene, benzoic acid, phenol and aniline) on the CxN-coated samples has been investigated. The CxN-coated samples were characterized by XPS, Raman spectroscopy and N-2 adsorption measurement at 77 K. The amount of nitrogen atoms bonded to three carbon atoms in graphene layers increased with increasing deposition temperature, while the surface areas of CxN-coated activated carbons decreased with increasing deposition temperature and duration. Molecular orbital calculation has suggested that the chemical interaction of CxN with aromatic compounds is enhanced due to low SOMO (Singly-Occupied Molecular Orbital) energy levels induced by nitrogen incorporation in graphene layers. The amounts of the adsorbed aromatic compounds per weight (g) of CxN-coated activated carbon were lower than those for original and heat-treated activated carbons, however, those per unit surface area (m(2)) of the CxN-coated samples were larger than those for the uncoated ones as suggested by molecular orbital calculation. (C) 2000 Elsevier Science Ltd. All rights reserved.