THE INFLUENCE OF SURFACE MODIFICATION OF BPL CARBONS ON AGING

The treatment of BPL carbon with various surface modifying agents, suc h as nitric acid, hydrogen, chlorine and ethylene, has been carried ou t. The treated and as-received carbon samples were aged under high hum idity conditions and changes in the surface functional groups were exa mined using temperature programmed desorption, enthalpy of immersion d eterminations in water and water adsorption isotherms. Aging of many o f the carbons at 84% RH for extended periods of time (up to 4 years) w as seen to increase the amount of desorbed oxygen from the surface, in crease the enthalpy of immersion in water and alter the initial uptake of water vapour at low relative pressures. These changes appeared to be retarded by low temperature (<180 degrees C) chlorine treatment. Ni tric acid oxidized BPL carbons containing high concentrations of surfa ce oxides before storage or aging showed little indication of further oxidation when subjected to high humidity conditions. Copyright (C) 19 96 Elsevier Science Ltd