The influence of surface modification of BPL carbons on aging Original Research Article

The treatment of BPL carbon with various surface modifying agents, such as nitric acid, hydrogen, chlorine and ethylene, has been carried out. The treated and as-received carbon samples were aged under high humidity conditions and changes in the surface functional groups were examined using temperature programmed desorption, enthalpy of immersion determinations in water and water adsorption isotherms. Aging of many of the carbons at 84% RH for extended periods of time (up to 4 years) was seen to increase the amount of desorbed oxygen from the surface, increase 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 °C) chlorine treatment. Nitric acid oxidized BPL carbons containing high concentrations of surface oxides before storage or aging showed little indication of further oxidation when subjected to high humidity conditions.