ADSORPTION OF WATER-VAPOR ON NONPOROUS CARBON

The surface of the nonporous carbon Cabot Black Pearls 570 was modified by oxidation in aqueous nitric acid. In an attempt to produce a series of carbons having a range of oxidation levels, the time of contact with the acid solution was varied from 1 to 8 h. The ''as recieved'' and oxidized samples were characterized by water vapor adsorption at 298 K, nitrogen adsorption at 77 K, and temperature-programmed desorption and enthalpy of immersion in water measurements at 298 K, The water vapor isotherms were analyzed by fitting to a modified D'Arcy-Watt equation and the relationships between the parameters thus obtained, and the surface oxide concentration and immersional enthalpies were examined.