EFFECTS OF REGENERATION CONDITIONS ON THE CHARACTERISTICS OF WATER-VAPOR ADSORPTION ON SILICA-GEL

Equilibrium adsorption and desorption isotherms of water vapor on a silica gel were measured at 288, 298, and 308 K. Isotherms were of type I according to Brunauer's classification and provided a single characteristic curve when correlated according to Polanyl's potential theory. Literature data on different samples of silica gel exhibited differences in uptake capacity from each other and from the present data. The uptake capacity at 298 K did not change significantly when regeneration temperatures were varied in the range of 373-442 K, nor when the regeneration time was increased from 4 to 16 h. The heats of adsorption suggest that silica gel has an energetically heterogeneous surface for water vapor adsorption.