KINETICS OF WATER-VAPOR ADSORPTION ON ACTIVATED CARBON

The adsorption of water vapor on a highly microporous carbon derived f rom the carbonization of coconut shell has been studied. This material was characterized by the adsorption of nitrogen at 77 K and carbon di oxide at 273 K. The micropore size distribution was determined using p robe molecule vapors at p/p(0) = 0.5 and 301 K. The adsorption and des orption characteristics of water vapor on the activated carbon were in vestigated over the pressure range 0-2.41 kPa (p/p(0) 0-0.9) in a stat ic water vapor system. The adsorption and desorption kinetics were stu died with different amounts of preadsorbed water for changes in vapor pressure of 0.303 kPa. The adsorption rate constants were also studied for three relative humidities for a dynamic flow system at a constant temperature. In these experiments the changes in vapor pressure were much higher than in the static vapor pressure experiments. The kinetic results for both the static atmosphere and dynamic flow systems are d iscussed in relation to their relative position on the equilibrium iso therm and the adsorption/desorption mechanism.