Micropore characterization of activated carbons of respirator cartridges with argon, carbon dioxide, and organic vapors of different vapor pressures

Activated carbon is the preferred adsorbent to remove organic vapor (OV) because of its micropore structure. For ten activated carbons of commercially available respirator cartridges, the microstructure were characterized using argon at 87.3 K, carbon dioxide at 273 K, and five organic vapors having different vapor pressures (dichloromethane, n-hexane, methyl isobutyl ketone (MIBK), m-xylene, and toluene) at 500 ppm, 294 K, and 40% relative humidity. The corresponding OV adsorption isotherm at relative vapor pressures ranging from 9 × 10−4 to 0.1 exhibited the characteristic Type I isotherm as verified by the Langmuir model. The Dubinin Radushkevish (DR) equation was applied to the argon and OV data to extrapolate the micropore volumes and the specific relative structural constants, B. The micropore volumes obtained with the OV experimental data were within 0-19% from the values of the argon data. Comparison between the DR predicted and experimental adsorption capacities showed that the OV approach could successfully predict the adsorption capacity for the tested OV. The complementary characterization with carbon dioxide showed that narrow micropores might play an important role in the adsorption.