1995 Volume 39 Issue 6 Pages 333-336
Adsorption-desorption behavior of water vapor on activated carbon and charcoal was investigated to assess the humidity-control capacity (HCC) of microporous carbon. The amount of water vapor adsorbed (W1) was measured for 26 microporous carbon samples at 25°C and relative pressure of 0.55. Relative pressure was increased to 0.90 and the amount of water vapor adsorbed (W2) was measured. Relative pressure was then lowered to 0.55 again and the amount of water vapor adsorbed (W3) measured again. W2-W3(≡W4) expresses HCC; microporous carbon with high W4 is desirable.
HCC of commercial charcoal was 20-30mg/g and less than that of commercial activated carbon. HCC of activated carbon was dependent on raw material and activation method. Activated carbon produced by chemical activation with zinc chloride had higher HCC than other types of activated carbon made by gas activation. Activated carbon obtained from coconut shell had lower HCC than activated carbon produced from wood or coal.
The relationship between adsorption-desorption behavior and porosity of carbon was examined. HCC of microporous carbon increased with pore volume.
