Characterizations of Activated Carbon–Methanol Adsorption Pair Including the Heat of Adsorptions

This paper presents adsorption isotherms and isosteric heats of adsorption for methanol vapor adsorption for two commercially available activated carbon samples—207EA granules and WS-480 pellets (Calgon Carbon, U.S.A.)—which were also fully characterized using nitrogen sorption at 77 K. The heat of adsorption of methanol as a function of loading was determined using the Clausius–Clapeyron approach with isotherms obtained at 5 °C, 15 °C, and 25 °C. The isosteric heats of adsorption increased sharply at the small coverage due to increasing effect of condensation heat with coverage. The heat reached a maximum and then varies little with loading, with the average values at around 46.6 kJ/mol for 207EA and 45.1 kJ/mol for WS-480. The higher heats of adsorption for the former activated carbon reflect its more microporous nature (around 78 % compare to 62 % for WS-480 activated carbon). The heat of adsorption data is also comparable to that obtained elsewhere for other activated carbons.