Physical Adsorption of Hydrogen Sulfide in Micropores of Zeolite and Activated Carbon

Adsorption isotherms of hydrogen sulfide on zeolite and activated carbon were obtained by a gravimetric method at 20° and 30°in order to elucidate the thermodynamic properties of adsorption of hydrogen sulfide in micropores of zeolite and activated carbon. The Dubinin-Astakhov equation could be applied to these adsorption isotherms. The net differential heat of adsorption q and the differential molar entropy of adsorption ΔS were calculated from the adsorption isotherms by using the following equations : q=E [(ln ao/a)1/n+αT/n (ln ao/a)1/n-1] and ΔS=-αE/n (ln ao/a)1/n-1. In all cases, q decreased with increasing degree of filling of micropores. It was considered that the micropores of zeolite and activated carbon are successively filled with hydrogen sulfide from the smallest pores to the largest ones. The differential molar entropy of adsorption became smaller with increase in the degree of filling. This entropy change suggests that hydrogen sulfide molecules are compactly filled in the micropores at the final stage of filling.