Adsorption of H2S and SO2on Bigadiç Clinoptilolite

Abstract

Abstract H2S and SO2 adsorption isotherms of Bigadic clinoptilolite and its Na−, K−, Ca−, and H−enriched forms were determined in the 0 to 100 kPa range at 25°C by using a constant volume adsorption system. Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Dubinin-Astakhov (D-A) models were applied to the isotherm data. Higher adsorption capacities and a larger increase in the amount adsorbed at higher pressures were observed for SO2, in agreement with its higher permanent dipole moment, resulting in stronger ion-dipole and dipole-dipole interactions for this molecule. The Ca-form exhibited a molecular sieving behavior for both gases, originating from the channel blockage caused by the cation locations in the sample. The highest capacities for both gases were obtained with the sample in its H-form, followed by the Na− and K-forms for SO2, parallel to the decrease in the electronegativity and ionic potential and the increase in the polarizability of the cation. In the case of H2S, the H-form was follow...