Removal of hydrogen sulfide in the gas phase by carbide slag modified bentonite

Abstract

Bentonite-based adsorbents for the removal of hydrogen sulfide (H₂S) were prepared by a wet-mixing method using carbide slag as the active component. The effects of carbide slag content, calcination temperature, calcination time, and reaction temperature on the H₂S adsorption capacity were investigated. The results showed that compared with the blank bentonite adsorbent, the carbide slag-modified bentonite-based adsorbent enhanced the chemisorption of H₂S. The adsorption capacity of the carbide slag modified bentonite adsorbent (2.50 mg g⁻¹) was more than 40 times higher than that of the blank bentonite-based adsorbent (0.06 mg g⁻¹) under optimal conditions. The optimal conditions for H₂S removal were 3 : 5 ratio of carbide slag-to-bentonite, calcination temperature of 450 °C for 2 h, and reaction temperature of 95 °C. H₂S was mainly removed in the mesopores and macropores of the adsorbent and was finally transformed to CaS and sulfate on the adsorbent surface. The adsorption process of H₂S followed the Freundlich adsorption isotherm equation and Bangham adsorption kinetic model.