Performance and mechanism of hydrogen sulfide removal by sludge-based activated carbons prepared by recommended modification methods.

The sludge-based activated carbons (SACs) were prepared by sewage sludge and corn straw and modified by ferric nitrate. The HS removal performance and the desulfurization mechanism of the modified SAC were studied. Results showed that breakthrough sulfur capacity and saturation sulfur capacity of the SAC prepared by recommended modification were 27.209 mg/g and 48.098 mg/g, which were as 4.68 times and 7.02 times larger as those before modification, respectively. Additionally, results showed that the desulfurization products of unmodified SAC were mainly sulfur, while that of modified SAC were mainly sulfate. These results indicated that ferric nitrate modification changed the way of hydrogen sulfide removal by SAC: the desulfurization process of unmodified SAC can be expressed as S → S → S → S, and the oxidative active component was dominated by O*, while that of modified SAC can be expressed as S → S → S, and the oxidative active components are both Fe and O*.