Screening of adsorbents for removal of H2S at room temperature

Abstract

The present paper describes the synthesis of H₂S selective adsorbents, which are environmentally economical for removal of H₂S at sewage plant facilities. A series of adsorbents (simple oxides of Ag, Cu, Zn, Co,Ni, Ca, Mn and Sn, mixed oxides of Zn containing Fe, Ni, Co, Mn, Cu, Al, Ti and Zr) derived from hydrous oxides and hydroxycarbonates of different metal ions were prepared. The performance of these adsorbents for the removal of H₂S was studied at room temperature by a batch method. Several adsorbents (CuO, Zn/Mn type, Zn/Ti/Zr type, Zn/Co type, and Zn/Al type) showed markedly high adsorptivity (100 ∼ 280 mg g⁻¹) for H₂S gas. A detailed characterization of the adsorbents and sulfided adsorbents was carried out using X-ray diffraction, DTA-TG, SEM and TEM analysis. The H₂S adsorption progresses by the chemical reaction of sulfide formation. The mixed metal oxides containing small crystallites of ZnO with hexagonal structure showed high H₂S uptakes. Analysis of sulfided adsorbents showed that microcrystalline particles were developed after sulfidation. DTA-TG analysis suggested that two kinds of processes, metal sulfide → metal sulfate → metal oxide reaction and metal sulfide → metal oxide reaction, take place during the thermal desorption of sulfur.