Effect of fly ash addition on the removal of hydrogen sulfide from biogas and air on sewage sludge-based composite adsorbents.
Desulfurization adsorbents were prepared from the mixtures of various compositions of New York City sewage sludge and fly ashes from SASOL, South Africa, by pyrolysis at 950 degrees C. The resulting materials were used as adsorbents of hydrogen sulfide from simulated dry digester gas mixture or moist air. The adsorbents before and after H(2)S removal were characterized using adsorption of nitrogen, elemental analysis, pH measurements, XRF, XRD, and thermal analysis. It was found that the addition of fly ash decreases the desulfurization capacity in comparison with the sewage sludge-based materials. The extent of this decrease depends on the type of ash, its content and the composition of challenging gas. Although the presence of CO(2) deactivates some adsorption sites to various degrees depending on the sample composition, the addition of ashes has a more detrimental effect when the adsorbents are used to remove hydrogen sulfide from air. This is likely the result of hydrophobicity of ashes since the H(2)S removal capacity was found to be strongly dependent on the reactivity towards water/water adsorption. On the other hand, the addition of ashes strongly decreases the porosity of materials where sulfur, as a product of hydrogen sulfide oxidation, can be stored.
Seredych
Mykola
M
Department of Chemistry, The City College of The City University of New York, 138th Street and Convent Ave., New York, NY 10031, USA.
Strydom
Christien
C
Bandosz
Teresa J
TJ
D000327:Adsorption; D000393:Air Pollutants / Q000302:isolation & purification*; D002244:Carbon / Q000737:chemistry*; D060729:Coal Ash; D006862:Hydrogen Sulfide / Q000302:isolation & purification*; D052638:Particulate Matter / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*
D000393:Air Pollutants; D060729:Coal Ash; D052638:Particulate Matter; D012722:Sewage; D002244:Carbon; D006862:Hydrogen Sulfide