Enhancement of the performance of activated carbons as municipal odor removal media by addition of a sewage-sludge-derived phase.
Two commercial low-cost activated carbons and wood-based char were mixed with dewatered sludge and pyrolized at 950 degrees C. The sludge content on a dry basis was 23%. The obtained composite adsorbents were characterized from the point of view of surface chemistry (pH) and texture (adsorption of nitrogen at its boiling point: surface area, pore volume, pore size distributions). Then hydrogen sulfide breakthrough capacities were measured using the home-designed dynamic test. The results revealed a significant increase in the capacity of the composite adsorbents compared to the unmodified carbons. Moreover, that increase was a few times greater than the hypothetical one predicted when desulfurization performance would be the sum of the contributions of both the sludge-derived and carbon phases. This is attributed to a synergetic effect related to the dispersion of the catalysts and the presence of small pores. Mixing activated carbon provides the active centers for oxidation (coming from sludge) and the developed pore system (from the activated carbon) where products of oxidation can be stored. Moreover, in the hydrophobic pore space the volatile organic compounds present in effluent air from a municipal waste treatment plant can be adsorbed. The selectivity for H2S oxidation, as in the case of pure activated carbon, depends on the pore sizes. Smaller pores lead to a higher yield of sulfuric acid; larger pores lead to a higher yield of sulfur.
Sioukri
Evilambia
E
Department of Chemistry, The City College of New York, 138th Street and Convent Avenue, New York, New York 10031, USA.
Bandosz
Teresa J
TJ
D002244:Carbon / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D009812:Odorants / Q000517:prevention & control*; D016062:Porosity; D012722:Sewage / Q000737:chemistry*; D013457:Sulfur Compounds / Q000302:isolation & purification*; D013464:Sulfuric Acids / Q000032:analysis; D014934:Wood
D012722:Sewage; D013457:Sulfur Compounds; D013464:Sulfuric Acids; D002244:Carbon; C033158:sulfuric acid