Biogas Hydrogen Sulfide Adsorption using Waste Tire Media Products

Author： Wang Ning Evans Eric A. Ellis Timothy G.

ISSN： 1938-6478

Source： Proceedings of the Water Environment Federation, Vol.2010, Iss.18, 2010-01, pp. : 39-58

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Abstract

Anaerobic waste treatment systems, including municipal digesters; industrial high-rate wastewater treatment systems; landfills; and solid waste reactors, convert energy rich organic compounds into valuable methane gas. Unfortunately, hydrogen sulfide often contaminates biogas resulting in problems with corrosion, health and safety issues, and SOx potential. A waste product from tires, tire derived rubber product (TDRP™), was discovered to possess the capacity to remove hydrogen sulfide from biogas. An in-depth study was undertaken to better understand the fundamental physical characteristics of TDRP™, and to learn more about the mechanism of hydrogen sulfide adsorption. Another rubber waste product, other rubber product (ORM™) was also researched. The TDRP™ and ORM™ was found to have a bulk density near 0.3 kg/m³, a particle density near 1 kg/m³, a moisture content near 1%, a carbon black content between 40 and 50%, and a surface area between 0.2 and 0.3 m²/g. Additionally, TDRP™ was found to contain a variety of trace metals including calcium, magnesium, iron, zinc, copper, and lead. Scanning electron microscopy was used to show the surface was rich with metals, sulfur, and oxygen. A comparison between TDRP™ and activated carbon was performed; it shows that the adsorption mechanism is different as a result of three orders of magnitudes difference in the ratio of relative adsorbed hydrogen sulfide to specific surface area. The effects of moisture content, zinc concentration, and surface oxidation on adsorption favor chemical reactions occurring on the surface of the TDRP™ and ORM™ samples. Analysis of experimental results and comparison to scientific literature, suggest that two components contribute to the H₂S adsorption—carbon black and zinc. The addition and extraction of zinc altered the H₂S adsorption capacity. Oxidation of the surface of TDRP™ and ORM™ also improved the adsorption capacity.