An investigation of H2S adsorption mechanisms on Tire Derived Rubber Particles (TDRP<sup>TM</sup>)
Two commercial rubber waste products, tire derived rubber particle (TDRPTM) and other rubber material (ORMTM), were found to adsorb hydrogen sulfide gas (H2S) from biogas. A number of experiments were conducted to investigate the adsorption mechanism, surface properties and breakthrough characteristics. The physical properties, composition and surface chemistry were investigated and compared with commonly available commercial H2S adsorbents, such as activated carbon and metal oxide, in order to compare performance and to assess the possible adsorption mechanism. Additional effects on H2S adsorption capacity of TDRPTM and ORMTM were also studied, including moisture content, zinc concentration, and size distribution.
The components of TDRPTM were similar to typical tire rubber. The specific surface area was less than 1% of activated carbon. The data support the thesis that TDRPTM is particle in nature rather than a porous material. Infrared analysis and Mass spectrum experiments showed no direct evidence that the adsorption was a pure physical process. The effects of moisture content, zinc concentration, and surface oxidation on adsorption favor chemical reactions occurring on the surface of the TDRPTM and ORMTM 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 TDRPTM and ORMTM also improved the adsorption capacity.