PYROLYSIS OF TIRE RUBBER - POROSITY AND ADSORPTION CHARACTERISTICS OFTHE PYROLYTIC CHARS

Tire rubber has been pyrolyzed at various temperatures under a nitroge n atmosphere. The resulting chars have been analyzed for their porosit y using nitrogen gas adsorption and for their aqueous adsorption chara cteristics using phenol, methylene blue, and the reactive dyes Procion Turquoise H-A and Procion Red H-E3B. Nitrogen adsorption isotherms we re modeled to the BET and Dubinin-Astakhov (DA) equations to determine effective surface areas, mesopore volumes, and micropore volumes. Res ults showed that pyrolysis of tire rubber was essentially complete air 500 degrees C and resulted in a char yield of approximately 42 wt %. Pyrolytic chars exhibited BET surface areas up to 85 m(2)/g and microp ore volumes up to 0.04 mL/g. Owing to their poorly developed micropore structure, the pyrolytic chars exhibited limited aqueous adsorption c apacity for compounds of small molecular weight, such as phenol. Howev er, the chars possessed significantly greater adsorption capacity for species of large molecular weight which was attributed to the presence of large mesopore volumes (up to 0.19 mL/g).