Pyrolysis of Tire Rubber:  Porosity and Adsorption Characteristics of the Pyrolytic Chars

Tire rubber has been pyrolyzed at various temperatures under a nitrogen atmosphere. The resulting chars have been analyzed for their porosity using nitrogen gas adsorption and for their aqueous adsorption characteristics using phenol, methylene blue, and the reactive dyes Procion Turquoise H-A and Procion Red H-E3B. Nitrogen adsorption isotherms were modeled to the BET and Dubinin−Astakhov (DA) equations to determine effective surface areas, mesopore volumes, and micropore volumes. Results showed that pyrolysis of tire rubber was essentially complete at 500 °C and resulted in a char yield of approximately 42 wt %. Pyrolytic chars exhibited BET surface areas up to 85 m2/g and micropore volumes up to 0.04 mL/g. Owing to their poorly developed micropore structure, the pyrolytic chars exhibited limited aqueous adsorption capacity for compounds of small molecular weight, such as phenol. However, 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).