Texture and surface chemistry of activated carbons obtained from tyre wastes

Tyre wastes and their blends with coal and a bituminous waste material obtained from the benzol distillation column of the by-product section of a coking plant were employed as a precursor for the production of activated carbons (ACs). Pyrolysis up to 850 C followed by physical activation with CO₂ yielded mesoporous carbons with different pore size distributions and surface areas depending on the degree of burn-off. ACs with surface areas of 475 and 390 m²/g were obtained for the two tyre wastes. The inclusion of coal in the blend gave rise to surface areas of up to 1120 m²/g due to an increase in the microporosity. The time needed to obtain the desired degree of burn-off depended on the reactivity of the char. The coal-containing materials required the longest amount of time. The surface chemistry of the samples was studied by Infrared spectroscopy (FTIR) and X-Ray photoelectron spectroscopy (XPS). The principal oxygenated groups found were quinones, lactones and carboxylic acids.