INVESTIGATION OF SURFACE-PROPERTIES OF AVGAMASYA ASPHALTITE

Surface properties of Avgamasya asphaltite were investigated by the ad sorption method using N2 and CO2 gases. In order to see the effect of ash content and pyrolysis temperature on the surface properties of asp haltite, samples were washed with 15% (v/v) HCI to reduce the ash cont ent, and then pyrolyzed in a nitrogen atmosphere between 773 and 1173 K. Surface areas were calculated from N2 adsorption data by the BET an d Dubinin-Polanyi (D-P) equations. Specific pore volumes were determin ed from N2 and CO2 adsorption data by applying the D-P equation. Pore volume distributions and average pore radius were calculated from N2 d esorption data by using the modified Kelvin equation. Surface areas ob tained by carbon dioxide (3-300 M2/g) were higher than the areas from nitrogen (2-47 M2 /g). Demineralization and pyrolysis changed the surf ace properties of samples. Surface areas and specific pore volumes hav e a maximum value around 873-973 K (pyrolysis temperatures). Pore radi us increases to 20 angstrom from 10 angstrom after 1073 K because of c orruption in the structure of asphaltite. Pore size distribution indic ated the presence of mesopores together with micropores.