THE SURFACE CHARACTERISATION OF ACTIVATED CARBON AND ACID ACTIVATED MONTMORILLONITE CLAY

Olive stones were carbonised to 1120 K and activated in steam at 1100 K. Adsorptive properties were measured by adsorption of nitrogen (77 K) and carbon dioxide (273 K) using the BET and Dubinin Radushkevich equations of adsorption to deduce effective surface areas. The carbonised stones had a surface area of 1070 m2/g. This sample had a micropore volume of 480 cm3/kg determined using the data of N2 adsorption and Dubinin Radushkevich (DR) equation and an integral pore volume of 599 cm3/kg including the mesopores. These characteristics make this activated carbon commercially attractive. The Gurvich rule applied to the data of carbon dioxide adsorption at 273 K considering the CO2 as a liquid, led to a pore volume of the activated carbon of 135 cm3/kg, not corresponding to the micropore volume of 276 cm3/kg calculated by the DR equation, showing that it is not as a liquid inside the pores.In the case of one acid activated montmorillonite clay the following values of surface properties: specific surface area of 223 m2/g, micropore volume of 90 cm3/kg (DR), cumulative pore volume of 159 cm3/kg were obtained from N2 adsorption-desorption data. A cumulative pore volume of 35 cm3/kg from the CO2 adsorption data was determined.