In this study, adsorption excess isotherms of n-heptane/benzene liquid mixture on hydrochloric acid leached bentonite powders were determined. Adsorptions were conducted at 25 degrees C for 48 h. Experimental results were evaluated with both Schay-Nagy (SN) and Everett (E) methods. Specific surface areas (S-SN and S-E) of the powders were calculated regarding monolayer adsorption capacity of the preferentially adsorbed benzene. Adsorption equilibrium constants (K >> 1) were obtained by the E-method. The S-E and S-SN values are closed to each other. S-E-values were found much lower than the corresponding Brunauer, Emmett and Teller (BET)-values. This difference was discussed with respect to the interaction of adsorbed molecules with solid surface, their collision diameter, molar cross sectional surface area and orientation in dense monolayer. Even the maximum for the S-E was not associated with the maxima for K and nanopore volume (V), their values changed approximately parallel to each other with respect to the HCl% by the leaching. (c) 2013 Elsevier B.V. All rights reserved.