On the use of standard DRK isotherms in Dubinin's t/F method

It is shown that the adsorption of benzene, carbon tetrachloride, dichlorom ethane and nitrogen by a typical non-porous carbon black follows the Dubini n-Radushkevich-Kaganer equation. The requirement for temperature invariance is fulfilled, with an average characteristic energy E-o=10.8 kJ mol(-1). T his expression is compared with the standard isotherms for benzene and carb on tetrachloride at 293 K proposed by Dubinin and used as a reference in th e so-called t/F method, which leads to the non-porous surface area of activ e carbons. It appears that Dubinin's isotherm contains inconsistencies, whi ch are compensated for internally. Alternative DRK expressions, applicable to different vapours, are therefore proposed. The present study also shows the limits of Dubinin's method with respect to comparison plots at higher r elative pressures. (C) 2000 Elsevier Science Ltd. All rights reserved.