Abstract
In order to evaluate a novel method for estimating solid surface areaas from the adsorption isotherm gradient at the linear portion of type II isotherms, the adsorption of toluene on glass plates having a geometrical surface area of 1152 cm 2 at 0° and 10°C was studied. The almost constant isotherm gradient value ( dv d ( P P s ), v : amount adsorbed) in a relative pressure ( P P s ) region from 0.15 to 0.45, as well as in the cases of aluminum foil and mica plates, showed a good fit with the monolayer capacity calculated using the average, proper molecular cross section of toluene. For various materials whose geometrical surface area were not known, the standard BET areas were compared with the areas estimated from the isotherm gradient of toluene adsorption and their reasonable agreement suggested the usefulness of the gradient method for the surface area estimation. Based on these results a theoretical basis and conditions for the use of the method were discussed by considering an alternative two-dimensional gas model on the low-energy adsorption surface. In addition, a small type B hysteresis found in the region of low relative pressure and at submonolayer adsorption on the glass plate sample pile was reported.
Published Version
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