After arrangement, the BET equation
takes the following form:
The BET equation
was then used to calculate the surface area based on an adsorption isotherm constructed from an 11 point [N.sub.2] physisorption experiment performed at -196[degrees]C.
The BET surface area, external surface area, total pore volume and the pore size of the samples were determine by using BET equation
and Quantachrome Nova Win2 (c), 1994 - 2002.
The pore structure of MCAC was determined by nitrogen adsorption isotherm at 77 K using BET equation
. SEM (JSM-6490LV) was completed on raw and MCAC.
The surface areas of samples were determined by using BET equation
(Table 1); the pore size distribution treated by using the BJH method, the surface element valence, and energy level of samples were characterized by X-ray photoelectron spectroscopy (XPS) in a Perkin-Elmer, USA.
Values for the monolayer water content of rice flour have been reported by Durakova and Menkov (2004) as 0.0714-0.0680g water/g dry solids in a temperature range of 10-40[degrees]C using the BET equation
. These values are in agreement with those reported in the present work (Table 11).
On the other hand, BET equation assumes that a number of layers of adsorbate molecules form on the surface of adsorbent, and that the Langmuir equation is applied to each layer of adsorption, thus
Equilibrium data for zinc indicates a multilayer adsorption, which can be best fitted using the BET equation (correlation coefficient [R.sup.2] = 0.986).
The water adsorption data for each soil were plotted according to the BET equation:
The mean value of c in the BET equation was 24 with a standard deviation of 5 for the 19 soil samples.
To extend BET equation to multicomponent adsorption, three kinds of n-component BET equations were proposed considering that adsorbed layers have evaporation-condensation characters for liquid mixture, supposing that the adsorbed layer of gas mixture is an ideal solution according to statistic thermodynamics and assuming gas mixture is immiscible liquid [28-31].
As a normal method to acquire surface area of shale, multipoint BET method testifies that BET equation can be applied to describe adsorption on shale at certain conditions (usually relative pressure below 0.4 P/[P.sub.0]).