Micromeritics TRISTAR II PLUS Operator's Manual page 280

B DFT Models
Note that the adsorption isotherms for pores larger than the one shown in the previous graph is
identical up to point c. The lower branch of the isotherm simply continues to a higher pressure for
larger pores. This trend is illustrated in the Figure 3, where isotherms for some larger size pores
are shown. It is clear that pore size is uniquely characterized by a corresponding critical pore-
filling pressure. At large pore sizes, density functional theory produces results for the critical filling
pressures that are in good agreement with those produced by the Kelvin equation.
Figure 4 shows model isotherms for pores in the micropore size range. Note the logarithmic scale
for pressure.
B - 6
Figure 3
Model Isotherms for Some Larger Pore
Widths Argon on Carbon at 87.3 K
Figure
Model Isotherms in the Micropore Size
Range of Pore Width Argon on Carbon
at 87.3 K
TriStar II Plus Operator Manual
303-42800-01 (Rev M ) — Sep 2023