Micromeritics ASAP 2460 - Dubinin-Radushkevich

ASAP 2460 Operator’s Manual Appendix C
246-42800-01 - Aug 2013 C-37
Dubinin-Radushkevich
The Dubinin-Radushkevich
13
equation is:
where:
 = the affinity coefficient of analysis gas relative to Po gas (for this application 
is taken to be 1)
B = a constant
Po = saturation vapor pressure of gas at temperature T
P = equilibrium pressure
Q = quantity adsorbed at equilibrium pressure (cm
3
/g STP)
Q
0
= the micropore capacity (cm
3
/g STP)
T = analysis bath temperature (K), from the Po and Temperature Options win-
dow
For each point designated for Dubinin-Radushkevich calculations, the following calculations are done:
The intercept, log(Vo ) can be found by performing a least-squares fit on the (LP,LV) designated pairs
where LP is the independent variable and LV is the dependent variable. Assuming the adsorption of gas
is restricted to a monolayer, Vo is the monolayer capacity. Based on this assumption, the following are
calculated:
a.) Slope (S cm
3
/g STP)
b.) Y-intercept (YI cm
3
/g STP)
c.) Error of the slope (S
err
cm
3
/g STP)
d.) Error of the y-intercept (YI
err
cm
3
/g STP)
e.) Correlation coefficient
Using the results of the above calculations, the following can be calculated:
Monolayer Capacity (cm
3
/g STP):
Qlog Q
0

BT
2

---------
Po
P
-------log
2
–log=
LV Qlog=
LP
Po
P
-------


2
log=
Q
0
10
YI
=