Biomedical Engineering Reference
In-Depth Information
Figure 7.24
Kinetics of adsorption and desorption.
The starting time for desorption is the time ta, and the surface concentration at
this instant is G
a
k c
k c
on
0
G =
G
(7.41)
a
0
+
k
on
0
off
The Langmuir equation for desorption is
d
G
= -
(7.42)
k
G
off
d t
and the kinetics of desorption is
G
-
k
t
-
t
(
)
=
e
off
a
(7.43)
G
a
Desorption kinetics follows an inverse exponential law (Figure 7.24). The tan-
gent to the desorption kinetic curve at
t= t
a
is given by
G
= -
1
k
(
t
-
t
)
(7.44)
off
a
G
a
and the derivative at
t = t
a
is
k
k c
d
G
off
on
0
(7.45)
= -
k
G = -
G
off
a
0
d t
k c
+
k
on
0
off
t
=
t
a
This last formula may be written under the form
d
d t
G
G
0
(7.46)
= -
1
1
+
t
=
t
a
k c
k
on
off
0
