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4.2 Design of Adsorption and Ion-Exchange Processes 341

1

0.8

0.6
o
C/C
0.4

0.2

0
-2 -1 0 1 2 3 4
N s (T-1)
Figure 4.34 Model plot.

From the definition of T (eq. (4.136)), it is clear that since

V
t o 0
Q

T should be positie. Using this constraint for v T , it can be seen that

T NT 1) N NT 1) min
(
(
N
T
0
1
1
This minimum value of N ( T – 1) corresponds to the lo alue of wer v X , i.e. 0. Hosince v , er we
the model solution, eq. (4.141), is asymptotic to the X – axis, the lo wer X to be used is 0.01.
This dimensionless exit concentration can be viewed as the “first appearance” concentra-
tion. This restriction provides the maximum alloable relatie flow rate or the minimum v w
residence time in order to hae the first appearance of the solute for v T
0. F or La 0.1,
[ N ( T )] min 1.2311 (eq. (4.141)).
1
Geometrical dimensions of the fixed bed: The volume of the bed is

M s 3
V 0.1 m

o
b