Page 308 - Adsorption, Ion Exchange & Catalysis- 2007, Elsevier - Copy

Else_AIEC-INGLE_cH004.qxd 7/1/2006 6:53 PM Page 304
304 4. Adsorption and Ion Exchange

Table 4.24

Experimental data
t (min) C t (mmol/L)
25 2.3
50 2
100 1.6
150 1.3
180 1.18

concentration were mixed with 8.5 g of bone char. In Table 4.24, some experimental kinetic
data are given (approximate values).
Choy and McKay used a homogeneous surface diffusion model (HSDM) taking into
account both external and internal transport, and found that the mean value of the solid dif-
fusion coefficient is 3.72 10 –9 cm 2 /s while k = 6.06 10 –4 cm/s.
f
Assuming a solid diffusion–controlled process, use the Patterson equation and find the
fusion coef corresponding solid difficient. Furthermore, find the impeller speed in order to
have the reported v alue for k .
f
Solution
To use Patterson’s model (eq. (4.52)), we first need the parameter w and thus the equi-
librium liquid-phase concentration C . The maximum loading of the zeolite particles for
e
the specific initial concentration can be calculated using the equilibrium relationship
(eq. (4.5)):

KC
q Q o 0.071 mmol/g
max M
1 KC
o
Then (eq. (4.123))
fX() C o V
0.910
1 X q m
max
The function f ( X ) is the dimensionless equilibrium relationship, which for the Langmuir
isotherm is (eq. (4.9))

X
fX()

La X 1
La
where La is given by (eq. (4.8))

1
La 0.0045
1 KC
o