Biomedical Engineering Reference
In-Depth Information
TABLE P17.10-1
Measured rate,
mol-A/(g-cat$s)
Pellet size, mm
Run 1
10.0
5.00
Run 2
1.00
10.0
17.11.
The enzyme, urease, is immobilized in Ca-alginate beads 2 mm in diameter. The
maximum intrinsic rate of urea hydrolysis is
r
max
¼
0.5 mol/(L
$
h) for the particular
enzyme loading is suspended media. Diffusivity of urea in Ca-alginate beads is
D
e
10
9
m
2
/s, and the intrinsic saturation constant for the enzyme is
¼
1.5
0.2 mmol/L. By neglecting the liquid film and Ca-alginate shell resistances on
the beads, determine the following when the urea concentration in the bulk liquid is
0.5 mmol/L:
(a)
Observed rate of hydrolysis
r
, Thiele modulus, and effectiveness factor.
(b)
Observed rate of hydrolysis
r
, Thiele modulus, and effectiveness factor for
a particle size of
d
p
¼
K
m
¼
4 mm.
17.12.
The enzyme, urease, is immobilized in Ca-alginate beads 2 mm in diameter.
When the urea concentration in the bulk liquid is 0.5 mmol/L, the rate of urea
hydrolysis is
r
¼
0.01 mol/(L
$
h). Diffusivity of urea in Ca-alginate beads is
10
9
m
2
/s, and the intrinsic saturation constant for the enzyme is
D
e
¼
1.5
0.2 mmol/L. By neglecting the liquid film and Ca-alginate shell resistances
on the beads,
(a)
Determine the maximum rate of hydrolysis
r
max
, Thiele modulus, and
effectiveness factor.
(b)
What would be the values of
r
max
, Thiele modulus, and effectiveness factor for
a particle size of
d
p
¼
K
m
¼
4 mm?
17.13.
Uric acid is degraded by uricase enzyme immobilized in porous Ca-alginate
beads. Experiments conducted with different bead sizes result in the following
rate data:
TABLE P17.13-1
Bead diameter
d
p
, mm
1
2
3
4
5
6
7
8
Rate, mg/(L
$
h)
200
198
180
140
100
70
50
30
(a)
Determine the effectiveness factor for particle sizes
d
p
¼
5 mm and
d
p
¼
7 mm.
(b)
The following data (
Table P17.13-2
) were obtained for
d
p
¼
5 mm at different bulk
uric acid concentrations.
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