Biomedical Engineering Reference
In-Depth Information
This included 7.68, 10.21, and 9.59 mol g
-1
for Ni
2+
Zn
2+
Cd
2+
, respectively. Nickel recovery
was lowest among the three ions (58.0%), while cadmium and zinc recovered 67.0% and
72.1%, respectively. This suggests the affinity of some of the Ni
2+
binding sites were higher
than those for each of the other two metal ions.
Sequence
Column a
Column b
Column c
Average
Std. Dev.
%RSD
Cd
28.26
22.63
25.49
25.46
2.56
10.05
Ni
23.57
20.79
23.35
22.57
1.84
8.16
Zn
24.56
24.88
26.76
25.40
1.57
6.16
Cd Ni
27.14
27.14
24.29
26.19
1.64
6.28
Cd Zn
30.33
24.57
24.51
26.47
3.34
12.62
Ni Cd
28.39
26.04
29.95
28.13
1.97
7.01
Ni Zn
29.72
25.95
25.57
27.08
2.29
8.47
Zn Cd
27.53
24.49
31.49
27.84
3.51
12.61
Zn Ni
25.99
26.09
27.66
26.58
0.94
3.52
Cd Ni Zn
30.83
27.00
30.06
29.30
2.02
6.91
Cd Zn Ni
27.89
24.21
27.54
26.55
2.03
7.64
Ni Cd Zn
32.89
26.00
25.42
28.10
4.15
14.78
Ni Zn Cd
21.63
24.57
27.69
24.63
3.03
12.29
Zn Cd Ni
27.45
27.45
40.95
31.95
7.80
24.40
Zn Ni Cd
26.27
23.75
23.62
24.55
1.49
6.09
Table 2. Influent metal bound at each stage of the sequential exposure study. Values
presented are given in moles metal per gram of modified biomaterial.
1.00E-06
6.00E-07
B
5.00E-07
8.00E-07
4.00E-07
6.00E-07
A
3.00E-07
4.00E-07
2.00E-07
2.00E-07
1.00E-07
0.00E+00
0.00E+00
0 0 0 0 0 0
Effluent Volume (mL)
0
0.5
1
1.5
2
2.5
Effluent Volume (mL)
Fig. 2. Simultaneous exposure of 0.2mM Ni
2+
(□), Cd
2+
(), and Zn
2+
() to modified
D. innoxia
column (A) and is subsequent striping using 1.0 M HCl (B).
3.3 Comparison of native and modified biomaterials
By examining the results from the native and modified
D. innoxia
studies together, a
hypothesis regarding the carboxyl sites contribution to the metal-ion binding process can be
formulated. It was proposed, in previous studies of
D. innoxia
, that esterification of
carboxylate sites can decrease metal uptake by as much as 40% (Drake, et al., 1996),
depending on the metal.
