Environmental Engineering Reference
In-Depth Information
100
MMA
80
60
DMA
40
20
0
3
5
7
9
11
pH
Figure 5.12
MMA () and DMA (
႒
) adsorption edges on TiO
2
. Total concentration:
MMA = DMA = 1 mg/L as As, TiO
2
= 0.2 g/l, 0.04 M KNO
3
.
(A)
DMA
(B)
As-Ti
DMA
As-Ti
MMA
MMA
0
1
2
3
4
5
6
3
5
7
9
11
13
R (Å)
k
(Å
-1
)
Figure 5.13
(A) The k
3
weighted observed (dotted line) and model calculated (solid
line) As K-edge EXAFS spectra and (B) Fourier transform magnitude resulting in a
radial distance structure for the MMA and DMA adsorption on TiO
2
at pH 7. The peak
positions are uncorrected for phase shift.
The EXAFS analysis shows that a mixed first shell is composed of oxygen and
carbon atoms at an average distance of 1.69 and 1.90 Å, respectively. Oxygen
coordination numbers (CN) of 3.0 and 1.9 is obtained for MMA and DMA, respectively.
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