Environmental Engineering Reference
In-Depth Information
0
Experimental data
Re gression
-1
2
= 0.998
y = -0.700x - 0.183 r
-2
-3
-4
1
2
3
4
5
Carbon Number, n
Figure 7.10
Anderson-Schultz-Flory plot for transformation of 150 mg/L carbon
tetrachloride by bimetallic Pd/Fe nanoparticles at 100 hours.
7.3.2
In-Situ Formation of Bimetallic Nanoparticles
As discussed above, bimetallic Pd/Fe nanoparticles exhibit excellent
performance for degradation of chlorinated organic compounds. However, challenges of
the engineered bimetallic iron nanoparticles include the cost (e.g., Pd, Au) and toxicity
(e.g., Ni) of catalytic metals. On the other hand, because the frequent occurrence of both
chlorinated organic solvents and metallic ions at the same site, it is possible to take
advantage of existing metallic ions (e.g., copper and nickel) as precursors of the second
metal. In situ formation of bimetallic iron nanoparticles can therefore be achieved when
monometallic iron nanoparticles are implemented.
7.3.2.1 Sequestration of Heavy Metals by Iron Nanoparticles
Figure 7.11 shows the results for removal of As(V), Cu(II) and Pb(II) by iron
nanoparticles. The initial concentration of heavy metals was 25 mg/L and the iron
loading was 2.5 g/L. The removal of As(V) follows pseudo-first order reaction kinetics.
The observed rate constant was 0.94 1/h (R
2
= 0.99), corresponding to a surface-area
normalized rate constant (
k
SA
) of 11.2 mL/hm
2
. This is a substantially high As(V)
removal rate for an elevated level of arsenic as compared to that obtained from most
Search WWH ::
Custom Search