Environmental Engineering Reference
In-Depth Information
Fig. 6.21 Loadings of transition metal ions on the amine-terminated mesoporous magnetic
particles as a function of solution pH from (A) single-element solutions; and (B) a solution
containing copper, nickel, and zinc, each at 0.5 mmol/L concentration
metal ions from a mixture follows the same order as seen in the single-metal systems,
i.e., Cu
2+
>
Ni
2+
>
Zn
2+
. Metal ion loading increases with increasing pH above 2
up to the limiting pH of 5.2 for copper and zinc, but not for nickel.
6.5.4.2 Stripping and Recycling
The adsorbed metals were successfully desorbed with 1 M aqueous HCl solu-
tions. The mechanism of copper detachment from silanized mesoporous-Fe
3
O
4
particles by acid washing is similar to that explained before [48]. In the reload-
ing test there is a decrease in the loading capacity of the recycled sorbents by
17%. The reasons for the observed decrease in the loading capacity of the
APTES-silanized mesoporous-Fe
3
O
4
particles after acid stripping of the loaded
