ferrate-treated phosphate with phosphate sorption on preformed iron(III) oxide/
oxyhydroxide nanoparticles.
The efficiency and mechanism of heavy metals and arsenic removal by ferrate
(VI) is dependent on the chemistry of the real water. Therefore, Kolařík et al. (2018)
focused on the description of the influence of commonly present inorganic ions and
organic carbon in waters on metal removal by ferrate(VI). Ions such as chlorides,
nitrates, carbonates, and sulfates as well as humic acid had marginal or no effect on
the efficiency in removing arsenates by ferrate(VI) (Fig. 8.11). By contrast, the
[Fe(VI)]/[P(V)] = 3:1
[Fe(VI)]/[P(V)] = 4:1
[Fe(VI)]/[P(V)] = 5:1
(a)
(e)
(f)
(b)
(c)
12.0
10.0
8.0
6.0
4.0
2.0
0.0
12.0
10.0
8.0
6.0
4.0
ex-situ, pH 7.0
2.0
0.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
Time, min
Time, min
Time, min
0
50 100 150 200 250 300
0
50 100 150 200 250 300
0
50 100 150 200 250 300
[Phosphate], mgL -1
[Phosphate], mgL -1
[Phosphate], mgL -1
pH 9.5
pH 8.0
pH 7.0
pH 6.0
pH 9.5
pH 8.0
pH 7.0
pH 6.0
pH 9.5
pH 8.0
pH 7.0
pH 6.0
(d) 100.0
99.5
99.0
98.5
98.0
97.5
100.0
99.5
99.0
98.5
98.0
97.5
100.0
99.5
99.0
98.5
98.0
97.5
97.0
Transmission (%)
Transmission (%)
Transmission (%)
Velocity (mm/s)
Velocity (mm/s)
Velocity (mm/s)
-10 -8 -6 -4 -2 0 2 4 6 8 10
-10 -8 -6 -4 -2 0 2 4 6 8 10
-10 -8 -6 -4 -2 0 2 4 6 8 10
5 K/5 T
Fe(VI)/P(V) = 3:1
“in-situ” conditions
5 K/5 T
Fe(VI)/P(V) = 5:1
“ex-situ” conditions
5 K/5 T
Fe(VI)/P(V) = 5:1
“in-situ” conditions
Data
Fit
γ-Fe
2
O
3
-T-sites
γ-Fe
2
O
3
-O-sites
γ-FeOOH
Data
Fit
γ-Fe 2
O
3
-T-sites
γ-Fe 2
O
3
-O-sites
γ-FeOOH
Data
Fit
γ-Fe
2
O
3
-T-sites
γ-Fe
2
O
3
-O-sites
γ-FeOOH
Fig. 8.10 Residual phosphate concentrations as a function of the reaction time and pH of the
reaction mixture at Fe/P mass ratio of (a) 3/1, (b) 4/1, and (c) 5/1. (d–f) In-field (5 T)
low-temperature (5 K)
57
Fe Mössbauer spectra of variously treated phosphate (Fe/P ¼ 3/1, 5/1
and at pH ~7.0 for sorption on preformed iron oxides). (Adapted from Kralchevska et al. 2016a)
196
L. Machala et al.