Geology Reference
In-Depth Information
4
Cr(OH)
4
-
Cr(OH)
3
0
CrOH
2+
Cr(OH)
2
+
Cr
3+
6
8
10
12
14
16
0
2
4
6
8
10
12
14
pH
1.0
0.8
Cr
3+
CrOH
2+
Cr(OH)
2
+
Cr(OH)
3
0
Cr(OH)
4
-
0.6
0.4
0.2
0.0
0
2
4
6
8
10
12
14
pH
It should be noted that, for higher values of {Cr
III
T
}, equilibria for
polymeric species should be included and that Cr(OH)
3
may pre-
cipitate. In the presence of iron, the mixed precipitate Fe
x
Cr
1
x
(OH)
3
may be formed.
Example 3.9 shows, however, that, for Al
III
, ligands such as F
and
SO
4
2
may compete successfully with the hydroxyl ion at low pH values
(see Section 3.3.1.2). For aqueous systems in contact with solid phases,
