Optimization of Arsenic Removal Process in Waste Acid …
715
14
12
10
8
6
4
2
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
Fe
Fe2O3
Fe3O4
Fe(OH)2
Fe(+2a)
Fig. 5 Pourbaix diagram of Fe, the abscissa and ordinate are pH and E(V )
20
40
60
80
-500
-450
-400
-350
-300
-250
-200
-150
2Fe+O 2 +2H2O=2Fe(OH) 4
4Fe(OH) 2 +O 2 +2H 2 O=4Fe(OH) 3
G
θ
(KJ/mol)
Temperature (°C)
Fe+CuSO 4 =Cu+FeSO 4
Δ
Fig. 6 Dependency of θ on temperatures for the main reactions of iron
2Fe + O 2 + 2H 2 O = 2Fe(OH) 2
(2)
4Fe(OH) 2 + O 2 + 2H 2 O = 4Fe(OH) 3 ↓
(3)
2Fe(OH) 3 Fe 2 O 3 + 3H 2 O
( 4 )
715
14
12
10
8
6
4
2
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
Fe
Fe2O3
Fe3O4
Fe(OH)2
Fe(+2a)
Fig. 5 Pourbaix diagram of Fe, the abscissa and ordinate are pH and E(V )
20
40
60
80
-500
-450
-400
-350
-300
-250
-200
-150
2Fe+O 2 +2H2O=2Fe(OH) 4
4Fe(OH) 2 +O 2 +2H 2 O=4Fe(OH) 3
G
θ
(KJ/mol)
Temperature (°C)
Fe+CuSO 4 =Cu+FeSO 4
Δ
Fig. 6 Dependency of θ on temperatures for the main reactions of iron
2Fe + O 2 + 2H 2 O = 2Fe(OH) 2
(2)
4Fe(OH) 2 + O 2 + 2H 2 O = 4Fe(OH) 3 ↓
(3)
2Fe(OH) 3 Fe 2 O 3 + 3H 2 O
( 4 )