Optimization of Arsenic Removal Process in Waste Acid …
709
Experimental Section
Experimental Materials
The waste acid used in the experiment was obtained from zinc smelting plant located
in Yunnan, containing heavy metal ions and harmful elements such as cadmium,
lead, fluorine, chlorine, and arsenic. The concentration of waste acid from a zinc
smelting plant in Yunnan was shown in Table 1, and the initial pH of waste acid was
2.1.
Orthogonal Array Experimental Design
Concerning relevant literature and combined with preliminary research, temperature
(factor A), the reaction time (factor B), pH (factor C), and the molar ratio of Fe/As
(factor D) were chosen for the present study. Four different levels were selected for
each factor. There have been no reports of the interaction among the four parameters
in the literature which we have read, and we have not found the interaction among the
four parameters in our previous studies. Therefore, the interaction among the four
parameters has not been considered in this paper. An orthogonal array of L 16 (4
4 ) was
used to assign the considered factors and levels in this study. The experimental factors
and their corresponding levels were illustrated in Table 2. The designed orthogonal
array was described in Table 3.
Table 1 Concentrations of waste acid elements
Composition
Cd
Cl
Pb
As
F
Concentration (mg/L)
101.7
829
116
629
456
Table 2 Orthogonal experimental factors and levels
Level
Factors
A
Temperature (°C)
B
The reaction time (min)
C
pH
D
The molar ratio of Fe/As
1
20
15
6
4
2
40
30
8
6
3
60
45
10
8
4
80
60
12
10
709
Experimental Section
Experimental Materials
The waste acid used in the experiment was obtained from zinc smelting plant located
in Yunnan, containing heavy metal ions and harmful elements such as cadmium,
lead, fluorine, chlorine, and arsenic. The concentration of waste acid from a zinc
smelting plant in Yunnan was shown in Table 1, and the initial pH of waste acid was
2.1.
Orthogonal Array Experimental Design
Concerning relevant literature and combined with preliminary research, temperature
(factor A), the reaction time (factor B), pH (factor C), and the molar ratio of Fe/As
(factor D) were chosen for the present study. Four different levels were selected for
each factor. There have been no reports of the interaction among the four parameters
in the literature which we have read, and we have not found the interaction among the
four parameters in our previous studies. Therefore, the interaction among the four
parameters has not been considered in this paper. An orthogonal array of L 16 (4
4 ) was
used to assign the considered factors and levels in this study. The experimental factors
and their corresponding levels were illustrated in Table 2. The designed orthogonal
array was described in Table 3.
Table 1 Concentrations of waste acid elements
Composition
Cd
Cl
Pb
As
F
Concentration (mg/L)
101.7
829
116
629
456
Table 2 Orthogonal experimental factors and levels
Level
Factors
A
Temperature (°C)
B
The reaction time (min)
C
pH
D
The molar ratio of Fe/As
1
20
15
6
4
2
40
30
8
6
3
60
45
10
8
4
80
60
12
10