4.2 Effect of pH
A key variable to efficiently perform homogeneous Fenton and photo-Fenton
processes is pH. This should be kept around 2.8 in order to minimize the formation
of iron complexes. This pH value, however, is considered as a limiting factor
[35, 42], and therefore, it is an important variable to be assessed in heterogeneous
processes. This variable was studied in the photo-Fenton process at three values (2.7,
5.0, and 8.0). To achieve the acidic values, 0.1 M H 2 SO 4 was added. The results
plotted in Fig. 6 show that both mineralization degree and rate are significantly
0
30
60
90
120
150
180
210
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
0.4g cat/L
0.5g cat/L
0.6g cat/L
0.7g cat/L
0.8g cat/L
C
O
T
/
C
O
T
0
time (min)
a
b
0.4
0.5
0.6
0.7
0.8
0.4
0.6
0.8
1.0
1.2
1.4
)
n
i
m
*
t
a
c
g
/
g
m
(
o
r
-
Catalyst Loading (g/L)
Fig. 5 (a) and (b) Effect of
catalyst loading on TOC
normalized content.
Experimental conditions:
temperature ¼ 30
C;
pH ¼ 2.7; stirring
speed ¼ 800 rpm
250
R. Natividad et al.