Chemistry Reference
In-Depth Information
35
30
3
3
25
1
2
20
1
1
2
3
15
2
3
10
5
0
0
20
40
60
80
100
Time (min)
5.19
Development of the hydrogen peroxide concentration in a solu-
tion containing paper pulp with a pH of ca. 8. The concentrations
were determined by means of a sensor system with (1) FIA-
expansion, (2) titration, and (3) strips.
At a laboratory scale, some preliminary experiments were performed to
determine hydrogen peroxide concentrations in solutions with pH < 10.5.
To this end, hydrogen peroxide solutions from a paper pulp process (pH ca.
8) were used, which were obtained from a French company. The results are
displayed in Fig. 5.19. Here, mainly relatively low hydrogen peroxide con-
centrations were examined, with output signals that were never higher than
35 mA. The pH in the detection cell was ca. 12.5, and the temperature fluc-
tuated around 318 K.
From Fig. 5.19, it appears that the hydrogen peroxide concentrations
obtained by means of the sensor system and through titration correspond
relatively well with each other (deviations always < 10%), and that the
system qualifies both to measure the hydrogen peroxide concentration and
to control it. To illustrate, Fig. 5.19 also shows the hydrogen peroxide con-
centrations obtained by means of strips (Merck), which are frequently used
in the paper industry. It is clear that the strips are rather inaccurate, com-
pared with the results obtained with the sensor system.
