Chemistry Reference
In-Depth Information
5
Amperometric detection of hydrogen
peroxide in bleaching and washing processes
P. WESTBROEK AND P. KIEKENS
5.1
Introduction
In this chapter, the development of an amperometric sensor will be
explained and discussed. The principle of the analysis method will be based
on the results described in Chapter 4; this means that use will be made of
the oxidation reaction of hydrogen peroxide in the prewave, and that the
concentration will be determined using the rate equation. In addition to
measurement of the electrical current response, temperature and pH will
therefore also be measured. Accordingly, it is interesting to start with an
investigation of the temperature influence.
5.2
Influence of temperature
5.2.1
Introduction
All the experimental results and the derived data obtained in the previous
sections apply with a temperature of 298.0 K. Since the temperature in
bleaching processes can vary considerably (working temperature of ca.
288-323 K), it is necessary to verify the way in which the electrode signal
depends on the temperature.
Most factors in parameter
G
(Chapter 4, Equations 4.55 and 4.56) and the
potential of the reference electrode are temperature-dependent; this is pos-
sibly also the case for factor
x
. Equation 4.56 also represents the concen-
tration of the hydroxide ion. This means that a potential sensor based on
the prewave will also have to contain a pH sensor. The hydroxide ion con-
centration derived from the output signal of this additional sensor needs to
be introduced in the algorithm for the calculation of the hydrogen perox-
ide concentration. As an additional sensor, a glass electrode is an obvious
choice, with a temperature-dependent potential, which is the case also for
the potential of the reference electrode associated with the glass electrode
and for the pH of the buffers. In this research work, the influence of
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