Chemistry Reference
In-Depth Information
log
I
=
log
G
¢ +
(
32
-
12
x
)
log
c
Lp
-
HO
2
(
)
[5.1]
+
32
x
-
12
log
c
+
0013 24
.
T
-
OH
or after anti-logarithming:
(
32 12
-
x
)
(
32
x
-
12
)
I
=¢
Gc
c
e
0 03049
.
T
[5.2]
Lp
-
-
OH
HO
2
5.3
Behaviour of the sensor electrode at
the laboratory scale
5.3.1
Influence of bleaching additives on the current signal
Introduction
In the previous sections, the investigated solutions contained only sodium
hydroxide and hydrogen peroxide. Apart from these basic ingredients,
industrial bleaching baths also contain a number of commercial 'additives'
(in reality, mainly mixtures of several active components, see Chapter 4,
section 4.2.) aiming at optimisation of the bleaching process. It is evident
that these additives can also contribute to the voltammetric behaviour of
hydrogen peroxide. Hence, it is clearly necessary to investigate in the next
stage the influence of additives on the prewave of the oxidation of hydro-
gen peroxide with glassy carbon and to examine the implications on the
possible development of a sensor for the pseudo-limiting-current of the
prewave.
The role that each of the different classes of bleaching additives plays
was elaborated in Chapter 4, section 4.2. Considering the wide variety of
additives, and classes of additive, available on the world market, and in
order to be able to control the number of variable parameters in the
planned research work, it was necessary to make a selective choice between
the numerous commercially available products. Therefore it was decided to
use products from Henkel, with at least one representative from each class
of additives. These are tensio-active agents in Cottoclarin
®
SV, Cottoclarin
®
BF and Seclarin
®
540; auxiliary stabilisers in Stabilol
®
K and Stabilol
®
HN;
and de-aeraters and de-foamers in Defindol
®
E. For reasons of control, a
limited number of additives from Sandoz were also investigated - notably
Sandopan with tensio-active agents and auxiliary stabilisers and Sandozin
with de-aeraters and de-foamers. By means of tests in different companies,
with products from several other manufacturers of additives and under dif-
ferent working conditions
1
, it can be shown that a generalisation of the
results obtained with the Henkel and Sandoz additives is appropriate. The
choice of additives from Henkel and Sandoz was based on the fact that
