Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 4, pp. 742−744.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
Yu.Ya. Bobyrenko, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 4, pp. 690−692.
Estimation of the Nature of the Silicon-Containing Component
in the Corrosion-Inhibiting Pigment Complex
by Means of Triethanolamine
Yu. Ya. Bobyrenko
Chelyabinsk State Pedagogical University, Chelyabinsk, Russia
Received July 6, 2009
Abstract—The nature of a silicon-containing component in a corrosion-inhibiting pigment complex was studied
by the potentiometric titration.
The “Kolor” LLC has developed a dry active pigment
complex, which endows paint coatings with a high ability
to protect metals from corrosion in salty and sea-waters.
This complex is used under various names within several
years. It is produced from ferrochrome slag and iron vit-
riol . It is free from toxic anticorrosion agents routinely
present in such pigments . It was assumed in  that
protective power of the complex is caused by several
mechanisms operating simultaneously: passivation of
a metal surface due to formation of slightly soluble sili-
cates on it; transformation of active silicates of the pig-
ment to semipermeable ﬁ lms in depth of a paint coating;
Donnan inhibition of diffusion of corrosion-active anions
in depth of a coat. The silicon-containing component of
a pigment is assumed to be the main effective agent.
The conclusion that the silicon-containing component
contains a low-molecular form of silicate was based on
the reaction of the pigment complex with pyrocatechol
. There are no other evidences.
The aim of the present work was to try and reﬁ ne this
conclusion by the potentiometric titration of pigment com-
plex mixtures with triethanolamine, as triethanolamine is
capable to form chelates with the silicon atom .
The pigment complex composition is (%): CaO
14–15, FeOOH 20–22, and SO
remaining is insoluble spinel of magnesium and chro-
mium oxides, and also hydration water. Iron hydroxide
in the form of goethite, calcium sulfate dihydrate, high-
temperature low-active spinel, and a silicate component
of an ambiguous nature  are considered as the main
components of the complex.
The operating procedure was as follows: 50 ml of
0.005–0.006 M KОН solution was poured on a mix-
ture of the pigment complex with triethanolamine (or
without it), and the mixture was left to stand for 2 min
in a closed vessel. The weighted sample of the pigment
was 0.5–1.0 g. Then the mixture was titrated by a 0.05 M
HCl solution under stirring at a rate of 100–150 rpm.
Measuring рН was carried out by a рН-340 device with
glass and silver chloride electrodes. In parallel to the
main titration we carried out a blank titration, where the
mixture under titration contained the same components
as the main titration mixture, except for a substance
to be analyzed. Absorption of Н
ions by the
substance under study was found as a difference of
volumes of HCl solution which were consumed for
the main and blank titration at a speciﬁ ed рН value
of the medium. The contents of active groups of the
pigment complex or of triethanolamine (mmol per 1 g
of a sample) at various pH values were calculated by
the formula