Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 2, pp. 182−186.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.N. Verezhnikov, I.I. Germasheva, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 2, pp. 193−197.
OF SYSTEMS AND PROCESSES
Colloid Chemistry Principles of Separation
of Pure Alkyl Sulfates
V. N. Verezhnikov and I. I. Germasheva
Voronezh State University, Voronezh, Russia
Sintez PAV, Research and Production Association of Synthetic Surfactants,
Open Joint-Stock Company, Shebekino, Russia
Received May 25, 2011
Abstract—Sodium dodecyl sulfate and other alkyl sulfates were treated by the method of polythermal conductometry
to remove primary alcohols. The electrical conductivity polytherms were analyzed. The composition of the liquid
and solid phases in equilibrium in the mixed solutions was determined. The method of the synthesis of chemical
purity colloids of alkyl sulfates and other ionogenic micelle forming surfactants was suggested based on the optimal
choice of crystallization temperature of the solutions.
Modern scientiﬁ c and high-technology areas (medi-
cine, pharmacy, electronics, and nanotechnology) greatly
need for high-purity surfactants (SAAs). One of the
most common methods of the preparation of metallic
nanoparticles uses surfactant micelles as unique nanoreac-
tors responsible for the synthesis topochemistry and the
size and morphology of the particles . For preparing
multimolecular layers, known as the Langmuir–Blodgett
ﬁ lms, the purity of SAAs is the particularly important
parameter . These nanosized planar structures arouse
a wide scientiﬁ c and practical interest.
The development of regular multilayer construction
technology with pre-programmed properties directly
depends on progress in the development of controllable
synthesis of high-purity surfactants. Meanwhile, practice
shows that synthesis of high-purity surfactants, such as
primary alkyl sulfates (one of the most commonly used
and well-studied class of surfactants), encounters con-
siderable difﬁ culties in removing impurities. Difﬁ culties
in treating alkyl sulfates to remove primary alcohols
have been reported elsewhere [3–7]. The same can be
said about removal of tetradecyl alcohol from tetradecyl
sulfate ; it retains even though the surface tension
isotherm minimum, criterion of SAA purity, is lack-
ing. Commercially pure sodium dodecyl sulfate always
contains traces of dodecanol . Traditional methods of
the treatment (recrystallization, extraction, foam frac-
tionation, and vacuum sublimation) do not often yield
the desired result.
It was shown that this arises from disregard of speciﬁ c-
ity of SAAs as micellization systems and their ability to
interact with the mixture components (primaryl alcohols
in the case of alkyl sulfates).
In the study, the effect exerted by micellization on the
phase separation upon puriﬁ cation of SAAs by crystalliza-
tion from solutions was determined and a simple method
was suggested for the synthesis of chemical purity col-
loids of alkyl sulfates, which satisfy to the requirements
of modern high technology.
Sodium dodecyl sulfate (AS-12) and sodium hexadec-
yl sulfate (AS-16) were synthesized from corresponding
alcohols (chemical purity grade) by the method reported
in . The resulting products were puriﬁ ed according to
our method described in the ﬁ nal part of the article. The
electrical conductivity polytherms were obtained with
a Р 5021conductometer at a heating rate not exceeding
0.5 deg min
at continuous agitation.