Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 4, pp. 651−655.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © T.N. Poyarkova, G.V. Kudrina, Yu.I. Prokof’ev, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 4, pp. 635−640.
AND INDUSTRIAL ORGANIC CHEMISTRY
Effect of Inorganic Electrolytes and Nonionogenic
Surfactants on the Stability of Soap Stock Emulsion
T. N. Poyarkova, G. V. Kudrina, and Yu. I. Prokof’ev
Voronezh State University, Voronezh, Russia
Received May 19, 2011
Abstract—Modes in which the fat component of the soap stock emulsion is extracted under heating and introduc-
tion of various nonionogenic surfactants and electrolytes were studied. The compression isotherms of the soap
stock and its mixtures with OP-7 and NaCl were examined by the Langmuir method, with 2D pressure recorded.
Recommendations were developed for separation of the soap stock emulsion for recovery of the fat component
from wastes produced in manufacture of vegetable oils.
Manufacture of sunﬂ ower oil involves processing of
its wastes, which poses ecological problems. The main
waste in the stage of alkaline reﬁ ning of vegetable oil is
the soap stock formed in an amount of up to 170 kg per
ton of reﬁ ned oil.
The value of the soap stock is in that it contains up to
40% fatty substances to which belong macromolecular
carboxylic acids, glycerides, soaps, and phospholipids.
However, application areas of the soap stock are lim-
ited because it contains accompanying impurities. In the
general case, the composition of the main components
of soap stock may depend on the type of a vegetable raw
material being processed, conditions and duration of its
storage, temperature, and kind of a neutralizing agent
[1, 2]. After the extraction, additional saponiﬁ cation and
hydrolysis of the neutral fat and phospholipids occurs in
soap stocks, which leads to formation of glycerides and
fatty acids. In addition, in prolonged storage, especially
at low temperatures, the soap stock takes on a highly
dense consistence and, for this reason, can hardly be ex-
tracted from tanks and vessels .
At present, soap stock fats mostly serve to obtain
soap that is used not only in cosmetic industry, but also
in emulsiﬁ cation, washing, dispersion, plasticization,
structuring, and modiﬁ cation of rheological properties
of various systems. According to the existing regula-
tions, soap stocks containing no less than 30 wt % to-
tal fat are accepted for transportation to soap-making
plants. However, reﬁ ning frequently yields more dilute
soap stocks containing 12–15 wt % fat components. In
this context, methods for raising the amount of the fat
component in the soap stock have been under intensive
developed in recent years. Several methods are known
for separation of the soap stock and recovery of fat com-
ponents from this waste . To the conventional meth-
ods belong chemical (decomposition of soap stocks with
concentrated sulfuric acid or sodium chloride), concen-
tration by evaporation, centrifugation, replacement of
a solvent upon introduction of alcohols. Each of these
methods has its own disadvantages, to which can be
attributed the low yield of fat components, substantial
energy consumption, and ﬁ re-hazardous technological
processes. Therefore, the topicality of the task consists
not only in raising the soap stock separation efﬁ ciency
and recovery of fat components from this waste, but also
in diminishing the energy expenditure for this process.
In this study, we separated the soap stock emulsion
by a method including combined effect of electrolytes
and de-emulsifying agents introduced into soap stock
under permanent agitation and heating.