Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 4, pp. 632−635.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
N.I. Yastrebova, A.Yu. Gorbunov, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 4, pp. 580−583.
OF SYSTEMS AND PROCESSES
Phase Separation Conditions in Systems Constituted
by a Nonionogenic Surfactant, Water,
and Sodium Carbonate
N. I. Yastrebova and A. Yu. Gorbunov
Saratov Military Institute for Biological and Chemical Safety, Saratov, Russia
Received July 15, 2009
Abstract—Dependence of the viscosity of aqueous solutions containing a nonionogenic surfactant, OP-10, and
sodium carbonate on temperature and concentrations of OP-10 and sodium carbonate was studied. The phase-
separation conditions were found for the systems under study.
Wastewater from many plants contains nonionogenic
surfactants (NISs), e.g., a foaming agent OP-10, an
oxyethylated alkylphenol. In addition to surfactants,
wastewater frequently contains electrolytes ,
e.g., sodium carbonate. Such wastewater cannot be
discharged into rivers and water basins because of
the high content of inorganic salts and NISs. Most
frequently, wastewater of this kind is evaporated to give
a dense residue delivered to burial .
In evaporation of wastewater, its viscosity changes
and gelation occurs, which hinders separation of a dense
residue. It becomes necessary to preliminarily purify
wastewater to remove NISs. Various methods used for
this purpose are known [2–5]. The most advisable, in
our opinion, is that based on the ability of NISs to form
a separate liquid phase on the solution surface upon
an increase in temperature [6–12]. This method is well
compatible with processes for wastewater evaporation.
The aim of our study was to examine the effect of
various factors on the viscosity of systems constituted
by OP-10, water, and sodium carbonate and the phase
separation conditions for these systems.
We used in the study a nonionogenic surfactant OP-
10 (oxyethylated p-isooctylphenol) with an average
number of oxyethylene groups equal to 10 [GOST
(State Standard) 84 33–81]. The mass fraction of the
main substance was no less than 80%, and that of water,
no more than 0.3%; pH 6–8. Solutions were prepared
with anhydrous sodium carbonate of pure grade, GOST
We prepared four sets of solutions with different
concentrations of OP-10 and sodium carbonate. The
concentrations were chosen by taking into account that
wastewater is concentrated in the course of evaporation
and relative concentrations of the components in
solution may change.
The viscosity of the solutions was determined with an
Ostwald capillary viscometer with a capillary diameter of
0.86 mm. The viscometer and the solutions under study
were thermostated in a Labtex LT-TWC/22 circulation
water thermostat. The viscosity was calculated by the
and η are, respectively, the viscosities of
water and a solution under study at a given temperature