Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 4, pp. 582−587.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © S.A. Demakhin, K.K. Il’in, A.G. Demakhin, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 4, pp. 546−551.
OF SYSTEMS AND PROCESSES
Liquid–Liquid Equilibrium and Critical Phenomena
in the Water–Isopropanol–Kerosene–Ethyl Silicate-40 System
S. A. Demakhin
, K. K. Il’in
, and A. G. Demakhin
Ekokhim Research and Production Enterprise, Limited Liability Company, Saratov, Russia
Chernyshevskii Saratov State University, Saratov, Russia
Received March 10, 2010
Abstract—Mutual solubility was studied for the components of pseudoquaternary system water–isopropanol–
kerosene–ethyl silicate-40, and the compositions of the system in the critical solubility points were determined.
Silicic acid esters and solutions thereof are
extensively used for limiting the water ingress into
oil and gas wells . Hydrolysis of these esters and
polycondensation of the resulting silanols are strongly
affected by the composition of the liquid phase based on
silicic aid esters and stratal water components.
Here, we studied phase equilibria and critical
phenomena in pseudoquaternary system water–
isopropanol–kerosene–ethyl silicate-40 with the aim
to formulate solutions best suited for oil and gas well
waterprooﬁ ng applications.
The solubility of the components in pseudoternary
liquid stratifying systems and in sections of the
pseudoquaternary system was determined at 25°C
by the Bancroft’s isothermal titration technique .
Homogeneous or heterogeneous mixtures of two (three)
components were prepared in 25-ml glass pycnometers
and subsequently titrated at a constant temperature
under regular stirring with the third (for pseudoternary
systems) or fourth (for pseudoquaternary system
sections) component till the appearance or disappearance
of opalescence (appearance or disappearance of one of
the phases). The mass of the third (fourth) component
added was determined by weighing. Replicate titrations
were carried out on mixtures with the same composition
until the results agreed within the accuracy. The ratio
of the total mass of the analyte system at the titration
end to the mass of the drop of the titrant was close to
that at which the relative error of determination of the
solubility is within 0.2%.
The composition of the system in the critical solu-
bility point was determined by the phase volume ratio
technique . Speciﬁ cally, for the ternary systems and
sections of the quaternary system we selected by the
trial and error method a binary (ternary) mixture such
that it exhibited critical opalescence in titration with the
third (fourth) component in the vicinity of the critical
solution point (±0.1°) and, upon settling of the resulting
ternary (quaternary) system till clariﬁ cation of the lay-
ers, separated into two liquid phases of equal volumes.
The experiments were carried out with a 25-ml cali-
brated pycnometer; the phase volumes were measured
accurately to within ~5%.
Water was puriﬁ ed on a DEM-20 MERA-POLNA
double-distiller. Chemically pure-grade isopropanol
(>99.8% main compound) was dried over calcined
potassium carbonate for 1 day, decanted, and distilled
on a 0.3-m Vigreux column, and the fraction with bp
82.2–82.4°С was collected. The puriﬁ ed alcohol was
stored over 4 Å molecular sieves. Water and isopropanol
were identiﬁ ed from the boiling point, refractive index,
and density. The physical constants of these solvents
were in a good agreement with the reference data .
Ethyl silicate-40 [GOST (State Standard) 26371–84]
and illuminating kerosene [TU (Technical Speciﬁ cations)