Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 10, pp. 1862−1866.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
V.V. Tarasov, N.E. Kruchinina, N.F. Kovalenko, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 10, pp. 1710−1714.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Effect of Diluent Additives on the Rate of Water Puriﬁ cation
to Remove Microdrops of Tri-n-Butyl Phosphate
by Hydrodynamic Heteroadagulation
V. V. Tarasov, N. E. Kruchinina, and N. F. Kovalenko
Mendeleev Russian University of Chemical Engineering, Moscow, Russia
Received February 17, 2009
Abstract—Effect of diluents on the coarsening of microdrops of tri-n-butyl phosphate by hydrodynamic
heteroadagulation on a carbon fabric in water was studied.
The effect of diluents on the extraction equilibrium
is a classical example of application of the theory of
solutions [1–4]. Diluents are required for performing
technological processes under optimal conditions. These
substances can provide necessary viscosity and density
of the phase of extractive agents, but more frequently,
they adjust such extraction parameters as coefﬁ cients of
element distribution and separation. The list of diluents
used in technology and their physicochemical parameters
can be found in the handbook .
Minor additions of diluents have an insigniﬁ cant effect
on the thermodynamic properties of the extractive systems
[1–4]. Any noticeable changes would be expected to occur
only in the kinetics of extraction–re-extraction processes.
However, the effect of diluents on the extraction kinetics
has been insufﬁ ciently studied. In , data indicating the
effect of diluents on the extraction rate of metals with
alkylphosphoric acids were reported. Advances in this
area can hardly be compared with achievements in the
application of the theory of solutions to description of the
effect of diluents on equilibrium properties of extractive
systems. There is no information about the behavior
of microdrops of, e.g., tri-n-butyl phosphate (TBP) on
solid surfaces. Such microdrops are formed in extraction
involving supersaturated phases. The microdrops are
adsorbed on walls, bafﬂ es, and other immobile members
of extraction apparatus, where occurs their hydrodynamic
heteroadagulation (HHA) (i.e., hydrodynamic adsorption
The formation of microdrops of TBP or TBP mixed
with diluents in raffinates is a topical problem of
radiochemical industry. Visually, rafﬁ nates of this kind
look as turbid, long unclariﬁ able phases. Accumulating at
certain places, they constitute a serious danger, which can
not only lead to loss of reagents, but even may develop
into a nuclear hazard. One of ways to tackle with this
phenomenon consists in eliminating the original cause
itself, i.e., in removing microscopic TBP drops.
The aim of this study was to determine how minor
additives of organic diluents affect the kinetics of
purification of the aqueous phase to remove TBP
microdrops by hydrodynamic heteroadagulation.
The procedure for preparing microscopic TBP drops
0.8–10 μm in diameter was described in most detail in [6–
8]. A quasi-stable emulsion of TBP drops was produced
with an IKA DI 25 disperser (Germany) at a rotor rotation
speed of 8000 rpm. Such a rotation of the rotor was
accompanied by imposition of emulsion ﬂ ow pulsations
at a frequency of 1333 Hz. At the same frequency varied
pulsations of pressure and shear stresses. Homogeneous
TBP solutions with various organic additives were
prepared by simple mixing of the diluents and TBP.
It has been shown [1, 5] that the kinetics of the
HHA process is described by the Eley–Rideal equation
modiﬁ ed by Tarasov for the case of the microdrops. For