Download (III) From Aqueous Solutions with Sodium Dodecyl Sulfate

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 9 (2016) pp 6350-6354
© Research India Publications. http://www.ripublication.com
Solvent Sublation of the TB (III) From Aqueous Solutions with Sodium
Dodecyl Sulfate
Dr. O. Lobacheva
Associate Professor, Dr., General α Physical Department,
National Mineral Resources University (Mining University), Saint Petersburg, Russia.
Berlinskii
Associate Professor, General α Physical Department,
National Mineral Resources University (Mining University), Saint Petersburg, Russia.
neutralizers in the production of magnets, phosphors,
capacitors, optical glass, ceramics, high-tech abrasive
materials, x-ray films. So their prices are ten times higher in
comparison with the total product.
For REE extraction from solutions leaching of the ore
concentrates using technology based on physic-chemical
methods: extraction by organic reagents, ion exchange [4, 5].
It deals with the application of ion flotation with surfaceactive substances (surfactants) [6, 7].
Solvent sublation ( S S ) is the adsorptive bubble method for
surface separation in which the gas bubbles floating up
transfer a substance adsorbed on them (sublate) from one
liquid into another. The method was suggested for the first
time by Sebba in 1962 [1,2]. Solvent sublation is a
combination of the flotation of ions or molecules with liquid
extraction. In this case, the term sublate refers to a chemically
individual substance in the form of which an ion being
recovered (colligend) is concentrated on the bubble surface.
The process is performed at low gas flow rates, at which the
integrity of the upper layer of the organic liquid is preserved.
The method is used for the recovery of valuable components
from lean technogenic raw materials and wastes from ore
processing and for the quantitative determination of traces of
metals and surfactants [2-6]. However, studies concerning
application of the solvent sublation method to recovery of
valuable components, in particular, of nonferrous and
rare-earth metal ions, are few and nonsystematic.
In addition, the volume of the organic phase is comparatively
small, as it is determined only by the capacity with respect to
sublate and the cross sectional area of the apparatus. The
process is implemented with small expenditure of gas, does
not destroy the upper layer of organic liquid. The method used
in the purification of wastewater from organic impurities and
for quantification of trace metals and surface-active
substances [2-8].
Research on the application of SS-process to extract heavy
metal ions small and unsystematic character. However, such a
feature of SS-approach, as the possibility of multiple
concentrations of metal ions in small volumes of organic
solvent, indicates the potential of this method to solutions
containing metal ions, with the purpose of their regeneration.
It should be noted that currently available information about
the nature of the organic phase are very limited. F. Sebba and
Abstract
The possibility of the experimental removal of the terbium
(III) from dilute aqueous solutions by adsorption-bubble
method-Solvent Sublation using sodium dodecyl sulfate
(NaDS) is determined. The dependences of the distribution
coefficients of Tb-dodecyl sulfates on pH of the equilibrium
aqueous phase in the above processes were determined.
Conditions for possible separation of the terbium (III) ions in
the adsorptive bubble recovery method under consideration are
discussed. Solvent Sublation process kinetic laws are defined
in the solutions containing terbium ions and surface-active
substance.
The solvent sublation-an adsorptive bubble separation method
surface, where pop-up bubbles of gas adsorbed on them to
tolerate the substance (sublet) from one fluid to another [1].
The solvent sublation is a combination of flotation ions or
molecules from liquid extraction. Unlike conventional solvent
extraction, in process of SS mass transfer from aqueous phase
to organic involving bubbles. This eliminates a number of
problems associated with emulsification. In addition, the
volume of the organic phase is comparatively small, as it is
determined only by the capacity with respect to sublate and
the cross sectional area of the apparatus. The process is
implemented with small expenditure of gas, does not destroy
the upper layer of organic liquid[2].
Keywords: Rare earth elements (terbium cations (III)),
surface active substance-sodium dodecyl sulfate, solvent
sublation process
Introduction
This study deals with the distribution of rare-earth element
(REE) ions in the aqueous phase-organic phase system
formed by model solutions of Tb 3+ nitrates and sodium
dodecyl sulfate was studied in solvent sublation process. 2octanol was used as organic phase. The use of rare earth
elements (REE) in a number of areas related to use of
undivided REE (metallurgy, manufacturing of catalysts for the
refining industry, the production of rechargeable batteries,
glass) [3].
The greatest demands on the world market are the individual
rare earth. They are used in the production of catalytic filter-
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 9 (2016) pp 6350-6354
© Research India Publications. http://www.ripublication.com
other authors [2,8,9] indicate that the organic phase ("trap")
must have a certain polarity, and meet the basic requirements
of organic phase in SS: the density, the smaller the density of
water, minimum solubility in water; the maximum ability to
accumulate sublet. Currently many authors on the basis of the
conducted researches showed that in the process of SS the
distribution of matter is determined by its ability to be
adsorbed on the walls of the bubbles passing through the
solution, and does not depend on the ratio of the volumes of
the phases.
Thus, the adsorption process sublate is a determining factor in
the process.
The process of SS has been little studied in comparison with
the method of foam separation. Initially, the solvent sublation
was proposed to extract ions using a surfactant, subsequently,
this process was implemented and in other cases: the
extraction of solutes on the basis of their surface activity and
in the flotation of sediments.
Despite the fact that the method is poorly understood, it is
possible to note some advantages of SS-method before the
foam separation.
In foam separation foam performs the necessary function of
raising the products of flotation and facilitating its removal,
but in some cases, for example, by the extraction of organic
ions the excess foam and slow its destruction can be only a
hindrance. An important property of the method is the high
degree of selectivity. In flotation process [9] using surfactants
the majority of dissolved impurities goes into the foam, while
in flotation, it is possible to achieve this separation, in which
part of the substance passes into the organic phase, and the
part comes back.
It should be noted that the foam separation from the solution
along with substance secreted by the leaves and water. This is,
firstly, reduces the efficiency of flotation, and reduces the
degree of concentration of substances in the process.
Secondly, in the experiments on foam separation of the water
consumes floating solution, and, ultimately, gives quite a full
curve in the experiment with a single source solution. In SSapproach this does not happen because the water in the form
of droplets all the time back in the aqueous phase [10-13].
Experimental data on solvent sublation systems, anionic
surfactant and the cation of the metal, indicate that in the
process of SS we can achieve a more efficient allocation of
substances than with foam separation.
Despite all the advantages, the method of SS has its
drawbacks:
1) not always possible to choose the solvent that would
have dissolved the formed sublat,
2) it is possible to form emulsions of water in organic
phase, with the possible contamination of this
unwanted organic phase components from aqueous
solution [2].
concentration of terbium ions in model solutions was 0.001
mol l-1.
Figure 1: Scheme of solvent sublation columns: 1-the organic
phase (alcohol-2-octanol), 2-the solution containing Tb(NO3)3
and NaDS, 3-porous partition (SCHOTT filter).
In the process of solvent sublation using classic glass column
[2], made in the form of a cylinder, the bottom of which
served as a filter SCHOTT. Scheme SS-column is represented
in Figure 1. Through a porous membrane was supplied gas
(nitrogen) from the cylinder. The gas flow was controlled by
Rota meter. In every experience with 200 ml of investigated
solution of Tb(NO3)3 containing NaDS, and 5 ml of organic
phase (2-octanol) were placed in a column with a diameter of
0.035 m and 0.45 m high. The gas velocity was 3.3∙10-4m3/h
in order not to break the layer of organic solvent above the
aqueous solution.
The experience lasted 2 hours. The process of solvent
sublation held to a constant residual concentration of ions of
terbium, which were determined according to standard
methods [14]. The pH of the solution was monitored using
ionomer "Anion 7010" with a glass electrode. To establish the
pH of the solutions used solutions of nitric acid or sodium
hydroxide. The solutions of metal salt prepared by the
gravimetric method, using a terbium nitrate hexahydrate.
For the determination of dodecyl sulphate ion (DS-) in the
solution we have chosen the method of potentiometric
titration using anion selective membrane. The method
developed at the Department of physical chemistry Saint
Petersburg State University [15], allows determining the
concentration of dodecyl sulfate-ion by the change in the
electromotive force of a galvanic cell during the titration. The
In our research we investigate the possibility of extraction of
ions of lanthanides terbium and method of solvent sublation
using as collector the anionic surfactant sodium dodecyl
sulfate (NaDS), as extragent-iso-octanol alcohol. The
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 9 (2016) pp 6350-6354
© Research India Publications. http://www.ripublication.com
titration was carried out with a solution of chloride of cetyl
trimethyl ammonium brand “Chemapol” concentration of
0.002 mol/kg the relative error of the titration was 2%.
The content of Tb3+ in organic phase was calculated by the
difference of concentrations at initial and equilibrium aqueous
phase:
сorg  (c0  caq ) 
Vaq
Vorg
,
Table 1: The change in the concentration of terbium (III) in
the aqueous phase in the solvent sublation process
C molkg-1
рH=5,2 pH=6,2 pH=7,1 pH=7,6 pH=8,2 pH=9,5
0
0,001
0,001
0,001
0,001
0,001
0,001
5 6,58·10-4 6,76·10-4 0,51·10-4 1,72·10-4 4,65·10-4 9,74·10-4
15 6,13·10-4 6,26·10-4 0,40·10-4 0,43·10-4 2,51·10-4 9,64·10-4
30 5.67·10-4 6,01·10-4 0,38·10-4 0,29·10-4 0,83·10-4 9,23·10-4
120 5,52·10-4 5,31·10-4 0,10·10-4 0,20·10-4 0,25·10-4 8,64·10-4
t min
(1)
where Corg and Сaq-concentration of metal ions in organic and
aqueous phases, respectively, mol/l; C0-the initial
concentration of the terbium ion in the aqueous phase, mol/kg;
Vaq and Vorg are the volumes of aqueous and organic phases,
respectively. The distribution coefficient of Tb+3 between
aqueous and organic phases was determined by the formula
[16]:
K distr 
Corg
Caq


Vaq  C0

 1
Vorg  Caq 
The concentration of terbium-ion was determined by
photometric method with Arsenazo III [14], the concentration
of chloride ions-mercurimetric titration with a mixed indicator
(alcohol solution 0.5 wt.% of the difenilkarbazide and 0.05
wt% of the bromophenol blue), the concentration of dodecyl
sulfate ion (DS-)-by potentiometric titration of 0.002 M of the
cetyltrimethyl ammonium chloride solution with ion-selective
electrodes consisting of silver chloride-EVL-1MZ placed in a
solution of NaDS and NaCl, and membrane, ion selective to
DS-. The membrane was made in the ionometric laboratory of
the Department of Physical Chemistry St. Petersburg State
University [15].
(2)
The distribution coefficient expresses the ratio of the
concentrations of substances in both phases, and this value
depends on the conditions of distribution and does not depend
on the volumes of the phases.
Currently many authors on the basis of the conducted
researches showed that in the process of solvent sublation the
distribution of matter is determined by its ability to be
adsorbed on the surface of the bubbles passing through the
solution, and does not depend on the ratio of the volumes of
the phases [2].
Thus, the adsorption process of the sublat is a determining
factor in the process.
The solvent sublation was performed in the pH range from 5.2
to 9.5. The results of the experiment are presented in Table 1,
2 and in Figure 2.
Table 2: The degree of the removal α and the distribution
coefficient Tb (III) in the process time 120 min, and initial
concentration of the Tb (III): C0 = 0.001 mol/kg.
pH=5.2
pH=6.2
pH=7.1
pH=8.2
pH=7.6
pH=9.5
0,0012
C mol/kg
0,0010
0,0006
0,0004
0,0002
t min
0,0000
20
40
60
80
100
120
k, min-1
5,2
6,2
7,1
7,6
8,2
9,5
0,08
0,06
0,19
0,13
0,11
0,03
Corg,
molkg-1
0,0179
0,0187
0,0396
0,0395
0,0384
0,0054
Сaq,
molkg-1·104
5,52·10-4
5,31·10-4
0,10·10-4
0,25·10-4
0,20·10-4
8,64·10-4
Kdistrib
%
32,5
35,3
4077,5
3062,6
999,1
6,3
44,8
46,9
99,1
98,7
96,2
13,6
From figure 2 it is seen that at the initial stage of the process
(5-15 minutes) removal of terbium ion is much more intense
than for subsequent flotation.
Thus, it is possible to find the optimal time for the process of
solvent sublation in solutions of terbium nitrate with an initial
concentration of 0.001 mol/kg. It is depending on the pH of
the solution from 15 minutes or more. Solvent sublation
process the kinetic curves show that the maximum extraction
of terbium ions occurs at pH = 7,1 for 20 minutes.
Over time, the concentration of Tb (III) asymptotically
approaches some finite value that is characteristic of the
parish system in the stationary state [3].
The kinetic dependences presented in Figure 2, can be
described by reaction equations of the first order, which
corresponds to the theory of Posner and Alexander [17].
The rate constants were calculated by the equation:
0,0008
0
pH
140
Figure 2: The kinetic dependence of the concentration of the
terbium ions on time solvent sublation process at different
values of the pH.
k
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1

ln
C 0  C eq
C  C eq
,
(3)
International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 9 (2016) pp 6350-6354
© Research India Publications. http://www.ripublication.com
where  -time of the process of solvent sublation, C0, and
Сeq-initial, current and stationary (equilibrium) concentration
of Tb (III) in the aqueous phase.
The first order of the process of SS-process shows the flow in
the stationary diffusion regime in which the limiting stage is
the diffusion of extracted particles in the Shtern layer at the
surface of gas bubbles. Adsorption of extracted particles on
the boundary solution-air adsorption is described by the stern
model, in which adsorption of ions occurs on a certain area of
the bubble surface in a monomolecular layer [3].
When examining Figure 2 it is note that depending on the pH
observed 4 types of kinetic curves:
1. When pH = 5.2 in SS the process of extraction of
holmium ions passes into a stationary regime with
high equilibrium concentrations. The maximum
extraction rate is 44,8 %.
2. At pH = 6,2 equilibrium concentration decreases, and
the degree of extraction increases, there is a tendency
to increase the speed of the process.
3. At pH 9,5 the rate of extraction of terbium ions
decreases not dramatically.
Over time, the concentration of Tb(III) approaches some finite
value that is characteristic of the parish system in a stationary
state. It is established that the pH value of the extract
determined above pH cation complexation [7]. On this basis,
it can be assumed that the terbium, in the process of solvent
sublation step the efuent is oated in the form of the primary
dodecyl
sulfate
from
dilute
aqueous
solutionsTb(OH)(C12H25OSO3)2.
The first order of the process of SS-process shows the flow in
the stationary diffusion regime in which the limiting stage is
the diffusion of extracted particles in the Shtern layer at the
surface of gas bubbles. Adsorption of extracted particles on
the boundary solution-air adsorption is described by the stern
model, in which adsorption of ions occurs on a certain area of
the bubble surface in a monomolecular layer [17].
At pH = 5,2 in solvent sublation the process of extraction of
holmium ions passes into a stationary regime with high
equilibrium concentrations. The maximum extraction rate is
44,8 %.
The explanation of the observed regularities is possible on the
basis of the consideration of forms of diffusing particles at
different pH values.
4. At pH=7,1-7,6 the equilibrium concentration is equal
0,20·10-4 mol /kg. Tb(III) is in the aqueous phase in
the form of TbOH(С12Н25ОЅО3)2.
At pH = 6,2 equilibrium concentration decreases, and the
degree of extraction increases, there is a tendency to increase
the speed of the process.
In the area of pH = 7,1-7,6 terbium monohydroxo-ion, as the
precipitate of hydroxide
is
formed. Sublat
is
TbOH(С12Н25ОЅО3)2.
In the area of pH = 7,1-7,6 terbium monohydroxo-ion, as the
precipitate of hydroxide
is
formed. Sublat
is
TbOH(С12Н25ОЅО3)2.
Gradients in the concentration of dodecyl sulfate anions and
monohydroxo-ions Tb (III) in the Stern layer increases with
increasing pH, both increase the degree of dissociation of the
acid and the extent of complexation. The result is a growth
rate constant. Therefore, the limiting stage of the process is
the diffusion of particles Tb(OH)2+.
At pH = 9,5 is terbium in the aqueous phase in the form of
complexes with dodecyl sulphate-ion and hydroxides. The
limiting stage of the process of extracting terbiium is
organocomplexes diffusion and adsorption of particles of
terbium hydroxide on the gas bubbles, which flows slowly,
and therefore, the rate constant of the process decreases
[18,19].
Experimental results on the extraction of terbium (III) method
of solvent sublation confirm that the extraction of Tb+3 is in
the form of basic salts of terbium dodecyl sulfate. Maximum
recovery occurs in the pH of formation of hydroxides, but
during the experiment, precipitation was not observed, which
can be explained by the formation in the aqueous phase of
stable complexes with hydroxo-cations with dodecyl sulphateion.
The rate of extraction of terbium ions decreases not
dramatically.
The explanation of the observed regularities is possible on the
basis of the consideration of forms of diffusing particles at
different pH values at pH 9,5.
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Conclusion
From experimental data it is seen that the maximum extraction
of Tb(III) occurs in the range pH 7,1 to 8,2 and the optimal
time of the process is 30 minutes.
[7]
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Biographical sketch
1. Lobacheva Olga: [email protected]
Date of birth-06.08.1959, Leningrad
School N 281-chemical, year of graduation 1976
Student-1976-1981-Leningrad State University,
The Сhemical Department.
Postgraduate student, engineer, researcher 1982-1988Leningrad state University, Chemical Department.
Ph. D. in Chemistry-1989
Associate Professor, Dr.-2003 to present time-National
Mineral Researches University “Mining University”, General
and physical chemistry Department
2. Berlinskii Igor: [email protected]
Date of birth-16.11.74
School № 4, Sosnovy Bor city of the Leningrad region
1999-2004-Student of Leningrad State University, Chemical
Department.
Engineer, 2004-2005-Institute of Macromolecular compounds
of the Russian Academy of Science
2005-2011-1-st category engineer, National Mineral
Researches University “Mining University”, Department of
General and Physical
PhD in Chemistry-2011
Assistant-2011-2013
Associated Professor-2013-present time-National Mineral
Researches University “Mining University”, General and
physical chemistry Department
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