Chin. J. Chem. Eng., 15(6) 916—918 (2007)
RESEARCH NOTES
Effect of Magnetic Field on the Extraction Process of Acetone-WaterTrichloroethane System*
SUN Yongli(孙永利), LIU Yong(刘勇), WU Songhai(吴松海) and JIA Shaoyi(贾绍义)**
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
Abstract In order to investigate the effect of magnetic field on the liquid-liquid extraction, the extraction in the
acetone-water-trichloroethane system was studied under magnetic field with different magnetic induction intensity.
The results showed that the effect of magnetic field was positive in the extraction process, and the partition coefficient and the yield of acetone increased with the increasing magnetic induction intensity by 5.16%—8.35% and
1.85%—5.70% respectively. The effect of magnetic field on the extraction was intensified when the temperature
became higher. The experimental data of the partition coefficient of acetone were correlated by the method of least
square in terms of a power-law correlation.
Keywords magnetic field, magnetic induction intensity, liquid-liquid extraction, acetone-water-trichloroethane
1
INTRODUCTION
Separation is an important process in the chemical industry. At present, more efforts in mass transfer
research are focused on improving separation efficiency, saving the energy and reducing the operation
cost. Magnetic separation is a new technology, which
can intensify the chemical separation process by applying magnetic field, such as distillation, crystallization, adsorption and leaching processes. The results
show that magnetization can change some physical
properties of materials such as viscidity, surface tension, saturated vapor pressure and so on[1—4]. It also
changes the phase equilibrium composition of
solid-liquid, liquid-liquid and gas-liquid[5—10] so as
to intensify separation processes[11—12].
Liquid-liquid extraction has been widely used as
an important unit operation in chemical engineering.
However, the effect of magnetic field on liquid-liquid
extraction is not reported. In order to investigate the
effects of magnetic field on the liquid-liquid extraction, the acetone-water-trichloroethane system was
studied under the various magnetic induction intensity.
The relation between the partition coefficient and the
yield of acetone and the magnetic induction intensity
was obtained. Also the experimental data were correlated with the least square method.
2 EXPERIMENTAL
2.1 Materials
The separation of acetone from water is a typical
industrial extraction process with trichloroethane as
extractant. In present study, the used materials were
listed as follows:
Water: deionized water.
Acetone: purity ≥ 99.7% (mass fraction), trichloroethane: purity ≥99.5%, both were purchased
from Tianjin 3rd Chemical Reagent Plant.
2.2
Magnetic field
Nd-Fe-B permanent magnet in the experiment
was made by Institute of Physics, Chinese Academy
of Sciences. The permanent magnet as outlined in
Fig.1 is a hollow cylinder. The parameters of magnetic
field are listed in Table 1.
Figure 1
Table 1
Magnetic
field
The sketch of magnet
Parameters of magnetic field
Magnetic induc- I.D. of magnet Height of
tion intensity E, T
x, m
magnet, m
1#
0.165
0.082
0.120
2
#
0.310
0.080
0.120
3#
0.515
0.080
0.120
2.3
Experimental device and flow chart
A schematic diagram of the liquid-liquid extraction in this work was shown in Fig.2. The main devices are as follows:
(1) Extractor: diameter 55mm and capacity of
250ml, made of stainless steel, with churn-dasher and
jacket to keep the desired temperature.
The impeller of churn-dasher is simple radial-flow
－
impeller with 32mm diameter at 160r·min 1 speed.
(2) Super thermostat: Model CS501, precision of
±0.5℃.
Received 2006-11-28, accepted 2007-06-26.
* Supported by the Program on Technological Development Plan of Tianjin (No.033180611).
** To whom correspondence should be addressed. E-mail: [email protected]
Effect of Magnetic Field on the Extraction Process of Acetone-Water-Trichloroethane System
917
3.2 Discussion
3.2.1 Effect of magnetic field on partition coefficient
At given temperature, the partition coefficient was
the ratio of concentrations of solute in extract phase and
raffinate phase at the equilibrium, defined as
y
kA = A
(1)
xA
which can be obtained from the data shown in Table 2.
The relation of partition coefficient kA and magnetic
induction intensity E was shown in Fig.3.
Figure 2 Experimental flow scheme of
liquid-liquid extraction
1—magnetic field; 2—extractor; 3—super thermostat;
4—churn-dasher
2.4
Experimental procedure
Firstly, 20g of solvent water (B) and 20g of solute acetone (A) were added into the extractor, and
then 18g of extractant trichloroethane (S) was added.
Stirring of the extractor was switched on for 40min to
reach the equilibrium. Then, the stirring was stopped
to allow settlement for 30min for phase separation.
The samples of the upper extract phase and the lower
raffinate phase were analyzed to obtain the concentration of extract phase yA and that of raffinate phase xA.
To ensure the reliability of the data, experiment was
done in duplicate.
2.5
Analytic method
Gas chromatogram was employed to analyze the
example.
Model: SP-420, made by BAIF Chromatograph
Instrument Center, Beijing.
Chromatogram column: HP-Innowax polyethylene glycol.
Chromatogram condition:
Temperature of detector
160℃
Temperature of gasification
150℃
Injection volume
0.2μl
－
H2 flux
30ml·min 1
－
Air flux
200ml·min 1
3 RESULTS AND DISCUSSION
3.1 Experimental results
The extraction in the acetone-water-trichloroethane
system was studied with magnets with different magnetic induction intensity, thereinto 0# (vacant experiment) stands for zero magnetic induction intensity.
The experiment temperature are 15℃, 30℃, 45℃
and 60℃ and the data of yA and xA are listed in Table 2.
Table 2
Magnetic field
Figure 3 Relationship between the magnetic induction
intensity E and the partition coefficient of acetone kA
temperature, ℃: ○ 15; △ 30; ● 45; ▲ 60
As shown in Fig.3, the partition coefficient kA
increased with increase of magnetic induction intensity E, showing a positive effect on the extraction
separation. The increase of the partition coefficient of
acetone ranges between 5.16%—8.35%.
The partition coefficient kA was correlated with
the following formula:
kA = AEα
(E≠0)
(2)
by the method of least square and the results are listed
in Table 3.
Table 3
Constants in the correlative expression
Temperature
t, ℃
Coefficient A
Power α
Correlative
coefficient R
15
30
45
60
1.2224
1.0828
1.0014
0.9246
0.01819
0.01493
0.01686
0.01774
0.9810
0.9802
0.9996
0.9985
3.2.2 Effect of magnetic field on yield
The yield of solute (A) was defined as
Effect of magnetic field on the compositions of extract phase and the raffinate phase
15℃
30℃
60℃
45℃
yA
xA
yA
xA
yA
xA
yA
xA
0#
0.4158
0.2662
0.4109
0.2728
0.4096
0.2819
0.4062
0.2937
1#
0.4237
0.2573
0.4205
0.2631
0.4192
0.2706
0.4183
0.2828
2#
0.4261
0.2548
0.4220
0.2608
0.4208
0.2687
0.4202
0.2807
#
0.4279
0.2545
0.4231
0.2604
0.4223
0.2674
0.4219
0.2796
3
Note: yA is composition of extract phase (mass fraction). xA is composition of raffinate phase (mass fraction).
Chin. J. Ch. E. 15(6) 916 (2007)
Chin. J. Ch. E. (Vol. 15, No. 6)
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φA =
mE yA
mF xF
(3)
The mass of extract phase mE was obtained
through mass balance. The overall mass balance:
mF + mS = mE + mR
(4)
and solute (A) mass balance:
mF xF = mE yA + mR xA
(5)
mF xF − ( mF + mS ) xA
yA − xA
yA
α
φA
Combining Eqs.(3), (4) and (5) leads to
mE =
mE
mF
mR
mS
R
xA
xF
(6)
The relation between φA and E are shown in
Fig.4.
REFERENCES
1
2
3
4
5
Figure 4
Relationship between the magnetic induction
intensity E and the yield of acetone φA
temperature, °C: ○ 15; △ 30; ● 45; ▲ 60
As shown in Fig.4, the yield of acetone φA increased generally with the increase of magnetic induction intensity E. The increase of the yield of acetone
ranges between 1.85%—5.70%.
3.2.3 Effect of temperature
From the experimental data in Figs.3 and 4, it
could be seen that with increase of the temperature,
both the partition coefficient kA and the yield φA of
the acetone decreased. Due to increase of the temperature, the solubility of acetone in water increased
and the area of separated phase reduced in the triangular phase diagram of the acetone-water-trichloroethane
system, which has some negative effect on the extraction.
NOMENCLATURE
A
E
kA
coefficient in Eq.(2)
magnetic induction intensity, T
partition coefficient
December, 2007
mass of extract phase, kg
mass of admixture were added into the extractor, kg
mass of raffinate phase, kg
mass of extractant, kg
correlative coefficient
composition of raffinate phase (mass fraction)
composition of admixture were added into the extractor,
(mass fraction)
composition of extract phase (mass fraction)
power in Eq.(2)
yield of solute, %
6
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