Research Article, Issue 1
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
------------------------
Amir Vahid
a,*
and Masoud Sohrab
b
a,*
Research Institute of Petroleum Industry (RIPI), West Entrance Blvd., Olympic Village, Tehran, 14857-33111, Iran
application for a specific task. These additives
are almost hazardous materials for environment.
The insulating (transformer) oil degradation under
working condition of high voltage transformers
occurs mainly due to oxidation and thermal
decomposition at high temperatures after long
period of using [4]. These oxidation products
of used insulating oil contain carboxylic acids,
ketones and alcohols, which then condense to from
polymeric materials [5]. The oxidation of products
caused to metal corrosion, viscosity increase, sludge
and varnish formation [6]. The acidity of used oil
is depended to oxidation of products [7]. Sodium
Combination of reduction with metallic sodium and
insulating oil via experimental design
1. Introduction
Used oils are the important contaminates of
ecosystems which leads to water and soil pollution
[1]. In other hands, the used oil is to provide a
source of valuable base oil [2]. The oil has duties
such as lubricating moving parts of engine, reducing
friction, cooling agent, act as an anti-corrosion,
protecting, against wear, act as an cleaning agent,
conducting force and removing contaminates [3].
Some additives added to the oil to enhance its
*Corresponding Author. Amir Vahid
E-mail: avahid753@gmail.com
DOI: https://doi.org/10.24200/amecj
A R T I C L E I N F O:
Received 21 Dec 2019
Revised form 19 Feb 2020
Accepted 10 Mar 2020
Available online 29 Mar 2020
Keywords:
Used oil,
Color reduction,
Total Acid Number,
Re-refining,
Mesoporous material,
Optimization.
A B S T R A C T
In this study, re-refining of used insulating oil by mesoporous silicate
material (MCM-41) and metallic sodium was investigated. Also, the
effect of silicate absorbents which was synthesized and functionalized
with aluminum (Al-MCM-41) was studied (18 wt% and 36 wt%). The
physical and structural properties of Al-MCM-41 were characterized by
FT-IR, BET, XRD, FESEM and the obtained results illustrated a successful
synthesis of the mesoporous material. The refined oil was treated by MCM-
41 adsorbent. After that, total acid number (TAN) of used insulating oil
was effectively reduced by metallic sodium. The effect of some parameters
such as contact time, temperature and the dosage (sodium and adsorbent
to oil ratio) was designed and optimized by response surface method
(RSM). The results showed that the acid number incredibly decreased
at 150, 60 min and 2% of sodium to oil. The color of the re-refined oil
was significantly reduced. The factors such as, time, temperature and
dosage was statistically studied by ANOVA. The adsorption of MCM-41
was also studied by this way. Based on proposed procedure, the modeling
was carried out. Treating of oil with MCM-41 after using metallic sodium
causes lower color of oil.
Ready Re-refining of used oils by metallic sodium and Al-MCM-41 Amir Vahid, et al
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
28
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
is a reactive metal which is easily oxidized. It has
a powerful affinity for certain oxidative organic
species. The rate of reaction depends on the metal-
oil interface. The rate of reaction between the solid
metal and the oxidation of oil products depends on
the extent of this interface. Sodium dispersions as
resemble emulsions having a high metal surface
area. The dispersion is used at a temperature which
is above that of the melting point of the sodium
(98°C). In this way a reasonable reaction rate can be
achieved [8]. The reaction of sodium with oxidation
products such as acid carbocyclic caused to obtain
the solid and hydrogen as below equation 1. The
reaction between sodium with ketones caused to
reduce ketones and obtained tertiary alcohol. Also,
the reaction of sodium with alcohols produced the
solid and hydrogen (Eq. 2).
2CH
3
3
COONa+H
2
(Eq. 1)
2CH
3
3
ONa+H
2
(Eq. 2)
Recycling of used oil is very important as less
energy and cost compared to refining of crude oil.
Recycling of used oil helps to air, soil and water
pollutions in the environment. Many sorbent were
used for recycling of used oil as oxidation and
refining of oil products. The various treatments
were used for improving used oil by acid-clay
process, solvent extraction, vacuum distillation and
hydrogenation methods. These are high technology
which combines a few generic methods in its
process. Due to the hard recycling of used oil, the
single method cannot be generated a standard
emission controlled process. So, for specific
processes of recycling waste oils, sophisticated
equipment was used. KTI and STP methods
combine the vacuum distillation and hydrofinishing
together. By the STP method, dehydration, vacuum
distillation, separation of the lubricating fraction
and hydrofinishing were used [9-17]. In this paper,
the MCM-41 was used for collecting product. By
heating oil, the oxidation products and absorption
of new oxidation products had created. For
determination of constituent’s acid number oil,
the titration of alcoholic base method was used
[18]. For determination of discoloration (reduce
oxidation products) and new oxidation products,
the spectrophotometer with wavelength of 419 nm
and 312 nm was used.
2. Experimental
2.1. Reagent and Materials
The cetyltrimethyl ammonium bromide (CTAB),
sodium silicate (Na
2
SiO
3
), polyethylene glycol
4000(PEG4000), ethanol, aluminum nitrate, acetic
acid, sodium hydroxide (NaOH), TAN , 2-propanol,
toluene, p-naphtholbenzein, potassium hydroxide,
and deionized water (DW) was purchased from
Merck, Germany and used for all synthesis and
TAN method.
2.2. Synthesis of MCM-41
For synthesis of MCM-41, 180 g of DW and 3.7
g of CTAB mixed at room temperature and then
11.1 g of ethanol was added to suspension until
receive colorless position and then, 11.1g sodium
silicate as silicate source, 0.6g PEG4000 was used.
The acid acetic 0.1 molar was used for fixing
PH near 9.5. The mixture was stirrer at room
temperature for 48h and then, put it awayfor1h.
The precipitate product was filtered and washed by
mixture of ethanol / DW (1:5 ratio) and dry at room
temperature for 24h. Finally, the solid cavities put
in electric furnace for 6h at high temperature up to
550°C (calcination process) [19].
2.3. Synthesis of Al-MCM-41
The synthesis of Al-MCM-41 method is similar to
the synthesis of MCM-41method. For the synthesis
of Al-MCM-41 method, the aluminum nitrate
(Aluminum source) was added to suspension and
then sodium silicate. For fixing PH, the NaOH
(0.1molar) was used for reducing acidic PH [20].
2.4. Characterization Method
The X-ray diffraction (XRD) patterns recorded on
seritef XRD 300 PTS. The X-ray diffractometer
29
adsorption-desorption isotherms for mesoporous
(BET) recorded on BELSORP-miniII. Fourier
transform infrared spectroscopy (FT-IR) recorded
to 4000-400cm
-1
area on a Thermo Nicolet Nexus
870. Scanning electron micros copy (SEM) images
obtained on Tescan Mira3Xmu.
2.5. Total Acid Number (TAN)
For determining of acid, 2 g of sample added to
20-30 mL of solvent and then the sample dissolved
completely in solvent (solvent: 100 mL toluene, 99
mL isopropanol and 1mL DW) and the resulting
single-phases solution was titrated at room
temperature with standard alcoholic base (solution
Hydroxide potassium 0.1 molar). Finally, the end
point indicated to changing color by adding 0.5
mL of p-naphtholbenzien solution (orange to green/
green-brown)[18].
2.6. Rening used oil by MCM-41 and silicate -
Aluminums
The absorbent and acid (0.15) diluted with Heptane
(1:9, 1 mL Oil + 9 mL Heptane) was added to used
insulating oils and the refining was determined at
419 nm area. First, 20 mL of used insulating oils
was poured in container 1 with amount of 0.2
g MCM-41, container 2 with amount of 0.2 AL-
MCM-41 (18wt%) and container 3 with amount of
0.2 g of Al-MCM-41 (36wt%). In order to favorite
contact between adsorbent and used insulating oils,
the mixture was shacked for 15 min and then the
sorbent separated t from used insulating oils by
centrifuging process.
2.7. The experiment of sodium with used oil
The refining of used oil based on acid number
0.15 which was diluted with Heptane 1:9 (1:9,
1 mL Oil + 9 mL Heptane) and absorbent 2.436,
was determined at 419 nm area.. 20 mL of used oil
was poured in two containers. The amount of 0.2 g
sodium metallic poured in container 1 and shacked
based on magnet stirrer for interaction with used
oil at room temperature (1 hour). In container 2,
we increased temperature up to 100°C and then 0.2
g of sodium metallic was added to used insulating
oils in present of magnet stirrer for 1h.
2.8. The experiment of sodium with used oil and
rening by absorbents
The effect of sodium with used oil and refining
by absorbents MCM-41, Al-MCM-41 were
investigated before and after use of sodium metallic.
The used oil contains acid number 0.26 that diluted
with Heptane 1:9 (1mL Oil + 9 mL Heptane) that
contain absorbent 2.794, 419 nm area. In first steps,
each absorbent was used based on refining method
at room temperature and then used sodium metallic
added at 100°C. In second steps, we used sodium
metallic at 100°C and next used absorbent at room
temperature.
2.9. Optimized effective factors on acid number
reduction
In this research, the effective parameters and
their interaction (acid reduction and oil color
reduction) were studied and optimized by RSM
method. Finally, a model in which could explain
influence effective parameters on reactions and
interaction between them. Three parameters predict
on influence factors on acid number reduction
and color oil reduction were obtained by sodium
metallic dosage, sodium metallic contact time and
temperature. So, this design based on BBD method
was used for experimental which could obtained
more information about influence parameters of
measurement. According to Design-Expert v7
software 17, the experimental was designed for
metallic sodium and refining absorbent MCM-
41 (Table 1). The experimental design of used
insulating oils contained 0.09 acid numbers based
on heptane diluted 1:9 ratios (1cc oil + 9cc heptane)
and absorbent 4.818 in 3.12 nm to area.
3. Results and Discussions
3.1. FT-IR Spectrums
The spectrums of FT-IR were shown in figures of
1, 2 and 3. The Waveland of 816 cm
-1
and 1050
cm
-1
related to Si-O-Si bonds vibration in MCM-
41 structure. The bands in 1050 cm
-1
related to
stretching vibration asymmetric Si-O-Si and related
30
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
to stretching vibration symmetric
Si-O-Si and 465cm
-1
is related to angular vibration
Si-O-Si. The bands of 3421cm
-1
and 1690 cm
-1
related to vibration of sinanol hydroxide group
that is the reason of adsorbent water molecules
which was shown in figure 2, 3. Based on figures,
the amount of metal and polarity structure was
increased [21, 22].
3.2. XRD analysis
According to XRD pattern especially diffraction
of XRD d
100
confirm mesoporous structure and hexagonal lattice
[23]. Well resolver sharp peaks at higher order
diffractions imply that long range order present in
this sample (Fig. 4).
Table 1. The design of experiment parameters
Dosege%Tamperature(°C)Contact time(min)experiments
2100601
21001802
2150603
21501804
6100605
61001806
6150607
61501808
4125399
412520110
49112011
415912012
1.2912512013
6.7112512014
412512015
412512016
412512017
Fig. 1. The FT-IR of MCM-41
*Corresponding author: avahid753@gmail.com
4
125
120
15
4
125
120
16
4
125
120
17
3. Results and Discussions
3.1. FT-IR Spectrums
The spectrums of FT-IR were shown in figures of 1, 2 and 3. The Waveland of 816 cm
-1
and 1050 cm
-1
related to Si-O-Si bonds vibration in MCM-41 structure. The bands in 1050 cm
-1
related to stretching
vibration asymmetric Si-O-Si and related to stretching vibration symmetric
Si-O-Si and 465cm
-1
is related to angular vibration Si-O-Si. The bands of 3421cm
-1
and 1690 cm
-1
related
to vibration of sinanol hydroxide group that is the reason of adsorbent water molecules which was shown
in figure 2, 3. Based on figures, the amount of metal and polarity structure was increased [21, 22].
Fig.1. The FT-IR of MCM-41 Fig. 2. The FT-IR of 18%wtAl-MCM-41
31
3.3. BET analysis
Nitrogen adsorption-desorption of MCM-41 and
36%wt Al-MCM-41 showed that the mesoporous
MCM-41 had pore diameter more 3 nm and specific
surface area about 919.65 m
2
g
-1
.
Mesoporous
functionlized with aluminium 36%wt(Al-
MCM-41) have been pore diameter of aout 2.6
nm and specific surface area about 526.92 m
2
g
-1
.
Decrease of surface area is due to the grafting of
alluminom species
3.4. FESEM analysis
Figure 5 amd 6 showed the images of FESEM for
MCM-41 and structure morphology with worm-
Fig. 2. The FT-IR of 18%wtAl-MCM-41
Fig. 3. The FT-IR of 36% wt Al-MCM-4
*Corresponding author: avahid753@gmail.com
4
125
120
15
4
125
120
16
4
125
120
17
3. Results and Discussions
3.1. FT-IR Spectrums
The spectrums of FT-IR were shown in figures of 1, 2 and 3. The Waveland of 816 cm
-1
and 1050 cm
-1
related to Si-O-Si bonds vibration in MCM-41 structure. The bands in 1050 cm
-1
related to stretching
vibration asymmetric Si-O-Si and related to stretching vibration symmetric
Si-O-Si and 465cm
-1
is related to angular vibration Si-O-Si. The bands of 3421cm
-1
and 1690 cm
-1
related
to vibration of sinanol hydroxide group that is the reason of adsorbent water molecules which was shown
in figure 2, 3. Based on figures, the amount of metal and polarity structure was increased [21, 22].
Fig.1. The FT-IR of MCM-41 Fig. 2. The FT-IR of 18%wtAl-MCM-41
*Corresponding author: avahid753@gmail.com
4
125
120
15
4
125
120
16
4
125
120
17
3. Results and Discussions
3.1. FT-IR Spectrums
The spectrums of FT-IR were shown in figures of 1, 2 and 3. The Waveland of 816 cm
-1
and 1050 cm
-1
related to Si-O-Si bonds vibration in MCM-41 structure. The bands in 1050 cm
-1
related to stretching
vibration asymmetric Si-O-Si and related to stretching vibration symmetric
Si-O-Si and 465cm
-1
is related to angular vibration Si-O-Si. The bands of 3421cm
-1
and 1690 cm
-1
related
to vibration of sinanol hydroxide group that is the reason of adsorbent water molecules which was shown
in figure 2, 3. Based on figures, the amount of metal and polarity structure was increased [21, 22].
Fig.1. The FT-IR of MCM-41 Fig. 2. The FT-IR of 18%wtAl-MCM-41
32
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
like intera-particle structure. The FESEM with
magnification 200000 and 100000 for MCM-41
was shown in Figure 5 and 6, respectively.
3.5. Analyzed rening used oil with MCM-41
absorbent
As comparing to BET analysis of Al-MCM-
41(36wt%), the effective surface area was more than
MCM-41. In Al-MCM-41, the reaction between
aluminum metal and oxidation products occurred
and therefore the acid number amount more than
used oil color decreased. The Al-MCM-41(18
wt%) has less aluminum metal as compared to Al-
MCM-41(36 wt%), therefore as low aluminum
amount, the less reaction between aluminum
and oxidation products occurred. In other words,
according to aluminum amount reduction, the
effective surface will increased and therefore the
amount of acid number reduce (Table 2).
As lacking metal according to BET analysis,
the MCM-41 has more effective surface than two
other absorbent and adsorbent oxidation products
*Corresponding author: avahid753@gmail.com
Figure 5, 6 showed the images of FESEM for MCM-41 and structure morphology with worm-like intera-
particle structure. The FESEM with magnification 200000 and 100000 for MCM-41 was shown in Figure
5 and 6, respectively.
Fig. 5. The FESEM of MCM-41(200000) Fig. 6. The FESEM of MCM-41(100000)
3.5. Analyzed refining used oil with MCM-41 absorbent
As comparing to BET analysis of Al-MCM-41(36wt%), the effective surface area was more than MCM-
41. In Al-MCM-41, the reaction between aluminum metal and oxidation products occurred and therefore
the acid number amount more than used oil color decreased. The Al-MCM-41(18 wt%) has less
aluminum metal as compared to Al-MCM-41(36 wt%), therefore as low aluminum amount, the less
reaction between aluminum and oxidation products occurred. In other words, according to aluminum
amount reduction, the effective surface will increased and therefore the amount of acid number reduce
(Table 2).
As lacking metal according to BET analysis, the MCM-41 has more effective surface than two other
absorbent and adsorbent oxidation products therefore acid number less reduce toward two other absorbent
and so oil color reduce more.
Table 2. .Results of refining analysis for used oil with MCM-41 and silicate rich Al
Type of absorbent
Absorbance(419nm)
Acid number
MCM-41
1.950
0.085
18wt%MCM-41
2.174
0.084
36wt%MCM-41
2.659
0.071
3.6. Metallic sodium reaction
The reduction power of metallic sodium with oxidation products at 100°C was appreciably higher than
that of 25°C. The melting point of metallic sodium is 98°C and therefore contact surface area with oil
*Corresponding author: avahid753@gmail.com
Figure 5, 6 showed the images of FESEM for MCM-41 and structure morphology with worm-like intera-
particle structure. The FESEM with magnification 200000 and 100000 for MCM-41 was shown in Figure
5 and 6, respectively.
Fig. 5. The FESEM of MCM-41(200000) Fig. 6. The FESEM of MCM-41(100000)
3.5. Analyzed refining used oil with MCM-41 absorbent
As comparing to BET analysis of Al-MCM-41(36wt%), the effective surface area was more than MCM-
41. In Al-MCM-41, the reaction between aluminum metal and oxidation products occurred and therefore
the acid number amount more than used oil color decreased. The Al-MCM-41(18 wt%) has less
aluminum metal as compared to Al-MCM-41(36 wt%), therefore as low aluminum amount, the less
reaction between aluminum and oxidation products occurred. In other words, according to aluminum
amount reduction, the effective surface will increased and therefore the amount of acid number reduce
(Table 2).
As lacking metal according to BET analysis, the MCM-41 has more effective surface than two other
absorbent and adsorbent oxidation products therefore acid number less reduce toward two other absorbent
and so oil color reduce more.
Table 2. .Results of refining analysis for used oil with MCM-41 and silicate rich Al
Type of absorbent
Absorbance(419nm)
Acid number
MCM-41
1.950
0.085
18wt%MCM-41
2.174
0.084
36wt%MCM-41
2.659
0.071
3.6. Metallic sodium reaction
The reduction power of metallic sodium with oxidation products at 100°C was appreciably higher than
that of 25°C. The melting point of metallic sodium is 98°C and therefore contact surface area with oil
*Corresponding author: avahid753@gmail.com
Fig.3. The FT-IR of 36% wt Al-MCM-4
3.2. XRD analysis
According to XRD pattern especially diffraction of XRD d
100
spacing in low angele 2θ region, the
confirm mesoporous structure and hexagonal lattice [23]. Well resolver sharp peaks at higher order
diffractions imply that long range order present in this sample.
Fig. 4. The low angle of XRD patterns for MCM-41
3.3. BET analysis
Nitrogen adsorption-desorption of MCM-41 and 36%wt Al-MCM-41 showed that the mesoporous
MCM-41 had pore diameter more 3 nm and specific surface area about 919.65 m
2
g
-1
.
Mesoporous
functionlized with aluminium 36%wt(Al-MCM-41) have been pore diameter of aout 2.6 nm and specific
surface area about 526.92 m
2
g
-1
. Decrease of surface area is due to the grafting of alluminom species
3.4. FESEM analysis
Fig. 4. The low angle of XRD patterns for MCM-41
Fig. 5. The FESEM of MCM-41(200000) Fig. 6. The FESEM of MCM-41(100000)
33
therefore acid number less reduce toward two other
absorbent and so oil color reduce more.
3.6. Metallic sodium reaction
The reduction power of metallic sodium with
oxidation products at 100°C was appreciably higher
than that of 25°C. The melting point of metallic
sodium is 98°C and therefore contact surface area
with oil increase at 100°C and renewed continuously
and amount of metallic sodium reaction with
oxidation products increased. One of oxidation
products was derivatives of carboxylic acids and
carbonyl groups which reduced at this temperature.
The sodium and TAN decreased by increasing
sodium reaction time and temperature. The reaction
between metallic sodium and oxidation products
was increased and this products caused to increase
the color of oil in this temperature (Table 3).
3.7. Analysis of metallic sodium and rening with
MCM-41 and Al- MCM-41
The adsorbent addition and reduction based on
metallic sodium is very important for re-refining
process. Table 4 showed, the results of experiments
at equal level of factors. The difference was
depended to the order of treatment with adsorbent
and reducing agent. The results showed, the first
treating based on adsorbent in better quality of final
re-refined insulating oil in terms of color. But the
TAN process had a slightly higher.
3.8. Optimized of effective factors acid number
reduction
According to DOE and temperature, dosage and
contact time, different results were obtained and
showed in Table 5. The ANOVA of he obtained
results is shown in Table 6. Prob>F is a good
measure of importance of each term in the first
order model. Interaction terms are also importance
although the BC has the lowest effect on the
response of model.
The model can be mentioned in the following
equation (Eq. 3) in terms of real factors. Adsorption
of byproducts by mesoporous materials is
investigated by DOE which was shown in Table 7.
Acidity calculating (A)
(Eq. 3)
+ (0.000263706
+
-5
-8
-
The quadratic equation (Eq. 4) has obtained after to
Table 2. .Results of refining analysis for used oil with MCM-41 and silicate rich Al
Type of absorbent Absorbance(419nm) Acid number
MCM-41 1.950 0.085
18wt%MCM-41 2.174 0.084
36wt%MCM-41 2.659 0.071
Table 3. Results of treatment of used insulating oil y metallic sodium.
Treatment temperature Absorbance(419nm) Acid number
metallic sodium 25°C 2.575 0.11
metallic sodium 100°C 2.890 0.03
Table 4. Analysis of metallic sodium and refining with absorbent MCM-41 and Al- MCM-
Type of absorbent Absorbance(419nm) Acid number (TAN)
Metallic sodium+MCM-41 2.404 0.045
Metallic sodium+18 wt% Al-MCM-41 2.678 0.05
Metallic sodium+36 wt% Al-MCM-41 3.094 0.05
MCM-41+ Metallic sodium 2.300 0.056
18 wt% Al-MCM-41+ Metallic sodium 2.267 0.055
36 wt% Al-MCM-41+ Metallic sodium 2.480 0.056
34
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
Table 5. Experimental design data for metallic sodium and MCM-41
Dosege (%)Tamperatur e(°C)contact time (min)Absorbance (312nm)Acid numberexperiments
200100604.5970.0091
2001001804.6550.0192
200150604.6750.0143
2001501804.4000.0114
600100604.6470.0165
6001001804.6590.0236
600150604.7230.0197
6001501804.5620.0148
400125394.7430.0149
4001252014.7600.01410
400911204.6790.01811
4001591204.7350.01912
1291251204.61400.1513
6711251204.4770.01414
4001251204.6590.01415
4001251204.6670.01416
4001251204.6250.01417
Table 6. Results of metallic sodium
P-Value Prob>FF-ValueMean squaredfSum of squaresSource
<0.000122.502.7560.000165model
0.02786.610.000000810.0000008A-Time
0.001418.920.000002310.0000023B-Temp
0.000427.270.000003310.0000033C-Dosage
<0.000174.640.000091110.0000911AB
0.04905.010.000006110.0000061AC
0.14072.550.000003110.0000031BC
--0.00000012100.0000012Residual
--0.0000001580.0000012Lack of fit
--020Pure Error
---160.00017Cor Total
Table 7. Results of adsorption of MCM-41.
P-Value Prob>FF-ValueMean squaredfSum of squaressource
<0.000130.80.018990.170model
0.003518.590.011410.0114A-Time
0.80030.0690.000004210.0000042B-Temp
0.02158.680.005310.0053C-Dosage
<0.000174.80.04510.045AB
0.04765.740.003510.0035AC
0.008113.340.008110.0081BC
0.013310.830.006610.0066A
2
0.012811.020.006710.0067B
2
<0.0001134.70.08210.082C
2
--0.0006170.0042Residual
0.481.320.006650.0033Lack of fit
--0.0004920.00099Pure Error
---160.174Cor Total
35
predict reduction of color of oil by MCM-41
Adsorption of predict reduction of color of oil by
MCM-41(Ads) (Eq. 4)
× Time)-
(0.009280222 × Temprature) + (0.001318102
-6
-6
-6
2
)
-5
2
-6
2
)
3.9. The effect of contact time
The graph of effect of time on acidity at dosage
(400) and temperature (125°C) is linear with
increasing of time, new oxidation products in oil
was produced more and therefore, the acid number
increased (Fig. 7).
3.10. The effect of temperature
The graph of temperature on acidity is linear which
was shown in Figure 8. By increasing of temperature
amount of acid number reduced and at 150°C the
lowest acid number obtained. By increasing of
temperature, the metallic sodium change to liquid an
also viscosity of oil significantly reduced, because
of its low viscosity index. As a result, the surface
was expanded when the temperature, diffusion of
oil and the surface of sodium particles increased.
Therefore, the amount of metallic sodium with
oxidation products as carboxylic acid has more
reaction and caused to reduce TAN.
3.11. The effective of metallic sodium dosage
Figure 9 showed that the graph of dosage on acidity
at temperature 125°C and contact time 120 min.
*Corresponding author: avahid753@gmail.com
<0.0001
134.7
0.082
1
0.082
C
2
_
_
0.00061
7
0.0042
Residual
0.48
1.32
0.0066
5
0.0033
Lack of fit
_
_
0.00049
2
0.00099
Pure Error
_
_
_
16
0.174
Cor Total
The quadratic equation (Eq. 4) has obtained after to predict reduction of color of oil by MCM-41
Adsorption of predict reduction of color of oil by MCM-41(Ads) (Eq.4)
Ads =4.801224864+( 0.002992049 * Time)-( 0.009280222 * Temprature)+( 0.001318102* Dosage)-(
0.0000505 * Time * Temprature)+( 1.75*10
-6
*Time* Dosage)+( 6.4*10
-6
*Temprature* Dosage)+(
8.74636*10
-6
* Time^2)+( 5.0816*10
-5
* Temprature^2)-( 2.77655*10
-6
* Dosage^2)
3.9. The effect of contact time
The graph of effect of time on acidity at dosage (400) and temperature (125°C) is linear with increasing
of time, new oxidation products in oil was produced more and therefore, the acid number increased (Fig.
7).
Fig.7. The effect of metallic sodium contact time on TAN.
3.10. The effect of temperature
The graph of temperature on acidity is linear which was shown in Figure 8. By increasing of temperature
amount of acid number reduced and at 150°C the lowest acid number obtained. By increasing of
temperature, the metallic sodium change to liquid an also viscosity of oil significantly reduced, because of
its low viscosity index. As a result, the surface was expanded when the temperature, diffusion of oil and
the surface of sodium particles increased. Therefore, the amount of metallic sodium with oxidation
products as carboxylic acid has more reaction and caused to reduce TAN.
Fig. 7. The effect of metallic sodium contact time on TAN.
Fig. 8. The effect of metallic sodium reaction temperature on TAN
*Corresponding author: avahid753@gmail.com
Fig. 8.
The effect of metallic sodium reaction temperature on TAN
3.11. The effective of metallic sodium dosage
Figure 9 showed that the graph of dosage on acidity at temperature 125°C and contact time 120 min. The
linear graph is clear. By increasing of metallic sodium, the higher amount of acid number in dosage 600%
was observed. Therefore, by increasing of metallic sodium, the more reaction between sodium and
oxidation products as in carboxylic acid was happened.
Fig. 9. The effect of metallic sodium dosage factor (sodium to oil ratio) on TAN
3.12. The effect of contact time on color of oil by MCM-41
Based on Figure 10, the graph of time factor on oil color at temperature (125°C) and contact dosage (400)
was constant. At 120 min, the color reduction was observed and after higher time, the color slightly
increasing.
36
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
*Corresponding author: avahid753@gmail.com
Fig. 8.
The effect of metallic sodium reaction temperature on TAN
3.11. The effective of metallic sodium dosage
Figure 9 showed that the graph of dosage on acidity at temperature 125°C and contact time 120 min. The
linear graph is clear. By increasing of metallic sodium, the higher amount of acid number in dosage 600%
was observed. Therefore, by increasing of metallic sodium, the more reaction between sodium and
oxidation products as in carboxylic acid was happened.
Fig. 9. The effect of metallic sodium dosage factor (sodium to oil ratio) on TAN
3.12. The effect of contact time on color of oil by MCM-41
Based on Figure 10, the graph of time factor on oil color at temperature (125°C) and contact dosage (400)
was constant. At 120 min, the color reduction was observed and after higher time, the color slightly
increasing.
*Corresponding author: avahid753@gmail.com
Fig. 10. The effect of contact time on oil color by MCM-41
3.13. The effect of reaction temperature on oil color
As can be seen in the curvature in Figure 11 until temperature 125°C, discoloration was occurred. After
125°C, the color was increased with slow slop.
Fig. 11 .The effect of reaction temperature on oil color by MCM-41
3.14. The effect of dosage on oil color by MCM-41
Figure 12 showed, the graph of dosage factor (metallic sodium ratio to oil ) on color of oil in time (125
min) and temperature (125°C) was linear. Based on the curvature, the color increased up to 400 dosages
and after it the color decreases.
The linear graph is clear. By increasing of metallic
sodium, the higher amount of acid number in dosage
600% was observed. Therefore, by increasing of
metallic sodium, the more reaction between sodium
and oxidation products as in carboxylic acid was
happened.
3.12. The effect of contact time on color of oil by
MCM-41
Based on Figure 10, the graph of time factor on oil
color at temperature (125°C) and contact dosage
(400) was constant. At 120 min, the color reduction
was observed and after higher time, the color
slightly increasing.
3.13. The effect of reaction temperature on oil
color
As can be seen in the curvature in Figure 11 until
temperature 125°C, discoloration was occurred.
After 125°C, the color was increased with slow
slop.
3.14. The effect of dosage on oil color by MCM-41
Figure 12 showed, the graph of dosage factor
(metallic sodium ratio to oil ) on color of oil in time
(125 min) and temperature (125°C) was linear.
Based on the curvature, the color increased up to
400 dosages and after it the color decreases.
The Figures 13, 14 and 15 displayed the interaction
Fig. 9. The effect of metallic sodium dosage factor (sodium to oil ratio) on TAN
Fig. 10. The effect of contact time on oil color by MCM-41
37
*Corresponding author: avahid753@gmail.com
Fig. 10. The effect of contact time on oil color by MCM-41
3.13. The effect of reaction temperature on oil color
As can be seen in the curvature in Figure 11 until temperature 125°C, discoloration was occurred. After
125°C, the color was increased with slow slop.
Fig. 11 .The effect of reaction temperature on oil color by MCM-41
3.14. The effect of dosage on oil color by MCM-41
Figure 12 showed, the graph of dosage factor (metallic sodium ratio to oil ) on color of oil in time (125
min) and temperature (125°C) was linear. Based on the curvature, the color increased up to 400 dosages
and after it the color decreases.
Fig. 11 .The effect of reaction temperature on oil color by MCM-41
Fig. 12. The effect of dosage on oil color by MCM-41
*Corresponding author: avahid753@gmail.com
Fig. 12. The effect of dosage on oil color by MCM-41
The Figures 13, 14 and 15 displayed the interaction of AB, AC and BC. The curvature of the model was
due to these terms. All main factors had interaction with each other.
Fig. 13. The effect of interaction factors sodium metallic contact time and reaction temperature it on oil
color by MCM-41
Fig. 13. The effect of interaction factors sodium metallic contact time and reaction temperature it on oil color by
MCM-41
*Corresponding author: avahid753@gmail.com
Fig. 12. The effect of dosage on oil color by MCM-41
The Figures 13, 14 and 15 displayed the interaction of AB, AC and BC. The curvature of the model was
due to these terms. All main factors had interaction with each other.
Fig. 13. The effect of interaction factors sodium metallic contact time and reaction temperature it on oil
color by MCM-41
38
Anal. Method Environ. Chem. J. 3 (1) (2020) 27-40
*Corresponding author: avahid753@gmail.com
Fig. 14. The effect of interaction factors sodium metallic contact time and dosage(sodium to oil
ratio) on color oil by MCM-41
Fig. 15. The effect of interaction factors sodium metallic reaction temperature and dosage (sodium to oil
ratio) on oil color by MCM-41
4. Conclusions
In this research, we studied re-refining of used insulating oil by metallic sodium and mesoporous silicate
containing aluminum. This method combines to adsorption and reduction of oxide species. The effective
factors including time, temperature and dosage of sodium was statistically studied by ANOVA. The
adsorption of mesoporous silica was also studied by this way. Based on proposed procedure, the modeling
was carried out. Treating of oil with mesoporous silicate after using metallic sodium causes lower color of
*Corresponding author: avahid753@gmail.com
Fig. 14. The effect of interaction factors sodium metallic contact time and dosage(sodium to oil
ratio) on color oil by MCM-41
Fig. 15. The effect of interaction factors sodium metallic reaction temperature and dosage (sodium to oil
ratio) on oil color by MCM-41
4. Conclusions
In this research, we studied re-refining of used insulating oil by metallic sodium and mesoporous silicate
containing aluminum. This method combines to adsorption and reduction of oxide species. The effective
factors including time, temperature and dosage of sodium was statistically studied by ANOVA. The
adsorption of mesoporous silica was also studied by this way. Based on proposed procedure, the modeling
was carried out. Treating of oil with mesoporous silicate after using metallic sodium causes lower color of
of AB, AC and BC. The curvature of the model was
due to these terms. All main factors had interaction
with each other.
4. Conclusions
In this research, we studied re-refining of used
insulating oil by metallic sodium and mesoporous
silicate containing aluminum. This method
combines to adsorption and reduction of oxide
species. The effective factors including time,
temperature and dosage of sodium was statistically
studied by ANOVA. The adsorption of mesoporous
silica was also studied by this way. Based on
proposed procedure, the modeling was carried out.
Fig. 14. The effect of interaction factors sodium metallic contact time and dosage(sodium to oil ratio) on color oil by
MCM-41
Fig. 15. The effect of interaction factors sodium metallic reaction temperature and dosage (sodium to oil ratio) on oil
color by MCM-41
39
Treating of oil with mesoporous silicate after using
metallic sodium causes lower color of oil. Treating
of oil by adsorption using MCM-41 followed
by reduction with metallic sodium is somehow
better in final quality of oil. This method is very
effective for re-refining of isolation oil which is
very important in the industry. Higher temperature
results in better quality of product because of
higher activity of sodium and oxidant species and
also better diffusion of these species to the surface
of active sites of sodium and mesoporous silica.
Aluminosilica is more polar than silica because of
its higher aluminum. But due to the higher acidic
nature of the surface of aluminosilica, it is weaker
adsorbent for the removal of acidic species from
the oil.
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