The American Journal of Applied Sciences
81
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TYPE
Original Research
PAGE NO.
81-86
10.37547/tajas/Volume07Issue05-08
OPEN ACCESS
SUBMITED
28 March 2025
ACCEPTED
19 April 2025
PUBLISHED
30 May 2025
VOLUME
Vol.07 Issue05 2025
CITATION
Abdullaeva Feruza Bayjon qizi, Salikhanova Dilnoza Saidakbarovna, &
Abdurakhimov Ahror Anvarovich. (2025). Regeneration Of Perlite After
Winterization Of Sunflower Oil. The American Journal of Applied Sciences,
7(05), 81
–
86. https://doi.org/10.37547/tajas/Volume07Issue05-08
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Regeneration Of Perlite
After Winterization Of
Sunflower Oil
Abdullaeva Feruza Bayjon qizi
PhD Student, Urgench State University, Uzbekistan
Salikhanova Dilnoza Saidakbarovna
Doctor of Technical Sciences, Professor, Institute of General and Inorganic
chemistry, Academy of Sciences of the Republic of Uzbekistan
Abdurakhimov Ahror Anvarovich
Doctor of Technical Sciences, Professor Tashkent Institute of Chemical
Technology, Uzbekistan
Abstract:
This article studies methods of regeneration
and their impact on the filtering capabilities of perlite. It
was found that increasing alkali concentration up to
40% at various ratios enhances the purification of
vegetable oil; however, with further regeneration, the
effectiveness decreases. Increasing acid concentration
raises the amount of distilled water required, leading to
higher costs and inefficient water usage. Regenerated
perlite after winterization filters saturated fatty acids
because, at lower temperatures, waxy substances and
saturated fatty acids begin to crystallize and precipitate
with the filtering agent. As a result, the content of
unsaturated fatty acids increases in the system.
Keywords:
Perlite, refining, vegetable oil, winterization,
vermiculite, calcination, expansion, adsorbents, waxy
substances, acid value, peroxide value.
Introduction:
One of the modern trends in the
development of the oil and fat industry worldwide is the
production of competitive functional food products
with enhanced biological value that are safe for
consumption. Therefore, developing and improving
methods for growing and processing vegetable oils to
produce high-quality oil and fat products is a key
objective [1-3].
In Uzbekistan, new equipment and technologies are
being actively introduced for producing light vegetable
oils from sunflower, soybean, and safflower, which
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The American Journal of Applied Sciences
differ in composition and properties from cottonseed
oil. For example, light oils contain waxy substances
(sterols, waxes, etc.) that are relatively rare in
cottonseed oil. In contrast, cottonseed oil contains a
significant amount of gossypol and its derivatives, as
well as various phospholipids [4].
Waxy and high-melting substances are removed from
refined or deodorized oil using winterization to obtain
salad oil, i.e., a more purified product ready for sale as
winterized commercial oil [5,6].
The appearance of vegetable oil is also a key quality
criterion. However, in recent years, due to a shortage
of oil-bearing crops, the industry has struggled to
produce clear oils because imported filtering materials
are expensive. Known waxy substances, with melting
points from 32 to 98 °C, form a fine and stable
suspension of crystals in the oil upon cooling
—
often
referred to as a “network.” This greatly deteriorates
the oil's appearance and quality [7]. None of the oil
refining stages (hydration, alkali neutralization,
bleaching, deodorization) significantly remove waxy
substances.
Waxy substances in oil (0.02% to 0.3%) not only affect
product quality but also complicate processing and
storage. They create problems during polishing
filtration and can negatively impact hydrogenation
catalysts [8].
The experimental part
There are several methods for removing waxes from
vegetable oils. One known method uses freezing, where
oil is cooled with added special filter powders that serve
as crystallization centers. After cooling, the sediment is
filtered out. A drawback of this method is that the
auxiliary filtering powders (e.g., zeolites, filter perlite)
contain pores and capillaries that get filled with wax and
neutral oil, leading to high oil losses and increased filter
consumption. These powders are single-use, and the
wax adsorbed on them is not reclaimed [8].
Another method involves adding a crystallization
initiator to the oil and separating the resulting crystals
using wax substances extracted from vegetable oils. In
this case, the used filtering powder from oil freezing acts
as the wax source. However, this also introduces
oxidation products (peroxides, anisidines, dienes,
trienes) into the oil from the used filtering powders,
degrading oil quality.
In Uzbekistan, filtering materials used in production
accumulate as waste after use, creating environmental
issues. Therefore, this study explores regeneration
methods.
Regeneration Method
Regeneration
was
performed
using
various
concentrations of alkalis (NaOH, KOH) as follows:
samples of used perlite were mixed with alkali at various
ratios and concentrations, stirred continuously at 40
–
45
°C for 30 minutes, then neutralized with distilled water
to pH 7. The neutralized material was dried and ground.
The results of the research are presented in Table 1.
Table 1.
Effect of Perlite Treatment with Alkali (KOH) on the Degree of Wax Removal
Alkali
Concentration (%)
Alkali-to-Perlite
Ratio
Degree of Vegetable Oil Purification After Regeneration,
%
1
2
3
10
1:0.5
73.5
68.7
62.4
1:1
78.4
75.1
72.4
1:1.5
85.0
81.4
77.2
1:2
89.1
84.4
77.9
20
1:0.5
75.6
72.7
68.4
1:1
82.6
79.6
74.5
1:1.5
88.4
85.2
80.1
1:2
91.2
88.6
81.4
30
1:0.5
76.9
72.8
70.6
1:1
79.7
76.8
73.8
1:1.5
87.8
84.3
81.3
1:2
93.4
90.7
87.8
40
1:0.5
77.2
68.7
62.4
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1:1
81.6
78.4
76.2
1:1.5
89.4
84.6
81.6
1:2
95.7
92.3
89.4
As seen from Table 1, increasing the alkali
concentration up to 40% at various ratios enhances the
degree of vegetable oil purification; however, with
further regeneration, the purification efficiency
decreases. An increase in acid concentration leads to
greater use of distilled water, which in turn raises
production costs and results in inefficient water
usage
—
an especially pressing issue in the Republic,
where water scarcity is a significant concern.
Based on the above table, it can be concluded that a
20% alkali solution with a 1:2 alkali-to-perlite ratio is
sufficient for regeneration, achieving a purification
efficiency of 91.2% on the first use.
After the regeneration of perlite, winterization of
various light vegetable oils was carried out, and their
organoleptic and physicochemical properties were
studied. The data are presented in Table 2.
As seen from Table 2, all indicators after winterization
meet the requirements of GOST standards; however,
these results correspond to the first stage after
regeneration. As shown in Table 1, regenerated perlite
begins to lose its effectiveness after the second or third
stage, which is why other regeneration methods will be
explored further.
Table 2
Fatty acid composition (FAC) before and after freezing with regenerated pearlite
Indicators
Vegetable oils
Refined sunflower oil Freeze-dried
Refined soybean oil
Pre-freezing
Post-wetting
Pre-freezing
Post-wetting
Acid number,
mg КОН/g
0,4
0,36
1,6
0,09
Peroxide
number, ½
mmol О/kg
4,6
3,4
5,4
4,6
Transparency
Muddy
transparent
Light clouding
transparent
Smell and taste
Specific odor and
taste
Typical according
to GOST for this
type
Specific odor and
taste
Typical according
to GOST for this
type
Further, the fatty acid composition of vegetable oils
(sunflower oil, soybean oil) freeze-dried with
regenerated perlite was studied.
Table 3.
Fatty acid composition (FAC) before and after freezing with regenerated pearlite
Name of
sunflower oil
fatty acids
Initial LCS
of sunflower
оіl, %
LCS after freezing of
refined sunflower oil with
regenerated pearlite, %
Initial
soybean oil
GLC, %
LCS after freezing of
refined soybean
oil with
regenerated pearlite,
%
Stearic acid
(С
18
Н
36
О
2
)
4,1
2,9
2,5
1,8
Palmitic acid
(С
16
Н
32
О
2
)
6,4
3,4
9,3
6,6
Myristic acid
(С
14
Н
28
О
2
)
0,07
-
0,2
-
Arachinic acid
(С
20
Н
44
О
2
)
0,25
-
0,17
2,4
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Oleic acid
(С
18
Н
34
О
2
)
19,1
22,5
21,5
27,2
Linoleic acid
(С
18
Н
32
О
2
)
67,09
71,2
52,9
61,4
Other housing
estates
2,99
100,0
13,43
99,4
As can be seen from Table 3. regenerated perlite after
freezing filters saturated fatty acids, because at
temperature decrease with waxy substances, also
saturated fatty acids begin to crystallize and to feed
with a filtering agent in a precipitate. This increases the
unsaturated fatty acids in the system.
For comparison of the initial and regenerated pearlite a
comparative analysis was carried out, the data of which
are summarized in Fig. 1.
Figure 1. Effect of temperature on the solubility of waxes
1 -perlite regenerated after the 2nd stage; 2-
regenerated after the 1st stage; 3- initial perlite.
It can be seen from Fig.1. that as the temperature
increases to 40 OC, the waxy substances dissolve
maximally. Solubility was determined by heating to 40
°C the oil was slowly cooled. The oil was then filtered
off the precipitate, degreased with hexane cooled to 0
oC, dried and weighed. The concentration of waxes
dissolved in the oil (solubility) was calculated using the
formula:
К
𝑐
=
М
𝑐𝑤.
− М
𝑜.
Мm
where: Kc= concentration of waxes in oil; mg/kg; Mcw.
- initial amount of waxes, mg; Mo- sediment on the
filter, mg; Mm- mass of filtered oil, kg.
As can be seen from the graph the initial perlite filters
better after freezing, compared to the regenerated
ones. However, after each regenerated perlite its
filtering capacity deteriorates. The intensity of the
crystallization process proceeds in two ways, i.e., by
supercooling, or by using initiators for inoculum
crystallization. Increasing supersaturation accelerates
the formation of nucleates, but it leads to a sharp
increase in the viscosity of the system, hampering the
diffusion processes of mass transfer, resulting in a
decrease in the size of crystals, which hinders the
deposition process. Therefore, it is rational to use an
initiator for the formation of crystallization centers,
which is pearlite.
Further, the influence of time on qualitative indicators
of frozen oils with regenerated perlite was studied. The
data of which are shown in Fig. 2.
Figure 2. Effect of storage time on the acid number of freeze-dried sunflower oils
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1-Source pearlite; 2-Regenerated pearlite after the 1st stage;
3-Regenerated pearlite after the 2nd stage;
Comparative data from Fig.2. shows that freezing with
initial perlite for a long time maximizes the retention
of the acid number of sunflower vegetable oil. Freezing
using regenerated perlite after the 1st or 2nd stage is
close to the original sample. This confirms about the
correctness of the regeneration process with the
selected alkali. Acid number during freezing with the
original perlite, increases from 0.3 mg KOH/g to 0.36
mg KOH/g after 60 days of storage. With regenerated
pearlite samples, the acid number increases from 0.3
mg KOH/g to 0.45 mg KOH/g after 60 days, confirming
the presence of residual alkali or other impurities in the
pearlite.
Thus, regeneration with alkali will save imported filter
material, which will reduce the cost of vegetable oil. It
was found that with increasing the concentration of
alkali up to 40% at various ratios, the degree of
purification of vegetable oil increases, but it decreases
with increasing the degree of regeneration. With
increase in acid concentration leads to increase in
distilled water which leads to increase in production
cost and waste of water. It is determined that
regenerated perlite after freezing filters saturated
fatty acids, because when the temperature decreases
with waxy substances, also saturated fatty acids begin
to crystallize and feed with the filtering agent in the
precipitate. This increases the unsaturated fatty acids in
the system.
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