INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 540
UDK 544.723:661.183:634.8
INVESTIGATION OF THE ADSORPTION PROPERTIES OF ACTIVATED CARBON
DERIVED FROM FRUIT PITS
Isakov Yusuf Khoriddinovich
E-mail:
Doctor of Philosophy (PhD) in Technical Sciences,
Senior Lecturer at the Department of Chemistry,
Faculty of Natural Sciences, Uzbekistan-Finland Pedagogical Institute.
Annotation:
This study investigates the adsorption properties of activated carbon derived from
fruit pit waste, specifically walnut, apricot, and peach pits. Activation was conducted at 800–
850°C using both thermal and thermochemical methods, including steam treatment and
chemical agents such as 10% ZnCl₂ and H₂SO₄ solutions. Benzene vapor was used as the
adsorbate to evaluate the adsorption efficiency of the produced carbon adsorbents. Key
parameters such as monolayer capacity (αₘ), saturation volume (Vs), specific surface area (S),
micropore volume (W₀), and mesopore volume (Wme) were calculated using BET theory and
micropore volume filling equations.
The results revealed that thermochemical activation significantly enhances the structural and
adsorption characteristics compared to thermal activation. For instance, FC-WP-136 showed a
3.2-fold increase in pore volume under thermochemical conditions, with surface area reaching
up to 1397.11 m²/g. Adsorption isotherms were classified as Type I, indicating microporous
structures with high initial benzene uptake. The average pore radius was found to decrease with
increased microporosity.
These findings demonstrate the effectiveness of utilizing agricultural waste as a raw material
for producing high-performance, selective carbon adsorbents. The study supports the
development of cost-effective, import-substituting technologies for environmental purification
and industrial applications.
Key words:
Activated carbon, Fruit pit waste, Thermochemical activation, Benzene adsorption,
Specific surface area, Micropore structure, BET analysis.
Introduction:
Nowadays, the rapid development of industrial and agricultural sectors in our
Republic and across the globe, along with the expanding application fields of activated carbon,
has led to an increasing demand for selective adsorbents. One of the urgent challenges is the
development of efficient, import-substituting technologies based on local raw materials. In this
context, the production of low-cost activated carbon from domestic resources remains a topical
issue.
The third priority area of the Action Strategy for the Further Development of the Republic of
Uzbekistan outlines important tasks aimed at the development of high-tech industrial
processing sectors, primarily through the deep processing of local raw materials into high-
quality end products. In this regard, scientific research into the production of selective carbon-
based adsorbents from local raw materials—specifically, fruit pits—and the determination of
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 541
their adsorption properties is of great importance. There is also a pressing need to develop
energy-efficient technologies for the production of selective carbon adsorbents.
Literature review:
Several methods are used to enhance the adsorption properties of carbon-
based adsorbents. These include thermal activation, steam activation, and chemical activation
techniques. Upon activation, the specific surface area of carbon adsorbents can reach up to 1000
m²/g, significantly improving their adsorption efficiency. [1; 340-p].
In our country, scientific studies have mainly focused on the adsorption of organic compounds
onto natural mineral compounds such as bentonites [2; p. 68], and on the adsorption of both
organic and inorganic substances onto synthetic zeolites [3; p. 64, 4; p. 64, 5; p. 48, 6; p. 48].
However, the effect of thermal treatment temperatures on the adsorption capacity of carbon
adsorbents derived from fruit pits has not been thoroughly investigated. Therefore, it is essential
to conduct a fundamental study on the adsorption of organic vapor molecules onto carbon-
based adsorbents activated by thermal and steam treatment at various temperatures.
Methodology:
Studying the effect of different thermal treatment temperatures on the
adsorption capacity of carbon-based adsorbents, including those derived from fruit pits, is of
great importance in adsorption processes. For this purpose, carbon adsorbents were prepared
from waste fruit pits of walnut, apricot, peach, and bitter almond trees grown in the territory of
Uzbekistan. The activation was carried out thermally at 400–500°C and using steam at 800–
850°C for 3 hours.
The adsorption of benzene vapors on the obtained carbon adsorbents was investigated.
Before being used as the adsorbate, benzene was purified and dried under vacuum conditions.
To ensure the vapor pressure matched the tabulated values for pure benzene, it was first cooled
and then heated to remove dissolved gases. After this preparation, adsorption measurements
were carried out.
Results:
As seen from the adsorption isotherms of benzene vapors (Figure 1), carbon
adsorbents derived from fruit pit waste and activated at 800–850°C using 10% aqueous ZnCl₂
solution (thermochemical activation) demonstrated varying adsorption behaviors. Benzene
adsorption was studied on the adsorbents labeled
AU-UK-74.5-800-850
,
AU-UK-136-800-850
,
and
AU-ZHU-136-800-850
. The imported
JACOBI-brand activated carbon
exhibited a
lower initial adsorption capacity compared to the two experimental adsorbents, particularly
AU-
ZHU-136 800-850
, indicating the competitive performance of locally produced carbon
materials.
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 542
Figure 1: Adsorption isotherms of benzene vapor on carbon adsorbents obtained from
fruit pit waste by thermochemical activation at 800–850°C:
(1) AU-UK-136, (2) AU-YUK-74.5, (3) AU-ZHU-136.
The specific surface areas (S) of the carbon materials obtained from fruit pit waste by
thermochemical activation at 800–850°C were found to be as follows:
AU-UK-136
– 1397.11
m²/g,
AU-YUK-74.5
– 1294.33 m²/g, and
AU-ZHU-136
– 985.09 m²/g. The saturation pore
volumes (Vs) of these samples were determined as:
AU-UK-136
– 0.2514057 cm³/g,
AU-
YUK-74.5
– 0.2059116 cm³/g, and
AU-ZHU-136
– 0.1962319 cm³/g.
The adsorption of benzene vapors on carbon adsorbents activated by steam at 800–850°C was
also investigated (Figure 2).
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 543
Figure 2: Adsorption isotherms of benzene vapor on carbon adsorbents derived from fruit
pit waste and thermally activated at 800–850°C:
(1) AU-UK, (2) AU-YUK, (3) AU-ZHU
From the adsorption isotherms obtained in the studied systems, it was found that the amount of
benzene adsorbed on carbon adsorbents thermally activated with steam at 800–850°C was
lower compared to those thermochemically activated at the same temperature range.
Specifically, benzene adsorption was lower by a factor of
1.28
for
AU-YUK-74.5
,
1.3
for
AU-
UK-136
, and
1.26
for
AU-ZHU-136
.
Such an increase in adsorption capacity observed in thermochemically activated samples
indicates that structural modifications occurred in the carbon adsorbents, even when the
activation temperatures were kept the same (800–850°C).
Furthermore, the adsorption of benzene vapors was studied for carbon adsorbents derived from
fruit pit waste and activated with 10% aqueous
H₂SO₄
vapor at 800–850°C (Figure 3).
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 544
Figure 3: Adsorption isotherms of benzene vapor on carbon adsorbents derived from fruit
pit waste and activated at 800–850°C using 10% H₂SO₄ vapor (thermochemical
activation):
(1) AU-UK, (2) AU-YUK, (3) AU-ZHU
According to the adsorption isotherms obtained in the studied systems, the amount of benzene
adsorbed on carbon adsorbents activated with 10% H₂SO₄ solution at 800–850°C was found to
be lower than that of adsorbents thermochemically activated without sulfuric acid under the
same conditions.
Specifically, the adsorption capacity decreased by a factor of
1.32
for
AU-YUK 74.5
,
1.25
for
AU-UK-136
, and
1.36
for
AU-ZHU-136
. This decrease in adsorption performance confirms
that structural differences occur in carbon adsorbents thermally and thermochemically activated
at identical temperatures (800–850°C), influencing their surface and pore characteristics.
As observed from the adsorption isotherms of the presented systems, the amount of adsorbed
benzene increased sharply from a relative pressure of
P/Ps = 0
up to approximately
P/Ps ≈ 0.4
,
after which the increase became more gradual, approaching saturation.The steep rise in the
isotherms at low relative pressures (
P/Ps ≈ 0.4
) indicates that benzene vapors are initially
adsorbed on surfaces with high adsorption potential, which is characteristic of microporous
structures.
Discussion
: In the studied systems, a steep slope in the adsorption isotherms was observed at
low relative pressures (P/Ps = 0.1–0.2), indicating significant uptake of benzene vapor at initial
stages. The adsorption isotherms of these samples with benzene vapor were found to
correspond to
Type I
in the classification of adsorption isotherms proposed by
Brunauer
. Type
I isotherms are characteristic of
microporous adsorbents
, which exhibit a sharp rise followed
by a near-vertical trend approaching the
P/Ps = 1
axis, forming an almost right angle.
The
specific surface area (S)
of the adsorbents was calculated using the
Brunauer–Emmett–
Teller (BET)
theory. In this approach, a linear relationship is obtained by plotting
P/Ps/[a(1 –
P/Ps)]
on the ordinate versus
P/Ps
on the abscissa.
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 545
The specific surface area of the adsorbents was calculated using the following formula:
S = а
m
N
0
(3.1)
S
– specific surface area (m²/g)
a
m
– amount adsorbed in a monomolecular layer (mol/kg)
N
A
– Avogadro’s number
ω
– surface area occupied by a single molecule (nm²)
Based on the adsorption isotherms of benzene vapor on the carbon adsorbents, several key
parameters were calculated, including the
monolayer adsorption capacity (α
m
)
,
saturation
volume (Vs)
(or
total adsorption capacity, αs
), and the
specific surface area (S)
.
The obtained results are summarized in
Table 1
.
Table 1.
Structural and Sorption Characteristics of Fruit Pit–Based Carbon Adsorbents Activated
by Thermal and Steam Methods According to Benzene Vapor Adsorption:
FC-WP, FC-AP, FC-WP-136, FC-WP-Ar-136, FC-WP-74.5, FC-WP-Ar-74.5, FC-WP-111,
FC-PP-78, FC-PP-98
Adsorbent
Activation
Temperature, °C
Monolayer
Capacity, aₘ,
mol/kg
Specific
Surface Area,
S·10⁻³, m²/kg
Saturation
Adsorption
Capacity,
aₛ,
mol/kg
FC-WP-136
800
о
С
1,06
255
2,64
800
о
С+
Water
Vapor
2,0
482
3,86
FC-WP-74,5
800
о
С
1,01
243
2,52
800
о
С+
Water
Vapor
1,82
438
3,8
FC-WP-111
800
о
С
0,7
169
2,1
800
о
С+
Water
Vapor
1,54
371
3,4
FC-PP-78
800
о
С
0,69
166
2,2
800
о
С+
Water
Vapor
1,48
357
3,2
FC-PP-98
800
о
С
0,74
178
2,3
800
о
С+
Water
Vapor
1,46
352
3,1
In all studied adsorbents, it was found that when the activation temperature was kept constant,
both thermochemical and steam activation methods yielded different results. Specifically,
thermochemical activation led to higher values of specific surface area (S) and saturation
capacity (α
s
) compared to steam activation.
As shown in Table 1 [7; pp. 25–32], in the case of activated carbons derived from fruit pit shells,
the specific surface area of thermochemically activated adsorbents was significantly greater
than that of steam-activated ones. Under such activation conditions, the release of volatile gases
and tars from the carbon structure facilitates the formation of additional porosity within the
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 546
adsorbent matrix.
In particular, for the sample steam-activated at 800°C (SACFPW – Steam-Activated Carbon
from Fruit Pit Waste), the structural and sorption characteristics were found to be superior
compared to other adsorbents. Compared to FPC-800 (fruit pit carbon activated
thermochemically), the specific surface area (S) increased by a factor of 1.9, and the saturation
capacity (αs) increased by 1.5 times [8; pp. 275–277].
This behavior is attributed to the chemical interaction between amorphous carbon and steam at
high temperatures (800°C), which results in the formation of additional micropores and cracks
within the carbon structure.
Based on the adsorption isotherms of benzene vapors and the Micropore Volume Filling Theory
(MVFT) equation, the micropore volume (W₀)
,
saturation adsorption volume (Vs), and
mesopore volume (Wme) of the adsorbents were calculated using the following formula:
W
me
= V
s
- W
0
S
V
r
s
del
4
10
2
=
The average pore radius was calculated using a standard formula.
It was found that thermochemical activation led to an increase in both the micropore volume
(W₀) and the adsorption volume at saturation, compared to thermal activation
alone.Furthermore, a decrease in the average pore radius was observed.
This reduction in average pore size is attributed to the fact that thermochemical activation
resulted in a greater proportion of micropores relative to mesopores, indicating a shift in the
pore structure toward finer porosity.
The corresponding results are presented in Table 2.
Table 2.
Pore Volume Characteristics of Wood-Based Chars Activated by Thermal and Steam
Methods According to Benzene Vapor Adsorption:
Adsorbent
Activation
Temperature, °C
W
0
∙10
3
W
me
∙10
3
Average Pore
Radius, rₐᵥₑ, Å
FC-WP-136
800
о
С
0,213
0,022
18,4
800
о
С+
Water
Vapor
0,295
0,048
14,2
FC-WP-74,5
800
о
С
0,204
0,020
18,4
800
о
С+
Water
Vapor
0,295
0,043
15,4
FC-WP-111
800
о
С
0,151
0,036
22,1
800
о
С+
Water
Vapor
0,269
0,034
16,3
FC-PP-78
800
о
С
0,170
0,026
23,6
800
о
С+
Water
Vapor
0,257
0,028
16,0
FC-PP-98
800
о
С
0,170
0,035
23,0
800
о
С+
Water
Vapor
0,251
0,025
15,7
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 547
For FC-WP-136, thermal activation by heating up to 800°C resulted in nearly a 2-fold increase
in pore volume, while thermochemical activation at the same temperature led to a 3.2-fold
increase [9; pp. 156–158]. The mesopore volume as a percentage of the total adsorption volume
(Vs) was 23.5% for FC-WP-136-800, 11% for FC-WP-74.5-800, 9.4% for FC-WP-111-800,
19.6% for FC-PP-78-800, and 20.5% for FC-PP-98-800 [10; pp. 277–278; 11; pp. 11367–
11371].
Conclusion:
In this study, activated carbon adsorbents were successfully synthesized from fruit
pit waste using both thermal and thermochemical activation methods at 800–850°C. The
structural and adsorption properties of the adsorbents were evaluated using benzene vapor as
the adsorbate. Thermochemical activation, especially with ZnCl₂ and H₂SO₄, significantly
improved key characteristics such as specific surface area, micropore volume, and adsorption
capacity compared to conventional steam activation.
The adsorption isotherms followed Type I behavior, confirming the formation of predominantly
microporous structures. Notably, the sample FC-WP-136 exhibited the highest specific surface
area (1397.11 m²/g) and superior benzene vapor uptake, with pore volume increasing by up to
3.2 times over non-activated samples. The results also showed a decrease in average pore radius,
indicating enhanced microporosity.
Overall, the findings demonstrate that fruit pit waste can serve as an effective, low-cost raw
material for producing high-performance carbon adsorbents. These materials show strong
potential for use in selective adsorption, environmental cleanup, and industrial gas purification
processes. The study contributes to the development of sustainable and import-substituting
technologies based on locally available biomass resources.
References:
1.
Isokov Y. et al. Effects of aviation kerosene contents on the environment and method of its
cleansing //E3S Web of Conferences. – EDP Sciences, 2021. – Т. 264. – С. 01036.
2.
XORIDDINOVICH I. Y., NORMAKHMAT Y. Determination of the Adoption
Characteristiscs of Activated Carbon on the Basis of Nut Seeds //International Journal of
Innovations in Engineering Research and Technology. – Т. 7. – №. 4. – С. 1-5.
3.
Xayrullo o'g P. U. et al. Using natural plant extracts as acid-base indicators and pKa value
calculation method //fan va ta'lim integratsiyasi (integration of science and education). –
2024. – Т. 1. – №. 3. – С. 80-85.
4.
Khoriddinovich I. Y. et al. Purification of spent methyldiethanolamine solutions with
activated carbon au-ko. – 2023.
5.
Исоков Ю. Х., Ёдгоров Н., Юсупов Ф. М. РАЗРАБОТКА И ИССЛЕДОВАНИЯ
СОРБЦИОННОГО
СПОСОБА
ОЧИСТКИ
ВОДЫ
//ИННОВАЦИОННЫЕ
ПОДХОДЫ В СОВРЕМЕННОЙ НАУКЕ. – 2019. – С. 130-133.
6.
Бобожонов Ж. Ш., Шукуров Ж. С., Тогашаров А. С. Растворимость системы
тетракарбамидохлората кальция-ацетат аммония-вода //Universum: технические
науки. – 2022. – №. 4-8 (97). – С. 30-33.
7.
Shukurov Z. S. et al. Component Solubilities in the Acetic Acid–Monoethanolamine–
Water System //Russian Journal of Inorganic Chemistry. – 2021. – Т. 66. – С. 902-908.
8.
Yusuf I. et al. DEVELOPMENT OF TERMOCHEMICAL CARBON ADSORBENTS
BASED ON FRUIT SEEDS AND APPLICATION IN SORPTION OF RARE METALS
//Universum: технические науки. – 2022. – №. 10-7 (103). – С. 4-8.
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 548
9.
Xayrullo o'g P. U. et al. The essence of the research of synthesis of natural indicators,
studying their composition and dividing them into classes //fan va ta'lim integratsiyasi
(integration of science and education). – 2024. – Т. 1. – №. 3. – С. 50-55.
10.
Nurmonova E., Berdimuratova B., Pardayev U. DAVRIY SISTEMANING III A GURUHI
ELEMENTI ALYUMINIYNING DAVRIY SISTEMADA TUTGAN O ‘RNI VA FIZIK-
KIMYOVIY XOSSALARINI TADQIQ ETISH //Modern Science and Research. – 2024. –
Т. 3. – №. 10. – С. 517-526.
11.
БОБОЖОНОВ Ж. Ш. и др. ИЗУЧЕНИЕ РАСТВОРИМОСТИ СИСТЕМЫ СН3СООН-
NH 3-H 2 O //Uzbek Chemical Journal/O'Zbekiston Kimyo Jurnali. – 2022. – №. 3.
12.
Бобожонов Ж. Ш. и др. Изучение растворимости системы Ca (ClO 3) 2–[90% C 2 H 5
OH+ 10% C 10 H 11 ClN 4]–H 2 O //Журнал неорганической химии. – 2021. – Т. 66. –
№. 7. – С. 921-924.
13.
Jiemuratova A., Pardayev U., Bobojonov J. COORDINATION INTERACTION
BETWEEN ANTHRANILIC LIGAND AND D-ELEMENT SALTS DURING CRYSTAL
FORMATION: A STRUCTURAL AND SPECTROSCOPIC APPROACH //Modern
Science and Research. – 2025. – Т. 4. – №. 5. – С. 199-201.
14.
Khusanov E. S. et al. Solubility of Components in the Acetic Acid–Triethanolamine–Water
System //Russian Journal of Inorganic Chemistry. – 2023. – Т. 68. – №. 11. – С. 1674-
1680.
