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Article

Development of Volumetric Adsorption Isotherms for Volcanic Fly Ash from Egypt for Carbon Dioxide Capture Under Elevated Pressure and Temperature

by
Sherif Fakher
*,
Abdelaziz Khlaifat
,
Ann Maria Salib
and
Ali Elsayed
Department of Petroleum and Energy Engineering, The American University in Cairo, Cairo 11835, Egypt
*
Author to whom correspondence should be addressed.
Processes 2025, 13(5), 1570; https://doi.org/10.3390/pr13051570
Submission received: 26 February 2025 / Revised: 5 April 2025 / Accepted: 16 May 2025 / Published: 19 May 2025
(This article belongs to the Special Issue Recent Advances in Hydrocarbon Production Processes from Geoenergy)
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Abstract

:
One of the most promising methods for direct carbon dioxide (CO2) capture from the atmosphere is using material-based adsorption. Fly ash, a solid waste material, has been found to have good adsorption potential for CO2. Since different fly ashes have different properties, their CO2 adsorption behaviors differ; therefore, it is important to develop separate isotherms for each fly ash to quantify its CO2 adsorption capacity. This research investigates the adsorption capacity of an extremely abundant volcanic fly ash in Egypt that is currently being researched for use in CO2 capture applications in Egypt. Adsorption was measured using the volumetric adsorption principle. Four adsorption isotherms for the volcanic fly ash were developed at different temperatures, including 23, 40, 60, and 80 °C. The adsorption capacity was found to be impacted by the temperature of the experiment, the pressure of the CO2, and the interactions occurring between the CO2 and the fly ash. As the temperature increased, the adsorption capacity increased significantly. This was primarily due to the expansion of fly ash particles at elevated temperatures, which resulted in a higher contact surface area between the fly ash and the CO2. This created more adsorption sites for the CO2, therefore increasing the CO2 adsorption potential significantly. This research can help facilitate the use of volcanic fly ash for CO2 capture applications in Egypt in the near future, hence reducing the overall CO2 emissions to the atmosphere.

1. Introduction

CO2 capture is a vital research topic to reduce greenhouse gas emissions into the atmosphere [1,2,3,4,5,6,7,8,9]. There are many methods for carbon capture; however, the majority of these methods are extremely costly, and therefore, their upscaling to real field plants is limited. CO2 adsorption to the surface of different materials is one of the most effective methods for direct carbon capture from the atmosphere [10,11,12,13,14,15,16]. The key to CO2 adsorption is the utilization of a material that has a high affinity for CO2 and also has a considerably large surface area for CO2 adsorption to occur in order to maximize CO2 capture [16,17,18,19,20,21,22,23].
Different materials have been studied for CO2 adsorption. Karimi [1] conducted a comprehensive review of CO2 separation and capture using different materials via adsorption. Karimi [1] conducted a comprehensive review of CO2 separation and capture using different materials via adsorption. Reddy [2] highlighted the significance of different physical materials on CO2 direct adsorption. The material researched had a high porosity and also a large contact surface area to allow for a high adsorption capacity. Boer [3] studies the use of zeolites as CO2 adsorbent material for carbon capture and storage. The zeolites were modified in a way that they can selectively adsorb the CO2, thus maximizing the adsorption capacity. Mehrmohammadi [4] utilized artificial intelligence through neural networks to model the CO2 adsorption capacity on different porous structures through the utilization of preliminary experimental results obtained using different materials. Giraldo [5] investigated the CO2 adsorption on carbon particles with modified surfaces leached through the utilization of nitric acid and ammonium aqueous solution. The modified surfaces had a larger overall adsorption surface area, thus improving CO2 adsorption capacity. Zeng [6] studied the ability of different porous materials conventionally used for CO2 capture to be utilized with flue gas for selective CO2 adsorption. The flue gas was composed of different gases, primarily carbon monoxide and CO2. Yu [7] performed a comprehensive review of CO2 capture using both adsorption methods and absorption methods. The research compared different methods and highlighted the advantages and limitations of each method.
Fly ash is considered a waste material that occurs as a byproduct of the combustion of other materials. Fly ash has been utilized extensively as a filler in many different industries. The main applications of fly ash are as cementing materials, either as a percentage in concrete or as a full replacement for conventional cement. Fly ash has also been researched for use in pavements instead of cement due to its high durability and significantly lower cost compared to conventional cement. Fly ash has also been researched as a CO2 capture material via adsorption [5,6,7,8,9,10,11,12]. The main limitation of fly ash in this area is the different properties of different fly ash types due to their widespread origin. Fly ash is a byproduct of the combustion of other materials. The type of material and its properties generate a fly ash with specific properties as well. Since the fly ash has different properties, their adsorption behavior differs significantly; therefore, there is a large variation in the adsorption capacity and behavior of fly ash worldwide [3].
Fly ash has a variety of properties depending on its origin. The type of biomass/coal used to generate the fly ash therefore has a strong impact on the physical and chemical properties of the ash [20,21,22,23,24,25]. Fly ash usually exists as a fine powder with colors ranging from brown to black, depending on the volume of unburnt carbon [26,27,28]. The particles are mostly spherical in shape with an amorphous nature and are, in most cases, solid, with some fly ash particles being hollow due to rapid formation, such as volcanic ash [29,30,31,32,33,34]. For coal-based fly ash, if the source of the coal is bituminous or subbituminous coal, the silicon content is usually high, reaching up to 60%, whereas lignite-based fly ash is lower, reaching a maximum of 40%. The iron content in the bituminous coal is much higher than in the other types, reaching 40%. The sulfur content in all three types is low, with the highest resulting from lignite. Volcanic fly ash has a considerable concentration of sulfur, reaching up to 10% in some cases [35,36,37,38,39]. Fly ash is classified into two broad categories including Class F and Class C. Class F has a low sodium, potassium, and calcium concentration, whereas Class C has a calcium concentration of up to 40% and a high concentration of sodium and potassium, making it more favorable in terms of usage as a binding material for cementing and other applications [7,39,40,41,42,43,44,45,46].
This research investigates the adsorption capacity of an extremely abundant volcanic fly that has been purified from heavy metal ash in Egypt, which is currently being researched for use in CO2 capture applications in Egypt. Volcanic ash has multiple advantageous properties compared to coal-based ash due to its large surface area and its hollow structure that can allow for large adsorption capacities. Four adsorption isotherms were developed at different temperatures and pressures in order to assess the performance of this fly ash under different conditions. The selected temperatures were chosen based on the different expected applications and different governorates where the volcanic fly ash will be used in Egypt.

2. Experimental Description

The experimental material, setup, and procedure followed to conduct all the experiments are mentioned and explained.

2.1. Experimental Material

The material used to conduct the experiments is as follows:
▪
Fly Ash: The fly ash used to conduct all the experiments in this research was provided as a greyish powder with a high aluminosilicate concentration. The volcanic fly ash provided was purified by the supplier to remove any traces of heavy metals and sulfur. The fly ash had 30% aluminum oxide, 10% iron oxide, 10% calcium oxide, 10% silicon oxide, and 25% sodium oxide, with the remaining concentration composed of sulfur oxide, potassium, and magnesium oxide, and loss on ignition. The surface area of the fly ash ranged between 3 and 7 m2/g;
▪
Water Bath: A water bath with distilled water was used to provide a constant temperature to the experimental setup across the experiments. The water bath had a slotted lid on it to ensure minimal water evaporation, with no pressure buildup;
▪
Precision Balance: A precision scale was used to weigh the fly ash packed into the adsorption vessel to ensure that all the experiments used the same weight of fly ash;
▪
CO2 Cylinder: The CO2 cylinder was used to provide a source of CO2 for the experiment. It was provided as a CO2 cylinder with a purity of 99.99%;
▪
Helium Cylinder: Helium was used to measure the void space volume between the fly ash particles prior to conducting the adsorption experiment;
▪
Pressure Transducers: Pressure transducers were connected to the sample cell and the reference cell to measure the pressure differential and the pressure equilibrium values for adsorption calculation.

2.2. Experimental Setup

An illustration of the experimental setup used to conduct all the experiments is shown in Figure 1. The setup is composed of a volumetric adsorption setup composed of a sample cell that houses the fly ash sample, a reference cell that houses the CO2 initially before expansion, pressure transducers to record the pressure, and a water bath to maintain constant temperature for the duration of the experiment. The transducers were calibrated based on the recommendation of the manufacturer by zeroing the transducer before conducting the experiment. This was conducted through the software. Once zeroed, the temperature reading was ensured to be similar to that of the room temperature to ensure that the transducers were functioning correctly. The CO2 is provided through a high-pressure CO2 cylinder with a pressure regulator to control the flow of CO2. The pressure transducers are connected directly to a computer to log and record the pressure values for the duration of the experiment. The logging system has an accuracy of four decimal places and can log four pressure readings every second.

2.3. Experimental Procedure

The procedure followed to conduct all the experiments in this research is as follows:
▪
The sample cell was fully packed with the volcanic fly ash sample. The weight of the fly ash sample was determined to be the same for all experiments. The sample cell was then sealed and vacuumed. The fly ash was used in the same manner in which it was provided, without the utilization of any additional alkaline activators. This was due to the high initial concentration of alkaline components in the fly ash;
▪
The experimental setup is placed in the water bath and is left for 12 h until the temperature homogenizes;
▪
The sample cell was filled with helium at the design pressure of the experiment. Following this, the void space volume was measured using helium expansion. This was used in the adsorption calculations to remove errors in the calculation due to the void space present between the fly ash particles. When the shale particles are placed in the reference cell, some small spaces will exist between the particles. This volume is referred to as the void volume and must be accounted for during each experiment, since this is considered excess volume that will be occupied by the CO2 and will not contribute to the adsorption. The void space therefore signifies the pores present between the grains and is thus similar to the total porosity of the system. The void volume is also an essential factor in the adsorption calculations, as was shown previously. The void volume is usually measured using a gas with extremely low adsorption; the gas used in this study to measure void volume is helium, which is the most widely used gas to measure adsorption. Helium has many advantages that make it extremely suitable to use when measuring the void space;
▪
Once the void space is measured, the CO2 adsorption experiment commences. The pressure transducers begin recording the pressure in both cells. Initially, the sample cell reads a negative gauge pressure due to vacuum, while the reference cell reads the reference pressure of the experiment;
▪
The valve connecting the sample cell and the reference cell is opened, and the CO2 is allowed to expand in the vacuumed sample cell. The pressure is then left to equilibrate between both cells. This can take between 8 h to 3 days, depending on the pressure and temperature conditions;
▪
Once equilibrium pressure is reached, the experiment is concluded, and the pressure is used to calculate the adsorption capacity for the design pressure. The experiment is then repeated at the same temperature for different pressure values. By measuring the CO2 adsorption at the same temperature at different pressure values, the adsorption isotherm for the fly ash can be determined for this specific temperature;
▪
Once the isotherm is developed at a specific temperature, the temperature is then changed, and the process is repeated to construct the isotherm for the elevated temperature.

3. Volumetric Adsorption

Adsorption is classified as physical adsorption (physisorption) and chemical adsorption (chemisorption). Physical adsorption is a low energy adsorption that occurs in multiple layers. It does not require high energy for the adsorbate to adhere to the adsorbent and does not require high pressure to desorb the adsorbate. It is a relatively high capacity adsorption due to its ability to form layers of adsorbate on the surface of the adsorbent. CO2 adsorption to volcanic fly ash exhibited physical adsorption based on the analysis of the adsorption behavior during experimentation [7,42,43,44,45,46,47,48].
Chemical adsorption is a high energy single layer adsorption. The bond between the adsorbate and the adsorbent form under high energy is considered a much stronger bond compared to physical adsorption. This bond requires high energy to dissociate and is therefore also more stable than physical adsorption bonds. Chemical adsorption does not exhibit the stacking effect found in physical adsorption and therefore cannot accommodate a large adsorption capacity compared to physical adsorption [28,49,50,51,52]. The conditions in which the experiments were conducted in this research were not suitable for chemical adsorption to occur; therefore, all the adsorption isotherms developed in this study followed physical adsorption.
There are many methods by which adsorption can be measured experimentally. The two most common methods for adsorption measurement are gravimetric adsorption and volumetric adsorption. Gravimetric adsorption relies on mass change to determine the volume of adsorption. It requires the utilization of an extremely high precision scale to be able to detect the very low weight adsorption value of the gas, especially in small experimental setups. As the volume of adsorption increases, the ability of gravimetric adsorption measurement to produce more reliable readings increases. Volumetric adsorption measurement relies on measurement of volume change due to adsorption. This method requires prior knowledge of the void space volume in order to be able to differentiate between the fluid present in the void spaces and the fluid that is actually adsorbed to the surface. Volumetric adsorption relies on knowledge of the properties of the fluid used, especially if the fluid is compressible, such as gases. Not accounting for the compressibility of gases would produce highly erroneous adsorption results. The compressibility of gases is usually accounted for using a gas super compressibility factor, determined experimentally or using correlation. The Dranchuk–Abou–Kassem correlation was used in this research to determine the value of super compressibility factors for the CO2. Based on this, the volume of adsorbed CO2 was calculated using the following equation:
n a d s = P Δ V z R T p u m p − P a f − V v o i d z a f R T
where n a d s is the number of moles of adsorbed CO2, P a f is the pressure of the experiment after CO2 expansion from the reference cell to the sample cell, V v o i d is the void space volume measured using helium, and z is the CO2 super compressibility factor determined using Dranchuk–Abou–Kassem correlation.
This research utilizes the concept of volumetric adsorption to measure the adsorption capacity of the CO2 onto the surface of the volcanic fly ash sample [28,48,49,50,51,52]. During CO2 adsorption, multiple adsorption/desorption hysteresis cycles are conducted on the same material. Based on the initial composition of the fly ash, this can result in a change in the properties of the fly ash, especially with constant repetition of the cycles. This research conducted only single adsorption desorption cycles, which is a limitation for the actual utilization of the fly ash in real tests. Future experiments will be conducted to assess the stabilized adsorption potential through cyclic stability testing [28,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68].

4. Results and Analysis

CO2 adsorption isotherms for the volcanic fly ash were developed at different temperatures including 23, 40, 60, and 80 C. All adsorption isotherms can be used for CO2 adsorption capacity prediction through extension of the experimental results for the isotherms. All isotherms were developed using pure CO2 with no additional gases. The research did not take into consideration gas selectivity, which is an important parameter for real life adsorption applications.

4.1. Adsorption Isotherm

An adsorption isotherm is a plot that can be used to determine the adsorption behavior for a specific material at different pressures. It can also be used to determine the maximum adsorption capacity for a material at a specific temperature regardless of the increase in pressure. At different temperatures, different adsorption isotherms are developed.
The isotherm presents a relationship between the number of moles of gas adsorbed per unit mass of the adsorbent on the y-axis, the volcanic fly ash in this research, and the pressure used to measure the adsorption value on the x-axis. The pressure on the x-axis is usually represented as a pressure ratio, as is used in this research. This is a ratio between the pressure used in the experiment, denoted P, and the saturation pressure of the CO2 at the specified temperature condition, denoted Po. The saturation pressure is a standard value that is determined experimentally and varies with temperature. Once experimental pressure reaches the saturation pressure of the CO2, the maximum adsorption capacity is reached. Exceeding the saturation pressure will result in not significant increase in the adsorption capacity, as long as the fly ash properties remain unchanged and the CO2 phase remains unchanged.

4.2. Adsorption Isotherm: 23 °C

The initial CO2 adsorption isotherm was developed at a temperature close to the average room temperature in Egypt, 23 °C. The saturation pressure of the CO2 at 23 °C was determined mathematically to be 903.6 psi. Based on this, adsorption was measured at different pressures and then divided by the saturation pressure to develop the isotherm. The CO2 adsorption isotherm using the volcanic fly ash sample at 23 °C is presented in Figure 2. Initially, the adsorption behavior is linear until a pressure ratio value of 0.44. Beyond this, the adsorption capacity seems to normalize at a value of 0.875 mmol/g. Based on these results, initially, as the pressure increased, more CO2 could adsorb to the fly ash sample. Once the maximum adsorption capacity at 23 °C was reached, increasing the pressure had no impact on CO2 adsorption; therefore, the adsorption isotherm plot normalized at the maximum adsorption value for the volcanic fly ash at this temperature.

4.3. Adsorption Isotherm: 40 °C

The second adsorption isotherm developed in this research was at 40 °C, shown in Figure 3. This temperature resembles the average high temperature in different governorates in Egypt. The saturation pressure of CO2 at this temperature was determined to be 1391.3 psi. Increasing the temperature resulted in an increase in the CO2 adsorption capacity of the fly ash. This was due to the expansion of the fly ash particles in the sample cell, which resulted in an increase in the overall surface area available for adsorption. This was verified when the void space volume, the volume not used for adsorption, was measured to be lower than that of the 23 °C experiment. The adsorption trend for pressure at 40 °C exhibited a more linear behavior compared to that of 23 °C, mainly due to the higher adsorption capacity. The maximum value for CO2 adsorption reached was more than 3 mmol per g of fly ash. The line begins to deviate from its linear behavior at elevated temperatures, indicating that the maximum adsorption capacity at this temperature is close to being reached. Since the same injection pressures were used across all experiments and due to the variation in CO2 saturation pressure with temperature, the pressure ratio on the x-axis reached a lower maximum value for every increase in temperature.

4.4. Adsorption Isotherm: 60 °C

When the temperature of the experiment increased to 60 °C, the CO2 saturation pressure was determined to be 2245.2 psi. Based on this, the adsorption isotherm for the 60 °C experiment was developed as shown in Figure 4. The adsorption capacity increased further with the increase in temperature, which supports the findings in the 40 °C adsorption isotherm. The void space was also found to decrease with the increase in temperature. The maximum adsorption capacity exceeded 5 mmol/g for the highest-pressure value used in the experiment. It is important to note that the behavior is linear with no obvious deviation in the line due to the much higher adsorption capacity still possible. This can be determined by generating a trendline for the adsorption isotherm following the same trend behavior as the 23 °C experiment. Using this, the maximum adsorption capacity at 60 °C can be estimated.

4.5. Adsorption Isotherm: 80 °C

The highest temperature isotherm generated in this research was at 80 °C. This temperature was selected since many exhaust flue gases are generated from factories and different facilities at temperatures near this value. The CO2 adsorption isotherm for the fly ash is presented in Figure 5. At 80 °C, the highest adsorption capacity for the fly ash was reached: more than 9 mmol/g. The CO2 saturation temperature was calculated to be 3523.5 psi. The linear behavior of the line indicates a much higher predicable adsorption capacity at higher pressure values. Since the 80 °C experiment was used to model flue gas being produced from exhausts, lower pressure values are more realistic, since the average pressures of flue gas from exhausts is 150 psi. Overall, the volcanic fly ash exhibits a good potential to be used as a CO2 capture material due to its high adsorption potential, especially at elevated temperatures.

5. Discussion

In order to show the difference between mass-based adsorption behavior (gravimetric adsorption) and volume-based adsorption behavior (volumetric), the adsorption isotherms were converted from moles to cubic centimeters (mL) and grams of CO2 per gram of fly ash. For all the results, the mass behavior follows the same behavior as the molar mass, while the volume behavior follows an opposite trend.
Figure 6 shows the mass and volume of CO2 adsorbed per unit mass of fly ash for the 23 °C and 40 °C experiments. As the temperature increases, the total mass of CO2 absorbed also increases. This was also observed in the adsorption isotherms, in mmol instead of grams. Increasing the pressure resulted in a decrease in the volume of CO2 per gram of fly ash due to the compression of the CO2 molecules at elevated pressures. Although the volume decreased, the overall mass increased with the increase in pressure, thus indicating an overall increase in the adsorption capacity at elevated pressure conditions. The conversion between the mass and volume was performed by using the density of CO2 at each pressure and temperature condition.
Figure 7 shows the mass and volume of CO2 adsorbed per unit mass of fly ash for the 60 °C and 80 °C experiments. Increasing the temperature increased the volume of CO2 adsorbed per unit mass of fly ash, as is evident from the comparison between the adsorption values in Figure 6 and Figure 7. With the increase in pressure, the volume of CO2 decreased due to the compression of the CO2 molecules. The rate of decrease in volume of the CO2 in the elevated temperature experiments is higher than the lower temperature experiments. This is mainly due to the larger volume of CO2 available, and the higher CO2 saturation pressure at the higher temperature experiments compared to the low temperature experiments. Although the volume decreased with pressure, the overall mass increased, which is an indication that the total amount of CO2 adsorbed increased.
Compared to other types of fly ash, the volcanic fly ash used in this research had a relatively higher adsorption capacity. This is primarily due to the conditions in which the volcanic fly ash was formed, which resulted in higher adsorption sites and hence a larger adsorption capacity. The adsorption values for coal-based fly ash, biomass (plant)-based fly ash, and the volcanic fly ash used in this research are presented in Table 1.

6. Conclusions

This research develops CO2 adsorption isotherms for a volcanic fly ash that is currently being researched for use as a CO2 capture agent in Egypt. Isotherms were developed at 23, 40, 60, and 80 °C. Based on these isotherms, the CO2 adsorption capacity under different conditions can be predicted. The main findings obtained from this research are as follows:
▪
The volcanic fly ash used in this research has a good potential for CO2 storage applications based on its ability to adsorb a large volume of CO2 on its surface;
▪
Increasing the temperature of the fly ash resulted in expansion of the particles, which in turn increased the available surface area for adsorption, thus increasing CO2 capture;
▪
Increasing the pressure of the injected CO2 resulted in an increase in the adsorption capacity. This trend was observed until the maximum available adsorption sites were occupied by CO2;
▪
Increasing pressure allows for the compression of a larger volume of CO2 in the available adsorption sites. This was observed by comparing the change in volume and mass of CO2 with pressure at each temperature.

Author Contributions

Conceptualization: S.F. and A.K.; Methodology: S.F., A.K. and A.E.; Software: S.F. and A.M.S.; Validation: S.F., A.K., A.E. and A.M.S.; Formal Analysis: S.F.; Writing—Original Draft: S.F. and A.K.; Supervision: S.F. and A.K.; Project Administration: S.F.; Funding Acquisition: S.F. and A.K. All authors have read and agreed to the published version of the manuscript.

Funding

Funding for this research was provided by The American University in Cairo through the Faculty Support Grant.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Acknowledgments

The authors would like to thank The American University in Cairo for funding this research project through their Faculty Support Grant.

Conflicts of Interest

The authors declare no conflicts of interest.

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Processes 13 01570 g001
Figure 1. Volumetric adsorption experimental setup.
Figure 1. Volumetric adsorption experimental setup.
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Figure 2. CO2/volcanic fly ash adsorption isotherm at 23 °C.
Figure 2. CO2/volcanic fly ash adsorption isotherm at 23 °C.
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Figure 3. CO2/volcanic fly ash adsorption isotherm at 40 °C.
Figure 3. CO2/volcanic fly ash adsorption isotherm at 40 °C.
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Figure 4. CO2/volcanic fly ash adsorption isotherm at 60 °C.
Figure 4. CO2/volcanic fly ash adsorption isotherm at 60 °C.
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Figure 5. CO2/volcanic fly ash adsorption isotherm at 80 °C.
Figure 5. CO2/volcanic fly ash adsorption isotherm at 80 °C.
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Figure 6. CO2 adsorption volume and mass per gram of fly ash at (a) 23 °C and (b) 40 °C.
Figure 6. CO2 adsorption volume and mass per gram of fly ash at (a) 23 °C and (b) 40 °C.
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Figure 7. CO2 adsorption volume and mass per gram of fly ash at (a) 60 °C and (b) 80 °C.
Figure 7. CO2 adsorption volume and mass per gram of fly ash at (a) 60 °C and (b) 80 °C.
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Table 1. Adsorption volume of different types of fly ash.
Table 1. Adsorption volume of different types of fly ash.
Fly Ash TypeMaximum Adsorption VolumeReference
Coal-Fired Power Plant0.6 g/g FA[37]
Pulversized Coal5 mmol/g FA[34]
Burnt Biomass8 cm3/g FA[49]
Biomass0.28 kg/kg FA[28]
Coal8 mmol/g FA[52]
Volcanic9 mmol/g FACurrent Study
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Fakher, S.; Khlaifat, A.; Salib, A.M.; Elsayed, A. Development of Volumetric Adsorption Isotherms for Volcanic Fly Ash from Egypt for Carbon Dioxide Capture Under Elevated Pressure and Temperature. Processes 2025, 13, 1570. https://doi.org/10.3390/pr13051570

AMA Style

Fakher S, Khlaifat A, Salib AM, Elsayed A. Development of Volumetric Adsorption Isotherms for Volcanic Fly Ash from Egypt for Carbon Dioxide Capture Under Elevated Pressure and Temperature. Processes. 2025; 13(5):1570. https://doi.org/10.3390/pr13051570

Chicago/Turabian Style

Fakher, Sherif, Abdelaziz Khlaifat, Ann Maria Salib, and Ali Elsayed. 2025. "Development of Volumetric Adsorption Isotherms for Volcanic Fly Ash from Egypt for Carbon Dioxide Capture Under Elevated Pressure and Temperature" Processes 13, no. 5: 1570. https://doi.org/10.3390/pr13051570

APA Style

Fakher, S., Khlaifat, A., Salib, A. M., & Elsayed, A. (2025). Development of Volumetric Adsorption Isotherms for Volcanic Fly Ash from Egypt for Carbon Dioxide Capture Under Elevated Pressure and Temperature. Processes, 13(5), 1570. https://doi.org/10.3390/pr13051570

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