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Article

Numerical Analysis of the Influence of Air Flow Rate on the Development of the Porous Structure of Activated Carbons Prepared from Macadamia Nut Shells

by
Mirosław Kwiatkowski
1,* and
Guojie Zhang
2,3
1
Faculty of Energy and Fuels, AGH University of Krakow, al. Adama Mickiewicza 30, 30-059 Krakow, Poland
2
State Key Laboratory of Clean and Efficient Coal Utilization, College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, China
3
Key Laboratory of Coal Science and Technology, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
*
Author to whom correspondence should be addressed.
Materials 2024, 17(24), 6264; https://doi.org/10.3390/ma17246264
Submission received: 14 October 2024 / Revised: 11 December 2024 / Accepted: 17 December 2024 / Published: 21 December 2024
(This article belongs to the Special Issue Adsorption Materials and Their Applications (2nd Edition))
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Abstract

:
This paper presents the numerical analysis of the influence of air flow rate on the porous structure development of activated carbons prepared from macadamia nut shells. The analyses based on nitrogen and carbon dioxide isotherms were carried out by the new numerical clustering-based adsorption analysis method. Therefore, it was possible to evaluate the porous structure with high precision and reliability. In particular, the results obtained showed that activated carbon prepared at an air flow rate of 700 cm3/min has the highest adsorption capacity with respect to this adsorbate, but with surface heterogeneity. On the other hand, numerical analysis based on carbon dioxide adsorption isotherms showed that the activated carbon with the highest adsorption capacity towards carbon dioxide is the sample obtained at an air flow rate of 500 cm3/min. The analyses conducted have shown that too high an air flow rate causes a violent oxidation reaction, leading to uncontrolled burning of the carbonaceous substance and destruction of the structure of the smallest micropores.

1. Introduction

One of the largest problems of the contemporary world, which has a significant impact on global climate change, is the observed gradual increase in the average temperature of the Earth’s atmosphere. This undesirable effect is caused by excessive emissions of greenhouse gases, particularly carbon dioxide (CO2), and the accumulation of these gases in the upper atmosphere [1]. The widespread burning of fossil fuels is largely responsible for anthropogenic CO2 emissions [2,3]. Consequently, numerous initiatives and measures are being taken to reduce CO2 emissions, of which the capture and use of this gas is widely recognised today as one of the most effective solutions for reducing its emissions into the atmosphere [4].
Among the many methods for capturing CO2, the most well-known are absorption [5,6] and adsorption techniques [7]. However, the method of adsorption on the surface of solids is very promising due to its high efficiency, widespread availability, and ease of regeneration of adsorbents, as well as the relatively low energy consumption needed for the process [7]. In contrast, of the many adsorbents used in CO2 capture processes, such as organometallic compounds [8], carbon foams [9], carbon aerogel fibres [10], and activated carbons (AC) with a highly developed specific surface area and microporous structure, are the most optimal under industrial conditions [11,12,13,14].
Activated carbons are most often produced by physical or chemical activation in which a microporous structure is developed [15,16]. Physical activation is mostly carried out as a two-step process that involves the carbonisation of an organic material with a high carbon content, followed by the activation of the resulting char at a high temperature, i.e., 700–1000 °C, in the presence of suitable oxidising gases such as carbon dioxide, oxygen, steam, or mixtures thereof [17]. The physical activation is a most popular method for obtaining activated carbons on an industrial scale due to the uncomplicated nature of the process and the simple design of the equipment used, the rapid process time, and the common availability of raw materials, despite the average development of the porous structure of the carbonaceous materials obtained [18]. It should be noted, however, that the physical activation process, because it is carried out at high temperatures, involves high energy costs [19].
The chemical activation process instead involves the direct treatment of an organic material or charcoal by impregnation with a chemical activating agent, such as potassium hydroxide, potassium carbonate, sodium carbonate, magnesium chloride, phosphoric acid, sulphuric acid, aluminium chloride, sodium chloride, or zinc chloride, followed by heating without air at temperatures of approximately 400–800 °C [20]. In the chemical activation, the process is conducted at lower temperatures compared to the physical activation process. Because activating agents act as dehydrating agents that inhibit the formation of tar and volatiles during the process, the yield of porous activated carbon can be increased, and the activation temperature and time can be reduced, likened to the physical activation [21,22].
As an alternative to the one-step chemical activation process, a two-step process can be used, whereby the raw material is first carbonised to produce charcoal, then impregnated with a chemical activating agent, and finally activation of the impregnated char at high temperature is carried out to produce activated carbon. The two-stage process has the advantage of providing an increased elemental carbon content in the final product, with the first carbonisation stage producing an initial porosity that is further developed by chemical activation [23].
The quantity of activator, the mass ratio of activator to raw material, and the reaction temperature are among the most significant parameters affecting the formation of the porous structure in the production of activated carbons by chemical activation [24]. It should also be noted that, in contrast to physical activation, chemical activation, which is carried out at much lower temperatures, can provide products with greater porous structure development and higher yields [25]. The properties of activated carbons are also highly dependent on the raw material. Most commercially available activated carbons are made from fossil fuel-based precursors, but there is an increasing emphasis on obtaining activated carbons from biomass waste materials, which are cheaper, readily available, renewable, structurally porous, and environmentally friendly [26,27,28,29,30].
As a result of the ever-increasing demands placed on the adsorption technique used in carbon dioxide capture processes, new methods of producing activated carbons and primary raw materials for their manufacture, as well as methods of modifying their adsorption properties, are being sought. Some of the most promising methods for producing activated carbons involve the use of molten inert salts [31].

2. Materials and Methods

The paper [32] proposes an original method to produce activated carbons (AC) from macadamia nut shells in a one-step process by pyrolysis in an air atmosphere using molten potassium chloride (KCl). In the aforementioned study, a group of activated carbons was obtained by mixing macadamia nut shells with KCl and melamine in deionised water, conducting the mixing process for 5 h. KCl, and melamine were purchased from Tianjin Kermel Chemical Reagent Company Limited.
The resulting mixture was then dried in an oven at 383 K, and the dried material was pyrolyzed at 973 K in an air stream at different air flow rates, i.e., 200, 500, and 700 cm3/min for 2 h. Obtained samples of activated carbons were labelled as uAC, where u denoted the air flow rate (cm3/min). Nitrogen adsorption isotherms were measured with Beishide PS2000 for the obtained activated carbon samples, from which, among other things, the specific surface area of SBET was calculated via the BET method [33], the total pores volume VT at P/P0 = 0.99, and the micropores volume Vo via the t-plot method [34].
The methods used in the mentioned research are, however, criticised for excessive simplifying assumptions that do not correlate with reality, including failure to take into account surface heterogeneity, as well as underestimation of pores size [35]. As a result of the growing demands placed on adsorbents, as already mentioned, techniques for their manufacture are being upgraded, but this requires a detailed valuation of the porous structure with particular regard to surface heterogeneity, which is not provided by the methods used in this study. Therefore, the concept of carrying out new reliable analyses of the determined adsorption isotherms using an advanced numerical method of clustering-based adsorption process analysis on heterogeneous surfaces (LBET) was developed [36,37,38,39,40].
The LBET method, which has been designated in detail in previous work [36,37,38,39,40], is based on a group of unique mathematical models of the adsorption process on the heterogeneous surfaces of carbonaceous adsorbents. The models mentioned have five parameters, i.e., the volume of the first adsorbed layer VhA, the dimensionless energy parameter for the first adsorbed layer QA/RT, the energy parameter for the higher adsorbed layers BC, the geometrical parameter determining the height of the adsorbate molecule clusters α, and the geometrical parameter of the porous structure determining the width of the adsorbate molecule clusters β, obtained by fitting LBET models to an empirical adsorption isotherm [36,37,38,39,40]. A fast numerical procedure for multivariate fitting was implemented in the LBET method, allowing the determination of the value of the surface heterogeneity parameter h and the shape of the adsorption energy distribution on the adsorbent surface.

3. Results

The results of the numerical analysis of the influence of air flow rate on the porous structure development of activated carbons prepared from macadamia nut shells in a one-step process by pyrolysis in an air atmosphere using molten potassium chloride (KCl) at different air flow rates, i.e., 200, 500, and 700 cm3/min based on nitrogen (N2) adsorption isotherms determined at 77 K, and carbon dioxide (CO2) isotherms determined at 273 K and 298 K using the LBET method, are summarised in Table 1, Table 2 and Table 3 and shown in Figure 1, Figure 2 and Figure 3.
The results of the analyses carried out on the basis of nitrogen adsorption isotherms via the LBET method, summarised in Table 1 and Figure 1 for the 200AC sample, i.e., obtained at an air flow rate of 200 cm3/min, showed that this material is characterised by nitrogen cluster growth limitations related to geometrical pore limitations, as indicated by the number of the best-fitted LBET model. The value of the VhA parameter determined for the 200AC activated carbon sample indicates a very small volume of the first adsorbed layer (VhA = 0.161 cm3/g), and the values of the geometrical parameters α and β indicate, respectively, that very low and significantly branching clusters of nitrogen molecules are formed in the pores of the analysed material. On the basis of the calculated values of the energy parameters QA/RT and BC, it can be concluded that on the surface of the 200AC sample there are favourable conditions for the multilayer adsorption process (QA/RT = −8.42, BC = 3.94). The value of the parameter h indicates that the surface of the analysed material is characterised by a low degree of heterogeneity (h = 2).
The shape of the adsorption energy distribution (AED LBET) determined for 200AC activated carbon (see Figure 1) shows that there is a predominant proportion of primary adsorption sites on the surface of this material with nearly equal adsorption energy and a small number of primary adsorption sites with a wider adsorption energy distribution.
The results of analyses via the LBET method obtained for activated carbon 500AC, i.e., prepared in air flow rate equal to 500 cm3/min, showed that this material is characterised by limitations in the growth of clusters of nitrogen molecules related to geometric limitations of pores, as indicated by the number of the best-fitted LBET model, i.e., 19. The value of the parameter VhA (VhA = 0.179 cm3/g) indicates a small volume of the first adsorbed layer, and the values of the geometric parameters α and β indicate, respectively, that in the pores of the analysed sample of activated carbon, low, slightly branching clusters of adsorbate molecules are formed (α = 0.14 and β = 1.26). Based on the values of energy parameters QA/RT and BC, i.e., for the first adsorbed layer and the subsequent layers, it can be concluded that the energy conditions for only a single-layer adsorption process occur on the surface of the 500AC activated carbon (QA/RT = −1.35 and BC = 1.00).
The value of the parameter h shows that the surface of the analysed 500AC activated carbon is heterogeneous (h = 3), and the shape of the adsorption energy distribution on the surface of the 500AC activated carbon shows, as in the case of the 200AC sample, a dominant share of sites with equal adsorption energy. However, the 500AC sample returns a higher proportion of adsorption sites with a wider adsorption energy distribution.
The last sample analysed was activated carbon obtained at an air flow rate equal to 700 cm3/min, designated as 700AC. This material was characterised by limits on the growth of nitrogen molecule clusters related to the competitive expansion of neighbouring clusters. The very high value of the VhA parameter obtained for this activated carbon, i.e., VhA = 0.642 cm3/g, is noteworthy, being considerably higher than the corresponding parameters determined for samples obtained at lower air flow rates, i.e., 200 cm3/min and 500 cm3/min, in turn. Low and significantly branching clusters of nitrogen molecules form in the pores of the 700AC activated carbon, as indicated by the values of the geometrical parameters (α = 0.18 and β = 3.33). The values of the adsorption energy parameters (QA/RT = −9.33 and BC = 7.73) showed preferential conditions for multilayer adsorption to occur on the surface of this sample. Note the significant value of the surface heterogeneity parameter (h = 5), which indicates that the surface of the analysed material is highly heterogeneous. On the other hand, the adsorption energy distribution (AED LBET) on the surface of the analysed 700AC activated carbon, determined by the LBET method and shown in Figure 1, indicates a predominant share of sites with a narrow range of adsorption energy and a much smaller share of sites with a wider range of adsorption energy.
In the case of the sample obtained at an air flow rate equal to 700 cm3/min, a significantly larger volume of the first adsorbed layer was observed compared to samples obtained at lower temperatures, but with an increase in the degree of surface heterogeneity. This is due to the fact that the high air flow rate favours the formation of micropores, thanks to the rapid removal of the carbon decomposition products from the surface. Note the high reliability of the results obtained, as indicated by the values of the parameters σe and wid, i.e., the dispersion value of the fitting error and the adsorption system identifiability index, respectively.
Analysis of the porous structure and adsorption properties of the tested activated carbons based on the carbon dioxide adsorption isotherms determined at 273 K via the LBET method (see Table 2) showed that in the case of the 200AC sample, the limitations on clusters of CO2 molecules expansion are due to the competitive expansion of neighbouring clusters, while in the case of the 500AC and 700AC activated carbons, the limitations on clusters of CO2 molecules expansion are due to geometrical pore limitations. The VhA parameter values determined for the samples analysed indicate a small volume of the first adsorbed layer, with the highest VhA parameter value obtained for the 500AC activated carbon and the lowest for 700AC. The determined values of the geometrical parameters α and β showed that very high and significantly branching clusters of carbon dioxide molecules form in the pores of the analysed samples.
The parameters QA/RT and BC obtained for the analysed samples on the basis of adsorption isotherms indicate strongly preferential conditions for the monolayer adsorption process to occur. In turn, it can be concluded from the values of the h parameters that the surface of the analysed samples is strongly heterogeneous with respect to carbon dioxide.
From the shapes of the adsorption energy distribution (AED LBET) on the surface of the analysed activated carbons, it can be concluded that there is a wide range of adsorption energy of primary adsorption sites on the surface. However, in the case of the activated carbon sample obtained at an air flow rate equal to 200 cm3/min, a predominant proportion of high-energy adsorption sites can be observed compared to the other two activated carbons analysed (Figure 2).
As part of this study, an analysis was also carried out on the basis of carbon dioxide adsorption isotherms determined at temperature 298 K. The results of the calculations are summarised in Table 3, and the adsorption isotherms and best-fitted LBET class models, as well as the adsorption energy distribution (AED LBET) on the surface of the analysed activated carbons, are shown in Figure 3.
In the case of an analysis of the results obtained for adsorption isotherms determined at 298 K, it should be borne in mind that the results obtained provide information on the adsorption process under these conditions and are not a sound basis for drawing reliable conclusions, particularly about the microporous structure of the materials on which this process occurs.
As can be seen from the results summarised in Table 3 for the analysis of carbon dioxide isotherms determined at 298 K, for all the activated carbons analysed, the limitations on the growth of clusters of carbon dioxide molecules are due to the competitive expansion of neighbouring clusters. In turn, the values of the VhA parameters indicate that the analysed activated carbons are characterised by a small volume of the first adsorbed layer, with the largest volume of the first adsorbed layer obtained for 500AC activated carbon and the smallest for 700AC activated carbon.
The values of geometrical parameters α and β determined for the analysed activated carbons suggest that high and significantly branching clusters of carbon dioxide molecules form in their pores, and the values of the energy parameters QA/RT and BC indicate that energy conditions favouring only monolayer adsorption occur on the surface of these materials. Note that the surface of all analysed samples is strongly heterogeneous, as indicated by the values of the h parameter (h = 9).
The shape of the AED LBET, i.e., adsorption energy distribution determined from carbon dioxide adsorption isotherms obtained at temperature 293 K via the LBET method, shows a wide range of adsorption energies on the surface of the analysed samples with a significant proportion of high-energy adsorption sites.

4. Conclusions

This paper presents the original results of a numerical analysis of the effect of air flow rate on the formation of the porous structure of activated carbons prepared from macadamia nut shells in a one-step process by pyrolysis in an air atmosphere using molten potassium chloride at different air flow rates. The analyses mentioned were based on nitrogen adsorption isotherms determined at 77 K, and carbon dioxide isotherms determined at 273 K and 298 K using the new numerical clustering-based adsorption analysis method.
Analyses based on nitrogen adsorption isotherms showed that activated carbon obtained at an air flow rate of 700 cm3/min has the highest adsorption capacity with respect to this adsorbate, but with significant surface heterogeneity. On the other hand, analysis based on carbon dioxide adsorption isotherms determined at 273 K showed that the activated carbon with the highest adsorption capacity is the sample obtained at an air flow rate of 500 cm3/min, noting, however, the very high surface heterogeneity for carbon dioxide adsorption, which may be undesirable in many industrial adsorption processes. The results of an analysis of the adsorption process based on adsorption isotherms determined at 298 K are also presented, which indicated that the temperature of the adsorption process has a significant effect on its course.
As demonstrated in the conducted studies, the air flow supports the oxidation of the reactive carbonaceous substance, thereby developing microporosity. However, excessively high air flow velocities can exacerbate the uncontrolled oxidation reaction, leading to the uncontrolled burning of the carbon material and the destruction of the smallest micropore structures. This effect was observed in the case of the 700AC activated carbons, as evidenced by the analysis of carbon dioxide adsorption isotherms determined for the tested activated carbons.

Author Contributions

Conceptualisation, M.K. and G.Z.; methodology, M.K.; software, M.K.; validation, M.K.; formal analysis, M.K.; investigation, M.K.; resources, G.Z.; data curation, G.Z.; writing—original draft preparation, M.K.; writing—review and editing, M.K.; visualisation, M.K.; supervision, M.K.; project administration, M.K. and G.Z.; funding acquisition, M.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by a research subvention from the Polish Ministry of Science and Higher Education for the AGH University of Krakow (No. 16.16.210.476).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Jiao, Y. Analysis of the impacts of carbon dioxide emission on climate change. Theor. Nat. Sci. 2023, 7, 120–127. [Google Scholar] [CrossRef]
  2. Song, J.; Tong, G.; Chao, J.; Chung, J.; Zhang, M.; Lin, W.; Zhang, T.; Bentler, P.M.; Zhu, W. Data driven pathway analysis and forecast of global warming and sea level rise. Sci. Rep. 2023, 13, 5536. [Google Scholar] [CrossRef]
  3. Pisciotta, M.; Pilorgé, H.; Feldmann, J.; Jacobson, R.; Davids, J.; Swett, S.; Sasso, Z.; Wilcox, J. Current state of industrial heating and opportunities for decarbonisation. Prog. Energ. Combust. Sci. 2022, 91, 100982. [Google Scholar] [CrossRef]
  4. Keller, D.P.; Lenton, A.; Littleton, E.W.; Oschlies, A.; Scott, V.; Vaughan, N.E. The effects of carbon dioxide removal on the carbon cycle. Curr. Clim. Change Rep. 2018, 4, 250–265. [Google Scholar] [CrossRef]
  5. Kim, S.; Ko, Y.; Lee, G.J.; Lee, J.W.; Xu, R.; Ahn, H.; Kang, Y.T. Sustainable energy harvesting from post-combustion CO2 capture using amine-functionalized solvents. Energy 2023, 267, 126532. [Google Scholar] [CrossRef]
  6. Khan, U.; Ogbaga, C.C.; Abiodun, O.-A.O.; Adeleke, A.A.; Ikubanni, P.P.; Okoye, P.U.; Okolie, J.A. Assessing absorption-based CO2 capture: Research progress and techno-economic assessment overview. Carbon Capture Sci. Technol. 2023, 8, 100125. [Google Scholar] [CrossRef]
  7. Underschultz, J.; Dodds, K.; Michael, K.; Sharma, S.; Wall, T.; Whittaker, S. Carbon capture and storage. In Sustainability in the Mineral and Energy Sectors; CRC Press: Boca Raton, FL, USA, 2016; pp. 437–452. [Google Scholar] [CrossRef]
  8. Cantador-Fernandez, D.; Suescum-Morales, D.; Esquivel, D.; Jiménez, J.R.; Fernández-Rodriguez, J.M. CO2 adsorption by ethane periodic mesoporous organosilica at low temperatures and high pressure. J. Environ. Chem. Eng. 2023, 11, 110582. [Google Scholar] [CrossRef]
  9. Maquíñez-Buitrago, D.F.; Ramos-Rincón, J.M.; Giraldo, L.; Moreno-Piraján, J.C. Carbon foams for CO2 adsorption: Synthesis, characterization and application. Hybrid Adv. 2024, 6, 100219. [Google Scholar] [CrossRef]
  10. Wang, Y.; Tang, X.; Wei, X.; Gao, S.; Jiang, L.; Yi, Y. Study of CO2 adsorption on carbon aerogel fibers prepared by electrospinning. J. Environ. Manag. 2024, 349, 119432. [Google Scholar] [CrossRef]
  11. Serafin, J.; Dziejarski, B. Activated carbons—Preparation, characterization and their application in CO2 capture: A review. Environ. Sci. Pollut. Res. 2024, 31, 40008–40062. [Google Scholar] [CrossRef] [PubMed]
  12. Kong, Z.; Zhang, H.; Zhou, T.; Xie, L.; Wang, B.; Jiang, X. Biomass-derived functional materials: Preparation, functionalization, and applications in adsorption and catalytic separation of carbon dioxide and other atmospheric pollutants. Sep. Purif. Technol. 2025, 354, 129099. [Google Scholar] [CrossRef]
  13. Siemak, J.; Mikołajczak, G.; Pol-Szyszko, M.; Michalkiewicz, B. Activated carbon for CO2 adsorption from avocado seeds activated with NaOH: The significance of the production method. Materials 2024, 17, 4157. [Google Scholar] [CrossRef]
  14. Liu, C.; Zhi, Y.; Yu, Q.; Tian, L.; Demir, M.; Colak, S.G.; Farghaly, A.A.; Wang, L.; Hu, X. Sulfur-enriched nanoporous carbon: A novel approach to CO2 adsorption. ACS Appl. Nano Mater. 2024, 7, 5434–5441. [Google Scholar] [CrossRef]
  15. Trinh, K.T.; Tsubota, T. Supercapacitors composed of Japanese cedar bark-based activated carbons with various activators. Mater. Chem. Phys. 2023, 307, 128148. [Google Scholar] [CrossRef]
  16. Tetteh, I.K.; Issahaku, I.; Tetteh, A.Y. Recent advances in synthesis, characterization, and environmental applications of activated carbons and other carbon derivatives. Carbon Trends 2024, 14, 100328. [Google Scholar] [CrossRef]
  17. Panwar, N.L.; Pawar, A. Influence of activation conditions on the physicochemical properties of activated biochar: A review. Biomass Conv. Bioref. 2022, 12, 925–947. [Google Scholar] [CrossRef]
  18. Castro, P.; Ferrarini, S.; Rimoli, M.; Merlo, A.; Nogueira, R.; Pires, E. Preparation and characterization of steam and CO2 activated carbon from Brazil nut shell. Biosci. J. 2023, 39, e39054. [Google Scholar] [CrossRef]
  19. Kumar, N.S.; Grekov, D.; Pré, P.; Alappat, B.J. Statistical approach to describe the properties of nanoporous carbons from lignin by chemical activation. Sustain. Mater. Technol. 2024, 40, e00939. [Google Scholar] [CrossRef]
  20. Ying, W.; Tian, S.; Liu, H.; Zhou, Z.; Kapeso, G.; Zhong, J.; Zhang, W. In situ dry chemical synthesis of nitrogen-doped activated carbon from bamboo charcoal for carbon dioxide adsorption. Materials 2022, 15, 763. [Google Scholar] [CrossRef]
  21. Yahia, E.H.; Serafin, J.; Román-Martínez, M.C.; Saidi, M.; Gallego, A.R.; Atlas, S.; Ouzzine, M. Valorization of argan paste cake waste: Enhanced CO2 adsorption on chemically activated carbon. J. Anal. Appl. Pyrol. 2024, 181, 106637. [Google Scholar] [CrossRef]
  22. Sreńscek-Nazzal, J.; Kamińska, A.; Serafin, J.; Michalkiewicz, B. Chemical activation of banana peel waste-derived biochar using KOH and urea for CO2 capture. Materials 2024, 17, 872. [Google Scholar] [CrossRef]
  23. Nandi, R.; Jha, M.K.; Guchhait, S.K.; Sutradhar, D.; Yadav, S. Impact of KOH activation on rice husk derived porous activated carbon for carbon capture at flue gas alike temperatures with high CO2/N2 selectivity. ACS Omega 2023, 8, 4802–4812. [Google Scholar] [CrossRef]
  24. Saputro, E.; Wulan, V.; Winata, B.; Yogaswara, R.; Erliyanti, N. Process of activated carbon form coconut shells through chemical activation. Natur. Sci. J. Sci. Technol. 2020, 9, 23–28. [Google Scholar] [CrossRef]
  25. Wang, L.; Xie, L.; Wu, J.; Li, X.; Ma, H.; Zhou, J. Sequential H3PO4–CO2 assisted synthesis of lignin-derived porous carbon: CO2 activation kinetics investigation and textural properties regulation. Renew. Energy 2022, 191, 639–648. [Google Scholar] [CrossRef]
  26. Bai, J.; Huang, J.; Yu, Q.; Demir, M.; Kilic, M.; Altay, B.N.; Hu, X.; Wang, L. N-doped porous carbon derived from macadamia nut shell for CO2 adsorption. Fuel Process. Technol. 2023, 249, 107854. [Google Scholar] [CrossRef]
  27. Raffah, B.M.; Knani, S.; Bouzid, M.; Alruqi, A.B.; Vieira, Y.; Dotto, G.L.; Lefi, N.; Lamine, A.B. Morphological, sterical, and localized thermodynamics in the adsorption of CO2 by activated biocarbon from the white rot fungi Trametes gibbosa. Sci. Total Environ. 2024, 939, 173326. [Google Scholar] [CrossRef]
  28. Aouay, F.; Attia, A.; Dammak, L.; Ben Amar, R.; Deratani, A. Activated carbon prepared from waste coffee grounds: Characterization and adsorption properties of dyes. Materials 2024, 17, 3078. [Google Scholar] [CrossRef]
  29. Zayed, A.M.; Metwally, B.S.; Masoud, M.A.; Mubarak, M.F.; Shendy, H.; Wahed, M.S.M.A. From non-conventional agricultural waste into sustainable and eco-friendly activated carbon through specified thermo-chemical protocol. Appl. Nanosci. 2024, 14, 21–32. [Google Scholar] [CrossRef]
  30. Koli, A.; Battu, A.K.; Motkuri, R.K.; Sabale, S. Hierarchical porous activated carbon derived from agro-waste for potential CO2 capture and efficient dye removal applications. Biomass Conv. Bioref. 2024, 14, 10177–10188. [Google Scholar] [CrossRef]
  31. Zhang, M.; Zhang, X.; Shi, E.; Liu, S.; Zhang, S.; Zou, Y. Molecular dynamics study on structures and adsorption capacity of activated carbon prepared from corn straw and sewage sludge by molten salt method. Appl. Phys. A 2024, 130, 117. [Google Scholar] [CrossRef]
  32. Wu, C.; Zhang, G.; Liu, J.; Wang, Y.; Zhao, Y.; Li, G. A green strategy to prepare nitrogen-oxygen co-doped porous carbons from macadamia nut shells for post-combustion CO2 capture and supercapacitors. J. Anal. Appl. Pyrol. 2023, 171, 105952. [Google Scholar] [CrossRef]
  33. Brunauer, S.; Emmett, P.H.; Teller, E. Adsorption of gases in multimolecular layers. J. Am. Chem. Soc. 1938, 60, 309–319. [Google Scholar] [CrossRef]
  34. Gregg, S.J.; Sing, K.S.W. Adsorption, Surface Area and Porosity, 2nd ed.; Academic Press Inc.: Cambridge, MA, USA, 1982. [Google Scholar] [CrossRef]
  35. Zelenka, T.; Horikawa, T.; Do, D.D. Artifacts and misinterpretations in gas physisorption measurements and characterization of porous solids. Adv. Colloid Interf. Sci. 2023, 311, 102831. [Google Scholar] [CrossRef] [PubMed]
  36. Kwiatkowski, M. Computer analysis of microporous structure by employing the LBET class models with various variants of the adsorption energy distribution in comparison to the classical equations. Langmuir 2007, 23, 2569–2581. [Google Scholar] [CrossRef]
  37. Kwiatkowski, M. Computer analyses of new numerical methods for the description of adsorption process and the reliability of identification of microporous structure parameters. J. Mol. Model. 2008, 14, 183–200. [Google Scholar] [CrossRef]
  38. Kwiatkowski, M.; Broniek, E.; Fierro, V.; Celzard, A. An evaluation of the impact of the amount of potassium hydroxide on the porous structure development of activated carbons. Materials 2021, 14, 2045. [Google Scholar] [CrossRef] [PubMed]
  39. Kwiatkowski, M.; Kalderis, D.; Tono, W.; Tsubota, T. Numerical analysis of the micropore structure of activated carbons focusing on optimum CO2 adsorption. J. CO2 Utiliz. 2022, 60, 101996. [Google Scholar] [CrossRef]
  40. Kwiatkowski, M.; Cansado, I.P.d.P.; Mourão, P.M. numerical analysis of the porous structure of activated carbons derived from synthetic polymers. Materials 2024, 17, 3122. [Google Scholar] [CrossRef]
Materials 17 06264 g001
Figure 1. The results of the analysis of a porous structure of activated carbons via the LBET method, based on nitrogen adsorption isotherms determined at 77 K, where AED LBET is the adsorption energy distribution.
Figure 1. The results of the analysis of a porous structure of activated carbons via the LBET method, based on nitrogen adsorption isotherms determined at 77 K, where AED LBET is the adsorption energy distribution.
Materials 17 06264 g001
Materials 17 06264 g002
Figure 2. Same as Figure 1, but presenting the results of the analysis of a porous structure of activated carbons, based on carbon dioxide adsorption isotherms determined at 273 K.
Figure 2. Same as Figure 1, but presenting the results of the analysis of a porous structure of activated carbons, based on carbon dioxide adsorption isotherms determined at 273 K.
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Figure 3. Same as Figure 1, but presenting the results of the analysis of a porous structure of activated carbons, based on carbon dioxide adsorption isotherms determined at 298 K.
Figure 3. Same as Figure 1, but presenting the results of the analysis of a porous structure of activated carbons, based on carbon dioxide adsorption isotherms determined at 298 K.
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Table 1. The results of the analysis of a porous structure of activated carbons via the LBET method, based on nitrogen adsorption isotherms determined at 77 K.
Table 1. The results of the analysis of a porous structure of activated carbons via the LBET method, based on nitrogen adsorption isotherms determined at 77 K.
ACModel
No.		VhA
[cm3/g]		αβQA/RTBChσewid
200AC180.1610.142.37−8.423.9420.250.81
500AC190.1790.141.26−9.481.0030.320.47
700AC70.6420.183.33−9.337.7350.130.52
Where AC is the analysed activated carbon; Model No. is the number of the best-fitted model of the LBET class; VhA is the volume of the first adsorbed layer; α is the geometrical parameter of the porous structure determining the height of the adsorbate molecule clusters; β is the geometrical parameter of the porous structure determining the width of the adsorbate molecule clusters; QA/RT is the dimensionless energy parameter for the first adsorbed layer; BC is the dimensionless adsorption energy parameter for the higher adsorbed layers; h is the surface heterogeneity parameter; σe is the dispersion value of the fit error; and wid is the adsorption system identifiability index.
Table 2. The results of the analysis of a porous structure of activated carbons via the LBET method, based on carbon dioxide adsorption isotherms determined at 273 K.
Table 2. The results of the analysis of a porous structure of activated carbons via the LBET method, based on carbon dioxide adsorption isotherms determined at 273 K.
ACModel
No.		VhA
[cm3/g]		αβQA/RTBChσewid
200AC150.2110.905.11−10.032.0790.0190.43
500AC290.2460.982.65−10.221.0090.030.19
700AC290.1850.992.22−10.891.0090.0130.21
Table 3. The results of the analysis of a porous structure of activated carbons via the LBET method, based on carbon dioxide adsorption isotherms determined at 298 K.
Table 3. The results of the analysis of a porous structure of activated carbons via the LBET method, based on carbon dioxide adsorption isotherms determined at 298 K.
ACModel
No.		VhA
[cm3/g]		αβQA/RTBChσewid
200AC150.1700.854.89−8.661.5190.0120.81
500AC150.1840.875.20−8.801.4190.0150.73
700AC150.1430.894.74−9.251.6390.00840.65
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Kwiatkowski, M.; Zhang, G. Numerical Analysis of the Influence of Air Flow Rate on the Development of the Porous Structure of Activated Carbons Prepared from Macadamia Nut Shells. Materials 2024, 17, 6264. https://doi.org/10.3390/ma17246264

AMA Style

Kwiatkowski M, Zhang G. Numerical Analysis of the Influence of Air Flow Rate on the Development of the Porous Structure of Activated Carbons Prepared from Macadamia Nut Shells. Materials. 2024; 17(24):6264. https://doi.org/10.3390/ma17246264

Chicago/Turabian Style

Kwiatkowski, Mirosław, and Guojie Zhang. 2024. "Numerical Analysis of the Influence of Air Flow Rate on the Development of the Porous Structure of Activated Carbons Prepared from Macadamia Nut Shells" Materials 17, no. 24: 6264. https://doi.org/10.3390/ma17246264

APA Style

Kwiatkowski, M., & Zhang, G. (2024). Numerical Analysis of the Influence of Air Flow Rate on the Development of the Porous Structure of Activated Carbons Prepared from Macadamia Nut Shells. Materials, 17(24), 6264. https://doi.org/10.3390/ma17246264

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