• International Journal of Technology (IJTech)
  • Vol 9, No 5 (2018)

The Hydrogen Adsorption Behavior of Mechano-Chemically Activated Carbon from Indonesian Low-rank Coal: Coupled Langmuir and Dubinin-Astakhov Isotherm Model Analysis

Sri Harjanto, Jaka Fajar Fatriansyah, Latifa Nuraini Noviana, Stefanno Widy Yunior

Corresponding email: fajar@metal.ui.ac.id

Published at : 25 Oct 2018
Volume : IJtech Vol 9, No 5 (2018)
DOI : https://doi.org/10.14716/ijtech.v9i5.2031

Cite this article as:
Harjanto, S., Fatriansyah, J.F., Noviana, L.N., Yunior, S.W., 2018. The Hydrogen Adsorption Behavior of Mechano-Chemically Activated Carbon from Indonesian Low-rank Coal: Coupled Langmuir and Dubinin-Astakhov Isotherm Model Analysis. International Journal of Technology. Volume 9(5), pp. 993-1005

Sri Harjanto Department of Metallurgy and Materials Engineering, Faculty of Engineering, Universitas Indonesia
Jaka Fajar Fatriansyah - Department of Metallurgical and Materals Engineering, Faculty of Engineering, Universitas Indonesia
Latifa Nuraini Noviana Department of Metallurgy and Materials Engineering, Faculty of Engineering, Universitas Indonesia
Stefanno Widy Yunior Department of Metallurgy and Materials Engineering, Faculty of Engineering, Universitas Indonesia
Email to Corresponding Author


This study aims to produce activated carbon from low-rank coal from East Kalimantan, Indonesia by a mechano-chemical method and to determine its adsorption parameters: hydrogen uptake/capacity, activation energy, the structural heterogeneity parameter, and the isosteric heat of adsorption. The hydrogen uptake/capacity of the coal was determined by a volumetric adsorption test using constant-volume-variable-pressure (CVVP). The characteristic adsorption parameters, such as hydrogen uptake, characteristic energy and heterogeneity structure factor, were determined using the coupled Langmuir and Dubinin-Astakhov (D-A) isotherm models, with the assumption that the hydrogen uptake value would be similar, irrespective of the model used. We found that the mechano-chemical method significantly reduced the particle size of the activated carbon relative to the untreated control, by approximately 60%. In addition, the activation process yielded a higher surface area for the activated carbon (390 m2/g) compared to the untreated control (90 m2/g). We also found that greater surface area led to a greater uptake of hydrogen by the activated carbon (40.17±1.56)×10-3 kg/kg than by the untreated control (7.94±1.56)×10-3 kg/kg. We also found that the heterogeneity factor of the activated carbon was 3.73±0.23, lower than the untreated control 4.65±0.56, which reflects the more heterogeneous pore diameter sizes for the activated carbon compared to the untreated control. Lastly, using the obtained adsorption parameters, we observed that the hydrogen uptake-dependent isosteric heat of adsorption on the activated carbon changed rapidly in the initial and final stages compared to the untreated control due to the adsorption of hydrogen by smaller pores which reside inside larger ones.

Activated carbon; Adsorption isotherms; Heterogeneity; Planetary ball mill; Sub-bituminous coal


Hydrogen is an ideal future fuel source. For example, it can be utilized in combustion to produce water, which does not contribute to air pollution (Serrano et al., 2009; Jiménez et al., 2010; Nasruddin et al., 2016). In fuel cell applications, hydrogen is directly converted into water, electricity and heat. Therefore, the use of hydrogen as an energy source may possibly reduce harmful emissions of greenhouse gases (such as carbon dioxide, carbon monoxide, hydrocarbons, nitrogen oxides, and sulphur oxides), and may reduce global dependence on fossil fuels, especially in the transportation sector. For hydrogen to be properly used aan energy source, an effective storage medium is needed. The required properties of a hydrogen storage medium are that it should be low in weight, low in price, easy to activate and have good availability, high volumetric and gravimetric hydrogen density, and long-term cycle stability (Niemann et al., 2008). Some examples of hydrogen storage materials are carbon-based ones such as activated carbon (Marsh et al., 1984) and graphite nanofiber (Chambers et al., 1998), and other materials such as metal organic frameworks (Li et al., 1999), zeolites (Dong et al., 2007), clathrate hydrates (Lee et al., 2005) and metal hydride (Schlapbach & Züttel, 2001).

Activated carbon is an appropriate choice for a hydrogen storage medium due to its high porosity (Nor et al., 2016), low bulk density (Caturla et al., 1991), reasonable cost (El Qada et al., 2006), relative abundance, and capability to store gases on its surface (De la Casa-Lillo et al., 2002). It can be produced from carbon-rich materials such as coal and various agricultural residues (Ioannidou & Zabaniotou, 2007). Among these, coal has the greatest potential as a carbon-containing material because it is relatively abundant and economical. Further, the production of activated carbon from coal can increase its commercial value.

Basically, activated carbon can be produced by two methods: by chemical activation (Marsh et al., 1984; Kumamoto et al., 1994; Ahmadpour & Do, 1997; Tsai et al., 1998) or by physical activation (Caturla et al., 1991; Ahmadpour & Do, 1996; Bouchelta et al., 2008; Nandi et al., 2012; Sekirifa et al., 2013). In this study, we develop a combination of physical/mechanical and chemical methods, known as the mechano-chemical method, to produce activated carbon by means of a planetary ball mill and with KOH introduced. Mechanically-driven activation is induced by imposing a mechanical force on a material, and chemical activation is induced by reacting a chemical compound with the material. We expect that the combination will produce activated carbon which has good characteristic adsorption parameters.

Several models have been developed to characterize gas adsorption in microporous materials (Do, 1998). Among them, the Dubinin-Astakhov (D-A) model is well known for its characterization of the non-homogeneous structure of microporous materials. In this model, some parameters can be revealed to evaluate the gas adsorption characteristics of microporous materials, such as carbon-based ones. Several previous studies have examined the D-A model to characterize the adsorption behaviour of multiple gas species on activated carbon materials (Hu & Ruckenstein, 2006; Ushiki et al., 2013; Wu et al., 2014) and have determined that it is applicable for such a purpose.

This study aims to produce activated carbon from Indonesian low-rank coal by a mechano-chemical method and to determine its adsorption parameters: hydrogen uptake/capacity, activation energy, the structural heterogeneity parameter, and the isosteric heat of adsorption. The volumetric method-based experiment was designed to determine the adsorption parameters, and two simultaneous isotherm methods—the Langmuir and D-A methods—were coupled to calculate the adsorption parameters properly. Further, the parameters obtained from the calculation can be used to predict the mechanism of hydrogen adsorption on the activated carbon surface.


Activated carbon has been produced from untreated Indonesian low-rank coal using a ball mill mechano-chemical method and its adsorption parameters have been successfully calculated using a coupled Langmuir and D-A isotherm model. It was found that the activated carbon has a higher pore volume and larger surface area than the low-rank coal. This leads to a higher hydrogen uptake or saturated amount of adsorbed hydrogen in the activated carbon compared to the untreated coal. The saturated hydrogen adsorption capacity of activated carbon led to an increase of about 500%, from 0.8% to 4.02%. From the calculation using the coupled Langmuir and D-A models, it is observed that the heterogeneity of energy distribution (which is related to the width of pore size distribution) of the activated carbon structure slightly increases, as shown by the n parameter, which is lower than that of untreated coal. It was found that the isosteric heat of adsorption increases rapidly at the initial and final stages of adsorption due to the adsorption of hydrogen on smaller micropores which reside inside larger ones.


The publication of this article is supported by the United States Agency for International Development (USAID) through the Sustainable Higher Education Research Alliance (SHERA) Program for the Universitas Indonesia Scientific Modeling, Application, Research and Training for City-centered Innovation and Technology (SMART CITY) Project, Grant #AID-497-A-1600004, Sub Grant #IIE-00000078-UI-1. Comprehensive discussions with and comments from Dr.-Ing. Nasruddin of the Department of Mechanical Engineering, Universitas Indonesia, are very much appreciated.


Ahmadpour, A., Do, D.D., 1996. The Preparation of Active Carbons from Coal by Chemical and Physical Activation. Carbon, Volume 34(4), pp. 471479

Ahmadpour, A., Do, D.D., 1997. The Preparation of Activated Carbon from Macadamia Nutshell by Chemical Activation. Carbon, Volume 35(12), pp. 1723–1732

Ahn, D.H., Gibbs, B.M., Ko, K.H., Kim, J.J., 2001. Gasification Kinetics of an Indonesian Sub-bituminous Coal-Char with CO2 at Elevated Pressure. Fuel, Volume 80(11), pp. 16511658

Baheti, V., Naeem, S., Militky, J., Okrasa, M., Tomkova, B., 2015. Optimized Preparation of Activated Carbon Nanoparticles from Acrylic Fibrous Wastes. Fibers and Polymers, Volume 16(10), pp. 21932201

Bouchelta, C., Medjram, M.S., Bertrand, O., Bellat, J.P., 2008. Preparation and Characterization of Activated Carbon from Date Stones by Physical Activation with Steam. Journal of Analytical and Applied Pyrolysis, Volume 82(1), pp. 70–77

Caturla, F., Molina-Sabio, M., Rodriguez-Reinoso, F., 1991. Preparation of Activated Carbon by Chemical Activation with ZnCl2. Carbon, Volume 29(7), pp. 999–1007

Chakraborty, A., Saha, B.B., Koyama, S., Ng, K.C., 2006. On the Thermodynamic Modeling of the Isosteric Heat of Adsorption and Comparison with Experiments. Applied Physics Letters, Volume 89(17), pp.171901-1–171901-3

Chambers, A., Park, C., Baker, R.T.K., Rodriguez, N.M., 1998. Hydrogen Storage in Graphite Nanofibers. The Journal of Physical Chemistry B, Volume 102(22), pp. 4253–4256

Choma, J., Burakiewicz-Mortka, W., Jaroniec, M., Gilpin R.K., 1993. Studies of the Structural Heterogeneity of Microporous Carbons using Liquid/Solid Adsorption Isotherms. Langmuir, Volume 9(10), pp. 2555–2561

De la Casa-Lillo, M.A., Lamari-Darkrim, F., Cazorla-Amorós, D., Linares-Solano, A., 2002. Hydrogen Storage in Activated Carbons and Activated Carbon Fibers. The Journal of Physical Chemistry B, Volume 106(42), pp. 10930–10934

Dubinin, M.M., 1975. In Progress in Membrane and Surface Science. In Cadenhead, D.A. (Ed.), Volume 9, Chapter 1, pp. 1–70, Academic Press, New York

Do, D.D., 1998. Adsorption Analysis: Equilibria and Kinetics, Imperial College Press, London, pp. 49–84

Dong, J., Wang, X., Xu, H., Zhao, Q., Li, J., 2007. Hydrogen Storage in Several Microporous Zeolites. International Journal of Hydrogen Energy, Volume 32(18), pp. 4998–5004

Elias, D.C., Nair, R.R., Mohiuddin, T.M.G., Morozov, S.V., Blake, P., Halsall, M.P., Ferrari, A.C., Boukhvalov, D.W., Katsnelson, M.I., Geim, A.K., Novoselov, K.S., 2009. Control of Graphene's Properties by Reversible Hydrogenation: Evidence for Graphene. Science, Volume 323(5914), pp. 610–613

El Qada, E.N., Allen, S.J., Walker, G.M., 2006. Adsorption of Methylene Blue onto Activated Carbon Produced from Steam Activated Bituminous Coal: A Study of Equilibrium Adsorption Isotherm. Chemical Engineering Journal, Volume 124(1-3), pp. 103110

Gil, A., Korili, S.A., 2000. Structural Heterogeneity of Microporous Materials from Nitrogen Adsorption at 77 K. Boletín de la Sociedad Española de Cerámica y Vidrio, Volume 39(4), pp. 535539

Harjanto, S., Yunior, S.W., Chodijah, S., Nasruddin, 2013.  Hydrogen Adsorption Behavior of Mechanically Milled and Pelletized Coconut Shell Activated Carbon. Material Science Forum, Volume 737, pp. 98–104

Hu, Y.H., Ruckenstein, E., 2006. Applicability of Dubinin-Astakhov Equation to CO2 Adsorption on Single-walled Carbon Nanotubes. Chemical Physics Letters, Volume 425(4-6), pp. 306–310

Ioannidou, O., Zabaniotou, A., 2007. Agricultural Residues as Precursors for Activated Carbon Production—A Review. Renewable and Sustainable Energy Reviews, Volume 11(9), pp. 1966–2005

Jaroniec, M., 1995. Characterization of Nanoporous Materials. In Pinnavaia, T.J.  and Thorpe, M.F.  (Ed), Access in Nanoporous Materials, pp. 255272, Plenum Press, New York

Jiménez, V., Sánchez, P., Díaz, J.A., Valverde, J.L., Romero, A., 2010. Hydrogen Storage Capacity on Different Carbon Materials. Chemical Physics Letters, Volume 485(1-3), pp. 152–155

Kumamoto, S., Takahashi, Y., Ishibashi, K., Noda, Y., Yamada, K., Chida, T., 1994. Production of Activated Carbon for Utilization of Bark from Russian Wood. Transaction Material Research Society Japan, Volume 18A (Ecomaterials), pp. 647–650

Lee, H., Lee, J.W., Kim, D.Y., Park, J., Seo, Y.T., Zeng, H., Moudrakovski, I.L., Ratcliffe, C.I., Ripmeester, J.A., 2005. Tuning Clathrate Hydrates for Hydrogen Storage. Nature, Volume 434, pp. 743746

Li, H., Eddaoudi, M., O'Keeffe, M., Yaghi, O.M., 1999. Design and Synthesis of an Exceptionally Stable and Highly Porous Metal-Organic Framework. Nature, Volume 402(6759), pp. 276–279

Limousin, G., Gaudet, J.P., Charlet, L., Szenknect, S., Barthes, V., Krimissa, M., 2007. Sorption Isotherms: A Review on Physical Bases, Modeling and Measurement. Applied Geochemistry, Volume 22(2), pp. 249–275

Marsh, H., Yan, D.S., O’Grady, T.M., Wennerberg, A., 1984. Formation of Active Carbons from Cokes using Potassium Hydroxide. Carbon, Volume 22(6), pp. 603–611

Martin, A., Loh, W.S., Rahman, K.A., Thu, K., Surayawan, B., Alhamid, M.I., Ng, K.C., 2011. Adsorption Isotherms of CH4 on Activated Carbon from Indonesian Low Grade Coal. Journal of Chemical & Engineering Data, Volume 56(3), pp. 361–367

Moreno-Castilla, C., Carrasco-Mar??n, F., López-Ramón, M.V., Alvarez-Merino, M.A., 2001. Chemical and Physical Activation of Olive-Mill Waste Water to Produce Activated Carbons. Carbon, Volume 39(9), pp. 1415–1420

Nandi, M., Okada, K., Dutta, A., Bhaumik, A., Maruyama, J., Derks, D., Uyama, H., 2012. Unprecedented CO2 Uptake over Highly Porous N-doped Activated Carbon Monoliths Prepared by Physical Activation. Chemical Communications, Volume 48(83), pp. 1028310285

Nasruddin, N., Kosasih, E.A., Kurniawan, B., Supriyadi, S., Zulkarnain, I.A., 2016. Optimization of Hydrogen Storage Capacity by Physical Adsorption on Open-ended Single-walled Carbon Nanotube as Diameter Function. International Journal of Technology, Volume 7(2), pp. 264–273

Niemann, U.M., Srinivasan, S.S., Phani, A.R., Kumar, A., Goswami, D.Y., Stefanakos, E.K., 2008. Nanomaterials for Hydrogen Storage Applications: A Review. Journal of Nanomaterials, Volume 2008, pp. 1–9

Nor, N.M., Sukri, M.F.F., Mohamed, A.R., 2016. Development of High Porosity Structures of Activated Carbon via Microwave-assisted Regeneration for H2S Removal. Journal of Environmental Chemical Engineering, Volume 4(4), pp. 4839–4845

Schlapbach, L., Züttel, A., 2001. Hydrogen-storage Materials for Mobile Applications. Nature, Volume 414(6861), pp. 353358

Sekirifa, M.L., Hadj-Mahammed, M., Pallier, S., Baameur, L., Richard, D., Al-Dujaili, A.H., 2013. Preparation and Characterization of an Activated Carbon from a Date Stones Variety by Physical Activation with Carbon Dioxide. Journal of Analytical and Applied Pyrolysis, Volume 99, pp. 155–160

Serrano, E., Guillermo, R., Javier, G.M., 2009. Nanotechnology for Sustainable Energy. Renewable and Sustainable Energy Reviews, Volume 13(9), pp. 2373–2384

Stoeckli, F., Jakubov, T., Lavanchy, A., 1994. Water Adsorption in Active Carbons Described by the Dubinin-Astakhov Equation. Journal of the Chemical Society, Faraday Transaction, Volume 90(5), pp. 783786

Sudibandriyo, M., Wulan, P.P., Prasodjo, P., 2015. Adsorption Capacity and Its Dynamic Behavior of the Hydrogen Storage on Carbon Nanotubes. International Journal of Technology, Volume 6(7), pp. 11281136

Tsai, W.T., Chang, C.Y., Lee, S.L., 1998. A low Cost Adsorbent from Agricultural Waste Corn Cob by Zinc Chloride Activation. Bioresource Technology, Volume 64(3), pp. 211–217

Ushiki, I., Ota, M., Sato, Y., Inomata, H., 2013. Measurement and Dubinin-Astakhov Correlation of Adsorption Equilibria of Toluene, Acetone, n-hexane, n-decane and Methanol Solutes in Supercritical Carbon Dioxide on Activated Carbon at Temperature from 313 to 353 K and at Pressure from 4.2 to 15.0 MPa. Fluid Phase Equilibria, Volume 344, pp. 101–107

Viswanathan, B., Neel, P.I., Varadarajan, T.K., 2009. Methods of Activation and Specific Applications of Carbon Materials. National Centre of Catalysis Research, Indian Institute of Technology Madras, Chennai, India

Welham, N.J., Berbenni, V., Chapman, P.G., 2002. Increased Chemisorption onto Activated Carbon After Ball-milling. Carbon, Volume 40(13), pp. 2307–2315

Wu, F.C., Wu, P.H., Tseng, R.L., Juang, R.S., 2014. Description of Gas Adsorption Isotherms on Activated Carbons with Heterogeneous Micropores using the Dubinin-Astakhov Equation. Journal of Taiwan Institute of Chemical Engineering, Volume 45(4), pp. 1757–1763