Pore size distributions derived from adsorption isotherms, immersion calorimetry, and isosteric heats: A comparative study

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Title: Pore size distributions derived from adsorption isotherms, immersion calorimetry, and isosteric heats: A comparative study
Authors: Madani, S. Hadi | Hu, Cheng | Silvestre Albero, Ana | Biggs, Mark J. | Rodríguez Reinoso, Francisco | Pendleton, Phillip
Research Group/s: Materiales Avanzados
Center, Department or Service: Universidad de Alicante. Departamento de Química Inorgánica | Universidad de Alicante. Instituto Universitario de Materiales
Keywords: Pore size distribution | Activated carbon | Adsorption isotherms | Immersion calorimetry | Isosteric heats
Knowledge Area: Química Inorgánica
Issue Date: Jan-2016
Publisher: Elsevier
Citation: Carbon. 2016, 96: 1106-1113. doi:10.1016/j.carbon.2015.10.072
Abstract: We compare the pore size distribution of a well-characterized activated carbon derived from model-dependent, adsorption integral equation (AIE) methods with those from model-independent, immersion calorimetry and isosteric heat analyses. The AIE approach applied to nitrogen gave a mean pore width of 0.57 nm; the CO2 distribution exhibited wider dispersion. Spherical model application to CO2 and diffusion limitations for nitrogen and argon were proposed as primary reasons for inconsistency. Immersion enthalpy revealed a sharp decrease in available area equivalent to a cut-off due to molecular exclusion when the accessible surface was assessed against probe kinetic diameter. Mean pore width was identified as 0.58 ± 0.02 nm, endorsing the underlying assumptions for the nitrogen-based AIE approach. A comparison of the zero-coverage isosteric heat of adsorption for various non-polar adsorptives by the porous test sample was compared with the same adsorptives in contact with a non-porous reference adsorbent, leading to an energy ratio or adsorption enhancement factor. A linear relationship between the energy ratio and probe kinetic diameter indicated a primary pore size at 0.59 nm. The advantage of this enthalpy, model-independent methods over AIE were due to no assumptions regarding probe molecular shape, and no assumptions for pore shape and/or connectivity.
Sponsor: The authors thank the Australian Research Council discovery program (DP110101293) for funding support and S.H.M also thanks the University of South Australia for a postgraduate research scholarship and travel support to Alicante. C.H. acknowledges a joint scholarship provided by China Scholarship Council (CSC) and the University of Adelaide.
URI: http://hdl.handle.net/10045/57839
ISSN: 0008-6223 (Print) | 1873-3891 (Online)
DOI: 10.1016/j.carbon.2015.10.072
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2015 Elsevier Ltd.
Peer Review: si
Publisher version: http://dx.doi.org/10.1016/j.carbon.2015.10.072
Appears in Collections:INV - LMA - Artículos de Revistas

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