Artículo
Characterization of PSD of activated carbons by using slit and triangular pore geometries
Azevedo, D. C. S.; Rios, R. B.; López, Raúl Horacio
; Torres, A. E. B.; Cavalcante, C. L.; Toso, J. P.; Zgrablich, Jorge Andres
Fecha de publicación:
06/2010
Editorial:
Elsevier Science
Revista:
Applied Surface Science
ISSN:
0169-4332
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
A mixed geometry model for activated carbons, representing the porous space as a collection of an undetermined proportion of slit and triangular pores, is developed, evaluated theoretically and applied to the characterization of a controlled series of samples of activated carbon obtained from the same precursor material. A method is proposed for the determination of the Pore Size Distribution (PSD) for such a mixed geometry model, leading to the unique determination of the proportion of pores of the two geometries fitting adsorption data. By using the Grand Canonical Monte Carlo (GCMC) simulation method in the continuum space, families of N2 adsorption isotherms are generated both for slit and triangular geometry corresponding to different pore sizes. The problem of the uniqueness in the determination of the PSD by fitting an adsorption isotherm using the mixed geometry model is then discussed and the effects of the addition of triangular pores on the PSD are analyzed by performing a test where the adsorption isotherm corresponding to the known PSD is generated and used as the “experimental” isotherm. It is found that a pure slit geometry model would widen the PSD and shift it to smaller sizes, whereas a pure triangular geometry model would produce the opposite effect. The slit and triangular geometry families of isotherms are finally used to the fit experimental N2 adsorption data corresponding to a family of activated carbons obtained from coconut shells through a one-step chemical activation process with phosphoric acid in air, allowing for the determination of the micropore volume, the proportion of slit and triangular pores and the PSD corresponding to the mixed geometry. The same experimental data were fit using both the conventional slit pore model and the mixed geometry model. From the analysis of the effect of different preparation procedures on the resulting PSDs, it is concluded that the proposed mixed geometry model may probably better capture the morphology and energetics of activated carbons prepared by chemical activation under mild temperatures.
Palabras clave:
Psd
,
Activated Carbon
,
Phosphoric Acid
,
Mixed Geometry
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Articulos(INFAP)
Articulos de INST. DE FISICA APLICADA "DR. JORGE ANDRES ZGRABLICH"
Articulos de INST. DE FISICA APLICADA "DR. JORGE ANDRES ZGRABLICH"
Citación
Azevedo, D. C. S.; Rios, R. B.; López, Raúl Horacio; Torres, A. E. B.; Cavalcante, C. L.; et al.; Characterization of PSD of activated carbons by using slit and triangular pore geometries; Elsevier Science; Applied Surface Science; 256; 17; 6-2010; 5191-5197
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