Reference : Effect of CO2 activation of carbon xerogels on the adsorption of methylene blue
Scientific journals : Article
Engineering, computing & technology : Materials science & engineering
Engineering, computing & technology : Chemical engineering
http://hdl.handle.net/2268/134247
Effect of CO2 activation of carbon xerogels on the adsorption of methylene blue
English
Páez Martínez, Carlos mailto [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Génie catalytique >]
Contreras, M. S. [Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, B6a, 4000 Liège, Belgium, TADiP Group, Department of Thermodynamics and Transport Phenomena, Simón Bolívar University, Caracas 1080, Venezuela]
Léonard, Angélique mailto [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Procédés et développement durable >]
Blacher, Silvia mailto [Université de Liège - ULg > Département des sciences cliniques > Labo de biologie des tumeurs et du développement >]
Olivera-Fuentes, C. G. [TADiP Group, Department of Thermodynamics and Transport Phenomena, Simón Bolívar University, Caracas 1080, Venezuela]
Pirard, Jean-Paul mailto [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Génie catalytique >]
Job, Nathalie mailto [Université de Liège - ULg > Département de chimie appliquée > Département de chimie appliquée >]
2012
Adsorption
Springer
18
3-4
199-211
Yes (verified by ORBi)
International
0929-5607
1572-8757
US
[en] Carbon xerogel ; CO 2-activation ; Intraparticle diffusion ; Kinetics ; Methylene blue adsorption ; Activation conditions ; Adsorption capacities ; Batch kinetics ; Carbon material ; Carbon surface ; Carbon xerogels ; Different mechanisms ; Effect of CO ; Graphene layers ; High-activation ; Initial rate ; Intra-particle diffusion ; Isotherm studies ; Langmuir isotherm ; Low activation ; Methylene Blue ; Micropore volumes ; Microporous activated carbons ; Monolayer coverage ; Physical activation ; Pseudo-first-order ; Pseudo-second-order kinetic models ; Rate limiting ; Rate-limiting steps ; Resorcinol formaldehydes ; Solid/liquid interfaces ; Surface area ; Activated carbon ; Adsorption ; Adsorption isotherms ; Aromatic compounds ; Binding energy ; Diffusion ; Enzyme kinetics ; Graphene ; Kinetic theory ; Microporosity ; Microporous materials ; Monolayers ; Reaction kinetics ; Carbon dioxide
[en] The effect of physical activation with CO2 of carbon xerogels, synthesized by pyrolysis of a resorcinolformaldehyde aqueous gel, on the adsorption capacities of Methylene Blue (MB) was studied. The activation with CO2 lead to carbon materials with micropore volumes ranging from 0.28 to 0.98 cm³/g -1 C. MB-adsorption isotherm studies showed that the increase of micropore volume and corresponding surface area led to: (i) a significant improvement in the capacity of MB-adsorption at monolayer coverage, from 212 to 714 mgg
-1 C, and (ii) an increase of the binding energy related to Langmuir isotherm constant up to 45 times greater than those of commercial microporous activated carbons used as reference (NORIT R2030, CALGON BPL and CALGON NC35). It is proposed that the increase of the binding energy results from chemical cleaning of the O-groups onto carbon surface as a consequence of CO2-activation, increasing the π-π interaction between MB and graphene layers of the carbon xerogels. Finally, a series of batch kinetics were performed to investigate the effect of CO2-activation conditions on the mechanism of MB-adsorption. Experimental data were fitted using pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. From pseudo-second-order kinetic model, one observes an increase in the initial rate of MB-adsorption from 0.019 to 0.0565 min
-1, by increasing the specific surface area from 630 to 2180 m²/g
-1 C via CO2-activation. Depending on the activation degree of the carbons, two different mechanisms control the MB-adsorption rate: (i) at low activation degree, the intraparticle diffusion is the rate-limiting phenomenon, whereas (ii) at high activation degree, the reactions occurring at the solid/liquid interface are the rate-limiting steps. © 2012 Springer Science+Business Media, LLC.
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS
Researchers ; Professionals
http://hdl.handle.net/2268/134247
10.1007/s10450-012-9394-2

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