Comparison of parameters calculated from the BET and Freundlich isotherms obtained by nitrogen adsorption on activated carbons: A new method for calculating the specific surface area

Passé-Coutrin, Nady; Altenor, Sandro; Cossement, Daniel; Jean-Marius, Corine; Gaspard, Sarra

doi:10.1016/j.micromeso.2007.08.032

Cited by 113 publications

(48 citation statements)

References 17 publications

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“…The specific surface areas of the carbons were calculated by the BET method (Passe-Coutrin et al 2008). The Dubinin-Raduskevich equation was applied to characterize the microporosity of the AC samples (Scherdel et al 2010), as follows,…”

Section: Analysis Of Surface Area and Pore Characteristicsmentioning

confidence: 99%

An Effective Method to Enhance Adsorption Capacity and Mesoporosity of Activated Carbon by Pre-Pyrolysis and Chemical Activation Procedures

Liou¹,

Wang²,

Liou³

2016

BioResources

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Activated carbons with large adsorption capacity and high mesopore fraction were obtained from rice straw by a combination of pre-pyrolysis and NaOH activation procedures. The experiments varied the prepyrolysis procedure, impregnation ratio of activating agent, and activation temperature. Samples were examined by inductively coupled plasmamass spectrometry (ICP-MS), X-ray diffractometry (XRD), field-emission scanning-electronic microscopy (FE-SEM), thermogravimetric analysis (TGA), and N2-adsorption analysis. The surface area and pore characteristics of the activated carbons were investigated by the Brunauer, Emmett, Teller (BET) method, Dubinin-Raduch (DR) model, and the t-plot method. The surface area, pore volume, and iodine adsorption capacity of the samples increased with increasing activation temperature and the impregnation ratio of the activating agent. A maximum surface area of 2093 m 2 /g was obtained at the activation temperature of 900 °C. The pore structure in the one-stage activation procedure was mainly microporous. Two-stage activation procedure efficiently enhanced mesopore volume, and therefore further increased the adsorption capacity of activated carbons. NaOH acted as both the activating agent in the reaction and as the cleaner to remove the ash. The results of this experiment will be useful in developing resource recovery systems from agricultural biomass.

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Section: Analysis Of Surface Area and Pore Characteristicsmentioning

confidence: 99%

An Effective Method to Enhance Adsorption Capacity and Mesoporosity of Activated Carbon by Pre-Pyrolysis and Chemical Activation Procedures

Liou¹,

Wang²,

Liou³

2016

BioResources

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“…O método usualmente empregado na determinação da área superficial é a análise das isotermas de adsorção/dessorção usando os modelos de BET (Brunauer, Emmett e Teller) ou BJH (Barrett, Joyner e Halenda) [22,23,24,25,26]. Os porosímetros por intrusão de mercúrio são normalmente usados na determinação das propriedades estruturais dos poros dos materiais [27,28].…”

Section: Introductionunclassified

Uso da voltametria cíclica e da espectroscopia de impedância eletroquímica na determinação da área superficial ativa de eletrodos modificados à base de carbono

Souza

Forbicini

2016

Eclet. Quim.

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Carbon-based electrodes as well the ion exchange electrodes among others have been applied mainly in the treatment of industrial effluents and radioactive wastes. Carbon is also used in fuel cells as substrate for the electrocatalysts, having high surface area which surpasses its geometric area. The knowledge of the total active area is important for the determination of operating conditions of an electrochemical cell with respect to the currents to be applied (current density). In this study it was used two techniques to determine the electrochemical active surface area of glassy carbon, electrodes and ion exchange electrodes: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experiments were carried out with 0.1 mol.L-1 KNO3 solutions in a three-electrode electrochemical cell: carbon-based working electrode, platinum auxiliary electrode and Ag/AgCl reference electrode. The glassy carbon and porous carbon electrodes with geometric areas of 3.14 x 10-2 and 2.83 х 10-1 cm2, respectively, were used. The ion exchange electrode was prepared by mixing graphite, carbon, ion exchange resin and a binder, and this mixture was applied in three layers on carbon felt, using a geometric area of 1.0 cm2 during the experiments. The capacitance (Cd) of the materials was determined by EIS using Bode diagrams. The value of 172 μF.cm-2 found for the glassy carbon is consistent with the literature data (~200 μF.cm-2). By VC, varying the scan rate from 0.2 to 2 mV.s-1, the capacitance CdS (S = active surface area) in the region of the electric double layer (EDL) of each material was determined. By EIS, the values of Cd, 3.0 x 10-5 μF.cm-2 and 11 x 103 μF.cm-2, were found for the porous carbon and ion exchange electrodes, respectively, which allowed the determination of active surface areas as 3.73 x 106 cm2 and 4.72 cm2. To sum up, the combined use of EIS and CV techniques is a valuable tool for the calculation of active surface areas of carbon-based electrodes.

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“…A forma empírica de uma isoterma de adsorção foi reconhecida em 1926 por Freundlich [35] , e, mais tarde, foi derivada teoricamente a partir da equação de Langmuir [35,36] , com a adoção do mecanismo de Langmuir e a introdução de uma série de hipóteses simplificadoras, os pesquisadores Brunauer, Emmet e Teller desenvolveram o método de BET [9,35,36,37] , para determinar a efetiva área de materiais sólidos que apresentam complicadas formas, tais como os materiais particulados porosos. A superfície de um pó é um fator importante que determina muitas de suas propriedades.…”

Section: Modelo Betunclassified

“…Ou seja, pela efetiva área de cada uma das moléculas de gás adsorvido pelo material sólido pode-se determinar sua área total [9,35,36] . Isto resulta na seguinte equação que descreve a isoterma: …”

Section: Modelo Betunclassified

“…A EIE é uma técnica eletroanalítica onde se aplica um potencial de [1] ;  A região da Dupla Camada Elétrica (DCE) é determinada com o intervalo entre os picos de redução e oxidação do eletrólito [1,41-44, 55, 56] ;  Tempo do ensaio depende da velocidade de varredura [1] ;  Em caso de perturbações no ensaio os pontos obtidos serão do potencial de equilíbrio [1,17,21,22] ;  Requer elevada relação superfície/volume do eletrodo poroso [1] ; Impedância  Utilização de sinais muitos pequenos que não perturbam as propriedades do eletrodo [15,[45][46][47] ;  Possibilidade de estudar reações Redox e medir as taxas destas reações em meios de baixa condutividade [15, 45-47, 49, 50] ;  A resistência de polarização e a capacitância da dupla camada podem ser determinadas numa mesma medida [15, 45-47, 49, 50] ;  A cinética eletródica é determinada por outros métodos [15,[45][46][47] ; BET  Determinação acurada da área superficial da amostra, independe da morfologia da partícula [9,10,35,37] ;  Depende da massa da amostra, precisa de um tamanho pré-determinado da amostra [9,10,35,37] ; Oxidação do CO  Permite determinar a área superficial ativa dos eletrodos das CaC [12,13,39,40,48] ;  Este método permite determinar a área superficial dos eletrodos das CaC, mas somente dos eletrocatalisadores metálicos, aplicação esta relacionada com muitas incertezas [12,39,40,48] ;…”

Section: Introductionunclassified

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Uso da voltametria cíclica e da espectroscopia de impedância eletroquímica na determinação da área superficial ativa de eletrodos modificados à base de carbono

Souza¹

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Comparison of parameters calculated from the BET and Freundlich isotherms obtained by nitrogen adsorption on activated carbons: A new method for calculating the specific surface area

Cited by 113 publications

References 17 publications

An Effective Method to Enhance Adsorption Capacity and Mesoporosity of Activated Carbon by Pre-Pyrolysis and Chemical Activation Procedures

An Effective Method to Enhance Adsorption Capacity and Mesoporosity of Activated Carbon by Pre-Pyrolysis and Chemical Activation Procedures

Uso da voltametria cíclica e da espectroscopia de impedância eletroquímica na determinação da área superficial ativa de eletrodos modificados à base de carbono

Uso da voltametria cíclica e da espectroscopia de impedância eletroquímica na determinação da área superficial ativa de eletrodos modificados à base de carbono

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