Adsorption of a reactive dye on chemically modified activated carbons - Influence of pH

J. J. M. Órfão, Andreia I. M. Silva, João C. V. Pereira, S. A. Barata, I. M. Fonseca, Patrícia C. C. Faria, Manuel Fernando R. Pereira

Research output: Contribution to journalArticle

228 Citations (Scopus)

Abstract

The surface chemistry of a commercial activated carbon with a slightly basic nature was modified by appropriate treatments in order to obtain two additional samples, respectively with acidic and basic properties, without changing its textural parameters significantly. Different techniques (N 2 adsorption at 77 K, temperature programmed desorption, and determination of acidity, basicity, and pH at the point of zero charge) were used to characterize the adsorbents. Kinetic and equilibrium adsorption data of a selected textile reactive dye (Rifafix Red 3BN, C.I. reactive red 241) on the mentioned materials were obtained at the pH values of 2, 7, and 12. The kinetic curves are fitted using the second-order model. The respective rate constants seem to diminish progressively with the initial concentration for the more diluted solutions tested, reaching a constant value at higher concentrations, which depends on the experimental system under consideration (adsorbent and pH). In general, the Langmuir model provides the best fit for the equilibrium data. The different uptakes obtained are discussed in relation to the surface chemical properties of the adsorbents. It is shown that the adsorption of the reactive (anionic) dye on the basic sample (prepared by thermal treatment under H 2 flow at 700 °C) is favored. This conclusion is explained on the basis of the dispersive and electrostatic interactions involved. Moreover, it is also shown that the optimal adsorption condition for all the activated carbons tested corresponds to solution pH values not higher than the pH pzc of the adsorbents, which may be interpreted by taking into account the electrostatic forces present.

Original languageEnglish
Pages (from-to)480-489
Number of pages10
JournalJournal of Colloid and Interface Science
Volume296
Issue number2
DOIs
Publication statusPublished - 15 Apr 2006

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Activated carbon
Adsorbents
Coloring Agents
Dyes
Adsorption
Kinetics
Electrostatic force
Temperature programmed desorption
Alkalinity
Coulomb interactions
Surface chemistry
Acidity
Chemical properties
Rate constants
Textiles
Heat treatment

Keywords

  • Activated carbon
  • Adsorption
  • pH
  • Reactive dyes
  • Surface chemistry

Cite this

Órfão, J. J. M. ; Silva, Andreia I. M. ; Pereira, João C. V. ; Barata, S. A. ; Fonseca, I. M. ; Faria, Patrícia C. C. ; Pereira, Manuel Fernando R. / Adsorption of a reactive dye on chemically modified activated carbons - Influence of pH. In: Journal of Colloid and Interface Science. 2006 ; Vol. 296, No. 2. pp. 480-489.
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title = "Adsorption of a reactive dye on chemically modified activated carbons - Influence of pH",
abstract = "The surface chemistry of a commercial activated carbon with a slightly basic nature was modified by appropriate treatments in order to obtain two additional samples, respectively with acidic and basic properties, without changing its textural parameters significantly. Different techniques (N 2 adsorption at 77 K, temperature programmed desorption, and determination of acidity, basicity, and pH at the point of zero charge) were used to characterize the adsorbents. Kinetic and equilibrium adsorption data of a selected textile reactive dye (Rifafix Red 3BN, C.I. reactive red 241) on the mentioned materials were obtained at the pH values of 2, 7, and 12. The kinetic curves are fitted using the second-order model. The respective rate constants seem to diminish progressively with the initial concentration for the more diluted solutions tested, reaching a constant value at higher concentrations, which depends on the experimental system under consideration (adsorbent and pH). In general, the Langmuir model provides the best fit for the equilibrium data. The different uptakes obtained are discussed in relation to the surface chemical properties of the adsorbents. It is shown that the adsorption of the reactive (anionic) dye on the basic sample (prepared by thermal treatment under H 2 flow at 700 °C) is favored. This conclusion is explained on the basis of the dispersive and electrostatic interactions involved. Moreover, it is also shown that the optimal adsorption condition for all the activated carbons tested corresponds to solution pH values not higher than the pH pzc of the adsorbents, which may be interpreted by taking into account the electrostatic forces present.",
keywords = "Activated carbon, Adsorption, pH, Reactive dyes, Surface chemistry",
author = "{\'O}rf{\~a}o, {J. J. M.} and Silva, {Andreia I. M.} and Pereira, {Jo{\~a}o C. V.} and Barata, {S. A.} and Fonseca, {I. M.} and Faria, {Patr{\'i}cia C. C.} and Pereira, {Manuel Fernando R.}",
note = "The authors are indebted to NORIT N.V., Amersfoort, the Netherlands, for providing the commercial activated carbon. This work was carried out with the support of the Funda{\cc}{\~a}o para a Ci{\^e}ncia e a Tecnologia (FCT) under program POCTI/FEDER (POCTI/1181) and Ag{\^e}ncia de Inova{\cc}{\~a}o (AdI) under program POCTI/FEDER (Project ANOXITRATA). P.C.C. Faria and S.A. Barata thank FCT for the research grants BD/16966/2004 and BD/13776/2003, respectively.",
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Adsorption of a reactive dye on chemically modified activated carbons - Influence of pH. / Órfão, J. J. M.; Silva, Andreia I. M.; Pereira, João C. V.; Barata, S. A.; Fonseca, I. M.; Faria, Patrícia C. C.; Pereira, Manuel Fernando R.

In: Journal of Colloid and Interface Science, Vol. 296, No. 2, 15.04.2006, p. 480-489.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Adsorption of a reactive dye on chemically modified activated carbons - Influence of pH

AU - Órfão, J. J. M.

AU - Silva, Andreia I. M.

AU - Pereira, João C. V.

AU - Barata, S. A.

AU - Fonseca, I. M.

AU - Faria, Patrícia C. C.

AU - Pereira, Manuel Fernando R.

N1 - The authors are indebted to NORIT N.V., Amersfoort, the Netherlands, for providing the commercial activated carbon. This work was carried out with the support of the Fundação para a Ciência e a Tecnologia (FCT) under program POCTI/FEDER (POCTI/1181) and Agência de Inovação (AdI) under program POCTI/FEDER (Project ANOXITRATA). P.C.C. Faria and S.A. Barata thank FCT for the research grants BD/16966/2004 and BD/13776/2003, respectively.

PY - 2006/4/15

Y1 - 2006/4/15

N2 - The surface chemistry of a commercial activated carbon with a slightly basic nature was modified by appropriate treatments in order to obtain two additional samples, respectively with acidic and basic properties, without changing its textural parameters significantly. Different techniques (N 2 adsorption at 77 K, temperature programmed desorption, and determination of acidity, basicity, and pH at the point of zero charge) were used to characterize the adsorbents. Kinetic and equilibrium adsorption data of a selected textile reactive dye (Rifafix Red 3BN, C.I. reactive red 241) on the mentioned materials were obtained at the pH values of 2, 7, and 12. The kinetic curves are fitted using the second-order model. The respective rate constants seem to diminish progressively with the initial concentration for the more diluted solutions tested, reaching a constant value at higher concentrations, which depends on the experimental system under consideration (adsorbent and pH). In general, the Langmuir model provides the best fit for the equilibrium data. The different uptakes obtained are discussed in relation to the surface chemical properties of the adsorbents. It is shown that the adsorption of the reactive (anionic) dye on the basic sample (prepared by thermal treatment under H 2 flow at 700 °C) is favored. This conclusion is explained on the basis of the dispersive and electrostatic interactions involved. Moreover, it is also shown that the optimal adsorption condition for all the activated carbons tested corresponds to solution pH values not higher than the pH pzc of the adsorbents, which may be interpreted by taking into account the electrostatic forces present.

AB - The surface chemistry of a commercial activated carbon with a slightly basic nature was modified by appropriate treatments in order to obtain two additional samples, respectively with acidic and basic properties, without changing its textural parameters significantly. Different techniques (N 2 adsorption at 77 K, temperature programmed desorption, and determination of acidity, basicity, and pH at the point of zero charge) were used to characterize the adsorbents. Kinetic and equilibrium adsorption data of a selected textile reactive dye (Rifafix Red 3BN, C.I. reactive red 241) on the mentioned materials were obtained at the pH values of 2, 7, and 12. The kinetic curves are fitted using the second-order model. The respective rate constants seem to diminish progressively with the initial concentration for the more diluted solutions tested, reaching a constant value at higher concentrations, which depends on the experimental system under consideration (adsorbent and pH). In general, the Langmuir model provides the best fit for the equilibrium data. The different uptakes obtained are discussed in relation to the surface chemical properties of the adsorbents. It is shown that the adsorption of the reactive (anionic) dye on the basic sample (prepared by thermal treatment under H 2 flow at 700 °C) is favored. This conclusion is explained on the basis of the dispersive and electrostatic interactions involved. Moreover, it is also shown that the optimal adsorption condition for all the activated carbons tested corresponds to solution pH values not higher than the pH pzc of the adsorbents, which may be interpreted by taking into account the electrostatic forces present.

KW - Activated carbon

KW - Adsorption

KW - pH

KW - Reactive dyes

KW - Surface chemistry

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U2 - 10.1016/j.jcis.2005.09.063

DO - 10.1016/j.jcis.2005.09.063

M3 - Article

VL - 296

SP - 480

EP - 489

JO - Journal of Colloid and Interface Science

JF - Journal of Colloid and Interface Science

SN - 0021-9797

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