Surface characterization of a polyacrylonitrile based activated carbon and the effect of pH on its adsorption from aqueous phenol and 2,3,4-trichlorophenol solution

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Abstract

Granular highly nanoporous activated carbon was prepared from polyacrylonitrile (PAN). The BET surface area was found to be 544 m 2/g with Vtot = 0.278 cm3/g, and Vmicro = 0.266 cm3/g. Aqueous treatment reduced the surface area to 364 m2/g. This carbon contains O and N related surface functional groups. Surface groups containing these hetero atoms are responsible for the acid/base character of this carbon in aqueous solutions. The microporous pore network produces a wide hysteresis loop, observed when the granular carbon was studied by continuous titration. This loop, which was found to diminish, but not to disappear completely when the particle size was reduced, is attributed to irreversible hydrolysis of surface esters and/or lactones. The surface concentration of the functional groups fitrated by the equilibrium Boehm method is 449.2 μequiv/g, of which 112.9 μequiv /g have acidic and 336.3 μequiv/g have basic character. Within the acidic species three subgroups were distinguished corresponding to carboxylic, lactonic and phenolic surface groups. PAN based carbon was investigated as a means of removing weak aromatic acids, phenol and 2,3,4-trichlorophenol from aqueous solutions. Both the adsorption capacity and the overall interaction parameter, K (both derived from a fit to the Langmuir equation) depend on the adsorbed species and on the pH. The former is a consequence of the different water solubilities of the solute molecules, while the latter stems from the pH sensitivity of both the surface functional groups and these weak acids. The effect of pH is more marked for 2,3,4-trichlorophenol.

Original languageEnglish
Pages (from-to)105-116
Number of pages12
JournalPeriodica Polytechnica: Chemical Engineering
Volume47
Issue number2
Publication statusPublished - 2003

Fingerprint

Polyacrylonitriles
Phenol
Activated carbon
Phenols
Adsorption
Carbon
Functional groups
Acids
polyacrylonitrile
2,3,4-trichlorophenol
Lactones
Hysteresis loops
Titration
Carboxylic acids
Hydrolysis
Esters
Solubility
Particle size
Atoms
Molecules

Keywords

  • Activated carbon
  • Adsorption
  • Aqueous phenols

ASJC Scopus subject areas

  • Chemical Engineering(all)

Cite this

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title = "Surface characterization of a polyacrylonitrile based activated carbon and the effect of pH on its adsorption from aqueous phenol and 2,3,4-trichlorophenol solution",
abstract = "Granular highly nanoporous activated carbon was prepared from polyacrylonitrile (PAN). The BET surface area was found to be 544 m 2/g with Vtot = 0.278 cm3/g, and Vmicro = 0.266 cm3/g. Aqueous treatment reduced the surface area to 364 m2/g. This carbon contains O and N related surface functional groups. Surface groups containing these hetero atoms are responsible for the acid/base character of this carbon in aqueous solutions. The microporous pore network produces a wide hysteresis loop, observed when the granular carbon was studied by continuous titration. This loop, which was found to diminish, but not to disappear completely when the particle size was reduced, is attributed to irreversible hydrolysis of surface esters and/or lactones. The surface concentration of the functional groups fitrated by the equilibrium Boehm method is 449.2 μequiv/g, of which 112.9 μequiv /g have acidic and 336.3 μequiv/g have basic character. Within the acidic species three subgroups were distinguished corresponding to carboxylic, lactonic and phenolic surface groups. PAN based carbon was investigated as a means of removing weak aromatic acids, phenol and 2,3,4-trichlorophenol from aqueous solutions. Both the adsorption capacity and the overall interaction parameter, K (both derived from a fit to the Langmuir equation) depend on the adsorbed species and on the pH. The former is a consequence of the different water solubilities of the solute molecules, while the latter stems from the pH sensitivity of both the surface functional groups and these weak acids. The effect of pH is more marked for 2,3,4-trichlorophenol.",
keywords = "Activated carbon, Adsorption, Aqueous phenols",
author = "K. L{\'a}szl{\'o} and E. Tomb{\'a}cz and K. Josepovits",
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journal = "Periodica Polytechnica: Chemical Engineering",
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T1 - Surface characterization of a polyacrylonitrile based activated carbon and the effect of pH on its adsorption from aqueous phenol and 2,3,4-trichlorophenol solution

AU - László, K.

AU - Tombácz, E.

AU - Josepovits, K.

PY - 2003

Y1 - 2003

N2 - Granular highly nanoporous activated carbon was prepared from polyacrylonitrile (PAN). The BET surface area was found to be 544 m 2/g with Vtot = 0.278 cm3/g, and Vmicro = 0.266 cm3/g. Aqueous treatment reduced the surface area to 364 m2/g. This carbon contains O and N related surface functional groups. Surface groups containing these hetero atoms are responsible for the acid/base character of this carbon in aqueous solutions. The microporous pore network produces a wide hysteresis loop, observed when the granular carbon was studied by continuous titration. This loop, which was found to diminish, but not to disappear completely when the particle size was reduced, is attributed to irreversible hydrolysis of surface esters and/or lactones. The surface concentration of the functional groups fitrated by the equilibrium Boehm method is 449.2 μequiv/g, of which 112.9 μequiv /g have acidic and 336.3 μequiv/g have basic character. Within the acidic species three subgroups were distinguished corresponding to carboxylic, lactonic and phenolic surface groups. PAN based carbon was investigated as a means of removing weak aromatic acids, phenol and 2,3,4-trichlorophenol from aqueous solutions. Both the adsorption capacity and the overall interaction parameter, K (both derived from a fit to the Langmuir equation) depend on the adsorbed species and on the pH. The former is a consequence of the different water solubilities of the solute molecules, while the latter stems from the pH sensitivity of both the surface functional groups and these weak acids. The effect of pH is more marked for 2,3,4-trichlorophenol.

AB - Granular highly nanoporous activated carbon was prepared from polyacrylonitrile (PAN). The BET surface area was found to be 544 m 2/g with Vtot = 0.278 cm3/g, and Vmicro = 0.266 cm3/g. Aqueous treatment reduced the surface area to 364 m2/g. This carbon contains O and N related surface functional groups. Surface groups containing these hetero atoms are responsible for the acid/base character of this carbon in aqueous solutions. The microporous pore network produces a wide hysteresis loop, observed when the granular carbon was studied by continuous titration. This loop, which was found to diminish, but not to disappear completely when the particle size was reduced, is attributed to irreversible hydrolysis of surface esters and/or lactones. The surface concentration of the functional groups fitrated by the equilibrium Boehm method is 449.2 μequiv/g, of which 112.9 μequiv /g have acidic and 336.3 μequiv/g have basic character. Within the acidic species three subgroups were distinguished corresponding to carboxylic, lactonic and phenolic surface groups. PAN based carbon was investigated as a means of removing weak aromatic acids, phenol and 2,3,4-trichlorophenol from aqueous solutions. Both the adsorption capacity and the overall interaction parameter, K (both derived from a fit to the Langmuir equation) depend on the adsorbed species and on the pH. The former is a consequence of the different water solubilities of the solute molecules, while the latter stems from the pH sensitivity of both the surface functional groups and these weak acids. The effect of pH is more marked for 2,3,4-trichlorophenol.

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