Comparative study of sorption kinetics and equilibrium of chromium (VI) on charcoals prepared from different low-cost materials

Margit Varga, Mihály Takács, G. Záray, Imre Varga

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

In the present study three types of agricultural waste materials, peanut shell, lapsi seeds and energy grass were carbonized by the same carbonization methods using mineral acids at elevated temperature. The resulted charcoals having approximately 60% carbon content were applied as low-cost adsorbents for the removal of Cr(VI) from aqueous solutions. The sorption kinetics at pH=1 and the sorption isotherms at different pHs were studied. Chromium concentration was measured by flame atomic absorption spectrometry (F-AAS) in the residual solution by an indirect way and was additionally checked by direct measurement using an XRF spectrometer. The adsorption isotherms were modeled by Langmuir and Redlich-Peterson equation. In order to achieve the maximal adsorption pH=1 was found to be optimal at every investigated charcoals. The maximal adsorption capacity varied between 205 and 230; 85 and 138; 34 and 40; and 30 and 33mgg-1 at pH=1; 2; 3; and 4 respectively at the different charcoals. The obtained pseudo-second-order rate constant was k2=4.0×10-4gmg-1min-1 at each type of activated carbons. The bond of Cr(VI) to the functional groups of charcoal seems to be irreversible in the case of dried Cr(VI) saturated charcoals. Both the model studies and the dissolution experiments provided evidence for this result. It was supposed on the basis of our results, that Cr(VI) bonds chemically to the activated carbon consequently the Cr(VI) saturated charcoals had no more contaminating effect in the environment.

Original languageEnglish
Pages (from-to)25-30
Number of pages6
JournalMicrochemical Journal
Volume107
DOIs
Publication statusPublished - Mar 2013

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Charcoal
Sorption
Kinetics
Costs
Activated carbon
Adsorption
Agricultural wastes
Atomic absorption spectrometry
Carbonization
Chromium
Adsorption isotherms
Adsorbents
Functional groups
Minerals
Isotherms
Seed
chromium hexavalent ion
Spectrometers
Rate constants
Dissolution

Keywords

  • Activated carbon
  • Adsorption
  • Agricultural waste
  • Charcoal
  • Chromium
  • Kinetics

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy

Cite this

Comparative study of sorption kinetics and equilibrium of chromium (VI) on charcoals prepared from different low-cost materials. / Varga, Margit; Takács, Mihály; Záray, G.; Varga, Imre.

In: Microchemical Journal, Vol. 107, 03.2013, p. 25-30.

Research output: Contribution to journalArticle

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