Characterization of Cr sorption and reduction on TiO2: Batch and XPS studies

Dinh Hung Doan, Young Jae Kim, Trung Minh Nguyen, Hye On Yoon, Sae Gang Oh, Ho Young Jo, Young Jae Lee

Research output: Contribution to journalArticle

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Abstract

Cr interactions with TiO2 were systematically studied using batch and spectroscopic investigations. Sorption of chromium on TiO2 at pH 4.5 increases with increasing Cr concentration. The sorption of Cr(III) is in good agreement with Langmuir isotherm model, whereas that of Cr(VI) is better accounted for by the Freundlich model. At pH 7.0, however, the uptake of Cr(III) by TiO2 is over 95 %, while the extent of Cr(VI) sorption on TiO2 is much less than that of pH 4.5. These results are consistent with SEM observations showing that precipitates of Cr(III) are dominant under neutral pH. The sorption of Cr(VI) on TiO2 decreases with increasing pH. However, Cr(VI) sorption decreases with increasing ionic strength below pH 4.5 whereas the sorption increases with ionic strength above pH 4.5. These observations suggest that Cr(VI) sorption is sensitive to ionic strength, and Cr(VI) could form weakly bound adsorption complexes at the TiO2-water interface. Phosphate competes with Cr(VI) for TiO2 surface sites during sorption processes, and Cr(VI) desorption accelerates and increases in the presence of phosphate. It is noted that the reduction of Cr(VI) is induced by sunlight on the TiO2 surface, but not detected in acidic solution throughout batch experiments at pH≥4.5 for 24 h.

Original languageEnglish
Article number2252
JournalWater, Air, and Soil Pollution
Volume226
Issue number1
DOIs
Publication statusPublished - 2014 Jan 1

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X-ray spectroscopy
Sorption
X ray photoelectron spectroscopy
sorption
Ionic strength
Phosphates
phosphate
chromium hexavalent ion
Chromium
Isotherms
chromium
Precipitates
Desorption
desorption
isotherm
scanning electron microscopy
adsorption
Adsorption
Scanning electron microscopy
Water

ASJC Scopus subject areas

  • Pollution
  • Environmental Chemistry
  • Environmental Engineering
  • Ecological Modelling
  • Water Science and Technology

Cite this

Characterization of Cr sorption and reduction on TiO2 : Batch and XPS studies. / Doan, Dinh Hung; Kim, Young Jae; Nguyen, Trung Minh; Yoon, Hye On; Oh, Sae Gang; Jo, Ho Young; Lee, Young Jae.

In: Water, Air, and Soil Pollution, Vol. 226, No. 1, 2252, 01.01.2014.

Research output: Contribution to journalArticle

Doan, Dinh Hung ; Kim, Young Jae ; Nguyen, Trung Minh ; Yoon, Hye On ; Oh, Sae Gang ; Jo, Ho Young ; Lee, Young Jae. / Characterization of Cr sorption and reduction on TiO2 : Batch and XPS studies. In: Water, Air, and Soil Pollution. 2014 ; Vol. 226, No. 1.
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N2 - Cr interactions with TiO2 were systematically studied using batch and spectroscopic investigations. Sorption of chromium on TiO2 at pH 4.5 increases with increasing Cr concentration. The sorption of Cr(III) is in good agreement with Langmuir isotherm model, whereas that of Cr(VI) is better accounted for by the Freundlich model. At pH 7.0, however, the uptake of Cr(III) by TiO2 is over 95 %, while the extent of Cr(VI) sorption on TiO2 is much less than that of pH 4.5. These results are consistent with SEM observations showing that precipitates of Cr(III) are dominant under neutral pH. The sorption of Cr(VI) on TiO2 decreases with increasing pH. However, Cr(VI) sorption decreases with increasing ionic strength below pH 4.5 whereas the sorption increases with ionic strength above pH 4.5. These observations suggest that Cr(VI) sorption is sensitive to ionic strength, and Cr(VI) could form weakly bound adsorption complexes at the TiO2-water interface. Phosphate competes with Cr(VI) for TiO2 surface sites during sorption processes, and Cr(VI) desorption accelerates and increases in the presence of phosphate. It is noted that the reduction of Cr(VI) is induced by sunlight on the TiO2 surface, but not detected in acidic solution throughout batch experiments at pH≥4.5 for 24 h.

AB - Cr interactions with TiO2 were systematically studied using batch and spectroscopic investigations. Sorption of chromium on TiO2 at pH 4.5 increases with increasing Cr concentration. The sorption of Cr(III) is in good agreement with Langmuir isotherm model, whereas that of Cr(VI) is better accounted for by the Freundlich model. At pH 7.0, however, the uptake of Cr(III) by TiO2 is over 95 %, while the extent of Cr(VI) sorption on TiO2 is much less than that of pH 4.5. These results are consistent with SEM observations showing that precipitates of Cr(III) are dominant under neutral pH. The sorption of Cr(VI) on TiO2 decreases with increasing pH. However, Cr(VI) sorption decreases with increasing ionic strength below pH 4.5 whereas the sorption increases with ionic strength above pH 4.5. These observations suggest that Cr(VI) sorption is sensitive to ionic strength, and Cr(VI) could form weakly bound adsorption complexes at the TiO2-water interface. Phosphate competes with Cr(VI) for TiO2 surface sites during sorption processes, and Cr(VI) desorption accelerates and increases in the presence of phosphate. It is noted that the reduction of Cr(VI) is induced by sunlight on the TiO2 surface, but not detected in acidic solution throughout batch experiments at pH≥4.5 for 24 h.

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