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Issue 8, 2009
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Exploring surface chemistry of nano-TiO2 for automated speciation analysis of Cr(III) and Cr(VI) in drinking water using flow injection and ET-AAS detection

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Abstract

The surface chemistry of TiO2 as well as the powerful adsorption capability of the nanometre material was used to separate inorganic chromium species in this work. When the pH of the sample solution is lower than the isoelectric point of TiO2, its surface is positively charged and anions of Cr(VI) can be adsorbed; on the contrary, the surface is negatively charged and cations of Cr(III) can be caught. Maximum adsorption rates of 34.5% and 95.4% for Cr(VI) at pH 3 and Cr(III) at pH 6 were obtained, respectively. Possible adsorption mechanisms were discussed considering the surface chemistry of TiO2 and the coordination chemistry of Ti, O and Cr. A simple and automated chromium speciation method was therefore developed using flow injection minicolumn separation and electrothermal atomic absorption spectrometric detection (ET-AAS). The adsorption and elution were incorporated in a flow injection program for selective preconcentration of Cr(III) or Cr(VI). As a result, no extra oxidizing/reducing process was necessary for an automated chromium speciation analysis. Factors influencing adsorption and elution of inorganic chromium species were carefully investigated. Detection limits as low as 0.01 µg L−1 for Cr(VI) and 0.006 µg L−1 for Cr(III) were achieved. The proposed method is highly sensitive and selective for inorganic chromium speciation analysis of drinking water.

Graphical abstract: Exploring surface chemistry of nano-TiO2 for automated speciation analysis of Cr(iii) and Cr(vi) in drinking water using flow injection and ET-AAS detection

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Publication details

The article was received on 02 Mar 2009, accepted on 14 May 2009 and first published on 04 Jun 2009


Article type: Paper
DOI: 10.1039/B904271G
Citation: J. Anal. At. Spectrom., 2009,24, 1098-1104

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    Exploring surface chemistry of nano-TiO2 for automated speciation analysis of Cr(III) and Cr(VI) in drinking water using flow injection and ET-AAS detection

    P. Wu, H. Chen, G. Cheng and X. Hou, J. Anal. At. Spectrom., 2009, 24, 1098
    DOI: 10.1039/B904271G

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