Photoredox reactions of environmental chromium
The role of direct photochemical reactions of Cr(VI) and Cr(III) species in the environmental degradation of organic matter was investigated by means of Cr(VI)/alcohol and Cr(III)/EDTA model systems under conditions mimicking the environmental ones. Photoreduction of Cr(VI) proceeds through reductiv...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2001-01-01
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| Series: | International Journal of Photoenergy |
| Online Access: | http://dx.doi.org/10.1155/S1110662X0100023X |
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| Summary: | The role of direct photochemical reactions of Cr(VI) and Cr(III) species in the environmental
degradation of organic matter was investigated by means of Cr(VI)/alcohol and Cr(III)/EDTA model systems
under conditions mimicking the environmental ones. Photoreduction of Cr(VI) proceeds through reductive
quenching of chromate(VI) excited within UV-A by an alcohol molecule. Although HCrO4− is more susceptible to the quenching than the CrO42− ion, and oxygen favours the reverse reaction, the reduction can be easy noticeable at air-saturated natural waters. Photoredox behaviour of [crEDTA(L)]n- is more complex: it is initiated also by photoreduction, Cr(III) hv→ Cr(II), which at alkaline medium and a large excess of O2 over Cr(II) is followed by the Cr(II) → Cr(VI) oxidation. Both the photoreductions are accompanied by oxidation
of organic matter. Due to the substitutional lability of the [crEDTA(L)]n- complexes the conditions can be
adjusted under which the Cr(VI)/Cr(III) forms are able to mediate the O2 oxidation of organic matter in the
environmental photocatalytic cycle. |
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| ISSN: | 1110-662X |