Details
| Original language | English |
|---|---|
| Pages (from-to) | 6229–6236 |
| Number of pages | 8 |
| Journal | LANGMUIR |
| Volume | 31 |
| Issue number | 22 |
| Early online date | 27 May 2015 |
| Publication status | Published - 9 Jun 2015 |
Abstract
The dynamics of the transfer of electrons stored in TiO 2 nanoparticles to Cr(VI) in aqueous solution have been investigated using the stopped flow technique. TiO 2 nanoparticles were previously irradiated under UV light in the presence of formic acid, and trapped electrons (e trap -) were made to react with Cr(VI) as acceptor species; other common acceptor species such as O 2 and H 2O 2 were also tested. The temporal evolution of the number of trapped electrons was followed by the decrease in the absorbance at 600 nm, and the kinetics of the electron-transfer reaction was modeled. Additionally, the rate of formation of the surface complex between Cr(VI) and TiO 2 was determined with the stopped flow technique by following the evolution of the absorbance at 400 nm of suspensions of nonirradiated TiO 2 nanoparticles and Cr(VI) at different concentrations. An approximately quadratic relationship was observed between the maximum absorbance of the surface complex and the concentration of Cr(VI), suggesting that Cr(VI) adsorbs onto the TiO 2 surface as dichromate. The kinetic analyses indicate that the electron transfer from TiO 2 to Cr(VI) does not require the previous formation of the Cr(VI)-TiO 2 surface complex, at least the complex detected here through the stopped flow experiments. When previously irradiated TiO 2 was used to follow the evolution of the Cr(VI)-TiO 2 complex, an inhibition of the formation of the complex was observed, which can be related to the TiO 2 deactivation caused by Cr(III) deposition.
ASJC Scopus subject areas
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Chemistry(all)
- Spectroscopy
- Chemistry(all)
- Electrochemistry
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In: LANGMUIR, Vol. 31, No. 22, 09.06.2015, p. 6229–6236.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Application of the Stopped Flow Technique to the TiO2-Heterogeneous Photocatalysis of Hexavalent Chromium in Aqueous Suspensions: Comparison with O2 and H2O2 as Electron Acceptors
AU - Meichtry, J.M.
AU - Dillert, R.
AU - Bahnemann, D.W.
AU - Litter, M.I.
N1 - Publisher Copyright: © 2015 American Chemical Society. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2015/6/9
Y1 - 2015/6/9
N2 - The dynamics of the transfer of electrons stored in TiO 2 nanoparticles to Cr(VI) in aqueous solution have been investigated using the stopped flow technique. TiO 2 nanoparticles were previously irradiated under UV light in the presence of formic acid, and trapped electrons (e trap -) were made to react with Cr(VI) as acceptor species; other common acceptor species such as O 2 and H 2O 2 were also tested. The temporal evolution of the number of trapped electrons was followed by the decrease in the absorbance at 600 nm, and the kinetics of the electron-transfer reaction was modeled. Additionally, the rate of formation of the surface complex between Cr(VI) and TiO 2 was determined with the stopped flow technique by following the evolution of the absorbance at 400 nm of suspensions of nonirradiated TiO 2 nanoparticles and Cr(VI) at different concentrations. An approximately quadratic relationship was observed between the maximum absorbance of the surface complex and the concentration of Cr(VI), suggesting that Cr(VI) adsorbs onto the TiO 2 surface as dichromate. The kinetic analyses indicate that the electron transfer from TiO 2 to Cr(VI) does not require the previous formation of the Cr(VI)-TiO 2 surface complex, at least the complex detected here through the stopped flow experiments. When previously irradiated TiO 2 was used to follow the evolution of the Cr(VI)-TiO 2 complex, an inhibition of the formation of the complex was observed, which can be related to the TiO 2 deactivation caused by Cr(III) deposition.
AB - The dynamics of the transfer of electrons stored in TiO 2 nanoparticles to Cr(VI) in aqueous solution have been investigated using the stopped flow technique. TiO 2 nanoparticles were previously irradiated under UV light in the presence of formic acid, and trapped electrons (e trap -) were made to react with Cr(VI) as acceptor species; other common acceptor species such as O 2 and H 2O 2 were also tested. The temporal evolution of the number of trapped electrons was followed by the decrease in the absorbance at 600 nm, and the kinetics of the electron-transfer reaction was modeled. Additionally, the rate of formation of the surface complex between Cr(VI) and TiO 2 was determined with the stopped flow technique by following the evolution of the absorbance at 400 nm of suspensions of nonirradiated TiO 2 nanoparticles and Cr(VI) at different concentrations. An approximately quadratic relationship was observed between the maximum absorbance of the surface complex and the concentration of Cr(VI), suggesting that Cr(VI) adsorbs onto the TiO 2 surface as dichromate. The kinetic analyses indicate that the electron transfer from TiO 2 to Cr(VI) does not require the previous formation of the Cr(VI)-TiO 2 surface complex, at least the complex detected here through the stopped flow experiments. When previously irradiated TiO 2 was used to follow the evolution of the Cr(VI)-TiO 2 complex, an inhibition of the formation of the complex was observed, which can be related to the TiO 2 deactivation caused by Cr(III) deposition.
UR - http://www.scopus.com/inward/record.url?scp=84931291802&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.5b00574
DO - 10.1021/acs.langmuir.5b00574
M3 - Article
VL - 31
SP - 6229
EP - 6236
JO - LANGMUIR
JF - LANGMUIR
SN - 0743-7463
IS - 22
ER -