Photocatalytic oxidation mechanism of methanol and the other reactants in irradiated TiO2 aqueous suspension investigated by OH radical detection

2015 ◽  
Vol 166-167 ◽  
pp. 32-36 ◽  
Author(s):  
Jie Zhang ◽  
Yoshio Nosaka
Keyword(s):  
Photocatalytic Oxidation ◽  
Aqueous Suspension ◽  
Oxidation Mechanism ◽  
The Other ◽  
Oh Radical ◽  
Radical Detection

OH radical detection in an optical engine

1993 ◽  
Author(s):  
Ali Serpenguzel ◽  
Robert T. Hahn ◽  
William P. Acker
Keyword(s):  
Oh Radical ◽  
Optical Engine ◽  
Radical Detection

Environmentally Friendly Photocatalytic Oxidation of Aromatic Alcohol to Aldehyde in Aqueous Suspension of Brookite TiO2

2008 ◽  
Vol 126 (1-2) ◽  
pp. 58-62 ◽  
Author(s):  
Maurizio Addamo ◽  
Vincenzo Augugliaro ◽  
Marianna Bellardita ◽  
Agatino Di Paola ◽  
Vittorio Loddo ◽  
...  
Keyword(s):  
Photocatalytic Oxidation ◽  
Aqueous Suspension ◽  
Environmentally Friendly ◽  
Aromatic Alcohol

Inorganic greywater matrix impact on photocatalytic oxidation: does flocculation of TiO2 nanoparticles impair process efficiency?

2011 ◽  
Vol 63 (12) ◽  
pp. 2808-2813 ◽  
Author(s):  
A. Armanious ◽  
A. Özkan ◽  
U. Sohmen ◽  
H. Gulyas
Keyword(s):  
Rate Constants ◽  
Electric Double Layer ◽  
Photocatalytic Oxidation ◽  
Process Efficiency ◽  
Point Of Zero Charge ◽  
Inorganic Salts ◽  
Co2 Absorption ◽  
Oh Radical ◽  
Radical Scavengers ◽  
Subsequent Formation

This study was conducted in order to clarify whether photocatalyst flocculation – as observed in biologically pretreated greywater – contributes to photocatalytic oxidation (PCO) efficiency impairment. Aqueous solutions of tetraethyleneglycol dimethylether spiked with different inorganic salts in concentrations as found in biologically treated greywater were investigated with respect to TiO2 flocculation and PCO mineralisation kinetics. Flocculation of the photocatalyst primarily depended on pH (which was affected by the salts) and how close pH was to the point of zero charge (PZC). Photocatalyst agglomeration was maximum at pH 5.5. With salt concentrations >7 mmol L−1, flocculation was strong even at pH far above PZC due to electric double layer compression. PCO rate constants were not unequivocally related to flocculation. Increasing pH was observed as the clearest factor deteriorating PCO efficiency. This was interpreted to result from impaired adsorbability of negatively charged oxidation intermediates as well as from enhanced CO2 absorption with increasing pH and subsequent formation of HCO3− anions which are OH radical scavengers.

The response of Härtel's turbidity test is controlled by the acidity of the conifer needle extracts rather than by the availability of Ca2+ ions

1999 ◽  
Vol 29 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Hartwig W Pfeifhofer
Keyword(s):  
Air Pollution ◽  
Oxalic Acid ◽  
Chelating Agents ◽  
Aqueous Suspension ◽  
Deionized Water ◽  
The Other ◽  
Main Principle ◽  
Turbidity Test ◽  
Chelating Compounds ◽  
Conifer Needle

Härtel's turbidity test (Trübungstest) has been one widely used diagnostic test for air pollution injury for decades. This test is based on the extraction of lipophilic substances into an aqueous suspension, whose light absorption is used as an indication of exposure to pollution. Little is known about the underlying principles controlling the response of the test. In this study, the influence of the cations Li+, Na+, K+, and Ca2+ and that of the anions Cl-, Br-, I-, and SO42- on the response of Härtel's test was reinvestigated. In contrast to an earlier study, both the extracts' absorbance and acidity were monitored. Additionally, the effects of the Ca-chelating agents ethylenediaminetetraacetate (EDTA) and oxalic acid were compared with that of deionized water and different buffers. All effects of ions including that of Ca2+ on the response of the test were accompanied by shifts of the extracts' acidity. Even small changes in the pH caused significant variations in the test's response. On the other hand, addition of the Ca chelating agents EDTA and oxalic acid to the solvent did not affect the response of the test when the pH was equal to solvents without Ca chelating compounds. Therefore, the previously published assumption that the availability of Ca2+ could be the main principle of the test's reaction mechanism was not confirmed.

Photocatalytic Oxidation Mechanism of As(III) on TiO2: Unique Role of As(III) as a Charge Recombinant Species

2010 ◽  
Vol 44 (23) ◽  
pp. 9099-9104 ◽  
Author(s):  
Wonyong Choi ◽  
Jiman Yeo ◽  
Jungho Ryu ◽  
Takashi Tachikawa ◽  
Tetsuro Majima
Keyword(s):  
Photocatalytic Oxidation ◽  
Oxidation Mechanism ◽  
Unique Role ◽  
A Charge

scholarly journals HETEROGENEOUS PHOTOCATALYTIC OXIDATION OF NO2−IN AQUEOUS SUSPENSION OF VARIOUS SEMICONDUCTOR POWDERS

1985 ◽  
Vol 14 (9) ◽  
pp. 1429-1432 ◽  
Author(s):  
Yoshio Hori ◽  
Akiyoshi Nakatsu ◽  
Shin Suzuki
Keyword(s):  
Photocatalytic Oxidation ◽  
Aqueous Suspension

scholarly journals Aqueous Photocatalytic Oxidation of Lignin: The Influence of Mineral Admixtures

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Elina Portjanskaja ◽  
Sergei Preis
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Oxidation ◽  
Catalyst Support ◽  
Oxidation Mechanism ◽  
Ion Concentration ◽  
Mineral Admixtures ◽  
Oh Radicals ◽  
Ferrous Ions ◽  
The Difference ◽  
The One

The photocatalytic oxidation (PCO) of UV-irradiated aqueous solutions containing lignin onTiO2was studied for the influence of ferrous ions. The addition ofFe2+, up to 2.8 mgL−1, to the acidic lignin solution leads to the drastic, for about 25%, increase in PCO efficiency. A further increase in ferrous ion concentration results in a decrease in PCO efficiency of lignin. The maximum PCO efficiency, up to 9.2 mgW−1h−1, was observed in neutral and slightly basic media: the oxidation mechanism with OH-radicals seems to prevail. Also, the difference in the PCO performance with a different attachment mode of titanium dioxide on the catalyst support was observed. Sprayed catalyst exhibited 1.5 times higher efficiency than the one attached by submersion, although sprayed one was easily resuspended in acidic lignin solutions. The efficiency of the N-doped photocatalyst active in visible light was observed to be negligible with lignin.

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