Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/8353
Title: The photocatalytic degradation of dicamba in TiO2 suspensions with the help of hydrogen peroxide by different near UV irradiations
Authors: Chu, W 
Wong, CC
Keywords: Dicamba
Hydrogen peroxide
Mechanism
Photocatalysis
Titanium dioxide
Issue Date: 2004
Publisher: IWA Publishing
Source: Water research, 2004, v. 38, no. 4, p. 1037-1043 How to cite?
Journal: Water research 
Abstract: The direct photolysis and the photocatalytic degradations of dicamba in TiO2 suspensions with and without the use of hydrogen peroxide were studied using two different monochromatic UV irradiations (300 and 350nm). Both the direct photolysis and photocatalytic degradations of dicamba follow pseudo-first-order decay kinetics. Photolysis reactions were slow but the corresponding photocatalysis rates were increased by about 3 and 5 times in the presence of TiO2 at 300 and 350nm of UV, respectively. Photocatalytic rates were increased with the pH at acidic to neutral ranges because of the increase of hydroxide ions, but the reaction was gradually retarded at the alkaline medium due to the effect of charges repulsion. The different proton sources causing various degrees of rate retardation were due to the presence of the corresponding counter anions. The results of H 2O2-assisted photocatalysis experiments showed that a low H2O2 dosage in photocatalysis using UV 300nm would enhance the decay rate of dicamba by 2.4 times, but an overdose of H 2O2 will retard the rate because of the expenditure of hydroxyl radicals. However, this process was found impracticable at UV 350nm due to the absorption characteristic of H2O2. A neutral initial pH level was found to favour the H2O2-assisted photocatalysis at UV 300nm. The reactions were highly retarded at the alkaline medium due to the unstable properties of H2O2.
URI: http://hdl.handle.net/10397/8353
ISSN: 0043-1354
EISSN: 1879-2448
DOI: 10.1016/j.watres.2003.10.037
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