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The photocatalytic degradation of dicamba in TiO2 suspensions with the help of hydrogen peroxide by different near UV irradiations.
Water Res. 2004 Feb; 38(4):1037-43.WR

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 350 nm). 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 350 nm 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 H2O2-assisted photocatalysis experiments showed that a low H2O2 dosage in photocatalysis using UV 300 nm would enhance the decay rate of dicamba by 2.4 times, but an overdose of H2O2 will retard the rate because of the expenditure of hydroxyl radicals. However, this process was found impracticable at UV 350 nm due to the absorption characteristic of H2O2. A neutral initial pH level was found to favour the H2O2-assisted photocatalysis at UV 300 nm. The reactions were highly retarded at the alkaline medium due to the unstable properties of H2O2.

Authors+Show Affiliations

Department of Civil and Structural Engineering, Research Centre for Environmental Technology and Management, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. cewchu@polyu.edu.hkNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

14769424

Citation

Chu, W, and C C. Wong. "The Photocatalytic Degradation of Dicamba in TiO2 Suspensions With the Help of Hydrogen Peroxide By Different Near UV Irradiations." Water Research, vol. 38, no. 4, 2004, pp. 1037-43.
Chu W, Wong CC. The photocatalytic degradation of dicamba in TiO2 suspensions with the help of hydrogen peroxide by different near UV irradiations. Water Res. 2004;38(4):1037-43.
Chu, W., & Wong, C. C. (2004). The photocatalytic degradation of dicamba in TiO2 suspensions with the help of hydrogen peroxide by different near UV irradiations. Water Research, 38(4), 1037-43.
Chu W, Wong CC. The Photocatalytic Degradation of Dicamba in TiO2 Suspensions With the Help of Hydrogen Peroxide By Different Near UV Irradiations. Water Res. 2004;38(4):1037-43. PubMed PMID: 14769424.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The photocatalytic degradation of dicamba in TiO2 suspensions with the help of hydrogen peroxide by different near UV irradiations. AU - Chu,W, AU - Wong,C C, PY - 2003/02/27/received PY - 2003/06/16/revised PY - 2003/10/28/accepted PY - 2004/2/11/pubmed PY - 2004/5/28/medline PY - 2004/2/11/entrez SP - 1037 EP - 43 JF - Water research JO - Water Res VL - 38 IS - 4 N2 - 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 350 nm). 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 350 nm 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 H2O2-assisted photocatalysis experiments showed that a low H2O2 dosage in photocatalysis using UV 300 nm would enhance the decay rate of dicamba by 2.4 times, but an overdose of H2O2 will retard the rate because of the expenditure of hydroxyl radicals. However, this process was found impracticable at UV 350 nm due to the absorption characteristic of H2O2. A neutral initial pH level was found to favour the H2O2-assisted photocatalysis at UV 300 nm. The reactions were highly retarded at the alkaline medium due to the unstable properties of H2O2. SN - 0043-1354 UR - https://www.unboundmedicine.com/medline/citation/14769424/The_photocatalytic_degradation_of_dicamba_in_TiO2_suspensions_with_the_help_of_hydrogen_peroxide_by_different_near_UV_irradiations_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0043-1354(03)00610-9 DB - PRIME DP - Unbound Medicine ER -