Document Detail


A study of the reaction mechanisms of the degradation of 2,4-dichlorophenoxyacetic acid by oxalate-mediated photooxidation.
MedLine Citation:
PMID:  15491669     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The oxidation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by FeII/H2O2/UV (FHU) and ferrous-oxalate/H2O2/UV (FOHU) processes was investigated and compared. The initial decay rate and the overall removal percentage were used as the performance indexes. To extensively explore the associated processes, the intermediates and the end products were also examined and compared. The results showed that the degradation of 2,4-D by FHU is slower than that of FOHU. The involvement of ferrous-oxalate in the reaction can greatly improve the initial decay rate of 2,4-D because of the higher light sensitivity of the organometallic complexes. The total removal of 2,4-D and its corresponding intermediates was found to be strongly dependent on the initial hydrogen peroxide concentration; an excessively low initial [H2O2] will terminate the process due to the deficiency of hydroxyl radicals in the solution. All of the major primary intermediates (2,4-dichlorophenol, 2-chloro-4-hydroxyphenoxyacetic acid, 4-chloro-2-hydroxyphenoxyacetic acid, 5-hydroxy-2,4-dichlorophenoxyacetic acid and 6-hydroxy-2,4-dichlorophenoxyacetic acid) have been identified and confirmed by LC-MS. A reaction mechanism was proposed for FHU and FOHU and verified by the evidence presented in this study.
Authors:
C Y Kwan; W Chu
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Water research     Volume:  38     ISSN:  0043-1354     ISO Abbreviation:  Water Res.     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-10-19     Completed Date:  2005-02-15     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0105072     Medline TA:  Water Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  4213-21     Citation Subset:  IM    
Affiliation:
Department of Civil and Structural Engineering, Research Centre for Environmental Technology and Management, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong.
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MeSH Terms
Descriptor/Qualifier:
2,4-Dichlorophenoxyacetic Acid / chemistry*
Herbicides / chemistry*
Hydrogen Peroxide / chemistry
Hydroxyl Radical / chemistry
Oxidants / chemistry
Oxidation-Reduction
Photochemistry
Ultraviolet Rays
Chemical
Reg. No./Substance:
0/Herbicides; 0/Oxidants; 3352-57-6/Hydroxyl Radical; 7722-84-1/Hydrogen Peroxide; 94-75-7/2,4-Dichlorophenoxyacetic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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