Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process
Qiang, Z; Liu, C; Dong, B; Zhang, Y
HERO ID
385256
Reference Type
Journal Article
Year
2010
Language
English
PMID
| HERO ID | 385256 |
|---|---|
| In Press | No |
| Year | 2010 |
| Title | Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process |
| Authors | Qiang, Z; Liu, C; Dong, B; Zhang, Y |
| Journal | Chemosphere |
| Volume | 78 |
| Issue | 5 |
| Page Numbers | 517-526 |
| Abstract | The degradation of alachlor by direct ozonation and advanced oxidation process O(3)/H(2)O(2) was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5+/-0.1M(-1)s(-1) at pH 7.0 and 20 degrees C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O(3)/H(2)O(2), respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2',6'-diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2'-acetyl-6'-ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2',6'-ethyl-acetanilide, 2-chloro-2',6'-acetyl-acetanilide and 2-chloro-2'-ethyl-6'-acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O(3) and O(3)/H(2)O(2) also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O(3)/H(2)O(2)). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O(3) or O(3)/H(2)O(2) treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly reduced. |
| Doi | 10.1016/j.chemosphere.2009.11.037 |
| Pmid | 20022076 |
| Wosid | WOS:000274370900004 |
| Is Certified Translation | No |
| Dupe Override | No |
| Comments | Source: Web of Science WOS:000274370900004 |
| Is Public | Yes |
| Language Text | English |
| Keyword | Alachlor; Ozone; O-3/H2O2; Byproduct; Mechanism; Toxicity |
| Is Qa | No |