Kinetics and mechanism for degradation of dichlorvos by permanganate in drinking water treatment

Chao Liu, Zhimin Qiang*, Craig Adams, Fang Tian, Tao Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

The degradation kinetics and mechanism of dichlorvos by permanganate during drinking water treatment were investigated. The reaction of dichlorvos with permanganate was of second-order overall with negligible pH dependence and an activation energy of 29.5 kJ·mol -1 . At pH 7.0 and 25 °C, the rate constant was 25.2 ± 0.4 M -1 s -1 . Dichlorvos was first degraded to trimethyl phosphate (TMP) and dimethyl phosphate (DMP) simultaneously which approximately accounted for <5% and ≥95% with respect to phosphorus mass, respectively. Further oxidation of DMP generated a final byproduct, monomethyl phosphate (MMP). MMP was for the first time identified as a major byproduct in chemical oxidation of dichlorvos. The kinetic model based on degradation mechanism and determined reaction rate constants allowed us to predict the evolution of dichlorvos and its byproduct concentrations during permanganate pre-oxidation process at water treatment plants. These results suggest that even though the dichlorvos concentration in surface water complies with the surface water quality standards of China (50 μg L -1 ), its concentration after conventional water treatment will most probably exceed the drinking water quality standards (1 μg L -1 ). Moreover, luminescent bacteria test shows that the acute toxicity of dichlorvos solution evidently increased after permanganate oxidation.

Original languageEnglish (US)
Pages (from-to)3435-3442
Number of pages8
JournalWater Research
Volume43
Issue number14
DOIs
StatePublished - Aug 1 2009

Keywords

  • Dichlorvos
  • Drinking water treatment
  • Kinetics
  • Mechanism
  • Permanganate

ASJC Scopus subject areas

  • Ecological Modeling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

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