Kinetics and mechanism for methiocarb degradation by chlorine dioxide in aqueous solution

Fang Tian, Zhimin Qiang*, Chao Liu, Tao Zhang, Bingzhi Dong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


The kinetics and mechanism for methiocarb (MC) degradation by aqueous ClO2 were investigated under simulated water treatment conditions. Experimental results indicate that the reaction between MC and ClO2 was of second-order overall, and the rate constant rapidly increased from 0.56 to 4.5 M-1 s-1 as the solution pH increased from 6.0 to 9.1 at 23 °C. The activation energy was determined to be 75 kJ mol-1 in the studied temperature range of 7-35 °C. Methiocarb sulfoxide (MCX) and methiocarb sulfone (MCN) were quantified to be the major byproducts from MC degradation. Unlike the sequential formation of sulfoxide and sulfone during the oxidation of many thioethers, the two byproducts were formed simultaneously during MC degradation by ClO2. The solution pH significantly affected the type and quantity of the degradation byproducts. For example, at pH 6.5 MCX and MCN accumulated as the reaction proceeded and finally accounted for 71% and 28% of MC degraded, respectively; while at pH 8.6 three more minor byproducts were identified. Though ClO2 can effectively oxidize MC in water, the significant increase in toxicity raises a potential risk to consumers.

Original languageEnglish (US)
Pages (from-to)646-651
Number of pages6
Issue number6
StatePublished - Apr 2010
Externally publishedYes


  • Byproducts
  • Chlorine dioxide
  • Kinetics
  • Mechanism
  • Methiocarb
  • Water treatment

ASJC Scopus subject areas

  • General Chemistry
  • Public Health, Environmental and Occupational Health
  • Pollution
  • Health, Toxicology and Mutagenesis
  • Environmental Engineering
  • Environmental Chemistry


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