Multifactor Statistical Analysis of H2O2-Enhanced Photodegradation of Nicotine and Phosphamidon

A. M. Nienow, Inez Hua, I C Poyer, J C Bezares-Cruz, Chad T. Jafvert

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Direct and indirect photolysis (lambda = 254 nm) of aqueous nicotine and phosphamidon were studied. A central composite design was used to explore the effects of initial [H2O2] (0-10 mM), pH (2.8-11.2), and ionic strength (I-c = 0.02-0.71 M) on the rate constants of nicotine and phosphamidon separately dissolved in a surface water surrogate matrix. Five levels of each factor were included in the design. For nicotine, the fastest predicted photochemical oxidation rate constant (k = 0.43 min(-1)) occurred under the following conditions: pH = 7.5, [H2O2] = 7.5 mM, and I-c = 0.02 M. This rate constant predicts that 90% of the nicotine will react within 5.4 min under these conditions. In general, the photochemical oxidation of nicotine is more rapid at lower ionic strength and near-neutral pH values. For phosphamidon, the fastest predicted oxidation rate constant (k = 0.65 min(-1)) occurred at a pH of 7.1 and [H2O2] of 5 mM. Under these conditions, 90% of the phosphamidon would react within 3.5 min of treatment. Like nicotine, the photochemical oxidation of phosphamidon is more rapid at near-neutral pH values. Ionic strength has no significant effect on the photochemical oxidation of phosphamidon.
Original languageEnglish (US)
Title of host publicationIndustrial & Engineering Chemistry Research
Pages3955-3963
Number of pages9
DOIs
StatePublished - 2009
Externally publishedYes

Publication series

NameIndustrial & Engineering Chemistry Research
Volume48

Keywords

  • dissolved organic-matter
  • fenton reaction
  • hydrogen-peroxide
  • natural-water
  • pesticides
  • photocatalytic degradation
  • rate constants
  • surface waters
  • tio2 suspensions
  • titanium-dioxide

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