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This article in JEQ

  1. Vol. 38 No. 5, p. 2034-2040
    Received: Sept 24, 2008

    * Corresponding author(s): alokb@iastate.edu
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Peroxidase-Mediated Polymerization of 1-Naphthol: Impact of Solution pH and Ionic Strength

  1. Alok Bhandari *a,
  2. Fangxiang Xub,
  3. David E. Kochc and
  4. Robert P. Hunterd
  1. a Dep. of Agricultural & Biosystems Engineering, Iowa State Univ., Ames, IA 50011
    b Dep. of Civil and Environmental Engineering, North Carolina State Univ., Raleigh, NC
    c Dep. of Anatomy & Physiology. Current address: Dep. of Geography, Kansas State Univ., Manhattan, KS
    d Dep. of Anatomy & Physiology, Kansas State Univ., Manhattan, KS. Current address: Elanco Animal Health, Greenfield, IN


Peroxidase-mediated oxidation has been proposed as a treatment method for naphthol-contaminated water. However, the impact of solution chemistry on naphthol polymerization and removal has not been documented. This research investigated the impact of pH and ionic strength on peroxidase-mediated removal of 1-naphthol in completely mixed batch reactors. The impact of hydrogen peroxide to 1-naphthol ratio and activity of horseradish peroxidase was also studied. Size exclusion chromatography was used to estimate the molecular weight distribution of oligomeric products, and liquid chromatography/mass spectrometry was used to estimate product structure. Naphthol transformation decreased with ionic strength, and substrate removal was lowest at neutral pHs. Solution pH influenced the size and the composition of the oligomeric products. An equimolar ratio of H2O2:naphthol was sufficient for optimal naphthol removal. Polymerization products included naphthoquinones and oligomers derived from two, three, and four naphthol molecules. Our results illustrate the importance of water chemistry when considering a peroxidase-based approach for treatment of naphthol-contaminated waters.

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