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Photoelectrochemical determination of chemical oxygen demand

  • US 7,759,125 B2
  • Filed: 08/11/2009
  • Issued: 07/20/2010
  • Est. Priority Date: 04/04/2003
  • Status: Active Grant
First Claim
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1. A method of determining chemical oxygen demand of a water sample under non exhaustive degradation conditions, comprising the steps ofa) applying a constant potential bias to a thin layer photoelectrochemical cell, having a photoactive nanoparticulate semiconductive working electrode and a counter electrode, and containing a supporting electrolyte solution;

  • b) illuminating the working electrode with a light source and recording the background photocurrent produced at the working electrode from the supporting electrolyte solution;

    c) adding a 5 μ

    l to 200 μ

    l of water sample, to be analysed, to the photoelectrochemical cell;

    d) illuminating the working electrode with a light source and recording the total photocurrent produced with the sample;

    e) deducting the back ground photocurrent from the total photocurrent produced with the sample to obtain the net photocurrent due to the oxidation of organic material in the samplef) determining the chemical oxygen demand of the water sample according to the following sequence of computations
    ilsample=nFAk[COD]sample=K[COD]sample
    ilstandard=nFAk{[COD]sample+[COD]standard}=K{[COD]sample+[COD]standard}WhereK=nFAk is a constant for given experimental conditionsn=number of electrons transferred during the photoelectrochemical degradation,F=Faraday constant,A=active electrode area,k=mass-transfer coefficient; and

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