Photoelectrochemical determination of chemical oxygen demand
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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Abstract
A photoelectrochemical assay apparatus and method for determining chemical oxygen demand (COD) of a water sample is described. The photoelectrochemical assay comprises:
- a) a measuring cell for holding a sample to be analysed
- b) a titanium dioxide nanoparticle photoelectric working electrode and a counter electrode disposed in said cell,
- c) a UV light source adapted to illuminate the photoelectric working electrode
- d) control means to control the illumination of the working electrode
- e) potential measuring means to measure the electrical potential at the working and counter electrodes
- f) analysis means to derive a measure of oxygen demand from the measurements made by the potential measuring means.
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17 Claims
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1. A method of determining chemical oxygen demand of a water sample under non exhaustive degradation conditions, comprising the steps of
a) 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 sample f) 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}Where K=nFAk is a constant for given experimental conditions n=number of electrons transferred during the photoelectrochemical degradation, F=Faraday constant, A=active electrode area, k=mass-transfer coefficient; and - View Dependent Claims (2, 3, 4, 5)
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6. A thin layer photoelectrochemical assay apparatus for determining oxygen demand of a water sample under non exhaustive degradation conditions which consists of
a) a measuring cell for holding 5 μ - l to 200 μ
l of a sample to be analysedb) a photoactive nanoparticulate semiconductive working electrode and a counter electrode disposed in said cell, c) a light source adapted to illuminate the photoactive working electrode d) control means to control the illumination of the working electrode, the applied potential bias, and photocurrent recording c) photocurrent measuring means to measure the photocurrent at the working electrode f) analysis means to derive a measure of oxygen demand according to the following sequence of computations
ilsample=nFAk[COD]sample=K[COD]sample
ilstandard=nFAk{[COD]sample+[COD]standard}=K{[COD]+[COD]}Where K=nFAk is a constant for given experimental conditions n=number of electrons transferred during the photoelectrochemical degradation, F=Faraday constant, A=active electrode area, k=mass-transfer coefficient; and - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- l to 200 μ
Specification