Water body chemical oxygen demand electrochemical measuring method

A chemical oxygen demand and electrochemical technology, which is applied in the direction of measuring devices, scientific instruments, and material analysis through electromagnetic means, can solve the problems of secondary pollution, etc., and achieve the effects of short time consumption, wide measurement range, and environmental friendliness

Active Publication Date: 2008-01-16
DALIAN UNIV OF TECH
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  • Abstract
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  • Application Information

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Problems solved by technology

This method uses PbO 2 The modified electrode as the main component will cause secondary pollution due to the dissolution of lead ions during use, and there is a certain environmental risk. According to the patent inventor published in "Electroanalysis" (2004, 16: 404-409) According to the article, the maximum range of COD measured by this method is 3000mg / L, and pre-dilution treatment is required when measuring sewage with high COD concentration

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Determination of a food industry wastewater, the wastewater mainly contains organic matter such as ethyl lactate. A nanocrystalline boron-doped diamond electrode is used as the working electrode with an area of ​​1 cm 2 , with a platinum sheet as the counter electrode and a saturated calomel electrode as the reference electrode, apply a potential of 2.00V, add standard test solutions of different COD concentrations to 15ml, 0.5mol / L, and pH value of 7 sodium nitrate solution, and record the response The current signal was measured 3 times in parallel, and the average value was taken to obtain the calibration curve between the current value and the COD of the standard sample, and the correlation coefficient was 0.9901. Under the same test conditions, the COD value of the food industry wastewater was measured to be 6833.7mg / L.

Embodiment 2

[0019] Determination of a pharmaceutical wastewater, the wastewater mainly contains adamantane, amines and other organic substances. A microcrystalline boron-doped diamond electrode is used as the working electrode with an area of ​​0.5 cm 2 , with a platinum sheet as the counter electrode and a saturated calomel electrode as the reference electrode, apply a potential of 2.55V, add standard test solutions of different COD concentrations to 10ml, 0.2mol / L, and pH value of 2 sodium sulfate solution, and record the response The current signal was measured 3 times in parallel, and the average value was taken to obtain the calibration curve between the current value and the COD of the standard sample, and the correlation coefficient was 0.9977. Under the same test conditions, the COD value of the pharmaceutical wastewater was measured to be 3814.5mg / L.

Embodiment 3

[0021] Determination of a food additive wastewater, which mainly contains organic substances such as alcohol-based cyclopentanone, acetic acid and diacetyl. A microcrystalline boron-doped diamond electrode is used as the working electrode with an area of ​​0.1 cm 2 , take the platinum mesh as the counter electrode, the saturated silver / silver chloride electrode as the reference electrode, apply a potential of 2.40V, add standard test solutions with different COD concentrations to 5ml, 0.05mol / L, and pH value of 1 sodium sulfate solution , record the corresponding current signal, measure 3 times in parallel, take the average value, and obtain the calibration curve between the current value and the COD of the standard sample, and the correlation coefficient is 0.9934. Under the same test conditions, the COD value of the food additive wastewater was measured to be 2532.8mg / L.

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Abstract

The invention relates to an electrochemistry measuring water chemical oxygen demand method; a working electrode, a counter electrode and a reference electrode are provided in a sodium sulfate electrolyte solution or a sodium nitrate electrolyte solution; constant potential is maintained; the chemistry oxygen demand value of a water sample is measured by measuring the response current generated by an oxidation organic substance. The invention is characterized in that the working electrode adopts microcrystal boron adulterated with diamond or nano-crystal boron adulterated with diamond; the PH value of the electrolyte solution is 1-7; the voltage exerted in the electrolyte solution is 2.24-2.28 V if the reference electrode is a standard hydrogen electrode. The invention has the advantages of environmental friendly, high accurate COD determination, wide measuring range, easy operation and small time consumption; the invention can be used to rapid test of COD in the samples of municipal sewage and industrial sewage.

Description

technical field [0001] The invention relates to a method for electrochemically measuring water body chemical oxygen demand (hereinafter referred to as COD), which belongs to the technical field of environmental monitoring. Background technique [0002] Chemical oxygen demand is an important index to measure the organic pollution of water quality, and the commonly used test method is the potassium dichromate method. This method takes a long time to test, and needs to consume expensive reagent silver sulfate and highly toxic reagent mercury sulfate, which is easy to cause secondary pollution. Then the coulometric method and photometric method developed at home and abroad to measure COD, although the measurement time has been improved, but it still needs to use toxic reagents such as potassium dichromate or mercury sulfate and high temperature digestion. Lee Kyong-Hoon et al proposed in "Electroanalysis" (2000, 12(16): 1334-1338) to use titanium dioxide powder suspended in the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/416
Inventor 全燮于洪斌王华陈硕赵慧敏
Owner DALIAN UNIV OF TECH
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