Method and device for detecting chemical oxygen demand of water body

A chemical oxygen demand and water technology, applied in the field of analytical chemistry, can solve the problems of low oxygen evolution potential, difficult to remove, large background current, etc., to achieve accurate detection results, timely detection, and high oxygen evolution potential.

Active Publication Date: 2010-02-03
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the oxygen evolution potential of the tin dioxide or lead dioxide anode used is not high (about 1.5-1.7V) and the background current is large. If the applied potential is too high, a large amount of oxygen evolution side reactions will occur, resulting in strong oxidation activity. The production rate of hydroxyl radicals, ozone, etc. is affected, thereby affecting the detection sensitivity of COD; at the same time, the surface of these electrodes is easily polluted by organic pollutants, and it is not easy to remove, resulting in poor measurement stability
In addition, during the preparation and use of these electrodes, toxic substances containing tin or lead will be precipitated, which will definitely have an impact on the environment
Therefore, due to the limitation of the selection and use of the key component-the working electrode material, most of the current research work in this area is still limited to the laboratory stage.

Method used

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  • Method and device for detecting chemical oxygen demand of water body
  • Method and device for detecting chemical oxygen demand of water body
  • Method and device for detecting chemical oxygen demand of water body

Examples

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Embodiment 1

[0034] This embodiment provides a method for detecting COD in water bodies, which can be used for water quality analysis, and the method includes:

[0035] A boron-doped diamond film electrode is set in the background solution as a working electrode, and a saturated calomel electrode or a silver / silver chloride electrode is used as a reference electrode, wherein the reference electrode is connected to the background through a salt bridge when a saturated calomel electrode is used. solution; when the reference electrode adopts a silver / silver chloride electrode, it is directly set in the background solution; on the boron-doped diamond film electrode, a constant potential relative to the reference electrode is applied, and after the reference current is determined, it is injected into the background solution Add the detected water body, make the boron-doped diamond film electrode electrolyze to generate hydroxyl radicals (OH) to oxidize the organic matter in the detected water bo...

Embodiment 2

[0042] In this example, Na 2 SO 4 The solution is the background solution, and the specific detection method is: accurately measure 10ml of 0.1mol / L Na with pH=2 2 SO 4 The solution was added into a reaction vessel with three electrodes, the BDD electrode was used as the working electrode, and the saturated calomel electrode was used as the reference electrode, and the potential of the working electrode relative to the reference electrode was set to 2.5V for constant potential scanning. After stabilization, inject a certain volume of glucose standard solution with known COD concentration into the background solution, record the increase value of the current after injection, inject a certain volume of water sample to be tested under the same conditions, and pass the current after injecting the water sample to be tested. The COD value of the injected water sample to be tested is calculated by comparing the increase value with the standard solution current increase value. Repe...

Embodiment 3

[0044] In this example, Na 2 SO 4 The solution is the background solution, and the specific detection method is: accurately measure 10ml of 0.1mol / L Na with pH=2 2 SO 4 Solution, join in the reaction vessel that is provided with three electrodes of the device described in embodiment one, take BDD electrode as working electrode, take silver / silver chloride electrode as reference electrode, stainless steel electrode as counter electrode, set working electrode relative to The potential of the reference electrode is 2.5V for constant potential scanning. After determining the reference current, inject a certain volume of glucose solution with known COD concentration into the uniformly mechanically stirred background solution, and record the increase value of the current after injection. Under the same conditions with PbO 2 The / Ti electrode is the detection electrode, and the potential is set to 1.5V for constant potential scanning. After the current is stable, the same volume o...

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Abstract

The invention discloses a method and a device for detecting chemical oxygen demand of a water body. The method comprises the following steps: applying 2.5V constant potential relative to a reference electrode to a boron-doped diamond film detection electrode as a working electrode by controlling an electrochemistry workstation; injecting certain volume of a sample to be detected into a backgroundsolution under a magnetic stirring condition; recording a current signal response of the working electrode acquired by the electrochemistry workstation in real-time; and calculating the chemical oxygen demand of the detected water body through current signals. The electrochemical detection method by the boron-doped diamond film detection electrode has the detection result in excellent comparable property compared with a national standard method, has high detection accuracy, wide the range without secondary pollution, and short electrode response time, ,and can meet the timely, quick and onlinerequirement in detecting the current environment. Compared with Pbo2 / Ti adopted in the current commercialized instrument, the detection signals have nearly one order of magnitude of predominance under the respective optimal use condition.

Description

technical field [0001] The invention relates to a detection technology, in particular to a method and a device for rapidly detecting the chemical oxygen demand (COD) of water, belonging to the field of analytical chemistry. Background technique [0002] With the implementation of total pollutant discharge control in our country, water quality monitoring is particularly urgent. Chemical oxygen demand (COD) is one of the important indicators for evaluating the degree of water pollution, and it is a must-test item for monitoring surface water and industrial wastewater. At present, standard method, photometric method and coulometric method are mostly used in the determination of COD in wastewater. The standard method is the potassium dichromate digestion method (GB11914-89). Its basic principle is to use dichromate as an oxidant to digest the reducing oxygen-consuming organic substances in water, and then use the titration method for determination. Since dichromate has strong ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/416
Inventor 只金芳王金良
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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