Method and device for detecting chemical oxygen demand of water body

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 ...

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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.

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