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Subaqueous chemical oxygen demand measuring apparatus and method and method based on flow injection sampling

A chemical oxygen demand, flow injection technology, applied in measuring devices, scientific instruments, material analysis by electromagnetic means, etc., can solve the problems of poor sealing of the detection device, the detection limit needs to be improved, secondary pollution, etc., to prevent The effect of liquid leakage, fast sample testing and stable performance

Active Publication Date: 2008-07-16
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

Using this analyzer reduces secondary pollution, but there is a problem that the detection device is not tightly sealed and easy to leak
At the same time, according to the articles published by the inventor of the patent in "Analytica Chimica Acta" (2005, 548: 199-204) and "Measurement Science and Technology" (2006, 17: 1995-2000), the working electrode used in this method is modified The material is PbO 2 or Rh 2 o 3 , PbO 2 Although it has a certain chemical stability, there is still a risk of secondary pollution caused by lead dissolution during use
with PbO 2 and Rh 2 o 3 The detection limits of COD for electrode modification materials are 15mg / L and 20mg / L respectively, so the detection limit of this method needs to be improved

Method used

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  • Subaqueous chemical oxygen demand measuring apparatus and method and method based on flow injection sampling

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Embodiment 1

[0024] Determination of a domestic sewage. A saturated calomel electrode was used as the reference electrode, and a platinum tube was used as the counter electrode and outlet tube. The control program of the flow injection sampler is set by the computer, and it is controlled to inject the sodium sulfate carrier solution with a pH value of 10 and a concentration of 0.5mol / L into the electrochemical flow detection cell at a constant flow rate of 0.5ml / min. When the flow liquid flows to the outlet tube, start the electrochemical analyzer, apply a voltage of 2.2V to the boron-doped diamond film working electrode, and then collect the generated current signal in real time. When the background current is stable, the program controls the flow injection sampler to automatically inject 150 μL of standard samples containing different chemical oxygen demand values ​​each time, and record the corresponding peak-shaped current signal. A standard curve was established with a correlation co...

Embodiment 2

[0026]Determination of a certain pharmaceutical wastewater, which mainly contains organic matter such as berberine. The silver / silver chloride electrode is used as the reference electrode, and the stainless steel tube is used as the counter electrode and outlet pipe. The control program of the flow injection sampler is set by the computer, and it is controlled to inject the sodium sulfate carrier solution with a pH value of 3 and a concentration of 0.05mol / L into the electrochemical flow detection cell at a constant flow rate of 5ml / min. When the liquid flows to the outlet tube, start the electrochemical analyzer, apply a voltage of 3.2V to the boron-doped diamond film working electrode, and then collect the generated current signal in real time. When the background current is stable, the program controls the flow injection sampler to automatically inject 50 μL of standard samples containing different chemical oxygen demand values ​​each time, and record the corresponding peak...

Embodiment 3

[0028] Determination of an industrial wastewater, the wastewater mainly contains phenolic organic matter. A silver / silver chloride electrode is used as the reference electrode, and a platinum tube is used as the counter electrode and outlet tube. The control program of the flow injection sampler is set by the computer, and it is controlled to inject the sodium sulfate carrier solution with a pH value of 6.5 and a concentration of 0.25mol / L into the electrochemical flow detection cell at a constant flow rate of 2.5ml / min. When the flow liquid flows to the outlet tube, start the electrochemical analyzer, apply a voltage of 2.8V to the boron-doped diamond film working electrode, and then collect the generated current signal in real time. When the background current is stable, the program controls the flow injection sampler to automatically inject 100 μL of standard samples containing different chemical oxygen demand values ​​each time, and record the corresponding peak-shaped cur...

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Abstract

The invention relates to a device and a method for measuring the chemical oxygen demand in water based on flowing injection sampling feeding, which belongs to the technical field of environment monitoring. The measuring device is composed of a flowing injection sampler feeder, a three-electrode system electrochemical circulation detecting pool and an electrochemical working station. The invention is characterized in that a working electrode of the electrochemical circulation detecting pool is a boron-doped diamond film electrode and is fixed on an inlet channel by a fastening bolt and is lined with a lock ring. The inlet channel, a reference electrode mounting channel and an outlet channel enlightened on an insulating, hard and corrosion-resistant pool body are mutually communicated. When in measurement, the pH value of a carrier liquid is 3 to 10 with a concentration of 0.05 to 0.5 mol / l. When the reference electrode adopts a saturated calomel electrode or an Ag / AgCl electrode, a positive voltage applied on the working electrode of the boron-doped diamond film electrode is 2.2 to 3.2V. The invention realizes the fast and accurate measurement of COD with no pollution.

Description

technical field [0001] The invention relates to a device and method for measuring chemical oxygen demand (hereinafter referred to as COD) in water based on flow injection sampling, and belongs to the technical field of environmental monitoring. Background technique [0002] COD is an important indicator to measure the organic pollution of water body. The standard test method for COD in my country is the potassium dichromate method. This method needs to digest the sample, the operation steps are complicated, the test time is long, and it needs to consume expensive reagent silver sulfate, highly toxic reagent mercury sulfate and oxidant potassium dichromate. Inevitably cause secondary pollution. The developed microwave-assisted digestion method, coulometric method, and photometric method to measure COD, although the measurement time has been improved, still need to use toxic reagents such as potassium dichromate, and the operation steps are cumbersome. [0003] In the COD det...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/416
Inventor 全燮于洪斌赵雅芝陈硕赵慧敏张耀斌
Owner DALIAN UNIV OF TECH
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