Photocoupling method for determining chemical oxygen demand in water body

Abstract

The invention discloses a photocoupling method for determining the chemical oxygen demand (COD) in a water body. The photocoupling method is characterized in that a quartz photoelectron-catalytic digester is arranged, a light transmitting window is formed at one side of the quartz photoelectron-catalytic digester, and the digester uses a substrate loaded with a semiconductor metal nano-film on the surface as a photoelectron-catalytic anode; a water sample to be detected is added into the digester, 0.5V-5.0V bias voltage is applied to the photoelectron-catalytic anode through a CHI electrochemical workstation, ultraviolet light irradiates the photoelectron-catalytic anode through the light transmitting window, and an electrochemical signal generated by thorough photoelectron-catalytic digestion of an organic contamination substrate in a digestion cuvette is determined to calculate the COD value of the water sample to be detected. The method can systematically couple the photocatalytic digestion process and the electrocatalytic digestion process in the same digestion system so as to rapidly, thoroughly and efficiently digest the organic contamination substrate in the water sample to be detected.

Description

technical field [0001] The invention belongs to the field of environmental protection and relates to a photoelectric coupling method for fast and accurate determination of chemical oxygen demand in water and waste water. Background technique [0002] Chemical oxygen demand (chemical oxygen demand, COD) has become an important monitoring and evaluation index in the field of environmental pollution monitoring. However, the widely used standard potassium dichromate reflux titration (COD Cr ), there are still many technical deficiencies. Mainly include: low monitoring sensitivity, long time-consuming (usually 2-3h), complex operation, incomplete digestion, expensive (Ag 2 SO 4 ) and toxic and harmful (Cr and Hg) reagents consume a lot, and at the same time, the secondary environmental pollution of heavy metal ions is also prominent. [0003] In order to effectively overcome the many technical drawbacks of the traditional COD measurement method, many alternative environmental...

AI Technical Summary

Problems solved by technology

[0008] However, there are still two key technical problems that need to be solved and further optimized in the existing PECOD measurement technology

On the one hand: photocatalyst materials are the core of the entire PECOD technology, but the photocatalyst materials currently used still have low catalytic activity, poor stability, weak selectivity and complicated preparation process, and the chemical reagents used are expensive and It may be toxic, and some catalysts have a certain degree of secondary pollution to the environment and the water to be tested; on the other hand, all the pollution substrate digestion process and analysis signal generation process in the existing PECOD measurement technology only come from a single photocatalytic Reaction, because the applied bias voltage is low enough, it cannot form a direct electrocatalytic digestion reaction mechanism, but can only promote the separation, transmission and utilization efficiency of photogenerated carriers, which also restricts the accuracy of the entire PECOD detection results to a large extent. degree and sensitivity

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