Method for determining potassium permanganate index in water by using DPD

Abstract

The invention discloses a method for determining a potassium permanganate index in water by using DPD. The method comprises the following steps: using sulfuric acid for acidizing a to-be-detected water sample and then adding excessive standard potassium permanganate solution; heating and reacting for a period of time and then utilizing the residual potassium permanganate therein to oxidize N,N-diethyl-1,4-phenylenediamine, thereby generating a red DPD free radical; adopting a visible spectrophotometer for determining an absorbance value of the DPD free radical on the position of characteristicwavelength 510nm or 551nm and using the absorbance value for calculating the concentration of the residual potassium permanganate; calculating the consumption of potassium permanganate according to the concentration of the residual potassium permanganate, thus obtaining the potassium permanganate index in the to-be-detected water sample. The method has the advantages of simple operation, short determining time, environmental-friendly reagents and high precision of determining result.

Description

technical field [0001] The invention belongs to the technical field of environmental monitoring, and in particular relates to a method for measuring potassium permanganate index in water by using DPD. Background technique [0002] The permanganate index refers to the amount consumed when treating water samples with potassium permanganate as the oxidant under certain conditions, expressed in mg / L of oxygen. Nitrite, ferrous salt, sulfide and other reducing organic substances in water and organic substances that can be oxidized under these conditions can consume potassium permanganate. Therefore, the permanganate index is one of the comprehensive indicators of the pollution degree of reducing organic (including inorganic) substances in the water body, and is an important indicator to measure the environmental quality. [0003] At present, in the determination method of permanganate index in fresh water such as river water, it is generally used that after the water sample is o...

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Problems solved by technology

Ji Guoliang and others changed the titration method to a spectrophotometric method such as ZL201510204737.X, oxidized ferrous ammonium sulfate with potassium permanganate after digestion, and used sulfosalicylic acid to interact with oxidized ferric ions to form a red complex. However, due to the poor anti-interference ability of this method, it is easily affected by the matrix in water, so the accuracy of this method is poor when determining the permanganate index.

In addition, Zhao Jianping changed the titration method to molecular spectroscopic absorption method such as ZL201010510809.0. Although this method is fast, accurate, safe and environmentally friendly, it needs to be used for routine determination of The permanganate index; therefore, the key to solve existing problems is to develop a method with simple operation, short measurement time and high accuracy of measurement results

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