Method and reagent composition for measuring chemical oxygen consumption in water

Abstract

The invention relates to the technical field of water analysis, in particular to a method and reagent composition for measuring chemical oxygen consumption in water. The method for measuring the chemical oxygen consumption in the water comprises the steps that 1, a water sample to be measured and a reagent I are mixed, the reagent I contains potassium dichromate, concentrated sulfuric acid and a catalyst, the concentration of potassium dichromate ranges from 0.062 g / L to 13.7 g / L, and the sample introduction volume of the reagent I is smaller than or equal to 5 mL; 2, the obtained mixture is decomposed at the temperature higher than 90 DEG C; 3, the chemical oxygen consumption in the water is obtained through calculation. According to the method and the reagent composition, the precision and accuracy of the chemical oxygen consumption detecting result can be effectively improved, meanwhile, the sample introduction volume, especially the sample introduction volume of concentrated sulfuric acid can be effectively reduced, and a water sample with high chemical oxygen consumption concentration can be detected. The method and the reagent composition can be especially suitable for a micro sample introduction mode, and the smaller the sample introduction volume is, the more obvious the advantages of the method and the reagent composition are.

Description

technical field [0001] The invention relates to the technical field of water analysis, in particular to a method for measuring chemical oxygen consumption in water and a reagent composition used in the method. Background technique [0002] Chemical oxygen demand refers to the amount of oxidant consumed by the oxidation of reducing substances in water by oxidants, expressed in mg / L of oxygen consumption per unit volume of water. Chemical oxygen demand, also known as chemical oxygen demand, reflects The pollution degree of reducing substances in water is a routine monitoring item in water quality testing and an important indicator for evaluating water pollution. At present, the most commonly used method for measuring chemical oxygen demand is the dichromate method. The principle of this method is used to define chemical oxygen demand as: under certain conditions, the solubility in water samples is oxidized by potassium dichromate. The mass concentration of oxygen correspondin...

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Problems solved by technology

[0008] At present, with the increasingly serious pollution and the increasing emphasis on environmental protection, the requirements for the detection of chemical oxygen consumption are also increasing. Reagents are used to detect chemical oxygen demand on water quality analysis instruments. The dosage needs to be at least roughly equivalent to the sum of the injection volume of the water sample to be tested plus other main reagents. On this premise, it is difficult to further reduce the injection volume of the water sample to be tested and potassium dichromate. The injection volume of sulfuric acid is also difficult to further reduce, so the amount of concentrated sulfuric acid discharged during the chemical oxygen demand detection process is very considerable, which can bring very serious secondary pollution to the environment; (2) time efficiency is too low: Also affected by the fact that the injection volume is difficult to further reduce, the time required for the chemical oxygen demand detection process is usually longer, and the time efficiency is a very important parameter for both industrial production and water quality monitoring. The time efficiency often means the loss of thousands or even hundreds of thousands of yuan; (3) usually compared with manual analysis, the injection volume of water samples is less, and the accuracy and stability of water quality analysis instruments are poor: the existing The relative standard deviation of the measurement results is large, and as the injection volume decreases, the accuracy and stability of the measurement are getting worse

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