Absorption cuvette and on-line monitoring titration method for ammonia nitrogen

Abstract

The invention relates to an absorption cuvette and an on-line monitoring titration method for ammonia nitrogen, and belongs to the field of analytical chemistry. The technical problem to be solved is to provide a new two-in-one device as a reaction container and a cuvette, and an on-line titration method for NH3-N with accurate measurement and good reliability. The invention is realized through the following technical scheme that the absorption cuvette comprises an absorption cell provided with at least two light transmission parallel planes, the lower part of the absorption cell is provided with a gas inlet, and the upper part of the absorption cell is provided with a titrating liquid inlet and an absorption liquid inlet. The absorption liquid is added into the absorption cell, a system automatically reads the transmittance of the absorption liquid in the absorption cell as a titrating end point T0; and after NH3 gas generated by the liquid to be detected is introduced into the absorption cell to react with the absorption liquid, the titration analysis is carried out, the system automatically and continuously reads the transmittance T1 of the reaction liquid during titrating, and the titration is finished when T1 is equal to T0. The method is accurate and reliable, and does not cause the phenomenon that the titration is not carried out or the titration does not stop.

Description

technical field [0001] The invention relates to an absorption cuvette and NH 3 -N on-line monitoring titration method belongs to the field of analytical chemistry. Background technique: [0002] According to the industry standards and enterprise standards issued by the Ministry of Environmental Protection, NH 3 -N online monitoring system is to add alkaline liquid to the waste liquid, (reaction formula: NH 4 + +OH - =NH 3 +H 2 O), heated and distilled at 120°C, the distilled gas NH 3 Absorption by boric acid solution (reaction formula: NH 3 - +H + =NH 4 + ), use methyl red as indicator, and then carry out neutralization titration with sulfuric acid solution (reaction formula: 2NH 4 + +SO 4 2- =(NH 4 ) 2 SO 4 ), calculate the ammonia nitrogen content in the water from the amount of titrant consumed. At present, the titration process adopted by domestic manufacturers of ammonia nitrogen meter is shown in figure 1 , the distilled gas enters the absorption ce...

AI Technical Summary

Problems solved by technology

[0003] Ordinary optical cuvettes are poorly sealed, easy to break, and difficult to clean after sticking to dirt. Moreover, the capacity of ordinary cuvettes is small, and the titration time will be relatively long when the system fails or measures high concentrations of ammonia nitrogen. Absorption pool The volume of liquid in will increase greatly and overflow

The distilled gas enters the absorption tank from the upper part, causing part of the distilled gas to stay above the surface of the absorbing liquid inside the absorbing tank, which cannot guarantee complete absorption by the absorbing liquid

In addition, artificially writing the titration end point requires manual zero adjustment to find the titration end point. At the same time, as time goes by, the color of the absorption solution fades and the transmittance changes. The T value filled in the program database is no longer the latest transmittance of the absorption solution. Luminosity, which affects the accuracy of the measurement

In addition, due to the change of the color of the indicator with the passage of time, the end point value deviates, causing the phenomenon that the monitor does not titrate or the titration does not stop

Images