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...

Examples

Embodiment 1

[0033] Embodiment 1 reproducibility test

[0034] use image 3 For the absorption cuvette shown, the absorption solution (boric acid solution with a T value of 18%) is added into the absorption pool from the upper absorption solution inlet 6, and the transmittance of the absorption solution is read through program control and automatically stored in the system as a titration End point T0; add alkaline solution (0.5% sodium hydroxide solution) to the waste liquid to be tested and heat at 120°C to distill out gaseous NH 3 , reaction formula: NH 4 + +OH - =NH 3 +H 2 O, gas NH 3 The gas is blown upward from the gas inlet 3 at the bottom of the absorption cuvette to be absorbed by the absorption liquid, and the reaction formula is: NH 3 +H + =NH 4 + .

[0035] After the distillation, the system reads the transmittance T1 of the reacted liquid in the absorption cell again, and compares it with the titration end point T0. If T1>T0, the titration starts. During the titratio...

Embodiment 2

[0052] Embodiment 2 tests actual waste water sample

[0053] test environment:

[0054] Ambient temperature: 25±5℃.

[0055] Humidity: 65% relative humidity.

[0056] Atmospheric pressure is 98KPa.

[0057] Power supply voltage (220±20)VAC.

[0058] Power frequency (50±0.5)Hz.

[0059] Reagent:

[0060] Absorbing solution: boric acid solution with a T value of 18%.

[0061] Distilling agent: 0.5% sodium hydroxide solution.

[0062] Titrant: 0.01mol / liter sulfuric acid solution.

[0063] use image 3 For the absorption cuvette shown, the absorption solution (boric acid solution with a T value of 18%) is added into the absorption pool from the upper absorption solution inlet 6, and the transmittance of the absorption solution is read through program control and automatically stored in the system as a titration End point T0; add alkaline solution (0.5% sodium hydroxide solution) to the waste liquid to be tested and heat at 120°C to distill out gaseous NH 3 , reaction fo...

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...

Examples

Embodiment 1

[0033] Embodiment 1 reproducibility test

[0034] use image 3 For the absorption cuvette shown, the absorption solution (boric acid solution with a T value of 18%) is added into the absorption pool from the upper absorption solution inlet 6, and the transmittance of the absorption solution is read through program control and automatically stored in the system as a titration End point T0; add alkaline solution (0.5% sodium hydroxide solution) to the waste liquid to be tested and heat at 120°C to distill out gaseous NH 3 , reaction formula: NH 4 + +OH - =NH 3 +H 2 O, gas NH 3 The gas is blown upward from the gas inlet 3 at the bottom of the absorption cuvette to be absorbed by the absorption liquid, and the reaction formula is: NH 3 +H + =NH 4 + .

[0035] After the distillation, the system reads the transmittance T1 of the reacted liquid in the absorption cell again, and compares it with the titration end point T0. If T1>T0, the titration starts. During the titratio...

Embodiment 2

[0052] Embodiment 2 tests actual waste water sample

[0053] test environment:

[0054] Ambient temperature: 25±5℃.

[0055] Humidity: 65% relative humidity.

[0056] Atmospheric pressure is 98KPa.

[0057] Power supply voltage (220±20)VAC.

[0058] Power frequency (50±0.5)Hz.

[0059] Reagent:

[0060] Absorbing solution: boric acid solution with a T value of 18%.

[0061] Distilling agent: 0.5% sodium hydroxide solution.

[0062] Titrant: 0.01mol / liter sulfuric acid solution.

[0063] use image 3 For the absorption cuvette shown, the absorption solution (boric acid solution with a T value of 18%) is added into the absorption pool from the upper absorption solution inlet 6, and the transmittance of the absorption solution is read through program control and automatically stored in the system as a titration End point T0; add alkaline solution (0.5% sodium hydroxide solution) to the waste liquid to be tested and heat at 120°C to distill out gaseous NH 3 , reaction fo...

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