CN-116893150-B - Gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method and device for fixing total nitrogen in pollution source waste gas

Abstract

The invention provides a gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas, which is characterized by comprising the following steps of S1 fully reacting the waste gas with an oxidant, S2 continuously fully reacting the waste gas after the reaction of S1 by adopting an absorption liquid, S3 collecting the oxidation liquid after the reaction of S1, reducing a nitrogen-containing compound in the oxidation liquid into nitric oxide after pretreatment, detecting the total nitrogen content I, S4 collecting the absorption liquid after the reaction of S2, and obtaining the total nitrogen content II, wherein the total nitrogen content I and the total nitrogen content II are added to obtain the total nitrogen content in the current waste gas. By the method, the accurate determination of the total nitrogen in the waste gas of the fixed pollution source can be realized.

Inventors

• XUE LIDONG
• ZHANG HUILAN
• ZHANG YOUYA
• YUAN MAO
• CHEN FAN
• XU RENJI
• ZHU HONGXIA

Assignees

• 中国环境监测总站
• 上海北裕分析仪器股份有限公司

Dates

Publication Date

20260505

Application Date

20230724

Claims (4)

1. 1. The gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas is characterized by comprising the following steps: s1, fully reacting waste gas with an oxidant, wherein the oxidant is an acidic potassium permanganate solution; S2, continuously and fully reacting the waste gas after the reaction of S1 by adopting an absorption liquid, wherein the absorption liquid is prepared from glacial acetic acid, sulfanilic acid and naphthalene ethylenediamine hydrochloride; S3, collecting oxidation liquid after the reaction of S1, reducing a nitrogen-containing compound in the oxidation liquid into nitric oxide after pretreatment, and detecting the total nitrogen content I by adopting a gas phase molecular absorption method, wherein the oxidation liquid is subjected to pretreatment as follows: s3-0, adding oxalic acid into the oxidation liquid for several times in an environment of 60-90 ℃, regulating the pH value to be neutral after clarification, and centrifuging to separate supernatant; s3-1, adding alkaline persulfate to the supernatant sample; s3-2, oxidizing into nitrate through ultraviolet digestion; S3-3, reducing the nitric oxide into nitric oxide by a reducing agent; S4, collecting the absorption liquid after the reaction of S2, and measuring by adopting a naphthalene ethylenediamine hydrochloride spectrophotometry to obtain the total nitrogen content II; S5, adding the total nitrogen content I and the total nitrogen content II to obtain the total nitrogen content in the current waste gas.
2. 2. A gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas as claimed in claim 1, wherein: for the absorption liquid in S4, the total nitrogen content II is calculated based on the absorbance of the azo dye at a wavelength of 540nm in proportion to the nitrogen dioxide content.
3. 3. A gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas as claimed in claim 1, wherein: an oxidation unit and an absorption unit are sequentially arranged along the flowing direction of the waste gas; wherein the oxidation unit comprises at least two groups of oxidation devices; The absorption unit comprises at least two groups of absorption devices.
4. 4. A gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas as claimed in claim 3, wherein: a water stop valve is arranged between the devices.

Description

Gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method and device for fixing total nitrogen in pollution source waste gas Technical Field The invention relates to the field of instrument analysis, in particular to a gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for total nitrogen in waste gas of a fixed pollution source. Background With the improvement of ultra-low emission of iron and steel enterprises in key areas, the method is basically completed. At present, the technical problems existing in the ultra-low emission reconstruction and evaluation monitoring of iron and steel enterprises are urgently needed to be solved. The prior oxidative denitration technology has insufficient scientific support, the actual desulfurization and denitration system is complex, and the research on nitrogen balance based on actual waste gas is rarely reported. Nitrogen balance refers to the sum of nitrogen elements in the feed nitrogen source = total nitrogen in flue gas + dust removal. The current ecological environment quality standard does not provide clear requirements for the limit value of total nitrogen in the waste gas with fixed pollution sources, but the corresponding manual analysis method for the total nitrogen in the waste gas with fixed pollution sources is lacking at home and abroad, so that the nitrogen balance problem in the oxidation and denitrification process cannot be effectively estimated, and the existing manual analysis method for nitrogen oxides cannot completely measure the total nitrogen in the flue gas. Disclosure of Invention The invention aims to overcome the defects, an absorption system of a 2-level oxidation tube and a 3-level absorption tube is adopted, a method for measuring total nitrogen in the oxidation liquid by a gas phase molecular absorption spectrometry is established, and when the sampling volume is 2.5L, the detection limit of the total nitrogen method is 3mg/m 3, so that the ultra-low emission reconstruction of iron and steel enterprises and the evaluation and monitoring of the oxidation denitration process of a sintering machine head are effectively supported. Based on the method provided by the invention, a technical basis and a data base are established for evaluating the feasibility of the oxidation denitration technology. The invention provides a gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas, which is characterized by comprising the following steps: S1, fully reacting waste gas with an oxidant; S2, adopting an absorption liquid to continuously and fully react the waste gas after the reaction of S1; s3, collecting the oxidized liquid after the reaction of S1, reducing the nitrogen-containing compound in the oxidized liquid into nitric oxide after pretreatment, and detecting the total nitrogen content I; s4, collecting the absorption liquid after the S2 reaction to obtain total nitrogen content II; S5, adding the total nitrogen content I and the total nitrogen content II to obtain the total nitrogen content in the current waste gas. Further, the gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas is characterized by comprising the following steps of: The oxidant in S1 is acidic potassium permanganate. Further, the gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas is characterized by comprising the following steps of: And S2, the absorption liquid is prepared from glacial acetic acid, sulfanilic acid and naphthalene ethylenediamine hydrochloride. Further, the gas phase molecular absorption spectrum-naphthalene ethylenediamine hydrochloride spectrophotometry method for fixing total nitrogen in pollution source waste gas is characterized by comprising the following steps of: the oxidizing solution in S3 is pretreated as follows: s3-0, adding oxalic acid into the oxidation liquid for several times in an environment of 60-90 ℃, regulating the pH value to be neutral after clarification, and centrifuging to separate supernatant; specifically, the method comprises preheating in a constant temperature water bath (80+ -5deg.C) for 2min, adding oxalic acid into the oxidation solution for several times while shaking (or stirring with glass rod) continuously, and gradually blackening the oxidation solution from purple to colorless, clear and transparent. Adding a small amount of 50% NaOH, stirring uniformly until the solution has stable white flocculent precipitate, and simultaneously making the pH value neutral, transferring all the oxidation solution into a 50ml centrifuge tube, centrifuging at 4000rpm for 5min, and collecting supernatant fo