Method for measuring ammonia content in ambient air and waste gas

Abstract

The invention discloses a method for measuring ammonia content in ambient air and waste gas, which comprises the following steps of: taking 10mL of absorption liquid samples, putting the absorption liquid samples into a sample tube, and sequentially putting the absorption liquid samples into corresponding positions of a sample plate of a sample injector of an analyzer according to an analysis table of the continuous flow injection analyzer; in an alkaline medium, ammonia in the absorption liquid sample reacts with hypochlorite released by 0.2 wt% of the sodium dichloroisocyanurate solution to generate chloramine; the method comprises the following steps: reacting chloramine with salicylate at 40 DEG C in the presence of sodium nitroferricyanide to form a blue-green compound, measuring absorbance at the wavelength of 665 nm, and measuring the content of ammonia in absorption liquid by using a calibration curve established by a standard solution to obtain the concentration of ammonia in ambient air and waste gas. According to the method, the steps of sample introduction, reaction, detection and the like are automatically completed through instruments, the determination work efficiency is improved, manual operation errors and external interference are reduced, the accuracy of a measurement result is high, and manual errors and labor cost of a manual spectrophotometric method are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring, and in particular to a method for measuring ammonia content in ambient air and waste gas. Background Art

[0002] Ammonia is the only alkaline gas in the atmosphere and is very easy to react with SO2 and NO in the atmosphere. X The reaction forms secondary inorganic aerosols, a major contributor to atmospheric particulate matter in many cities, and hence smog. Ammonia is often the single largest source of atmospheric nitrogen deposition, returning to the surface through both dry and wet precipitation as rainwater. It is a major factor in soil acidification and water eutrophication, with long-term impacts on the environment, human and animal health, and reduced biodiversity. Ammonia is highly soluble in water, highly volatile, a strong irritant, and toxic.

[0003] At present, the determination methods of ammonia in ambient air and exhaust gas are mainly based on HJ 533-2009 "Determination of Ammonia in Ambient Air and Exhaust Gas - Nessler's Reagent Spectrophotometric Method" and HJ 534-2009 "Determination of Ammonia in Ambient Air - Sodium Hypochlorite-Salicylic Acid Spectrophotometric Method". Both methods use manual spectrophotometry to detect samples. The analysis steps are relatively complicated, pre-processing is required, the labor cost is high, and it is easy to produce human error interference. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for determining the ammonia content in ambient air and exhaust gas. This method overcomes the defects of traditional ammonia determination and adopts a continuous flow injection analyzer to automatically complete the steps of sampling, reaction, and detection through the instrument, thereby improving the efficiency of the determination operation, reducing human operation errors and external interference, and achieving high accuracy of the measurement results, thereby reducing the human errors and labor costs of manual spectrophotometry.

[0005] To solve the above technical problems, the method for determining the ammonia content in ambient air and exhaust gas of the present invention comprises the following steps: Step 1: Take 10mL of absorption liquid sample and put it into the sample tube. According to the analysis table of the continuous flow injection analyzer, put it into the corresponding position of the analyzer injector sample tray in sequence. Step 2: In an alkaline medium, ammonia in the absorption liquid sample reacts with hypochlorite released from a 0.2 wt% sodium dichloroisocyanurate solution to generate chloramine; Step 3: At 40°C and in the presence of sodium nitroferricyanide, chloramine reacts with salicylate to form a blue-green compound. The absorbance is measured at a wavelength of 665nm. The ammonia content in the absorption liquid is measured using a calibration curve established using a standard solution to obtain the ammonia concentration in the ambient air and exhaust gas.

[0006] Furthermore, the absorption liquid samples were sampled at three different points using a 50 mL absorption tube at a flow rate of 0.5 to 1 L / min, and the gas sampling lasted for at least 45 min.

[0007] Furthermore, the absorption tube contains 0.01 mol / L sulfuric acid absorption liquid. The present method for determining ammonia content in ambient air and exhaust gas employs the aforementioned technical solution. Specifically, a 10 mL sample of absorption liquid is placed in a sample tube and sequentially placed on the analyzer's sample tray according to the analysis table of a continuous flow injection analyzer. In an alkaline medium, the ammonia in the absorption liquid reacts with hypochlorite released from a 0.2 wt% sodium dichloroisocyanurate solution to form chloramine. At 40°C and in the presence of sodium nitrosoferricyanide, the chloramine reacts with salicylate to form a blue-green compound. The absorbance is measured at a wavelength of 665 nm. A calibration curve established using standard solutions is used to determine the ammonia content in the absorption liquid and, consequently, the ammonia concentration in the ambient air and exhaust gas. This method overcomes the shortcomings of traditional ammonia determination by utilizing a continuous flow injection analyzer, automating the steps of injection, reaction, and detection. This improves measurement efficiency, reduces human error and external interference, and achieves highly accurate results, reducing the human error and labor costs associated with manual spectrophotometry. DETAILED DESCRIPTION

[0008] The method for determining the ammonia content in ambient air and exhaust gas of the present invention comprises the following steps: Step 1: Take 10mL of absorption liquid sample and put it into the sample tube. According to the analysis table of the continuous flow injection analyzer, put it into the corresponding position of the analyzer injector sample tray in sequence. Step 2: In an alkaline medium, ammonia in the absorption liquid sample reacts with hypochlorite released from a 0.2 wt% sodium dichloroisocyanurate solution to generate chloramine; Step 3: At 40°C and in the presence of sodium nitroferricyanide, chloramine reacts with salicylate to form a blue-green compound. The absorbance is measured at a wavelength of 665nm. The ammonia content in the absorption liquid is measured using a calibration curve established using a standard solution to obtain the ammonia concentration in the ambient air and exhaust gas.

[0009] Preferably, the absorption liquid sample is sampled at three different points using a 50 mL absorption tube at a flow rate of 0.5 to 1 L / min, and the sampling time is at least 45 minutes.

[0010] Preferably, the absorption tube contains 0.01 mol / L sulfuric acid absorption liquid.

[0011] To verify the correctness of this method, a certified standard sample of ammonia with a concentration of 0.797±0.038 mg / L was determined according to the above steps and repeated three times. The results were 0.808 mg / L, 0.796 mg / L, and 0.814 mg / L, respectively, with an average value of 0.806 mg / L. Within the range of standard samples, the accuracy of this method meets the requirements.

[0012] This method and HJ 533-2009 "Determination of Ammonia in Ambient Air and Waste Gases - Nessler's Reagent Spectrophotometric Method" were used to analyze the same sample. The samples were tested using different detection methods, and the test results are shown in the following table: As can be seen from the above table, the relative deviation between the determination results of this method and the manual spectrophotometric method is less than 5%, and the difference in results is not large and is within a reasonable range, proving that this method fully meets the accuracy requirements for the determination of ammonia content in ambient air and exhaust gas.

[0013] This method uses a continuous flow injection analyzer to determine the ammonia content in ambient air and exhaust gas. The instrument automates the steps of sampling, reaction, and detection, allowing the detection of a large number of samples in a short period of time, thereby improving work efficiency. By precisely controlling the mixing of samples and reagents, reaction conditions, and online detection, human operating errors and external interference are reduced, and the measurement results are highly accurate, thereby reducing the human errors and labor costs of manual spectrophotometry and providing reliable measurement results.

Claims

1. A method for determining the ammonia content in ambient air and exhaust gas, characterized in that The steps include: Step 1: Take 10mL of absorption liquid sample and put it into the sample tube. According to the analysis table of the continuous flow injection analyzer, put it into the corresponding position of the analyzer injector sample tray in sequence. Step 2: In an alkaline medium, ammonia in the absorption liquid sample reacts with hypochlorite released from a 0.2 wt% sodium dichloroisocyanurate solution to generate chloramine; Step 3: At 40°C and in the presence of sodium nitroferricyanide, chloramine reacts with salicylate to form a blue-green compound. The absorbance is measured at a wavelength of 665nm. The ammonia content in the absorption liquid is measured using a calibration curve established using a standard solution to obtain the ammonia concentration in the ambient air and exhaust gas.

2. The method for determining the ammonia content in ambient air and exhaust gas according to claim 1, characterized in that: The absorption liquid samples were sampled at three different points using a 50 mL absorption tube at a flow rate of 0.5 to 1 L / min for at least 45 min.

3. The method for determining the ammonia content in ambient air and exhaust gas according to claim 2, characterized in that: The absorption tube contains 0.01 mol / L sulfuric acid absorption liquid.

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