Method for measuring sulfuric acid mist by ion chromatography

Abstract

The invention discloses a method for measuring sulfuric acid mist by ion chromatography, which is characterized in that in the sampling and blank sample setting process of a standard HJ544-2016 sulfuric acid mist measuring method, an absorption bottle filled with absorption liquid is used as follows: the absorption liquid is added into an impact type absorption bottle, and the added absorption liquid is 50ml of isopropanol solution with the volume concentration of 80%; mobile phases used for ion chromatography detection are 3.2 mmol / L sodium carbonate solution and 1.0 mmol / L sodium bicarbonate solution, and acetone accounting for 10% of the total volume of the mobile phases is added into the mobile phases; the solvent of the isopropanol solution is water. By optimizing and improving the mobile phase and the absorption liquid used in the standard detection, the separation degree of the sulfate ion peak is improved, the impurity peak with the separation degree of 0.3 in the sample impurity peak is effectively and completely separated, the interference is eliminated, and the accuracy of the sulfuric acid mist determination result is improved.

Description

Technical Field

[0001] The present application relates to the field of environmental protection technology, and in particular to a method for measuring sulfuric acid mist by ion chromatography. Background Art

[0002] Sulfur-based acid production is an important sulfuric acid production process, primarily involving sulfur combustion, oxidation reaction, condensation, and concentration. The primary raw material is sulfur. Combustion of sulfur produces gases such as sulfur dioxide and sulfur trioxide, which are continuously oxidized, absorbed, and concentrated in the sulfuric acid production unit to produce highly concentrated sulfuric acid. This production process generates exhaust gas, which includes sulfuric acid mist and sulfur dioxide gas. Because sulfuric acid mist is highly corrosive, accurate monitoring of the sulfuric acid mist content in the treated exhaust gas is essential to ensure environmental safety. Current standards define sulfuric acid mist as consisting of small sulfuric acid droplets, sulfur trioxide, and soluble sulfate salts in particulate matter. Exhaust gas from sulfur combustion, mineral smelting, and sulfuric acid production is a form of air pollution. Current standards define sulfuric acid mist as consisting of small sulfuric acid droplets, sulfur trioxide, and soluble sulfate salts in particulate matter. Sulfuric acid mist can occur in plants that directly produce or use sulfuric acid, as well as from exhaust gases from plants that use coal, petroleum, or heavy oil as raw materials and fuels. After sulfur dioxide gas in the exhaust gas is oxidized into sulfur trioxide, it combines with moisture in the air to form sulfuric acid mist. Sulfur dioxide in the atmosphere can undergo an oxidation reaction to form sulfuric acid mist.

[0003] Sulfuric acid mist is a common pollutant in the sulfuric acid production industry's tail gas. This is primarily caused by SO₃ gas that is not fully absorbed by the tail gas absorber, combining with water to form tiny acid mist particles. This acid mist not only corrodes equipment but also forms acid rain when released into the atmosphere, contaminating soil and water, affecting plant and animal growth, and harming the human respiratory system.

[0004] On March 29, 2016, the Ministry of Ecology and Environment approved HJ544-2016, "Determination of Sulfuric Acid Mist in Waste Gases from Stationary Pollution Sources - Ion Chromatography Method," for implementation on May 1, 2016, simultaneously repealing the previous standard, HJ544-2009. Upon implementation, the new standard will be used to measure sulfuric acid mist in waste gas emitted from stationary pollution sources. Stationary pollution sources refer to pollution sources with fixed emission locations, typically industrial production facilities, such as factory chimneys (coal-fired power plants, steel mills, cement plants, chemical plants, etc.); boiler exhaust outlets; industrial kiln exhaust outlets; waste incinerator exhaust outlets; exhaust devices used in process reactions; and other types of organized industrial emission outlets. Environmental protection requirements for monitoring are required.

[0005] The standard spectrum of sulfuric acid mist determination disclosed in standard HJ544-2016 is as follows Figure 1 As shown; However, in the actual monitoring process, it was found that there was an unknown peak at the sulfate ion peak position. Figure 2 As shown, Figure 2 In accordance with the method in standard HJ544-2016, the tail gas of 800,000 tons / year sulfuric acid unit of Sanhuan Zhonghua was collected and tested in 2017. Figures 1 and 2 When the sample was analyzed according to the method specified in HJ 544-2016, the sulfate peak exhibited a distinct "double-hump" shape, flattened and not sharp. However, the peak remained normal after the addition of the standard sample, indicating that the sample was experiencing interference from impurities at the sulfate ion peak. The resolution of the impurity from the sulfate ion peak was only 0.3, far below the 1.5 required for accurate determination of chromatographic components. This resulted in inaccurate determination of sulfate ions in the sample. This could cause the ion chromatography determination of sulfuric acid mist to deviate from the true value, resulting in an abnormally high concentration exceeding the standard.

[0006] However, the current standard HJ544-2016 does not explain how to eliminate the impact of interference peaks on measurement results, resulting in the above problem being unable to be effectively solved.

[0007] The information disclosed in the background section is only intended to enhance understanding of the overall background of the invention and should not be considered as an admission or any form of suggestion that the information constitutes the prior art already known to a person of ordinary skill in the art. Summary of the Invention

[0008] In response to the above technical problems, the present application provides an ion chromatography method for determining sulfuric acid mist. By optimizing and improving the mobile phase and absorption liquid used in the standard test, the separation of sulfate ion peaks is improved, and the effective and complete separation of impurity peaks with a separation degree of 0.3 in the sample impurity peaks is achieved, interference is eliminated, and the accuracy of the sulfuric acid mist determination results is improved.

[0009] The present application provides an ion chromatography method for determining sulfuric acid mist. In the sampling and setting blank sample process of the standard HJ544-2016 sulfuric acid mist determination method, the absorption bottle containing the absorption liquid used is as follows: the absorption liquid is added to the impact absorption bottle, and the absorption liquid added is 50 ml of an isopropyl alcohol solution with a volume concentration of 80%; The mobile phase used for ion chromatography was a 3.2 mmol / L sodium carbonate solution and a 1.0 mmol / L sodium bicarbonate solution, with acetone added to the mobile phase to account for 10% of the total volume of the mobile phase; The solvent of the isopropyl alcohol solution is water.

[0010] Preferably, before sampling, the sampling points are arranged and the sampling devices at each sampling point are installed in accordance with the requirements of GB / T 16157.

[0011] Preferably, the method further comprises: setting at least 2 sets of full-procedure blank samples at the sampling point as blank samples.

[0012] Preferably, the ion chromatography detection conditions are: using a sulfuric acid solution with a volume concentration of 5‰ as the regeneration liquid; a flow rate of 1.00 ml / min, a suppressor current of 75 mA, a detector temperature of 30°C, a column temperature of 20°C, and an injection volume of 10 µL.

[0013] Preferably, the method further comprises: preparing a series of standard gradient concentration solutions of potassium sulfate with concentrations of 0 mg / L, 1.00 mg / L, 2.00 mg / L, 5.00 mg / L, 10.0 mg / L, and 20.0 mg / L, respectively; Use ion chromatography to measure the gradient concentration solutions, and draw a standard curve with retention time as the horizontal axis and instrument response value as the vertical axis.

[0014] Preferably, the method includes: preparing a sample.

[0015] Preferably, preparing the sample comprises: Transfer the washing liquid, filter cartridge, and absorption liquid in the 1# absorption bottle into a 100ml stoppered colorimetric tube, wash the screw-capped wide-mouth polyethylene sealed tube and the inner wall of the 1# impact absorption bottle, add the washing liquid into the stoppered colorimetric tube, and adjust the volume; The stoppered colorimetric tube was placed in an ultrasonic cleaner and ultrasonicated for 45 minutes. The mixture was cooled and mixed. The extract was filtered through a 0.45 µm water-based microporous membrane filter into a clean container to obtain a sample 1 to be tested.

[0016] Preferably, preparing the sample comprises: Transfer all the samples in the 2# absorption bottle into another 100 ml stoppered colorimetric tube, wash the inner wall of the 2# absorption bottle, and add the washing liquid into the stoppered colorimetric tube to make up the volume to obtain sample 2 to be tested.

[0017] Preferably, the following tests are performed on sample 1 or 2 respectively, and the sum of the obtained results is the result of the group of samples: The sample is injected into an ion chromatograph to determine the sulfate concentration of the sample; The blank sample was injected into ion chromatography to determine the sulfate concentration.

[0018] The beneficial effects of this application include: 1) The ion chromatography method for determining sulfuric acid mist provided in this application determines through experimental detection that the impurity composition of sulfuric acid mist tail gas is O2, N2, CH4 and SO2, and determines that the main interfering factor is SO2; by improving the composition of the ion chromatography mobile phase solution of the detection instrument, the impurity peaks SO3 and SO2 water-soluble substances that enter the absorption liquid in the tail gas are effectively separated in the test results, and the separation degree R between the two is increased from 0.6 to 2.2, meeting the chromatographic peak separation requirements, avoiding the interference of sulfite on the sulfuric acid mist detection results, and realizing the accurate determination of sulfuric acid mist.

[0019] 2) The ion chromatography method for determining sulfuric acid mist provided in this application achieves a sulfate recovery rate of 96-102% in spiked samples, meeting national standards. This method is intended to be used as a revised test method for standard HJ544-2016 and to be widely promoted and used to guide standard sample determination. This will help avoid misjudgments in environmental law enforcement and contribute to protecting the atmospheric environment and promoting green production in enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the standard spectrum for the determination of sulfuric acid mist by ion chromatography in standard HJ544-2016; Figure 2 To determine the actual spectrum of sulfuric acid mist in the actual collected samples according to the standard method; Figure 3 SO3 obtained in Example 1 of this application 2- Solution, SO4 2- Qualitative analysis comparison chromatogram of solution and sample solution; a is the detection of SO3 in the sample alone 2- Chromatogram of SO4 in the sample detected separately; b is the chromatogram of SO4 in the sample detected separately 2- Chromatogram of Figure 2 ; Figure 4 SO3 obtained in Example 2 of this application 2- 、SO4 2- Comparison of the ion chromatography results in HJ544-2016 obtained with different mobile phase compositions in the mixture; a is the result obtained when 1% methanol is added to the mobile phase; b is the result obtained when 1% ethanol is added to the mobile phase; c is the result obtained when 1% acetone is added to the mobile phase; SO3 2- 、SO4 2- Preparation of mixed standard solution: Use water as solvent and sodium sulfate to prepare 20mg / L SO4 2- Solution; use water as solvent and prepare 20mg / L SO3 using sodium sulfite 2- Solution; resulting SO4 2- solution, SO3 2- The solutions were mixed in equal volumes at a ratio of 1:1 to obtain a mixed solution; Figure 5 SO3 obtained in Example 3 of this application 2- 、SO4 2- Comparison of ion chromatography results in HJ544-2016 after adding different amounts of acetone to the mobile phase of the mixed solution; a is the result obtained when 1% acetone was added to the mobile phase; b is the result obtained when 5% acetone was added to the mobile phase; c is the result obtained when 10% acetone was added to the mobile phase; Figure 6 The exhaust gas sampling device specified in GB / T 16157 used in Example 4 of the present application; Figure 7 The method provided for this application was invited to participate in the experimental data collection and revision information collection form of standard HJ544-2016. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0022] Unless otherwise specified, the materials and instruments used in the following examples were obtained from commercial channels; the detection methods used were all existing methods unless otherwise specified.

[0023] For the methods used in the following examples, any content not described in detail can refer to the "Determination of Particulate Matter and Sampling Method for Gaseous Pollutants in Exhaust Gas from Stationary Pollution Sources" (GB16157-1996), "Ion Chromatography Method for Determination of Sulfuric Acid Mist in Exhaust Gas from Stationary Pollution Sources" (HJ544-2016), and the Determination of Sulfuric Acid Mist in Sulfuric Acid Industry Tail Gas (GB / T38685-2020) for on-site collection experiments of sulfuric acid mist.

[0024] Example 1 Design an experiment to detect impurity components in sulfuric acid mist tail gas: By analyzing the process principle, process flow and production raw and auxiliary materials of the existing sulfuric acid production device, it is found that H2, O2, N2, CO, CO2, CH4, H2S and SO2 impurities may exist in the sulfuric acid tail gas. According to the method in standard HJ544-2016, 5 samples were collected for the following tests. Then, the above impurities in the sulfuric acid tail gas were tested using the methods and instruments shown in Table 1. The results are listed in Tables 2 and 3. Figure 3 middle.

[0025] Table 1 Impurity detection of sulfuric acid mist exhaust sample Table 2 Results of determination of impurities in tail gas from sulfuric acid plant The test results show that there are O2, N2, CH4 and SO2 impurities in sulfuric acid tail gas. O2, N2 and CH4 will not be absorbed by the alkaline absorption liquid, so they will not interfere with the measurement. SO2 and sulfuric acid mist will be absorbed by the alkaline absorption liquid together, and will be respectively SO3 2- 、SO4 2- The form exists in the absorption liquid. When measured by ion chromatography, due to the same valence, similar composition and close affinity of the two, the presence of SO2 in the tail gas may cause the absorption liquid to form excess SO3 2- 、SO4 2- , interfering with the accuracy of sulfate determination results.

[0026] according to Figure 3 From a to c, it can be seen that the peak times of sulfite and sulfate are very close. When sulfite and sulfate exist in the sample at the same time, a "double hump" will appear, which is inseparable and partially overlaps.

[0027] Example 2 Study of additives in mobile phase Considering the safety, economy and feasibility of the instruments and reagents, the mobile phase used in the ion chromatography method of standard HJ544-2016 (3.2mmol / L sodium carbonate-1.0mmol / L sodium bicarbonate mobile phase) was added with 1% of the total volume of methanol, ethanol and acetone respectively. The SO3 2- 、SO4 2- The mixed solution was analyzed and the test results were as follows Figure 4 The mobile phase used was 1 L.

[0028] from Figure 4 It can be seen that after adding 1% acetone to the mobile phase, SO3 2- 、SO4 2- The separation effect of acetone is the best, and peaks with a certain spacing can be formed; therefore, the separation effect of different acetone concentrations was further tested.

[0029] Example 3 Study on different acetone addition amounts in fluidity The difference from Example 2 is that 1%, 5%, and 10% acetone were added to the mobile phase, and then the SO3 was determined according to the ion chromatography method in standard HJ544-2016. 2- 、SO4 2- Mixed liquid, compare the separation effect, the results are as follows Figure 5 shown.

[0030] Depend on Figure 5 It can be seen that when 10% of the total volume of acetone is added to the mobile phase, the separation (R) is the best, R>2 (the chromatographic peak separation requires R≥1.5), which meets the requirements of accurate determination and realizes the SO3 2- 、SO4 2- Complete separation in the assay.

[0031] Example 4 Actual Measurement 1. Sampling points and sampling devices at each sampling point According to the relevant provisions of GB / T 16157, the sampling points of exhaust gas emissions are arranged in the sulfuric acid production system of the Sanhuan Phosphate Plant, and sampling is carried out at each sampling point. The exhaust gas sampling device used for sampling is shown in Figure 6 .

[0032] 2. Sampling Install the filter cartridge into the filter cartridge clamp at the head of the sampler, and connect two 1# and 2# impact absorption bottles in series behind the smoke sampler. Each absorption bottle is filled with 50ml of 80% volume concentration isopropyl alcohol solution (the solvent is water) as the exhaust gas absorption liquid. The absorption liquid can avoid absorbing SO2 in the exhaust gas, collect sulfur trioxide gas and small droplets that penetrate the filter cartridge, and then connect it to the empty bottle and dryer.

[0033] The connecting pipe should be as short as possible, and the system's airtightness and reliability should be checked. Insert the sampler equipped with a filter cartridge into the exhaust pipe at the sampling point and sample at a constant rate. During sampling, the temperature of the smoke gun should not be lower than the flue gas temperature. Collect five samples at equal intervals within one hour, and simultaneously measure temperature and pressure parameters.

[0034] After sampling, take out the filter cartridge and place it in a screw-capped wide-mouth polyethylene sealed tube. Rinse the sampling nozzle and the inner wall of the curved tube with experimental water (pure water). Add the washing liquid into the sealed tube, cover the bottle stopper, and seal the 1# and 2# impact absorption bottles with polyethylene bottles for testing.

[0035] 3. Set up blank sample Each time you collect samples, you should bring at least two sets of blank samples. Bring the filter cartridges from the same batch and the absorption bottle filled with absorption liquid to the sampling site, without connecting them to the sampler. After sampling, bring them back to the laboratory for testing as blank samples.

[0036] 4. Ion chromatography reference conditions The mobile phase used for chromatographic analysis consisted of 3.2 mmol / L sodium carbonate solution and 1.0 mmol / L sodium bicarbonate solution, supplemented with acetone at 10% of the total mobile phase volume. The regeneration solution was 5‰ sulfuric acid solution (solvent in water). The flow rate was 1.00 ml / min, the suppressor current was 75 mA, the detector temperature was 30°C, the column temperature was 20°C, and the injection volume was 10 µL.

[0037] 5. Draw a standard curve Accurately pipette 0.00 ml, 1.00 ml, 2.00 ml, 5.00 ml, 10.00 ml and 20.00 ml of potassium sulfate standard solution (100 mg / L) into a group of 100 ml volumetric flasks, dilute to volume with laboratory water and mix thoroughly.

[0038] A series of potassium sulfate standard gradient solutions were prepared, with concentrations of 0 mg / L, 1.00 mg / L, 2.00 mg / L, 5.00 mg / L, 10.0 mg / L, and 20.0 mg / L, respectively. Each gradient solution was measured using an ion chromatograph, and a standard curve was plotted with retention time as the horizontal axis and instrument response as the vertical axis.

[0039] 6. Prepare the sample Transfer the sample (washing liquid and filter cartridge) in the sealed tube and the absorption liquid in the first absorption bottle to a 100ml stoppered colorimetric tube. Wash the screw-capped wide-mouth polyethylene sealed tube and the inner wall of the first impact absorption bottle with an appropriate amount of laboratory water. Add the washing liquid to the stoppered colorimetric tube and adjust the volume to the mark (the filter cartridge must be immersed). Place the stoppered colorimetric tube in an ultrasonic cleaner and sonicate for 45 minutes. Cool and mix thoroughly. Filter the extract through a 0.45µm water-based microporous membrane filter into a clean container to obtain sample 1.

[0040] Transfer all the samples in the 2# absorption bottle into another 100 ml stoppered colorimetric tube, wash the inner wall of the 2# impact absorption bottle with an appropriate amount of experimental water, and add the washing liquid to the stoppered colorimetric tube to make up the volume to obtain sample 2 to be tested.

[0041] Five samples were collected according to the above method, and each group of samples included: sample 1 and sample 2.

[0042] 7. Determination of samples The obtained samples 1 and 2 were subjected to the following tests respectively, and the obtained results were added together to form the final results of this group of samples, which are listed in Table 3: The same chromatographic conditions and analytical steps as those used to draw the standard curve were followed. The sample was injected into an ion chromatograph to determine the sulfate concentration of the sample. The retention time was used for qualitative analysis and the instrument response value was used for quantitative analysis. The obtained retention time and instrument response value were recorded respectively.

[0043] The full-process blank determination is carried out according to the same chromatographic conditions and analytical steps as those for drawing the standard curve. The full-process blank sample is injected into the ion chromatograph to determine the sulfate concentration in the full-process blank sample.

[0044] The results are listed in Table 3.

[0045] , Method Accuracy Verification After preparing test samples 1 and 2 from the five groups of samples obtained in the above steps, the following tests were performed on test samples 1 and 2 respectively. The sum of the obtained results is the final result of the group of samples and is listed in Table 3: Procedure: Add sulfate standard solution to each sample according to Table 3 and measure using an ion chromatograph according to standard HJ544-2016. Use retention time as the horizontal axis and instrument response value as the vertical axis. The instrument calculates the sample spike recovery rate to verify the accuracy of the method. The spike recovery test results are as follows: Table 3 Results of spike recovery experiment using the new method As can be seen from the above, the spiked recoveries obtained by the method provided by the present applicant are all between 95% and 105%, indicating that the detection results of sulfate ion by this method are highly accurate.

[0046] This application provides a test method and is invited to participate in the experimental data collection and revision of standard HJ544-2016. Information collection is as follows Figure 7 This method can effectively reduce the interference of impurities in acid mist exhaust and improve the accuracy of detection results.

[0047] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining sulfuric acid mist by ion chromatography, characterized in that: In the sampling and blank sample setting process of the standard HJ544-2016 sulfuric acid mist determination method, the absorption bottle containing the absorption liquid used is: adding the absorption liquid to the impact absorption bottle, the added absorption liquid is 50ml of 80% isopropyl alcohol solution; The mobile phase used for ion chromatography was a 3.2 mmol / L sodium carbonate solution and a 1.0 mmol / L sodium bicarbonate solution, with acetone added to the mobile phase to account for 10% of the total volume of the mobile phase; The solvent of the isopropyl alcohol solution is water.

2. The method for measuring sulfuric acid mist by ion chromatography according to claim 1, wherein: Before sampling, the sampling points shall be arranged in accordance with the requirements of GB / T16157 and the sampling devices at each sampling point shall be installed as shown in Figure 6.

3. The method for measuring sulfuric acid mist by ion chromatography according to claim 1, wherein: Also includes: At least two sets of full-procedure blank samples should be set up at the sampling point as blank samples.

4. The method for measuring sulfuric acid mist by ion chromatography according to claim 1, wherein: The ion chromatography detection conditions were as follows: sulfuric acid solution with a volume concentration of 5‰ was used as the regeneration solution; the flow rate was 1.00 ml / min, the suppressor current was 75 mA, the detector temperature was 30°C, the column temperature was 20°C, and the injection volume was 10 μL.

5. The method for measuring sulfuric acid mist by ion chromatography according to claim 1, wherein: Also includes: A standard series of gradient concentration solutions of potassium sulfate were prepared with concentrations of 0 mg / L, 1.00 mg / L, 2.00 mg / L, 5.00 mg / L, 10.0 mg / L, and 20.0 mg / L, respectively; Use ion chromatography to measure the gradient concentration solutions, and draw a standard curve with retention time as the horizontal axis and instrument response value as the vertical axis.

6. The method for measuring sulfuric acid mist by ion chromatography according to claim 1, wherein: include: Prepare the specimen.

7. The method for measuring sulfuric acid mist by ion chromatography according to claim 6, wherein: Preparation of the sample includes: Transfer the washing liquid, filter cartridge, and absorption liquid in the 1# absorption bottle into a 100ml stoppered colorimetric tube, wash the screw-capped wide-mouth polyethylene sealed tube and the inner wall of the 1# impact absorption bottle, add the washing liquid into the stoppered colorimetric tube, and adjust the volume; The stoppered colorimetric tube was placed in an ultrasonic cleaner and ultrasonicated for 45 minutes. The mixture was cooled and mixed. The extract was filtered through a 0.45µm water-based microporous membrane filter into a clean container to obtain a sample 1 to be tested.

8. The method for measuring sulfuric acid mist by ion chromatography according to claim 6, wherein: Preparation of the sample includes: Transfer all the samples in the 2# absorption bottle into another 100 ml stoppered colorimetric tube, wash the inner wall of the 2# absorption bottle, and add the washing liquid into the stoppered colorimetric tube to make up the volume to obtain sample 2 to be tested.

9. The method for measuring sulfuric acid mist by ion chromatography according to claim 7 or 8, characterized in that: The following tests are performed on sample 1 or 2 respectively, and the sum of the results is the result of the sample group: The sample is injected into an ion chromatograph to determine the sulfate concentration of the sample; The blank sample was injected into ion chromatography to determine the sulfate concentration.

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