Absorbing solution containing gold stabilizer and application thereof in ICP-MS detection of flue gas mercury

Abstract

This invention specifically relates to an absorbent containing a gold stabilizer and its application in ICP-MS detection of mercury in flue gas, belonging to the field of flue gas pollutant detection technology in thermal power plants. The absorbent is composed of a 2%~10% (v / v) nitric acid aqueous solution and a 100 μg / L gold ion stabilizer. This absorbent can effectively detect Hg in flue gas. 0 Hg 2+ and Hg p This invention achieves comprehensive and efficient capture of three forms of mercury, with a capture efficiency ≥98% and a concentration deviation of ≤5% within 24 hours. It also provides the application of this absorbent in ICP-MS detection, with a detection limit as low as 0.01 μg / L and repeatability RSD ≤3%. This invention offers advantages such as simple operation, low cost, and strong adaptability to various operating conditions, accurately meeting the needs of trace mercury detection in flue gas from thermal power plants.

Description

Technical Field

[0001] This invention belongs to the field of flue gas pollutant detection technology in thermal power plants, specifically relating to an absorbent containing a gold stabilizer and its application in ICP-MS detection of mercury in flue gas. Background Technology

[0002] The flue gas emitted by coal-fired power plants contains elemental mercury (Hg). 0 ), divalent mercury (Hg) 2+ ) and particulate mercury (Hg p Trace amounts of mercury (μg / m³) exist in forms such as ) 3 (Level I) posed a serious threat to the ecological environment and human health, and accurate monitoring of these areas is a key aspect of environmental protection management.

[0003] Currently, existing technologies for mercury detection in flue gas from thermal power plants mainly fall into three categories: The first category is absorption liquid capture combined with cold atomic absorption / fluorescence spectroscopy (such as the HJ 543 standard). This method uses conventional absorption liquids such as potassium permanganate-sulfuric acid to capture mercury, and then detects it using a cold atomic absorption spectrophotometer (CVAAS) or a cold atomic fluorescence spectrophotometer (CVAFS). This type of method suffers from high blank values ​​in the absorption liquid and is sensitive to Hg... 0 The first type suffers from drawbacks such as low capture efficiency, poor stability, weak anti-interference capability of the detection instrument, and high detection limit. The second type involves adsorption tube capture combined with pyrolysis / chemical desorption (e.g., HJ 917 standard). This method uses activated carbon adsorption tubes to capture mercury, but after sampling, it requires pyrolysis or chemical desorption to release the mercury for detection. This method is cumbersome, has unstable desorption efficiency, and cannot directly detect all forms of mercury. The third type is the online continuous monitoring system (Hg-CEMS, such as HJ 1439 standard), which uses a dedicated pretreatment module and online monitoring instrument for real-time detection. However, this method suffers from drawbacks such as expensive equipment, high failure rate, immature core technology, and difficulty in tracing the detection results.

[0004] Inductively coupled plasma mass spectrometry (ICP-MS) boasts high sensitivity and low detection limits, making it widely used in trace element detection. However, when applied to mercury detection in flue gas, existing ICP-MS techniques suffer from severe mercury memory effect and sample volatilization due to the lack of a dedicated absorbent system, resulting in poor repeatability. Furthermore, traditional pre-filtration treatments often lead to mercury adsorption loss and incomplete impurity removal, affecting detection accuracy. In addition, existing absorbent systems (such as potassium permanganate-sulfuric acid) have poor compatibility with ICP-MS; manganese ions and other contaminants can suppress the detection signal, and additional acid conversion is required, potentially causing mercury loss or contamination.

[0005] Therefore, developing an absorbent system that is compatible with ICP-MS technology, can achieve comprehensive and efficient capture of the three forms of mercury in flue gas, and is easy to operate and cost-effective, along with its supporting detection method, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the technical problems existing in mercury detection in flue gas from thermal power plants, such as poor absorbent stability, incomplete mercury capture, insufficient detection accuracy, cumbersome operation procedures, high detection costs, and poor adaptability to operating conditions, this invention provides an absorbent containing a gold stabilizer and its application in ICP-MS detection of mercury in flue gas. This invention constructs a complete solution from sample collection to quantitative detection by optimizing the absorbent system, standardizing the sampling process, improving pretreatment methods, and perfecting mass spectrometry detection steps. This achieves accurate and efficient detection of trace mercury in flue gas from thermal power plants, effectively overcoming the core defects of existing technologies.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides an absorbent solution containing a gold stabilizer for ICP-MS detection of mercury in flue gas.

[0009] The absorbent solution of the present invention is composed of a nitric acid aqueous solution with a volume ratio of 2% to 10% and a gold ion stabilizer with a concentration of 100 μg / L added thereto; the absorbent solution does not contain potassium permanganate, sulfuric acid and ethanol.

[0010] This invention selects nitric acid aqueous solution as the main absorbent based on its good compatibility with the ICP-MS detection system. Nitric acid medium can be directly introduced into the ICP-MS sample introduction system without the need for acid medium conversion, avoiding potential mercury loss or contamination during the conversion process. Simultaneously, high-purity nitric acid aqueous solution itself has a low blank value, effectively reducing background interference in the detection.

[0011] The gold ions in the gold ion stabilizer described in this invention can react with Hg, which exists in elemental form in flue gas. 0 A stable gold-mercury complex is formed, effectively suppressing the volatilization loss of mercury during sampling, storage, and transportation. Simultaneously, this complex exhibits good stability in the ICP-MS injection system, preventing mercury adsorption in the instrument tubing, thus eliminating the mercury memory effect and improving detection repeatability. Nitric acid aqueous solution can efficiently dissolve Hg in flue gas. 2+ and particulate Hg p This enables the comprehensive capture of all three forms of mercury.

[0012] In some embodiments, the absorbent is used to absorb Hg in the flue gas of thermal power plants. 0 Hg 2+ and Hgp The capture efficiency of the three forms of mercury can reach over 98%, and the concentration deviation of the captured mercury sample is ≤5% within 24 hours, demonstrating excellent capture performance and stability.

[0013] Secondly, the present invention provides the application of the above-mentioned gold-containing absorbent in the ICP-MS detection of mercury in flue gas.

[0014] The application includes the following steps:

[0015] (1) Flue gas sampling: The absorbent liquid described in this invention is loaded into a U-shaped porous glass plate absorption bottle, and flue gas from the thermal power plant is collected by the flue gas collection device to make the flue gas fully contact the absorbent liquid and complete the capture of mercury.

[0016] During flue gas sampling, an automatic sampling device is preferred. The sampling flow rate is controlled at 0.3 L / min, the sampling nozzle temperature is set at 150℃, and the sampling time is controlled between 30 min and 1 hour. The sampling flow rate has been optimized experimentally to ensure sufficient contact between the flue gas and the absorbent while avoiding incomplete absorption due to excessive flow rate. Heating the sampling nozzle to 150℃ prevents condensation of saturated water vapor in the flue gas from diluting or contaminating the sample. After sampling, the inlet and outlet of the U-shaped porous glass plate absorption bottle are immediately sealed with rubber caps to prevent leakage of the absorbent and volatilization of mercury.

[0017] In some embodiments, the flue gas collection device includes a power plant chimney (1), a flue gas sampling port (2) located on the flue wall (3), a flue gas collector (4), a sampling nozzle (6), a gas flow controller (7), a polytetrafluoroethylene tube (9), and a U-shaped porous glass plate absorption bottle (10); the flue gas collector (4) is fixedly connected to the sampling nozzle (6) through a flange connection port (5), and the sampling nozzle (6) is inserted into the flue gas sampling port (2); the sampling nozzle (6) is connected to the gas flow controller (7); the flue gas outlet (8) of the gas flow controller (7) is connected to the U-shaped porous glass plate absorption bottle (10) containing the absorbent liquid (11) through the polytetrafluoroethylene tube (9).

[0018] (2) Sample pretreatment: Transfer the mercury-containing absorption liquid after capturing mercury element in step (1) into a centrifuge tube, centrifuge at 4000 r / min for 5 minutes to precipitate solid impurities, and directly aspirate the supernatant after centrifugation to obtain the sample to be tested.

[0019] This invention employs low-speed centrifugation for sample pretreatment. Centrifugation effectively removes solid impurities such as dust and particulate matter carried in flue gas, achieving an impurity removal rate of ≥99%, thus avoiding contamination and signal interference caused by impurities entering the ICP-MS instrument. Simultaneously, centrifugation eliminates the need for filter media, preventing the adsorption and loss of mercury on filter paper, with a mercury loss rate ≤1%, ensuring sample integrity. This method is simple and efficient, requiring only 5 minutes for single sample pretreatment, representing an efficiency improvement of over 60% compared to traditional filtration methods.

[0020] Before centrifugation, it is preferable to place the sealed U-shaped porous glass plate absorption bottle in a light-proof sample storage box and transport it to the analytical laboratory to avoid sunlight exposure causing mercury volatilization or changes in the properties of the absorption liquid.

[0021] (3) Quantitative detection by mass spectrometry: The sample to be tested obtained in step (2) is introduced into the ICP-MS mass spectrometer for detection. The concentration of mercury in the sample is calculated by combining the standard curve, and the concentration of mercury in the flue gas of the thermal power plant is calculated based on the sampling volume.

[0022] In some embodiments, the present invention optimizes the preparation method of the standard curve. Specifically, using a 2% nitric acid solution containing 100 μg / L gold ions as the dilution medium, a 1000 μg / mL mercury standard stock solution is serially diluted using a gravimetric method to prepare a series of mercury standard solutions with concentrations ranging from 0.5 to 10 μg / L, establishing a standard curve with a linear correlation R² ≥ 0.999. The gravimetric method allows for precise control of the dilution ratio, avoiding errors that may be introduced by the volumetric method; the standard solution and the sample solution use the same dilution medium (2% nitric acid solution containing gold ions), eliminating the influence of medium differences on the detection results; the addition of a gold ion stabilizer to the standard solution prevents the volatilization loss of mercury during storage, ensuring the stability of the standard curve.

[0023] The method described in this invention performs quantitative detection by mass spectrometry, with a detection limit as low as 0.01 μg / L, which can meet the requirements for detecting μg / m³ in flue gas from thermal power plants. 3 The system meets the requirements for precise detection of trace mercury; the detection repeatability RSD is ≤3%, which is significantly better than existing detection methods; and the presence of gold ion stabilizers can effectively eliminate the mercury memory effect, ensuring the accuracy and consistency of detection results.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) This invention pioneered the "nitric acid + gold ion" absorption liquid system. The nitric acid medium is perfectly compatible with ICP-MS, and the gold ions and Hg... 0 Forming stable complexes to achieve Hg 0 Hg 2+ and Hg pThe system achieves comprehensive and efficient capture of three forms of mercury, with a capture efficiency of ≥98%, and the concentration deviation of the captured mercury sample is ≤5% within 24 hours, solving the technical problems of poor stability of existing absorbents and incomplete mercury capture.

[0026] (2) The present invention uses low-speed centrifugation for sample pretreatment, with an impurity removal rate of ≥99% and a mercury loss rate of ≤1%. Compared with traditional filtration methods, it removes impurities more thoroughly, loses less mercury, and is more efficient. At the same time, the standard curve preparation method is optimized to eliminate media differences and mercury memory effect, achieving a detection limit as low as 0.01 μg / L and repeatability RSD ≤3%, which can accurately meet the trace mercury detection needs of thermal power plants.

[0027] (3) The absorbent system of the present invention has the ability to neutralize high concentrations of SO2 in flue gas. The gold-mercury complex is stable and is not affected by large fluctuations in flue gas temperature and humidity, and can meet the mercury detection needs under complex operating conditions in thermal power plants.

[0028] (4) The method of the present invention has a clear process and simple steps. It does not require complex and expensive online monitoring equipment. The detection cost is reduced by more than 50% compared with Hg-CEMS. It has extremely high practical value and promotion prospects. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the flue gas collection method and device of the present invention.

[0030] In the diagram: 1-Power plant chimney, 2-Flue gas sampling port, 3-Flue wall, 4-Flue gas collector, 5-Flange connection port, 6-Sampling nozzle, 7-Gas flow controller, 8-Gas flow controller flue gas outlet, 9-PTFE tube, 10-U-shaped porous glass plate absorption bottle, 11-Absorbent liquid. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0032] After reading the contents disclosed in this invention, those skilled in the art can make appropriate adjustments or substitutions to the process parameters of the methods and applications described in this invention without departing from the spirit and scope of this invention. Such obvious adjustments, substitutions or combinations should be included within the protection scope of this invention.

[0033] Unless otherwise specified, the materials, reagents, instruments and testing methods used in the following embodiments can be obtained commercially or prepared, operated and implemented with reference to conventional methods disclosed in the art.

[0034] It should be noted that all technical parameters described in this document as numerical ranges (such as temperature, ratio, time, content, etc.) should be understood as encompassing all possible sub-ranges and specific numerical points within that range, regardless of whether the specific numerical value or sub-range is explicitly listed. Unless otherwise specified, the technical terms used in this document have the meanings commonly understood by those skilled in the art.

[0035] like Figure 1 As shown, the flue gas collection device of the present invention includes a power plant chimney 1, a flue gas sampling port 2 disposed on the flue wall 3, a flue gas collector 4, a sampling nozzle 6, a gas flow controller 7, a polytetrafluoroethylene (PTFE) tube 9, and a U-shaped porous glass plate absorption bottle 10. The connections are as follows: the flue gas collector 4 is fixedly connected to the sampling nozzle 6 via a flange connection 5; the sampling nozzle 6 is inserted into the flue gas sampling port 2; the sampling nozzle 6 is connected to the gas flow controller 7; the flue gas outlet 8 of the gas flow controller 7 is connected to the U-shaped porous glass plate absorption bottle 10 containing absorbent liquid 11 via the PTFE tube 9.

[0036] During flue gas sampling, the flue gas collector 4 is activated. Flue gas from the power plant chimney 1 is extracted through the sampling nozzle 6, enters the gas flow controller 7 for flow regulation, and then flows through the polytetrafluoroethylene tube 9 into the U-shaped porous glass absorption bottle 10. The flue gas comes into full contact with the absorption liquid 11, efficiently capturing the mercury element. The exhaust gas is then discharged from the absorption bottle outlet. This device achieves constant temperature and constant flow sampling of power plant flue gas through sampling nozzle heating and precise flow control by the gas flow controller, ensuring the efficiency of mercury capture and the representativeness of the sample.

[0037] Example 1

[0038] This embodiment provides an absorbent containing a stabilizer and a precise ICP-MS method for detecting mercury in flue gas. The specific steps are as follows:

[0039] (1) Preparation of absorption solution: Take a 2% nitric acid aqueous solution as the main body of the absorption solution, add gold ion standard solution to it, so that the gold ion concentration in the final solution is 100 μg / L, mix evenly, and obtain the absorption solution system of the present invention.

[0040] (2) Flue gas sampling: Refer to Figure 1 The apparatus shown involves placing 10 mL of the aforementioned absorbent solution into a U-shaped porous glass plate absorption bottle. The automatic sampling mode of the flue gas collector is activated, the sampling flow rate is set to 0.3 L / min, the sampling nozzle is heated to 150°C, and sampling is conducted at this constant temperature for 30 minutes to ensure efficient capture of mercury from the flue gas by the absorbent solution. After sampling, the inlet and outlet of the U-shaped porous glass plate absorption bottle are immediately sealed with rubber caps, and the bottle is placed in a light-proof sample storage box and transported back to the laboratory.

[0041] (3) Sample pretreatment: Transfer all the absorption liquid in the U-shaped porous glass plate absorption bottle to a centrifuge tube, balance it, and place it in a centrifuge. Centrifuge at 4000 r / min for 5 minutes. After centrifugation, carefully aspirate the supernatant with a pipette and transfer it to a clean sample bottle to obtain the sample solution to be tested. The test results showed that the impurity removal rate in this step was 99.2%, and the mercury loss rate was 0.8%.

[0042] (4) Quantitative detection by mass spectrometry:

[0043] A 2% nitric acid solution containing 100 μg / L gold ions was used as the dilution medium. A 1000 μg / mL mercury standard stock solution was serially diluted by gravimetric analysis to prepare a 10 μg / mL intermediate mercury stock solution and a series of working mercury standard solutions with concentrations of 0.5, 1, 2, 5, and 10 μg / L. These working standard solutions were then analyzed using an ICP-MS mass spectrometer. The mercury mass spectral signal intensity at each concentration was recorded. A standard curve was plotted with concentration on the x-axis and signal intensity on the y-axis. Linear fitting yielded the standard curve equation Y = aX + b, with a linear correlation coefficient R0. 2 = 0.9992.

[0044] The sample solution was introduced into an ICP-MS mass spectrometer for detection, and the mercury ion mass spectrum signal intensity was obtained. Substituting this signal into the standard curve equation, the concentration of mercury in the sample solution was calculated. Combined with the sampling volume V (V = flow rate × time = 0.3 L / min × 30 min = 9 L), the final mercury concentration in the flue gas from the thermal power plant was calculated to be 0.02 μg / m³. 3 The same sample was measured six times repeatedly, and the calculated relative standard deviation (RSD) was 2.5%, with no obvious mercury memory effect observed during the instrument's detection process.

[0045] Example 2

[0046] This embodiment is basically the same as Embodiment 1, except that the following process parameters have been adjusted:

[0047] (1) Preparation of absorption solution: A nitric acid aqueous solution with a volume ratio of 10% was used as the main body of the absorption solution, and the gold ion concentration was maintained at 100 μg / L.

[0048] (2) Flue gas sampling: The sampling time was set to 1 hour (60 minutes), and the other sampling parameters (sampling flow rate 0.3 L / min, sampling nozzle temperature 150℃, etc.) were the same as in Example 1.

[0049] Measurements showed that the impurity removal rate of the pre-centrifugation treatment step in this embodiment was 99.5%, and the mercury loss rate was 0.6%. The established standard curve showed a linear correlation coefficient R0. 2= 0.9995, indicating that the standard curve has a good linear relationship. The calculated mercury concentration in the flue gas is 0.03 μg / m³. 3 The same sample was measured six times, and the relative standard deviation (RSD) was calculated to be 2.2%. The instrument did not show any obvious mercury memory effect during the detection process.

[0050] Example 3

[0051] This embodiment is basically the same as Embodiment 1, except that the following process parameters have been adjusted:

[0052] (1) Preparation of absorption solution: A 5% nitric acid aqueous solution was used as the main body of the absorption solution, and the gold ion concentration was maintained at 100 μg / L.

[0053] (2) Flue gas sampling: The sampling time was set to 45 minutes, and the other sampling parameters (sampling flow rate 0.3 L / min, sampling nozzle temperature 150℃, etc.) were the same as in Example 1.

[0054] Measurements showed that the impurity removal rate of the pre-centrifugation treatment step in this embodiment was 99.3%, and the mercury loss rate was 0.7%. The established standard curve showed a linear correlation coefficient R0. 2 = 0.9993, indicating that the standard curve has a good linear relationship. The calculated mercury concentration in the flue gas is 0.025 μg / m³. 3 The same sample was measured six times, and the relative standard deviation (RSD) was calculated to be 2.4%. The instrument did not show any obvious mercury memory effect during the detection process.

[0055] Comparative Example

[0056] To verify the superiority of the technical solution of this invention, this comparative example was set up. The standard method specified in "HJ 543-2009 Determination of Mercury in Exhaust Gas from Stationary Sources by Cold Atomic Absorption Spectrophotometry" was used for detection, that is, flue gas was sampled using acidic potassium permanganate absorbent solution, and after pretreatment such as digestion, the sample was measured using a cold atomic absorption spectrophotometer.

[0057] Using the same sampling points as in Example 1, parallel sampling and testing were conducted on flue gas emitted from the same thermal power plant. The results showed that, due to the high blank value of the acidic potassium permanganate absorbent and the easy adsorption and volatilization loss of mercury during sampling and pretreatment, the average value of the final measured mercury concentration in the flue gas was approximately 15% lower than the average value of the detection results in Examples 1-3 of this invention, and the relative standard deviation (RSD) between parallel samples was greater than 10%. Therefore, the accuracy and stability of the comparative method are significantly inferior to those of this invention.

[0058] In summary, the absorbent containing stabilizer and the ICP-MS method for precise mercury detection in flue gas provided by this invention effectively solve the problems of unstable mercury capture, low detection accuracy, and cumbersome operation in the prior art through the synergistic optimization of the absorbent, pretreatment, and detection conditions. It achieves accurate, efficient, and low-cost detection of trace mercury in flue gas from thermal power plants, and has extremely high practical value and broad application prospects.

Claims

1. An absorbent solution containing a gold stabilizer for ICP-MS detection of mercury in flue gas, characterized in that, It consists of a nitric acid aqueous solution with a volume ratio of 2%-10% and a gold ion stabilizer with a concentration of 100 μg / L added thereto; the absorbent does not contain potassium permanganate, sulfuric acid and ethanol.

2. The absorbent liquid containing the gold stabilizer according to claim 1, characterized in that, The absorbent is used to capture Hg in flue gas from thermal power plants. 0 Hg 2+ and Hg p Mercury in three forms, and the concentration deviation of the mercury-captured sample is ≤5% within 24 hours.

3. The application of an absorbent containing a gold stabilizer as described in claim 1 or 2 in the ICP-MS detection of mercury in flue gas, characterized in that, Includes the following steps: (1) Flue gas sampling: The absorbent liquid described in claim 1 or 2 is loaded into a U-shaped porous glass plate absorption bottle, and flue gas from the thermal power plant is collected by the flue gas collection device to make the flue gas fully contact the absorbent liquid and complete the capture of mercury. (2) Sample pretreatment: Transfer the mercury-containing absorption liquid after capturing mercury element in step (1) into a centrifuge tube, centrifuge at 4000 r / min for 5 minutes to precipitate solid impurities, and directly aspirate the supernatant after centrifugation to obtain the sample to be tested. (3) Quantitative detection by mass spectrometry: The sample to be tested obtained in step (2) is introduced into the ICP-MS mass spectrometer for detection. The concentration of mercury in the sample is calculated by combining the standard curve, and the concentration of mercury in the flue gas of the thermal power plant is calculated based on the sampling volume.

4. The application according to claim 3, characterized in that, In step (1), an automatic sampling device is used to sample the flue gas. The sampling flow rate is controlled at 0.3 L / min, the sampling nozzle temperature is set at 150℃, and the sampling time is controlled between 30 min and 1 hour. After sampling, the inlet and outlet of the U-shaped porous glass plate absorption bottle are immediately sealed with rubber caps.

5. The application according to claim 3, characterized in that, In step (1), the flue gas collection device includes a power plant chimney (1), a flue gas sampling port (2) set on the flue wall (3), a flue gas collector (4), a sampling nozzle (6), a gas flow controller (7), a polytetrafluoroethylene tube (9), and a U-shaped porous glass plate absorption bottle (10); the flue gas collector (4) is fixedly connected to the sampling nozzle (6) through a flange connection port (5), and the sampling nozzle (6) is inserted into the flue gas sampling port (2); the sampling nozzle (6) is connected to the gas flow controller (7); the flue gas outlet (8) of the gas flow controller (7) is connected to the U-shaped porous glass plate absorption bottle (10) containing the absorption liquid (11) through the polytetrafluoroethylene tube (9).

6. The application according to claim 3, characterized in that, In step (2), before centrifugation, the sealed U-shaped porous glass plate absorption bottle is placed in a light-proof sample storage box and transported to the analytical laboratory.

7. The application according to claim 3, characterized in that, In step (3), the standard curve is prepared by the following method: using a 2% nitric acid solution containing 100 μg / L gold ions as the dilution medium, the 1000 μg / mL mercury standard stock solution is diluted stepwise by weighing to prepare a series of mercury standard solutions with concentrations of 0.5~10 μg / L, and a standard curve with linear correlation R²≥0.999 is established.

8. The application according to claim 3 or 7, characterized in that, In step (3), the detection limit of the mass spectrometry quantitative detection is as low as 0.01 μg / L, the detection repeatability RSD is ≤3%, and the mercury memory effect can be eliminated.

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