Accurate detection method for analyzing fluorine content in sludge by ion chromatography coupling technique

Abstract

The invention belongs to the technical field of fluorine content detection, and provides an accurate detection method for analyzing fluorine content in sludge by ion chromatography, which comprises the following steps: weighing a sludge sample in a polytetrafluoroethylene digestion tank; adding hydrofluoric acid and perchloric acid into the digestion tank; according to the method, by optimizing the sample pretreatment step and combining microwave digestion with hydrofluoric acid and perchloric acid, the sludge sample is efficiently decomposed, it is ensured that fluorine elements are completely released into the solution, impurity interference is reduced, the detection sensitivity and accuracy are remarkably improved by precisely controlling the temperature and time of the digestion process and conducting detection, and the method is suitable for large-scale popularization and application. The method improves the detection efficiency, reduces the sample pretreatment time, optimizes instrument parameters and drawing of a calibration curve, ensures the reliability and repeatability of a detection result, can more accurately evaluate the fluorine content in the sludge, provides a more scientific and reliable basis for environmental evaluation and selection of a treatment process, and is suitable for popularization and application. The problems of inaccurate detection and low efficiency in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorine content detection, and specifically is a method for accurately detecting the fluorine content in sludge by using ion chromatography combined technology. Background Art

[0002] Accurate detection of fluoride content in sludge is the core prerequisite for environmental risk prevention and control and resource utilization. Excessive fluoride will pollute groundwater through soil infiltration, causing regional fluoride poisoning and threatening aquatic ecology. Accurate detection can ensure the compliance of sludge disposal, ensure the safety of building materials / agricultural use, and optimize disposal plans through data-driven optimization, reducing pollution risks and economic costs, and achieving dual protection of environmental and economic benefits.

[0003] However, existing fluorine content detection methods have some limitations. Although traditional methods such as ion chromatography have high sensitivity, they may be interfered with by multiple ions when processing sludge samples with complex matrices, resulting in inaccurate detection results. In addition, these methods usually require a long sample pretreatment time and have low detection efficiency. Although inductively coupled plasma emission spectrometer (ICP) has high sensitivity and the ability to detect multiple elements simultaneously, in the detection of sludge samples, how to effectively decompose the sample and reduce the interference of matrix effects is a technical problem that needs to be solved urgently. Existing sample pretreatment methods often cannot completely release the fluorine element, or introduce other impurities during the digestion process, affecting the accuracy of the detection results.

[0004] To this end, those skilled in the art have proposed a method for accurately detecting the fluorine content in sludge using ion chromatography combined technology to solve the problems raised by the background technology.

[0005] The above information disclosed in this background technology is only for enhancing understanding of the background technology of the present invention and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a method for accurately detecting the fluorine content in sludge by using ion chromatography-coupled technology to solve the problem that the fluorine content detection method in the prior art has some limitations.

[0007] To achieve the above objectives, the present invention provides a method for accurately detecting the fluorine content in sludge by using ion chromatography coupled technology, comprising the following steps:

[0008] S1. Weigh the sludge sample into a polytetrafluoroethylene digestion tank;

[0009] S2. Add hydrofluoric acid and perchloric acid to the digestion tank, seal the digestion tank and place it in a microwave digestion system for digestion;

[0010] S3. Transfer the digested solution to a volumetric flask and dilute to volume with deionized water to obtain the solution to be tested;

[0011] S4. Use an inductively coupled plasma emission spectrometer and an ion chromatograph to respectively measure the characteristic spectrum intensity and ion chromatographic peak area of fluorine in the test solution, and calculate the fluorine content in the sludge based on the calibration curve.

[0012] Preferably, the weighed amount of the sludge sample in S1 is 0.5g±0.05g.

[0013] Preferably, the amount of hydrofluoric acid added to S2 is 5 mL, and the amount of perchloric acid added is 2 mL.

[0014] Preferably, the digestion procedure of the microwave digestion system in S2 includes:

[0015] Stage 1: Power 1000W, temperature rise to 120℃, maintain for 5 minutes;

[0016] The second stage: power 1200W, temperature rise to 180℃, maintain for 10 minutes;

[0017] The third stage: power 1500W, temperature rise to 220℃, maintain for 30 minutes.

[0018] Preferably, the fixed volume of the volumetric flask in S3 is 100 mL.

[0019] Preferably, the measurement wavelength of the characteristic spectrum intensity of fluorine in S4 is 259.94 nm.

[0020] Preferably, the step of drawing the calibration curve in S4 is:

[0021] Accurately pipette the fluorine standard stock solution and prepare a series of standard solutions with deionized water;

[0022] The standard solutions were introduced into the inductively coupled plasma emission spectrometer in sequence, and the spectral intensity value of each standard solution was measured;

[0023] The standard solutions are introduced into the ion chromatograph in sequence, and the ion chromatographic peak area of each standard solution is measured;

[0024] Draw a calibration curve with the concentration of the standard solution as the horizontal axis and the spectral intensity value as the vertical axis.

[0025] Preferably, the concentration range of the standard solution is 0.1 μg / mL to 10.0 μg / mL.

[0026] Preferably, according to the linear regression equation of the calibration curve, the spectral intensity value of the sample solution is substituted into the equation to calculate the concentration of fluorine in the sample solution;

[0027] The fluoride content in sludge was calculated using the following formula:

[0028] Fluoride content in sludge (mg / kg) = (C×V) ÷ m×1000

[0029] Where C is the fluorine concentration in the sample solution (μg / mL), V is the constant volume (mL), and m is the mass of the sludge sample (g).

[0030] Preferably, the method further comprises the following quality control steps:

[0031] Verification experiments were performed using fluorine standard substances of known concentration;

[0032] A known amount of fluorine standard solution was added to some sludge samples to conduct spike recovery experiments;

[0033] The same batch of sludge samples were measured repeatedly and the relative standard deviation was calculated.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention optimizes the sample pretreatment steps and adopts a combination of microwave digestion and hydrofluoric acid and perchloric acid to efficiently and thoroughly decompose sludge samples, ensuring that the fluorine element is completely released into the solution while reducing interference from other impurities. In addition, by precisely controlling the temperature and time of the digestion process and using a Thermo Fisher Pro XP model ICP instrument and ion chromatography for detection, the sensitivity and accuracy of detection are significantly improved. This not only improves detection efficiency and reduces sample pretreatment time, but also ensures the reliability and repeatability of detection results by optimizing instrument parameters and drawing calibration curves. Through these improvements, the level of fluorine content in sludge can be more accurately assessed, providing a more scientific and reliable basis for environmental assessment and selection of treatment processes, thereby effectively solving the problems of inaccurate detection and low efficiency in the prior art.

[0036] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a process for accurately detecting fluorine content in sludge using ion chromatography coupled technology according to an embodiment of the present invention;

[0038] Figure 2 The figure is a schematic diagram of a specific process of a method for accurately detecting the fluorine content in sludge using ion chromatography combined technology according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. It should be noted that the drawings are schematic and not to scale. For the sake of clarity and convenience, the relative sizes and proportions of the parts shown in the drawings are exaggerated or reduced in size, and any sizes are only illustrative and not restrictive.

[0040] Example:

[0041] See also Figure 1 - Figure 2 As shown in the figure, a precise detection method for fluorine content in sludge using ion chromatography technology, including sample collection and preparation:

[0042] Sample collection: Collect representative samples from the sludge. To ensure the uniformity and representativeness of the samples, the collected sludge samples need to be fully mixed;

[0043] Sample weighing: Use a high-precision analytical balance to weigh 0.5g ± 0.05g of sludge sample. Accurate weighing is a key step to ensure the accuracy of test results, because a small change in sample size may lead to significant deviations in test results. Ensure the representativeness and uniformity of the sample, providing a reliable basis for subsequent testing;

[0044] Sample placement: Place the weighed sludge sample into a polytetrafluoroethylene digestion tank, ready for subsequent digestion treatment.

[0045] Sample digestion treatment:

[0046] Add reagents: Add 5 mL of hydrofluoric acid and 2 mL of perchloric acid to the digestion tank. Hydrofluoric acid is used to decompose silicate and other components in the sludge, while perchloric acid assists digestion to ensure that the fluorine element in the sample is completely released into the solution.

[0047] Digestion vessel preparation:

[0048] Seal the digestion tank to ensure that there is no leakage during the digestion process;

[0049] Microwave digestion:

[0050] After sealing the digestion vessel, place it in the microwave digestion system and perform digestion according to the preset program. Microwave digestion uses microwave energy to quickly heat the sample, making the chemical reaction more rapid and thorough. The digestion process is divided into three stages:

[0051] Stage 1: Power 1000W, temperature rise to 120℃, maintain for 5 minutes;

[0052] The second stage: power 1200W, temperature rise to 180℃, maintain for 10 minutes;

[0053] The third stage: power 1500W, temperature rise to 220℃, maintain for 30 minutes;

[0054] Digestion completed:

[0055] After digestion is completed, the digestion tank is removed from the microwave digestion system and cooled to room temperature to efficiently decompose the sludge sample, ensuring that the fluorine element is completely released into the solution, reducing impurity interference and improving the sensitivity and accuracy of detection.

[0056] Solution transfer and volume adjustment:

[0057] Solution transfer:

[0058] Carefully transfer the digested solution to a 100 mL volumetric flask, ensuring that all the solution is completely transferred. Rinse the digestion tank several times with a small amount of deionized water to ensure that there is no residual solution.

[0059] Fixed volume:

[0060] Use deionized water to make up to 100 mL mark to ensure uniform concentration of the solution. Shake the solution to make the fluorine element in the solution evenly distributed, which is convenient for subsequent spectral measurement. Ensure uniform concentration of the solution, reduce loss during sample transfer, and improve the stability and accuracy of the test results.

[0061] Blank test:

[0062] Each time a sample is digested, a blank test is performed at the same time, that is, no sludge sample is added, and the remaining steps are the same as sample processing. The blank test is used to deduct background interference to ensure the accuracy of the test results, deduct background interference, verify the reliability of the detection method, and improve the accuracy and credibility of the test results.

[0063] Ion chromatography detection:

[0064] Instrument preparation: Turn on the ion chromatograph, preheat it and set the parameters. According to the ion chromatograph manual, optimize the instrument parameters, including flow rate, column temperature, detection wavelength, etc., to obtain the best detection sensitivity and stability;

[0065] Standard curve drawing:

[0066] Accurately pipette the fluorine standard stock solution and prepare a series of standard solutions with deionized water (e.g., 0.1 μg / mL, 0.5 μg / mL, 1.0 μg / mL, 5.0 μg / mL, 10.0 μg / mL);

[0067] The standard solutions were introduced into the ion chromatograph in sequence, and the retention time and peak area of each standard solution were measured;

[0068] Draw the calibration curve of ion chromatography with the concentration of the standard solution as the horizontal axis and the peak area as the vertical axis. Calculate the linear regression equation and correlation coefficient of the calibration curve to ensure that the correlation coefficient is greater than 0.999, indicating that the calibration curve has a good linear relationship.

[0069] Sample determination:

[0070] The test solution and blank solution were sequentially introduced into the ion chromatograph to measure their retention time and peak area. Each sample was measured 3 times and the average value was taken as the final measurement result.

[0071] According to the linear regression equation of the calibration curve, the peak area value of the sample solution is substituted into the equation to calculate the concentration of fluorine in the sample solution.

[0072] Spectral measurement and result calculation:

[0073] Instrument preparation:

[0074] Turn on the inductively coupled plasma optical emission spectrometer (ICP), using the Thermo Fisher Pro XP ICP, preheat and set parameters. According to the Thermo Fisher Pro XP ICP manual, optimize the instrument parameters, including RF power, plasma gas flow, auxiliary gas flow, nebulizer gas flow, etc., to obtain the best detection sensitivity and stability. Select a suitable observation height (usually 10mm to 15mm) to reduce the interference of matrix effects, effectively improve the sensitivity and stability of the detection, reduce the interference of matrix effects, and ensure the accuracy and reliability of the test results.

[0075] Wavelength selection:

[0076] Based on the characteristic spectral line of fluorine, 259.94nm was selected as the detection wavelength. This wavelength has high sensitivity and selectivity, can effectively avoid interference from other elements, improve the sensitivity and selectivity of detection, reduce interference from other elements, and ensure the accuracy and reliability of the test results;

[0077] Calibration curve drawing:

[0078] Accurately pipette the fluorine standard stock solution and prepare a series of standard solutions with deionized water (such as 0.1μg / mL, 0.5μg / mL, 1.0μg / mL, 5.0μg / mL, and 10.0μg / mL). Introduce the standard solutions into the ICP in sequence, measure the spectral intensity value of each standard solution, plot a calibration curve with the concentration of the standard solution as the abscissa and the spectral intensity value as the ordinate, calculate the linear regression equation and correlation coefficient of the calibration curve, and ensure that the correlation coefficient is greater than 0.999, indicating that the calibration curve has a good linear relationship. The linear relationship of the standard solution ensures that the calibration curve has a good linear relationship, provides a basis for quantitative analysis, and ensures the accuracy and reliability of the test results;

[0079] Sample determination:

[0080] The test solution and blank solution were sequentially introduced into the ICP, and their spectral intensity values were measured. Each sample was measured 3 times, and the average value was taken as the final measurement result.

[0081] Result calculation:

[0082] According to the linear regression equation of the calibration curve, the spectral intensity value of the sample solution is substituted into the equation to calculate the concentration of fluorine in the sample solution. The fluorine content in the sludge is calculated using the following formula:

[0083] Fluoride content in sludge (mg / kg) = (C×V) ÷ m×1000

[0084] Wherein, C is the fluorine concentration in the sample solution (μg / mL), V is the constant volume (mL), and m is the mass of the sludge sample (g);

[0085] By taking the average value of multiple measurements, random errors are reduced, and the stability and accuracy of the test results are improved. The accuracy and reliability of the test results are ensured through formula calculation.

[0086] Quality Control and Quality Assurance:

[0087] Verification experiments were conducted using fluorine standard substances of known concentration to ensure the accuracy and reliability of the detection method. A known amount of fluorine standard solution was added to some sludge samples for spike recovery experiments. The spike recovery rate was calculated. The spike recovery rate should be between 90% and 110%, indicating that the detection method has good accuracy and precision. Multiple repeated measurements were performed on the same batch of sludge samples, and the relative standard deviation (RSD) was calculated. The RSD should be less than 5% to ensure the repeatability and stability of the test results. The accuracy and reliability of the detection method were ensured through standard substance verification and spike recovery experiments. Repeatability experiments ensured the stability and reliability of the test results, providing quality assurance for the successful implementation of the overall plan.

[0088] Result analysis and reporting:

[0089] Prepare a detailed test report, including sample information, test methods, instruments, reagents, sample pretreatment, instrument settings, test results, quality control and quality assurance measures, etc. The report clearly lists the measured value, standard deviation, relative standard deviation, spike recovery rate, and other data of the fluorine content in the sludge, ensuring data integrity and traceability. Conduct necessary discussion and analysis of the test results, provide reasonable suggestions and conclusions, and provide complete test records to facilitate subsequent data query and analysis. Through detailed data analysis and discussion, provide a scientific basis for the environmental assessment and treatment of sludge.

[0090] As can be seen from the above, the present invention optimizes the sample pretreatment steps and adopts a combination of microwave digestion combined with hydrofluoric acid and perchloric acid to efficiently and thoroughly decompose the sludge sample, ensuring that the fluorine element is completely released into the solution while reducing the interference of other impurities. In addition, by precisely controlling the temperature and time of the digestion process and using a Thermo Fisher Pro XP model ICP instrument and ion chromatography for detection, the sensitivity and accuracy of the detection are significantly improved. Not only is the detection efficiency improved and the sample pretreatment time reduced, but the reliability and repeatability of the detection results are also ensured by optimizing the instrument parameters and drawing the calibration curve. Through these improvements, the level of fluorine content in the sludge can be more accurately assessed, providing a more scientific and reliable basis for environmental assessment and the selection of treatment processes, thereby effectively solving the problems of inaccurate detection and low efficiency in the prior art.

[0091] All standard parts used in the present invention are commercially available, and special-shaped parts can be customized according to the description in the specification and drawings. The specific connection methods of each part adopt conventional means such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts, and equipment all adopt conventional models in the prior art. In addition, the circuit connections adopt conventional connection methods in the prior art and will not be described in detail here. Any matters not described in detail in this specification belong to the prior art known to professionals skilled in the art.

[0092] In the drawings of the embodiments disclosed in the present invention, only the structures involved in the embodiments disclosed in the present invention are involved. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0093] 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 accurately detecting fluorine content in sludge by using ion chromatography technology, characterized in that: The following steps are involved: S1. Weigh the sludge sample into a polytetrafluoroethylene digestion tank; S2. Add hydrofluoric acid and perchloric acid to the digestion tank, seal the digestion tank and place it in a microwave digestion system for digestion; S3. Transfer the digested solution to a volumetric flask and dilute to volume with deionized water to obtain the solution to be tested; S4. Use an inductively coupled plasma emission spectrometer and an ion chromatograph to respectively measure the characteristic spectrum intensity and ion chromatographic peak area of fluorine in the test solution, and calculate the fluorine content in the sludge based on the calibration curve.

2. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 1, characterized in that: The weighed amount of the sludge sample in S1 is 0.5 g ± 0.05 g.

3. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 2, characterized in that: The amount of hydrofluoric acid added to the S2 is 5 mL, and the amount of perchloric acid added is 2 mL.

4. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 3, characterized in that: The digestion procedure of the microwave digestion system in S2 includes: Stage 1: Power 1000W, temperature rise to 120℃, maintain for 5 minutes; The second stage: power 1200W, temperature rise to 180℃, maintain for 10 minutes; The third stage: power 1500W, temperature rise to 220℃, maintain for 30 minutes.

5. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 4, characterized in that: The fixed volume of the volumetric flask in S3 is 100 mL.

6. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 5, characterized in that: The characteristic spectrum intensity of fluorine in the S4 is measured at a wavelength of 259.94 nm.

7. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 6, characterized in that: Steps for drawing the calibration curve in S4: Accurately pipette the fluorine standard stock solution and prepare a series of standard solutions with deionized water; The standard solutions were introduced into the inductively coupled plasma emission spectrometer in sequence, and the spectral intensity value of each standard solution was measured; The standard solutions are introduced into the ion chromatograph in sequence, and the ion chromatographic peak area of each standard solution is measured; The calibration curves of inductively coupled plasma method and ion chromatography method were drawn respectively with the concentration of the standard solution as the horizontal axis and the spectral intensity value as the vertical axis.

8. The method for accurately detecting fluorine content in sludge by using ion chromatography technology according to claim 7, characterized in that: The concentration range of the standard solution is 0.1 μg / mL to 10.0 μg / mL.

9. The method for accurately detecting fluorine content in sludge by using ion chromatography according to claim 8, characterized in that: According to the linear regression equation of the calibration curve, the spectral intensity value of the sample solution is substituted into the equation to calculate the concentration of fluorine in the sample solution; The fluoride content in sludge was calculated using the following formula: Fluoride content in sludge (mg / kg) = (C×V) ÷ m×1000 Where C is the fluorine concentration in the sample solution (μg / mL), V is the constant volume (mL), and m is the mass of the sludge sample (g).

10. The method for accurately detecting fluorine content in sludge by using ion chromatography technology according to claim 9, characterized in that: Quality control steps are also included: Verification experiments were performed using fluorine standard substances of known concentration; A known amount of fluorine standard solution was added to some sludge samples to conduct spike recovery experiments; The same batch of sludge samples were measured repeatedly and the relative standard deviation was calculated.

Images