Method for detecting components of industrial waste residues through EDTA-XRF combination
The EDTA-XRF coupled method solves the problems of low efficiency and insufficient accuracy in the analysis of industrial waste residue components in existing technologies, and realizes rapid and accurate multi-element quantitative analysis, which is suitable for quantitative analysis of complex matrix samples.
Patent Information
- Application Number
- CN202512010651.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-20
AI Technical Summary
In the analysis of industrial waste residue, existing technologies are inefficient and costly using chemical methods, while XRF methods lack accuracy and are difficult to achieve rapid and accurate quantitative analysis of multiple elements.
The EDTA-XRF combined method was adopted. Through standardized sample pretreatment, the mass fraction of calcium was determined by EDTA, the system scaling factor k was calculated, and the relative content of each element was obtained by XRF, thus realizing the leap from absolute quantification of single elements to absolute quantification of multiple elements.
It enables rapid, accurate, and low-cost multi-element analysis of industrial waste residue components, improves the accuracy of XRF methods and the efficiency of chemical methods, and is suitable for quantitative analysis of complex matrix samples.
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Figure CN121703349A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of industrial solid waste composition analysis technology, specifically relating to a method for detecting the composition of industrial waste residue using EDTA-XRF coupled with other methods. Background Technology
[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.
[0003] Industrial waste residues, such as calcium carbide slag, fly ash, metallurgical slag, and desulfurization ash, are the main solid wastes generated during industrial production. Rapid and accurate detection of their chemical composition is a crucial prerequisite for realizing the resource utilization of waste residues, environmental risk assessment, and production process optimization.
[0004] Currently, the analysis of industrial waste residue mainly relies on two technical approaches: the first is wet chemical analysis, such as EDTA complexometric titration for determining calcium content. This method is based on well-defined stoichiometric reactions, has high accuracy, and is considered a benchmark method. Its results have absolute traceability and strong resistance to interference from complex matrices. However, its analytical procedures are cumbersome, time-consuming, and labor-intensive, requiring specialized chemical analysts. Furthermore, a single experiment typically only yields information on the content of a single element. To perform a comprehensive analysis of more than ten elements in waste residue would be extremely time- and economically costly, failing to meet the efficiency requirements of industrial production.
[0005] The second category is instrumental analysis, represented by X-ray fluorescence spectrometry (XRF). XRF technology has become the preferred tool for rapid on-site screening and semi-quantitative analysis due to its outstanding advantages such as fast analysis speed, simple pretreatment, and the ability to simultaneously determine multiple elements from sodium to uranium. However, XRF is essentially a relative analysis method; its quantitative principle relies on comparing the X-ray fluorescence intensity of the sample to a series of standard samples. Industrial waste residues are complex in composition, highly heterogeneous, and have varied mineral phases, making it difficult to perfectly match the matrix of the instrument's built-in standard curve. This "matrix effect" causes significant absorption and enhancement effects, resulting in a non-negligible systematic bias in the direct XRF measurement results, especially for major and trace elements. In the absence of standard materials that highly match the waste residue being tested, XRF reports can often only serve as a "semi-quantitative" reference and cannot be used in decision-making scenarios requiring precise quantification.
[0006] Currently, the industry faces the following problems when it comes to the precise composition analysis of industrial waste residue: if chemical methods are used in full to pursue accuracy, the efficiency will be low and the cost will be unbearable; if XRF method is relied upon alone to pursue efficiency, the accuracy of the data is questionable and may mislead subsequent applications. Summary of the Invention
[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for detecting the components of industrial waste using EDTA-XRF coupling, so as to achieve rapid, accurate, and low-cost multi-element analysis of the components of industrial waste.
[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides a method for detecting the components of industrial waste using EDTA-XRF coupled imaging, comprising the following steps: The industrial waste residue to be tested was dried and then subjected to high-temperature incineration to obtain a reference sample. The reference sample is divided into a first sample and a second sample. The mass fraction of calcium A (Ca) in the first sample was determined by EDTA complexometric titration. The second sample was analyzed by X-ray fluorescence spectroscopy to obtain the relative mass percentage of each element, including calcium, where the relative mass percentage of calcium is R(Ca). The system scaling factor k of the current sample is calculated based on k = A(Ca) / R(Ca); The absolute mass percentage A(i) of each element i is calculated using the formula A(i) = k × R(i).
[0009] This invention discloses a method for accurately detecting the components of industrial waste residue by inventively combining EDTA complexometric titration with X-ray fluorescence spectrometry (XRF).
[0010] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows: The core of the EDTA-XRF coupling method of this invention is to establish a quantitative transfer chain with the EDTA reference value as the core. Through unified sample pretreatment, the consistency of the EDTA and XRF analysis reference points is ensured; a reliable reference value is obtained by measuring EDTA; a broad elemental signal spectrum is obtained through XRF; and finally, through the calculated system scaling factor k, the accuracy of EDTA at the "point" is successfully transferred to the breadth of XRF at the "surface", completing the leap from "absolute quantification of single elements" to "absolute quantification of multiple elements".
[0011] This invention is the first to elevate the EDTA and XRF methods from parallel and independent methods into an organically combined analytical system, reconstructing the quantitative analysis logic of complex samples and transforming the traditional approach of "finding matching standards" into the innovative approach of "establishing internal benchmarks and realizing signal scaling".
[0012] The detection method of this invention fully leverages the absolute quantitative advantage of the EDTA method for specific elements and extends it to the entire analytical spectrum of XRF through a mathematical model, enabling the combined system to possess both the accuracy of chemical methods and the efficiency of instrumental methods.
[0013] This combined model provides a new paradigm for the analysis of complex matrix samples, and is particularly suitable for industrial waste with variable composition. It has extremely high value in the fields of quality control, resource utilization and environmental assessment. Attached Figure Description
[0014] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0015] Figure 1 This is a flowchart of a method for detecting the components of industrial waste using EDTA-XRF coupled with XRF. Detailed Implementation
[0016] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0017] To address the technical problems existing in the prior art, this invention provides a method for detecting the components of industrial waste using EDTA-XRF coupled with other methods, comprising the following steps: The industrial waste residue to be tested was dried and then subjected to high-temperature incineration to obtain a reference sample. The reference sample is divided into a first reference sample and a second reference sample; The mass fraction of calcium A (Ca) in the first reference sample was determined by EDTA complexometric titration. The relative mass percentage of each element, including calcium, was obtained by X-ray fluorescence spectroscopy in the second reference sample. The relative mass percentage of calcium was R(Ca). The system scaling factor k of the current sample is calculated based on k = A(Ca) / R(Ca); The absolute mass percentage A(i) of each element i is calculated using the formula A(i) = k × R(i).
[0018] Drying removes free moisture from industrial waste residue, ensuring a constant sample weight and preventing sample splashing, clumping, or weight errors caused by moisture evaporation during subsequent high-temperature incineration. This ensures that the initial state of the sample used for subsequent EDTA titration and XRF detection is consistent. The purpose of high-temperature calcination is to further decompose the organic matter in the waste residue, fix volatile components (such as sulfides) on the basis of drying, and transform the complex inorganic mineral phase into a stable and homogeneous chemical form, thereby ensuring the consistency of the matrix during EDTA complexometric titration and XRF analysis, and providing a reliable basis for the combined use of the two methods.
[0019] By using a uniform drying and high-temperature ignition pretreatment, the matrix of the samples used for EDTA and XRF analysis is ensured to be the same. This ensures that the matrix effects (such as absorption and enhancement) experienced by each element during XRF detection are systematic—that is, the proportion of interference to the relative signal intensity R(i) of different elements in the same sample is consistent.
[0020] k is calculated as the ratio of the true calcium content A(Ca) measured by EDTA to the relative calcium content R(Ca) measured by XRF. Essentially, it reflects the systematic conversion coefficient between the XRF signal and the true content within the sample matrix. Due to the systematic nature of matrix interference, this coefficient can be extended to other elements in the same sample; that is, the true content A(i) of each element is equal to its relative XRF content R(i) multiplied by k.
[0021] In some embodiments, the drying method is to continuously heat the product in an oven at 105±5℃ (GB / T 20264-2006, GB / T 3007-2017) until it reaches a constant weight.
[0022] In some embodiments, the high-temperature calcination method is: calcining in air at a temperature of 950±20℃ (GB / T34231-2017) in a muffle furnace for at least 1 hour.
[0023] The purpose of high-temperature calcination is to thoroughly decompose the organic matter in industrial waste residue, fix volatile components (such as sulfides), and transform complex inorganic mineral phases into stable and homogeneous chemical forms, thereby ensuring the consistency of matrix analysis between EDTA and XRF methods.
[0024] In some embodiments, the EDTA complexometric titration method includes the following steps: The first reference sample was completely digested by heating with concentrated hydrochloric acid to obtain the mother liquor to be tested; Add dilute sodium hydroxide solution to the mother liquor to be tested and adjust the pH value to 6.5-7.5; Then add triethanolamine solution and concentrated sodium hydroxide solution to adjust the pH of the mother liquor to above 12; Add calcium red indicator to it and titrate with EDTA standard titrant of known concentration until the system color changes abruptly to blue and does not revert within 30 seconds; The calcium content in the reference sample is calculated based on the volume of EDTA titrant consumed.
[0025] The low concentration of dilute sodium hydroxide solution allows for a gentler and easier-to-control pH adjustment process, preventing premature precipitation of calcium or other interfering ions due to excessively high local pH. This ensures solution system stability and facilitates precise maintenance of the pH within the target range of 6.5-7.5. This pH range is crucial for the subsequent addition of triethanolamine solution to mask Fe. 3+ Al 3+ Interfering ions provide a suitable environment, enhance the complexation effect of the masking agent, reduce the influence of interfering ions on the calcium content of EDTA titration, and ensure accurate determination of the reference value A (Ca).
[0026] Adjust the pH of the mother liquor to be tested to above 12 so that calcium ions form titratable hydroxides in a strongly alkaline environment.
[0027] Concentrated sodium hydroxide solution can rapidly raise the pH of the test stock solution to above 12, ensuring that calcium ions quickly form hydroxides that can be complexed and titrated by EDTA, while avoiding the instability of ion forms that may occur in the intermediate pH stage. Concentrated sodium hydroxide can quickly create a strongly alkaline environment, causing interfering ions such as magnesium ions to form insoluble hydroxide precipitates, completely eliminating their interference with calcium content determination and ensuring the accuracy of the reference value A(Ca). If dilute sodium hydroxide solution is used to adjust the pH to above 12, a large amount of solution needs to be added, which will significantly dilute the concentration of calcium ions in the test stock solution, affecting the sensitivity and accuracy of subsequent EDTA titration results.
[0028] Preferably, the concentration of the dilute sodium hydroxide solution is 0.1-1 mol / L.
[0029] Preferably, the concentration of the concentrated sodium hydroxide solution is 6-10 mol / L.
[0030] Preferably, the volume concentration of the triethanolamine solution is 15-25%.
[0031] In some embodiments, the system scaling factor k is 0.1-0.5.
[0032] In some embodiments, element i is selected from at least one of the elements Na, magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K), titanium (Ti), iron (Fe), or strontium (Sr).
[0033] In some embodiments, the industrial waste includes, but is not limited to, carbide slag, fly ash, metallurgical slag, desulfurization ash, or coal gangue.
[0034] The present invention will be further described in detail below with reference to the accompanying drawings and 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 the invention.
[0035] Example 1 1. Sample pretreatment: A sample of chemical waste residue was dried in an oven at 105°C for 2 hours until constant weight, and the moisture content was found to be 33.06%. The dried sample was then placed in a muffle furnace and calcined at 950°C for 2 hours to completely decompose the organic matter and stabilize the inorganic mineral phase. After cooling, the sample was ground into powder using an agate mortar and pestle.
[0036] 2. Determination of reference value [A(Ca)] using EDTA method: Accurately weigh 0.3000g of the ignited sample and place it in a 250mL beaker. Add 5mL of concentrated hydrochloric acid, cover with a watch glass, and heat on a hot plate at low temperature until completely dissolved. After cooling, transfer the entire solution to a 250mL volumetric flask, dilute to the mark with deionized water, and mix well. This is the "mother liquor". Accurately pipette 25.00mL of the mother liquor into a 250mL Erlenmeyer flask.
[0037] (1) Adjust the pH of the test solution to 7 using 0.5 mol / L dilute sodium hydroxide solution (for wide-range test paper detection); (2) Add 6 mL of 20% triethanolamine solution, shake well, and mask Fe. 3+ Al 3+ Interfering ions; (3) Add 6 mol / L concentrated sodium hydroxide solution to adjust the pH to above 12 (the solution should be clear at this point; if it is turbid, check the masking effect). (4) Add about 30 mg of calcium red indicator (ground with sodium chloride at a ratio of 1:100), and the solution will turn a distinct wine red color; (5) Titrate with 0.1000 mol / L EDTA standard titrant until the solution changes from wine red to pure blue and does not revert to the original color within 30 seconds. Record the volume of EDTA consumed as V = 2.21 mL. A(Ca) = (0.1000 × 2.21 × 40.08 / 1000) / (0.3000 × 25 / 250) × 100%=20.53%.
[0038] 3. XRF method for determining relative content [R(Ca) and R(i)]: The calcined and ground powder sample was pressed into tablets and analyzed using X-ray fluorescence spectrometry (XRF). The tablets were prepared using the Zetium method (Panaco, Netherlands), with an Rh target and a power of 2400W. The Omnian qualitative and semi-quantitative method was employed to obtain the relative content of each element, and the results are shown in Table 1. The relative content of calcium, R(Ca), was 89.638%.
[0039] Table 1. Relative content of each element
[0040] 4. Calculate the scaling factor k: k = A(Ca) / R(Ca) = 20.53 / 89.638 ≈0.2290; 5. Absolute quantitative conversion: Calculate the absolute content of each element using the formula A(i) = R(i) × k: Sulfur (S): A(S) = 2.722% × 0.2290 = 0.623%; Iron (Fe): A(Fe) = 1.152% × 0.2290 = 0.264%; Silicon (Si): A(Si) = 3.681% × 0.2290 = 0.843%; Aluminum (Al): A(Al) = 2.208% × 0.2290 = 0.506%; Magnesium (Mg): A(Mg) = 1.869% × 0.2290 = 0.428%; Phosphorus (P): A(P) = 0.589% × 0.2290 = 0.135%; Chlorine (Cl): A(Cl) = 0.399% × 0.2290 = 0.091%; Titanium (Ti): A(Ti) = 0.382% × 0.2290 = 0.087%; Potassium (K): A(K) = 0.293% × 0.2290 = 0.067%; Strontium (Sr): A(Sr) = 0.156% × 0.2290 = 0.036%; Sodium (Na): A(Na) = 0.056% × 0.2290 =0.013%.
[0041] Comparative Example 1 In contrast, the same sample was quantitatively analyzed directly using the universal calibration curve built into the same XRF spectrometer, and some of the results are compared with the detection results of Example 1, as shown in Table 2.
[0042] The specific procedure for ICP detection is as follows: Accurately weigh approximately 0.1 g of sample into a digestion vessel. Add a small amount of water to moisten the sample, then add 6 mL of nitric acid, 2 mL of hydrochloric acid, and 3 mL of hydrofluoric acid sequentially. Cap the vessel and place it in a graphite digester. Heat to 180-190°C using a step-by-step temperature ramp and maintain this temperature for at least 30 minutes, until the solution becomes clear. Afterward, open the cap and heat at 150°C to remove excess HF and silanol. After cooling, rinse the inner cap and inner wall with a small amount of dilute nitric acid (2%). Quantitatively transfer the digest to a 50 mL plastic volumetric flask. Just before final volume adjustment, add 1.0 mL of yttrium internal standard solution (1000 mg / L), then dilute to the mark with 2% nitric acid and mix well.
[0043] ICP detection parameters: RF power: 1150 W; plasma gas flow rate: 15 L / min; auxiliary gas flow rate: 0.8 L / min; nebulizer gas flow rate: 0.70 L / min; injection pump speed: 1.5 mL / min; observation method: high-salt sample, radial observation.
[0044] Spectral lines analyzed: Ca: 315.887 nm; Si: 251.611 nm; S: 180.731 nm; Al: 396.152 nm; Fe: 259.940 nm; Mg: 279.553 nm; Ti: 334.941 nm; K: 766.490 nm; Sr: 407.771 nm; Na: 589.592 nm; internal standard Y: 371.029 nm.
[0045] Table 2 Comparison of detection results between comparative examples and embodiments
[0046] Results and Analysis As shown in Table 1, the XRF results without EDTA showed significant systematic bias for all elements, especially for the major element calcium, where the bias was as high as +1.62%. This fully demonstrates the unreliability of directly using XRF for quantification in complex matrices. However, after correction using the method of this invention, the content values of each element were effectively corrected, upgrading XRF from a "semi-quantitative" tool to a "quasi-absolute quantitative" tool for specific complex systems.
[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for detecting the components of industrial waste residue using EDTA-XRF coupled imaging, characterized in that: Includes the following steps: The industrial waste residue to be tested was dried and then subjected to high-temperature incineration to obtain a reference sample. The reference sample is divided into a first reference sample and a second reference sample; The mass fraction of calcium A (Ca) in the first reference sample was determined by EDTA complexometric titration. The relative mass percentage of each element, including calcium, was obtained by X-ray fluorescence spectroscopy in the second reference sample. The relative mass percentage of calcium was R(Ca). The system scaling factor k of the current sample is calculated based on k = A(Ca) / R(Ca); The absolute mass percentage A(i) of each element i is calculated using the formula A(i) = k × R(i).
2. The method for detecting the components of industrial waste residue using EDTA-XRF coupling according to claim 1, characterized in that: The drying method is as follows: heating continuously in an oven at 105±5°C until constant weight is achieved.
3. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 1, characterized in that: The high-temperature calcination method is as follows: calcination in air at a temperature of 950±20℃ in a muffle furnace for at least 1 hour.
4. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 1, characterized in that: The EDTA complexometric titration method includes the following steps: The first reference sample was completely digested by heating with concentrated hydrochloric acid to obtain the mother liquor to be tested; Add dilute sodium hydroxide solution to the mother liquor to be tested and adjust the pH value to 6.5-7.5; Then add triethanolamine solution and concentrated sodium hydroxide solution to adjust the pH of the mother liquor to above 12; Add calcium red indicator to it and titrate with EDTA standard titrant of known concentration until the system color changes abruptly to blue and does not revert within 30 seconds; The calcium content in the reference sample is calculated based on the volume of EDTA titrant consumed.
5. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 4, characterized in that: The concentration of the dilute sodium hydroxide solution is 0.1-1 mol / L.
6. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 4, characterized in that: The concentration of the concentrated sodium hydroxide solution is 6-10 mol / L.
7. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 4, characterized in that: The triethanolamine solution has a volume concentration of 15-25%.
8. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 1, characterized in that: The system scaling factor k is 0.1-0.
5.
9. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 1, characterized in that: The element i is selected from at least one of sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, titanium, iron, or strontium.
10. The method for detecting the components of industrial waste using EDTA-XRF coupling according to claim 1, characterized in that: The industrial waste residues include, but are not limited to, carbide slag, fly ash, metallurgical slag, desulfurization ash, or coal gangue.