Method for detecting copper ion content in chemical cleaning process

Abstract

The invention discloses a method for detecting the content of copper ions in a chemical cleaning process, which comprises the following steps of: firstly, controlling the pH value of a cleaning solution to be detected to be 2.5-6.0, then adding excessive N-(4-sulfonyl phenyl)-sodium diethyldithiocarbamate into the cleaning solution to be detected, and fully mixing and reacting the N-(4-sulfonyl phenyl)-sodium diethyldithiocarbamate and the cleaning solution to be detected; then judging the absorbance of a reaction product in the step S1 by utilizing a colorimetric method; and finally, determining the concentration of the copper ions in the cleaning solution to be detected according to the absorbance and a pre-constructed copper ion concentration-absorbance standard curve. The method effectively solves the technical problems of complicated and time-consuming operation, low accuracy and weak anti-interference capability of a copper ion detection method in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of copper ion detection and relates to a method for detecting copper ion content in a chemical cleaning process. Background Art

[0002] Copper ions are a common presence in boiler chemical cleaning. Controlling the dynamic balance of copper ions is a key challenge affecting equipment safety and cleaning effectiveness. Some captive power plants use copper feedwater systems or copper condenser tubes. This leads to high levels of copper scale in boiler deposits, with typical components such as copper oxide (CuO) and cuprous oxide (Cu2O) accounting for 5% to 30% of the total deposit. During the cleaning process, copper ions can electrochemically corrode the furnace material, causing corrosion rates to exceed specified limits. Excessive copper ion content in the cleaning solution can lead to impurity deposition and corrosion of other metal components in subsequent processes. Excessive copper ion content may indicate incomplete cleaning, failing to effectively remove copper surface dirt and oxides. Therefore, accurately controlling the copper ion content in the cleaning solution is crucial to ensuring cleaning effectiveness, controlling the cleaning process, and ensuring the safe operation of subsequent equipment.

[0003] Currently, existing methods for copper ion detection primarily include titration, atomic absorption spectroscopy, and spectrophotometry. Titration requires the precise preparation and addition of multiple chemical reagents and rigorous control of reaction conditions, resulting in a time-consuming and tedious process that is unsuitable for real-time monitoring of rapidly changing concentrations during chemical cleaning. Furthermore, determining the titration endpoint relies heavily on operator experience and subjective visual judgment, which can be prone to human error in cleaning environments with poor lighting or inherently colored solutions, leading to poor reproducibility. Atomic absorption spectroscopy, considered one of the "gold standards" for trace metal element analysis in laboratory settings, offers high sensitivity and accuracy. However, its expensive instrumentation, high maintenance costs, and demanding operator expertise make the detection process complex, making it unsuitable for large-scale, rapid on-site testing. While spectrophotometry is simpler and slightly faster than titration, it is susceptible to interference from other metal ions, colored substances, and turbidity in the solution, leading to inaccurate results. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a method for detecting the copper ion content in a chemical cleaning process, thereby solving the technical problems of the prior art copper ion detection method, such as complicated and time-consuming operation, low accuracy and weak anti-interference ability.

[0005] The present invention is achieved through the following technical solutions: A method for detecting copper ion content in a chemical cleaning process comprises the following steps: S1: Control the pH value of the cleaning solution to be tested to 2.5-6.0, then add an excess of sodium N-(4-sulfonylphenyl)-diethyldithiocarbamate to the cleaning solution to be tested and allow it to fully mix and react; S2: Determine the absorbance of the reaction product of step S1 using colorimetry; S3: Determine the concentration of copper ions in the cleaning solution to be tested according to the absorbance and a pre-constructed copper ion concentration-absorbance standard curve.

[0006] Preferably, before adding sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate to the cleaning solution to be detected, the cleaning solution to be detected is filtered using an aqueous filter membrane.

[0007] Preferably, the pore size of the filter membrane is 0.22 μm to 0.45 μm.

[0008] Preferably, the pH value of the cleaning solution to be tested is controlled to be 2.5-6.0 by a buffer solution; The buffer solution is one of potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, acetic acid-sodium acetate buffer solution, phosphate buffer solution, and acetate buffer solution.

[0009] Preferably, a masking agent is added to the cleaning solution to be detected before adding sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate to the cleaning solution to be detected.

[0010] Preferably, the masking agent is fluoride.

[0011] Preferably, when the absorbance of the reaction product of step S1 is determined by colorimetry, the measurement wavelength range is 400-700 nm.

[0012] Preferably, when the absorbance of the reaction product of step S1 is determined by colorimetry, the measurement wavelength range is 436 nm.

[0013] Preferably, in step S1, the reaction temperature is 15-30° C., and the reaction time is 2-5 min.

[0014] Preferably, in step S2, the test is performed 3 to 5 times in parallel, and the average value of the absorbance is taken as the final absorbance value.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses a method for detecting the copper ion content in a chemical cleaning process, which uses sodium N-(4-sulfonylphenyl)-diethyldithiocarbamate (SP-DDTC) as a chelating agent. The sulfonic acid group (-SO3 -) is a strong hydrophilic group, which significantly improves the water solubility of the chelating agent. Therefore, it can directly react with copper ions in the aqueous phase to form a yellow-brown complex (SP-DDTC-Cu) without the need for organic solvent extraction. Compared with the traditional method, the method of the present invention is simpler to operate by sampling, adding SP-DDTC to the aqueous phase for reaction, colorimetry, and quantitative determination. In addition, in the present invention, by adding an excess of SP-DDTC and controlling the pH of the reaction system to 2.5-6.0, the sulfonic acid group of SP-DDTC enhances the affinity of S atoms to Cu through the electron-withdrawing effect. 2+ The electrophilic binding ability of SP-DDTC-Cu can be stably reacted in the pH range of 2-9, ensuring 100% complexation of copper ions and improving detection accuracy. At the same time, the molar absorption coefficient of the SP-DDTC-Cu complex is high and the sensitivity is higher, which further improves the accuracy of the detection results. In addition, the SP-DDTC introduced in the present invention has a larger volume of the sulfonic acid phenyl group, which makes the coordination cavity of the chelating agent more compatible with Cu. 2+ (ionic radius 0.073nm), and Fe 3+ (0.064nm), Ni 2+ (0.069nm) plasma is difficult to enter the cavity due to the volume difference, which reduces the competitive binding, and the chelating agent and the positively charged Fe 3+ (+3 valence) produces electrostatic repulsion, further preventing Fe 3 + Combined with SP-DDTC, the anti-interference ability of the method is effectively improved.

[0016] Furthermore, before adding sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate to the cleaning solution to be tested, the cleaning solution to be tested is filtered using an aqueous filter membrane to eliminate interference from suspended matter.

[0017] Furthermore, the pore size of the filter membrane is 0.22 μm to 0.45 μm, which can improve detection accuracy.

[0018] Furthermore, the pH value of the cleaning solution to be tested is controlled to 2.5-6.0 by using a potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, which can resist pH fluctuations of residual acids (such as HCl and citric acid) in the cleaning solution and ensure reaction stability.

[0019] Furthermore, before adding sodium N-(4-sulfonylphenyl)-diethyldithiocarbamate to the cleaning solution to be detected, a masking agent is added to the cleaning solution to be detected to eliminate competitive ion interference.

[0020] Furthermore, the masking agent is a fluoride, which can effectively complex Fe 3+ / Al 3+ Interfering ions.

[0021] Furthermore, when the absorbance of the reaction product of step S1 is determined by colorimetry, the measurement wavelength range is 400-700 nm, and a wide scan can be performed to verify whether the absorption peak is symmetrical and eliminate interference from impurities.

[0022] Furthermore, when the absorbance of the reaction product of step S1 is determined by colorimetry, the measurement wavelength range is 436 nm, which allows the molar absorption coefficient of the SP-DDTC-Cu complex to reach a peak value.

[0023] Furthermore, in step S1, the reaction temperature is 15-30° C. and the reaction time is 2-5 min, which can prevent the SP-DDTC-Cu complex from forming too slowly and inhibit the thermal decomposition of SP-DDTC-Cu.

[0024] Furthermore, in step S2, parallel testing is performed 3 to 5 times, and the average absorbance is taken as the final absorbance value, which can reduce random errors and identify abnormal data. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Schematic diagram of a process for detecting copper ion content in a chemical cleaning process in Example 1 of the present invention; Figure 2 The copper ion concentration-absorbance standard curve established in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0029] All features, such as values, amounts, contents, and concentrations, described herein as numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0030] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0031] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0032] The present invention provides a method for detecting copper ion content during chemical cleaning. This method, based on the rapid chelation reaction of a novel chelating agent and combined with a portable colorimeter, enables rapid quantitative analysis of copper ions. This method features simple operation, rapid detection, reliable results, and low cost, making it suitable for real-time monitoring at chemical cleaning sites. The chelating agent used in this invention is sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate, which rapidly chelates with copper ions in the cleaning solution to form a stable colored complex. This chelating agent exhibits high selectivity and effectively avoids interference from other metal ions.

[0033] Preferably, sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate is used as a chelating agent, which rapidly reacts with copper ions at room temperature to form a stable yellow complex. The introduction of the sulfonatophenyl group enhances its solubility in aqueous solution and selectivity for copper ions, significantly improving reaction rate and detection accuracy.

[0034] Preferably, the pH of the reaction system is controlled between 5.5 and 6.5 by adding an appropriate amount of potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution to maintain this pH range. Under these pH conditions, the chelation reaction is complete within 1 to 3 minutes, and the absorbance of the complex is stable, facilitating subsequent detection.

[0035] After complexation, the absorbance of the resulting colored complex is measured using a portable colorimeter, allowing for rapid quantitative analysis of the copper ion content using a standard curve method. This portable colorimeter is compact and portable, making it suitable for use in chemical cleaning applications. Equipped with a high-precision optical detection system, it accurately measures the absorbance of the yellow complex at a specific wavelength (436 nm).

[0036] The above-mentioned detection process also involves the establishment of a standard curve. Specifically, a series of copper ion standard solutions of varying concentrations (e.g., 10 mg / L, 25 mg / L, 50 mg / L, 75 mg / L, and 100 mg / L) are prepared and reacted with a chelating agent under optimized reaction conditions. The absorbance of each standard solution at 436 nm is then measured using a portable colorimeter. A standard curve is plotted with copper ion concentration as the horizontal axis and absorbance as the vertical axis. During actual testing, a sample of the chemical cleaning solution is reacted with the chelating agent, and the absorbance is measured using a portable colorimeter. The copper ion concentration in the sample is then quickly calculated based on the standard curve.

[0037] The above method involves mixing the cleaning liquid sample with the chelating agent, and immediately measuring the result using a portable colorimeter after the reaction. The entire detection process can be completed within 5 minutes, which is convenient, fast and highly accurate.

[0038] In a further preferred embodiment, an appropriate amount of masking agent is added to the sample solution before detection to improve the accuracy of the test results. Chemical cleaning solutions generally contain a variety of interfering ions, such as iron ions and nickel ions, which react similarly with chelating agents, affecting the accuracy of copper ion detection. To eliminate interference, an appropriate amount of masking agent is added to the sample solution before detection. For example, when there is interference from iron ions, fluoride (such as sodium fluoride) is added as a masking agent. Fluoride can form a stable complex with iron ions, inhibiting the reaction of iron ions with chelating agents, while having no significant effect on the reaction of copper ions with chelating agents.

[0039] Specifically, a method for detecting copper ion content in a chemical cleaning process in the present invention comprises the following steps: S1: Add an excess of sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate (SP-DDTC) to the cleaning solution to be tested. Oscillate and mix at a pH of 2.5-6.0 and 15-30°C for 2-5 minutes to allow the copper ions to react completely to form a yellow-brown complex. Before adding sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate to the cleaning solution to be tested, the cleaning solution to be tested is filtered using an aqueous filter membrane; preferably, the pore size of the filter membrane is 0.22 μm to 0.45 μm to remove suspended particulate matter in the cleaning solution to be tested; Preferably, a buffer solution is used to maintain the pH value of the reaction system at 2.5-6.0.

[0040] The buffer solution is one of potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, acetic acid-sodium acetate buffer solution, phosphate buffer solution, and acetate buffer solution.

[0041] Further preferably, before the chelating reaction, a masking agent is added to the cleaning solution to be detected, wherein the masking agent is fluoride, and further preferably the masking agent is sodium fluoride; S2: Determine the absorbance of the reaction product of step S1 using a colorimetric method; specifically, transfer the reaction solution to a cuvette with a 1 cm optical path, measure the absorbance at a wavelength of 400-700 nm, preferably 436 nm, perform 3-5 parallel measurements and take the average value to reduce operational errors and improve data reliability.

[0042] S3: Determine the concentration of copper ions in the cleaning solution to be tested according to the absorbance and a pre-constructed copper ion concentration-absorbance standard curve.

[0043] In the process of establishing the copper ion concentration-absorbance standard curve, a series of copper ion standard solutions with different concentrations (such as 10 mg / L, 25 mg / L, 50 mg / L, 75 mg / L, 100 mg / L) are prepared, and potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution is added to the system to maintain the pH value of the reaction system at 2.5~6.0, fluoride is added as a masking agent, and then a chelating agent is added to the copper ion standard solutions with different concentrations, mixed and reacted, and the absorbance of the corresponding system is determined; then, a standard curve is drawn with copper ion concentration as the horizontal axis and absorbance as the vertical axis, that is, the copper ion concentration-absorbance standard curve, and the correlation coefficient R of the copper ion concentration-absorbance standard curve is 0. 2 ≥0.995.

[0044] The sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate (SP-DDTC) of the present invention optimizes the copper ion detection performance from four dimensions: solubility, selectivity, reaction kinetics, and anti-interference ability by introducing sulfonic acid groups. It is particularly suitable for the detection of Cu ions in complex matrices (such as industrial wastewater and biological samples). 2+ The introduction of sulfonic acid groups into the sodium N-(4-sulfonylphenyl)-diethyldithiocarbamate chelating agent enhances its hydrophilicity, making it a highly water-soluble chelating agent that can react directly in pure water phase, avoiding the use of organic solvents. In addition, the introduction of sulfonic acid phenyl groups in SP-DDTC increases steric hindrance, making the chelating agent more sensitive to Cu 2+ The coordination cavity is more matched, which reduces the competition of other ions and improves the anti-interference ability. The traditional chelating agents used are sodium diethyldithiocarbamate (Na-DDTC), Fe 3+ When Na-DDTC is present, the absorbance error of the system is as high as 15%.2+ When Fe is present, the absorbance error of the Na-DDTC system is as high as 10%, while after using the chelating agent of the present invention, the absorbance error of the Fe 3+ When the SP-DDTC system is present, the absorbance error is less than 2%. 2+ When SP-DDTC is present, the absorbance error of the system is less than 1%. This is mainly because SP-DDTC has a strong affinity for Cu at pH 4-6. 2+ The selectivity coefficient (logK{Cu / M}) is 1~2 orders of magnitude higher than that of Na-DDTC. The sulfonic acid group can reduce Fe 3+ Close to (Fe 3+ Easily repelled by -SO3⁻).

[0045] The method of the present invention does not require organic solvent extraction and can be directly developed in the aqueous phase, simplifying the operation process. It has a wide pH adaptability and can be used in the pH range of 2 to 9. Traditional Na-DDTC is easily decomposed under acidic conditions. At the same time, the SP-DDTC-Cu chelating agent has better stability and stronger tolerance to light and oxidation, making it suitable for long-term detection. At the same time, the electron-withdrawing effect of the sulfonic acid group in SP-DDTC reduces the electron cloud density of the S atom, enhancing the Cu 2+ The SP-DDTC-Cu complex exhibits enhanced electrophilic binding ability, resulting in a faster reaction, typically completing within 30 seconds. Ultraviolet-visible spectroscopy (UV-Vis) reveals that the molar absorptivity (ε) of the SP-DDTC-Cu complex is approximately 20% to 30% higher than that of conventional Cu-DDTC. Kinetic experiments demonstrate that its second-order reaction rate constant (k²) is significantly higher than that of Na-DDTC.

[0046] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0047] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0048] Example 1 like Figure 1As shown, this embodiment detects the copper ion concentration in the cleaning wastewater after chemical cleaning of a power plant boiler, including the following steps: Experimental materials and equipment Reagents: Chelating agent: 0.1% (w / v) aqueous solution of sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate (SP-DDTC) (prepared immediately before use); Buffer solution: pH=5.0 potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution; Copper standard stock solution: 1000 mg / L (purchased from the National Center for Standardized Materials, diluted to a series of 10-100 mg / L working solutions); Deionized water (resistivity ≥ 18.2 MΩ·cm).

[0049] equipment Vacuum filtration device (equipped with 0.45μm water filter membrane); Constant temperature oscillator (accuracy ±1°C); Visible spectrophotometer (model: UV-2550, equipped with 1 cm quartz cuvette); Pipette (1mL, 5mL, 10mL, accuracy ±0.01mL); Volumetric flask (50 mL, Class A).

[0050] Implementation steps Step 1: Sample preparation (sampling and filtration) Sampling: Use a clean polyethylene bottle to take 100 mL of the cleaning solution to be tested from the outlet of the cleaning system, seal it and store it in a refrigerator at 4°C (test within 24 hours); Filtration: Take 20 mL of sample and vacuum filter it through a 0.45 μm filter membrane to remove suspended particles in the sample (such as corrosion products and undissolved cleaning agent residues). Collect the filtrate in a 50 mL clean beaker.

[0051] Step 2: Chelation reaction (adding chelating agent reaction) Add reagents: Take 20 mL of filtered sample, transfer the filtrate to a 50 mL volumetric flask, add 5 mL of pH 5.0 potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution to adjust the system pH to ensure that the chelating reaction between the chelating agent and copper ions proceeds under optimal conditions). Then add 2 mL of 0.1% chelating agent solution to make the chelating agent excessive to ensure complete reaction of the copper ions. Reaction conditions: Add deionized water to the mark, shake well, and place in a 25°C constant temperature oscillator at 150 rpm for 10 minutes to allow the chelating agent to fully react with the copper ions to form a yellow-brown complex. Reaction equation: Cu 2+ + 2SP-DDTC- → Cu(SP-DDTC)2 (precipitation) Step 3: Colorimetric analysis (injection into a cuvette to measure absorbance) Prepare the cuvette: let the reaction solution stand for 5 minutes to allow the complex to stabilize. Use a pipette to inject 3 mL of the solution into a 1 cm quartz cuvette. Use deionized water as a blank control. Measure absorbance: Set the wavelength of the spectrophotometer to 436 nm, which is the maximum absorption peak of the SP-DDTC-copper complex. After adjusting the zero point through preliminary experiments, measure the absorbance of the blank and sample in turn. Measure three times in parallel and take the average value.

[0052] Step 4: Quantitative calculation Establish a standard curve: Take 20 mL of each of the 10, 25, 50, 75, and 100 mg / L copper standard working solutions and treat them according to steps 1, 2, and 3. Measure the absorbance and obtain the following data: Table 1 Absorbance corresponding to different copper ion concentrations during the process of establishing the standard curve in this example

[0053] The obtained standard curve is as follows Figure 2 As shown, substituting the average absorbance of the sample (0.371) into the linear equation, the copper ion concentration in the cleaning solution to be tested is obtained to be approximately 36 mg / L.

[0054] Example 2 In this embodiment, high concentration of Fe 3+ 、Ni 2+ The copper ion detection in the cleaning solution was carried out to verify the anti-interference performance of the scheme of the present invention. Specifically: Experimental materials and equipment Sample: Simulated cleaning fluid (containing Cu 2+ 20mg / L, Fe 3+ 10mg / L, Ni 2+ 5 mg / L, citric acid as matrix, pH = 4.5); Reagents: SP-DDTC solution (0.1%), Na-DDTC solution (0.1%, traditional chelating agent), phosphate buffer (pH = 4.5), sodium fluoride (10 g / L); Equipment: Same as Example 1.

[0055] Implementation steps (1) Sample processing Take 20mL of the simulated solution, filter it with a 0.45μm filter membrane, and add 1mL of sodium fluoride (to mask Fe 3+ ), divided into two groups: Experimental group: add 2 mL of 0.1% SP-DDTC and 5 mL of pH 5.0 potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution; Control group: add 2 mL of 0.1% Na-DDTC and 5 mL of pH=5.0 potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution.

[0056] (2) Reaction and colorimetry Both groups were diluted to 50 mL with deionized water, shaken at 25°C for 3 min, and the absorbance was measured at 436 nm (repeated 3 times).

[0057] 3. Results and Analysis Table 2 shows the test results of the experimental group and the control group in this embodiment.

[0058] in conclusion: The error of the experimental group (SP-DDTC) was only 0.9% (<2%), much lower than the 16.3% (>10%) of the control group (Na-DDTC); This is mainly due to the steric hindrance of the sulfonic acid group of SP-DDTC (matching Cu 2+ coordination cavity) and electrostatic repulsion (-SO3 - Fe rejection 3+ ), significantly inhibited the Fe 3+ 、Ni 2+ The anti-interference ability is better than traditional Na-DDTC.

[0059] Example 3 This example utilizes the detection of copper ions in the cleaning solution under acidic conditions (pH = 2.5) to verify the wide pH adaptability of the present solution.

[0060] Experimental materials and equipment Sample: Simulated HCl cleaning solution (containing Cu 2+ 50mg / L, pH=2.5); Reagents: SP-DDTC solution (0.1%), Na-DDTC solution (0.1%), potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution (pH = 6.0); Equipment: Same as Example 1.

[0061] Implementation steps (1) Sample processing Take 20 mL of the simulated liquid filtered with a 0.45 μm filter membrane and divide it into two groups: Experimental group: add 2 mL 0.1% SP-DDTC + 5 mL pH = 6.0 potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution; Control group: add 2 mL of 0.1% Na-DDTC + 5 mL of pH=6.0 potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution.

[0062] (2) Reaction and stability test Both groups were diluted to 50 mL with deionized water, shaken at 25°C for 3 minutes, and the absorbance at 436 nm was measured at 0 minute (immediately), 10 minutes, and 30 minutes, respectively.

[0063] Results and Analysis The test results of this embodiment are shown in Table 3.

[0064] Table 3 shows the test results of the experimental group and the control group in this embodiment.

[0065] As shown in Table 3, the absorbance of the experimental group (SP-DDTC) decreased by only 1.0% within 30 minutes under acidic conditions of pH = 3.0, indicating good stability; while the absorbance of the control group (Na-DDTC) decreased by 19.1% within 30 minutes. This is because traditional Na-DDTC is easily decomposed under acidic conditions (-CS2 - The group is protonated and loses its chelating ability); The SP-DDTC of the present invention enhances the electron-withdrawing effect of the sulfonic acid group (enhancing the S atom to Cu 2+ The electrophilic binding of the traditional method can stably react in the pH range of 2 to 9, solving the problem of instability under acidic conditions.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for detecting copper ion content in a chemical cleaning process, characterized in that: The following steps are involved: S1: Control the pH value of the cleaning solution to be tested to 2.5-6.0, then add an excess of sodium N-(4-sulfonylphenyl)-diethyldithiocarbamate to the cleaning solution to be tested and allow it to fully mix and react; S2: Determine the absorbance of the reaction product of step S1 using colorimetry; S3: Determine the concentration of copper ions in the cleaning solution to be tested according to the absorbance and a pre-constructed copper ion concentration-absorbance standard curve.

2. The method for detecting copper ion content in a chemical cleaning process according to claim 1, wherein: Before adding sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate to the cleaning solution to be tested, the cleaning solution to be tested is filtered using an aqueous filter membrane.

3. The method for detecting copper ion content in a chemical cleaning process according to claim 2, wherein: The pore size of the filter membrane is 0.22 μm to 0.45 μm.

4. The method for detecting copper ion content in a chemical cleaning process according to claim 1, wherein: The pH value of the cleaning solution to be tested is controlled to 2.5~6.0 by using a buffer solution; The buffer solution is one of potassium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, acetic acid-sodium acetate buffer solution, phosphate buffer solution, and acetate buffer solution.

5. The method for detecting copper ion content in a chemical cleaning process according to claim 1, wherein: Before adding sodium N-(4-sulfonatophenyl)-diethyldithiocarbamate to the cleaning solution to be detected, a masking agent is added to the cleaning solution to be detected.

6. The method for detecting copper ion content in a chemical cleaning process according to claim 5, characterized in that: The masking agent is fluoride.

7. The method for detecting copper ion content in a chemical cleaning process according to claim 1, wherein: When the absorbance of the reaction product of step S1 is determined by colorimetry, the measurement wavelength range is 400-700 nm.

8. The method for detecting copper ion content in a chemical cleaning process according to claim 1, wherein: When the absorbance of the reaction product of step S1 is determined by colorimetry, the measurement wavelength range is 436 nm.

9. The method for detecting copper ion content in a chemical cleaning process according to claim 1, wherein: In step S1, the reaction temperature is 15-30° C., and the reaction time is 2-5 min.

10. The method for detecting copper ion content in a chemical cleaning process according to claim 1, characterized in that: In step S2, the test was performed 3 to 5 times in parallel, and the average absorbance value was taken as the final absorbance value.

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