Method for detecting tin content in tin bronze electroplating solution

Abstract

The invention relates to the technical field of tin content detection, and particularly discloses a method for detecting the tin content in tin bronze electroplating liquid. The method comprises the following steps: accurately preparing a tin standard working solution with the concentration of 20-200mg / L according to gradient, detecting the tin standard working solution with each concentration through an atomic absorption spectrometer, determining the absorbance, and establishing a concentration-absorbance standard curve of the tin standard working solution; the method comprises the following steps: treating a to-be-detected tin bronze electroplating solution sample, measuring the absorbance of a to-be-detected sample solution, converting the tin element concentration in the to-be-detected sample solution on the basis of an established tin standard working solution concentration-absorbance standard curve, and further calculating the mass concentration of tin in the to-be-detected sample solution. The method has high accuracy, the adding standard recovery rate is 99.0-100.3%, the precision test RSD is far less than 5%, and the precision and accuracy of the detection result are far higher than those of the traditional detection method.

Description

Technical Field

[0001] The invention belongs to the technical field of tin content detection, and particularly relates to a method for detecting the tin content in a tin bronze electroplating solution. Background Art

[0002] Tin bronze electroplating is the most widely used and largest-scale alloy electroplating process in China. Accurate measurement of tin content is one of the core control parameters of the tin bronze electroplating process, which directly affects the coating quality and production efficiency.

[0003] The existing method for detecting the tin content in tin bronze electroplating solution is mainly EDTA titration method, which has the following main disadvantages:

[0004] (1) Interference from copper ions in the plating solution: In tin bronze electroplating solution, the concentration of copper ions is often much higher than that of tin ions, and copper ions have a stronger complexing ability than tin ions. If titrated directly, EDTA will preferentially complex with copper ions, resulting in distorted tin determination results. Therefore, a masking agent needs to be added for masking.

[0005] (2) Different tin complexing abilities at different price points: Since Sn 4+ With Sn 2+ The two have different complexing abilities with EDTA, so it is necessary to add an oxidant (such as H2O2) to first 2+ Oxidized to Sn 4+ , Sn that is not completely oxidized 2+ This will lead to low test results.

[0006] (3) The operation steps are cumbersome and time-consuming: EDTA titration usually requires the solution pH to be in the range of 5 to 6. This method requires multiple pH adjustment, heating, cooling, masking of interfering ions, and other operations. The operation steps are as many as more than 10 steps and take more than 60 minutes.

[0007] (4) Difficulty in judging the titration end point: During the titration process, the solution is not colorless and transparent, but turbid, and the color change at the titration end point is not sharp, which affects the color judgment of the titration end point, and the error between different operators is large.

[0008] Patent publication number CN115389435A describes a method for detecting tin content in polylactic acid using graphite furnace atomic absorption spectrometry (GFAAS). This method requires mixing the sample to be tested with a digestion solution and soaking it for 10 hours, then heating it in a microwave digester for 40 to 80 minutes, and then diluting the treated sample to obtain a test solution. However, in actual engineering applications at electroplating companies, the number of samples to be tested often reaches dozens, and the tin content of the samples must be determined quickly and accurately. This method requires an excessively long pretreatment time of more than ten hours. Furthermore, when using GFAAS to test large batches of samples, the graphite tube wears out quickly and requires frequent replacement, resulting in high operating costs.

[0009] When conventional flame atomic absorption spectrometry is used to detect tin content, tin easily forms difficult-to-dissociate oxides in the flame, resulting in a decrease in the number of tin atoms in the free radical state and a relatively low absorption signal value, making it difficult to measure low-concentration samples. In addition, the tin element in the tin bronze electroplating solution exists in the form of sodium stannate. When the electroplating solution sample is directly diluted and tested without treatment, the sodium stannate in the sample will immediately hydrolyze into insoluble tin hydroxide and precipitate to the bottom of the test solution, resulting in a higher tin concentration below the test solution than above. If the test sample is diluted with alkaline sodium hydroxide solution, although the problem of sodium stannate hydrolysis can be avoided, the viscosity and surface tension of the test sample solution will increase, resulting in increased resistance when the sample is drawn into the instrument, reducing the atomization efficiency of the burner, and ultimately interfering with the sample's absorption signal value.

[0010] The combined effects of these factors make it difficult to accurately measure the tin content in tin-bronze electroplating solutions using conventional flame atomic absorption spectrometry. Therefore, a new method for measuring the tin content in tin-bronze electroplating solutions has become an urgent issue. Summary of the Invention

[0011] Aiming at the defects and problems existing in the current detection of tin content in tin bronze electroplating solution, the present invention provides a method for detecting the tin content in tin bronze electroplating solution.

[0012] A method for detecting the tin content in a tin bronze electroplating solution, characterized in that it comprises the following steps:

[0013] Step 1: Preparation of tin standard working solution: Prepare a tin standard working solution with a concentration of 20-200 mg / L accurately according to the gradient, and store it in a cool and dark place for later use;

[0014] Step 2: Draw a standard curve: Set the atomic absorption spectrometer parameters, wait for the instrument to balance and the baseline to stabilize, and then perform absorbance detection on the prepared tin standard working solutions of various concentrations. Repeat the reading of each concentration of the tin standard working solution three times, and take the average value to obtain the absorbance of each concentration of the tin standard working solution. Establish a standard curve of tin standard working solution concentration-absorbance;

[0015] Step 3: Sample preparation: Accurately measure 0.2-5 ml of the tin bronze electroplating solution sample to be tested into a 100 ml volumetric flask, add 2-10 ml of analytical grade acid solution, and shake well; then place the volumetric flask on an electric stove and heat it. After the sample in the volumetric flask begins to boil, maintain it for 10-30 seconds. After observing that the color of the sample in the volumetric flask changes from red to yellow, stop heating; after the sample cools, dilute to the mark with deionized water and shake well to obtain the sample solution to be tested;

[0016] Step 4: Based on the atomic absorption spectrometer parameters set in step 2, use the atomic absorption spectrometer to detect the absorbance of the sample solution to be tested, repeat the reading three times, and take the average value to obtain the absorbance of the solution to be tested; based on the established standard curve of tin standard working solution concentration-absorbance, calculate the tin element concentration in the sample solution to be tested;

[0017] Step 5: Calculate the mass concentration of tin in the sample solution to be tested:

[0018] ρ=ρ1V / V0

[0019] Where: ρ represents the mass concentration of tin in the tin-bronze electroplating solution to be tested, g / L; ρ1 represents the concentration of tin element in the solution to be tested, g / L; V represents the volume of the diluted tin-bronze electroplating solution to be tested, mL; V0 represents the volume of the measured tin-bronze electroplating solution sample to be tested, mL.

[0020] In the above method for detecting the tin content in the tin bronze electroplating solution, in step 1, standard tin working solutions with concentrations of 20, 40, 100, 150, and 200 mg / L are accurately prepared according to a gradient.

[0021] In the above-mentioned method for detecting the tin content in the tin bronze electroplating solution, in step 1, accurately measure 0.2, 0.4, 1.0, 1.5, and 2.0 mL of a 10,000 μg / mL tin standard solution into a 100 mL volumetric flask, then add 2 mL of analytical grade concentrated hydrochloric acid to each volumetric flask, dilute to the scale with deionized water, and shake thoroughly to obtain tin standard working solutions with concentrations of 20, 40, 100, 150, and 200 mg / L.

[0022] In the above-mentioned method for detecting the tin content in the tin bronze electroplating solution, the atomic absorption spectrometer parameters are as follows: element type Sn; lamp current 24A; wavelength 286.33nm; slit width 0.7nm; burner head angle 0 degrees; supporting gas air; supporting gas flow rate 10L / min; acetylene flow rate 2.0-4.0L / min; reading interval 3s; repeated reading 3 times.

[0023] In the above-mentioned method for detecting the tin content in the tin bronze electroplating solution, the acetylene flow rate is 3.78 L / min.

[0024] The above method for detecting the tin content in the tin bronze electroplating solution, the standard curve of the tin standard solution concentration-absorbance established in step 2 is y=0.0013x+0.0004, R 2 =0.9997.

[0025] In the above-mentioned method for detecting the tin content in the tin bronze electroplating solution, the analytical grade acid solution added in step 3 is concentrated hydrochloric acid, concentrated nitric acid, or a mixture of concentrated hydrochloric acid and concentrated nitric acid in a certain proportion.

[0026] In the above-mentioned method for detecting the tin content in the tin bronze electroplating solution, the analytically pure acid solution is concentrated hydrochloric acid.

[0027] In the above method for detecting the tin content in the tin bronze electroplating solution, in step 3, accurately measure 1 ml of the tin bronze electroplating solution sample to be tested into a 100 ml volumetric flask, add 5 ml of analytical grade concentrated hydrochloric acid, and shake well.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The detection method provided by the present invention is used to monitor the tin content in the electroplating solution and electroplating wastewater of an electroplating enterprise. The reagents used are simple and easily available, the operation steps are simple and convenient, the daily analysis cost is low, the detection efficiency is high, and time cost is saved. Among them, the pretreatment method for the tin bronze electroplating solution solves the problem of easy hydrolysis of sodium stannate when the electroplating solution sample is directly diluted in the conventional method, and also avoids the problem of increased sample solution viscosity and surface tension caused by using alkaline sodium hydroxide solution to dilute the sample.

[0030] 2. The detection method provided by the present invention has high accuracy, with a spike recovery rate between 99.0% and 100.3%, and a precision test RSD of 0.86%, which is much less than 5%. The precision and accuracy of the detection results are much higher than those of traditional detection methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The standard curve of the concentration and absorbance of the tin standard working solution of the present invention is shown in FIG. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1: This example provides a method for detecting the tin content in a tin bronze electroplating solution. The method mainly includes the following contents:

[0034] (1) Drawing of standard curve

[0035] (1) Preparation of tin standard working solution

[0036] Accurately measure 0.2, 0.4, 1.0, 1.5, and 2.0 mL of a 10,000 μg / mL tin standard solution into a 100 mL volumetric flask. Then add 2 mL of analytical grade concentrated hydrochloric acid to each volumetric flask, dilute to the mark with deionized water, and shake well to obtain tin standard working solutions with concentrations of 20, 40, 100, 150, and 200 mg / L. Store in a cool, dark place until use.

[0037] (2) Atomic absorption spectrometer parameters

[0038] Following the relevant atomic absorption spectrometer operating instructions, turn on the air compressor and adjust the compressed air pressure to 0.35 MPa. Open the acetylene cylinder and adjust the pressure reducing valve to 0.9 MPa. Turn on the atomic absorption spectrometer power switch. After the instrument is initialized, turn on the computer and access the atomic absorption spectrometer workstation. Turn on the tin hollow cathode lamp and invoke the dedicated analysis method.

[0039] The instrument parameters are as follows:

[0040] Element type: Sn;

[0041] Lamp current: 24A;

[0042] Wavelength: 286.33nm;

[0043] Slit width: 0.7 nm;

[0044] Combustion head angle: 0 degrees;

[0045] Supporting gas: air;

[0046] Gas flow rate: 10L / min;

[0047] Acetylene flow rate: 3.78L / min;

[0048] Reading interval: 3s;

[0049] Repeat reading: 3 times;

[0050] Wait for the instrument to equilibrate under the selected method.

[0051] (3) Drawing of standard curve

[0052] Under the instrument analysis conditions in (2), the analysis operation can be started after the instrument is balanced and the baseline is stable. The absorbance of each concentration of tin standard working solution is detected. Each tin standard working solution is read three times and the average value is taken to obtain the absorbance of each concentration of tin standard working solution. The statistical results are shown in Table 1 below.

[0053] Table 1 Concentration and absorbance of tin standard working solution

[0054] Concentration of tin standard working solution (mg / L) absorbance 20 0.0245 40 0.0511 100 0.1274 150 0.1923 200 0.2510

[0055] Establish a concentration-absorbance standard curve of tin standard working solution. Figure 1 As shown by Figure 1 It can be seen that the standard curve is y=0.0013x+0.0004, R 2 =0.9997.

[0056] (2) Tin bronze electroplating solution sample test

[0057] (1) Sample pretreatment: Accurately measure 1 ml of the tin bronze electroplating solution sample to be tested into a 100 ml volumetric flask, add 5 ml of analytical grade concentrated hydrochloric acid, and shake well; then place the volumetric flask on an electric stove to heat it. After the sample in the volumetric flask begins to boil, maintain it for 15-20 seconds. After observing that the color of the sample in the volumetric flask changes from red to yellow, stop heating; after the sample cools down, dilute to the mark with deionized water and shake well to obtain the solution to be tested.

[0058] (2) Using an atomic absorption spectrometer, measure the absorbance of the solution to be tested three times, and take the average value to obtain the absorbance of the solution to be tested. The absorbance of the solution to be tested is converted on the established standard curve of tin concentration-absorbance to obtain the tin concentration in the solution to be tested.

[0059] (3) Calculate the mass concentration of tin in the tin bronze electroplating solution to be tested:

[0060] ρ=ρ1V / V0;

[0061] Where: ρ represents the mass concentration of tin in the tin-bronze electroplating solution to be tested (g / L); ρ1 represents the concentration of tin in the solution to be tested (g / L); V represents the volume of the diluted tin-bronze electroplating solution to be tested (mL); and V0 represents the volume of the measured tin-bronze electroplating solution sample to be tested (mL).

[0062] The method described in this example was used for 10 parallel measurements, and the mass concentration ρ of tin in the electroplating solution was calculated according to the formula ρ = ρ1V / V0. The results are listed in Table 2.

[0063] Table 2 Mass concentration ρ of tin in electroplating solution and precision results

[0064]

[0065] As can be seen from the results in Table 2, the RSD of the precision test results of the method of the present invention for detecting the tin content in the tin bronze electroplating solution is much less than 5%, the detection data has good precision, and the method is accurate and reliable.

[0066] Example 2: In order to further verify the accuracy of the method of the present invention, in this example, after the electroplating solution to be tested was pretreated according to the method of Example 1, a certain amount of 10000 μg / mL tin standard solution was added, and then the volume was made up to the scale line with deionized water. The solution was shaken thoroughly, and the tin concentration of the sample was detected according to the method of the present invention, and the spiked recovery was calculated. The test results are shown in Table 3.

[0067] Table 3 Recovery rate of spiked electroplating solution samples

[0068]

[0069]

[0070] As can be seen from the data in Table 3, the method for detecting the tin content in the tin bronze electroplating solution using the atomic absorption spectrometer of the present invention has a high recovery rate of 99.0% to 100.3%, indicating that the detection method provided by the present invention has good precision and high accuracy.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for detecting the tin content in a tin bronze electroplating solution, characterized in that: The following steps are involved: Step 1: Preparation of tin standard working solution: Prepare a tin standard working solution with a concentration of 20-200 mg / L accurately according to the gradient, and store it in a cool and dark place for later use; Step 2: Draw a standard curve: Set the atomic absorption spectrometer parameters, wait for the instrument to balance and the baseline to stabilize, and then perform absorbance detection on the prepared tin standard working solutions of various concentrations. Repeat the reading of each concentration of the tin standard working solution three times, and take the average value to obtain the absorbance of each concentration of the tin standard working solution. Establish a standard curve of tin standard working solution concentration-absorbance; Step 3. Sample preparation: Accurately measure 0.2-5 ml of the tin bronze electroplating solution sample to be tested and add it to a 100 ml volumetric flask. Add 2-10 ml of analytical grade acid solution and shake well. Then place the volumetric flask on an electric stove and heat it. After the sample in the volumetric flask begins to boil, maintain it for 10-30 seconds. After observing that the color of the sample in the volumetric flask changes from red to yellow, stop heating. After the sample cools, dilute to the mark with deionized water and shake well to obtain the sample solution to be tested. Step 4: Based on the atomic absorption spectrometer parameters set in step 2, use the atomic absorption spectrometer to detect the absorbance of the sample solution to be tested, repeat the reading three times, and take the average value to obtain the absorbance of the solution to be tested; based on the established standard curve of tin standard working solution concentration-absorbance, calculate the tin element concentration in the sample solution to be tested; Step 5: Calculate the mass concentration of tin in the sample solution to be tested: ρ=ρ1V / V0 Where: ρ represents the mass concentration of tin in the tin-bronze electroplating solution to be tested, g / L; ρ1 represents the concentration of tin element in the solution to be tested, g / L; V represents the volume of the diluted tin-bronze electroplating solution to be tested, mL; V0 represents the volume of the measured tin-bronze electroplating solution sample to be tested, mL.

2. The method for detecting the tin content in the tin bronze electroplating solution according to claim 1, wherein: In step 1, standard tin working solutions with concentrations of 20, 40, 100, 150, and 200 mg / L were accurately prepared according to a gradient.

3. The method for detecting the tin content in the tin bronze electroplating solution according to claim 2, wherein: In step 1, accurately measure 0.2, 0.4, 1.0, 1.5, and 2.0 mL of the 10,000 μg / mL tin standard solution into a 100 mL volumetric flask. Then, add 2 mL of analytical grade concentrated hydrochloric acid to each volumetric flask, dilute to the mark with deionized water, and shake thoroughly to obtain tin standard working solutions with concentrations of 20, 40, 100, 150, and 200 mg / L.

4. The method for detecting the tin content in the tin bronze electroplating solution according to claim 1, wherein: The parameters of the atomic absorption spectrometer are: element type Sn; Lamp current 24A; wavelength 286.33nm; slit width 0.7nm; burner head angle 0 degree; combustion air; combustion air flow rate 10L / min; acetylene flow rate 2.0-4.0L / min; reading interval 3s; repeat reading 3 times.

5. The method for detecting the tin content in the tin bronze electroplating solution according to claim 4, wherein: The acetylene flow rate is 3.78 L / min.

6. The method for detecting the tin content in the tin bronze electroplating solution according to claim 1, wherein: The standard curve of tin standard solution concentration-absorbance established in step 2 is y=0.0013x+0.0004, R 2 ＝0.9997。 7. The method for detecting the tin content in a tin bronze electroplating solution according to claim 1, wherein: The analytical grade acid solution added in step 3 is concentrated hydrochloric acid, concentrated nitric acid, or a mixture of concentrated hydrochloric acid and concentrated nitric acid in a certain proportion.

8. The method for detecting the tin content in the tin bronze electroplating solution according to claim 7, wherein: The analytical grade acid solution is concentrated hydrochloric acid.

9. The method for detecting the tin content in a tin bronze electroplating solution according to claim 1, wherein: In step 3, accurately measure 1 ml of the tin bronze electroplating solution sample to be tested and add it to a 100 ml volumetric flask. Add 5 ml of analytical grade concentrated hydrochloric acid and shake well.

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