Method for detecting content of gelatin in copper electrolyte based on C3N4 fluorescent probe regulated and controlled by energy band

Abstract

The invention belongs to the technical field of copper electrolyte additive detection, and discloses a method for detecting the content of gelatin in a copper electrolyte based on an energy band regulation and control C3N4 fluorescent probe. Due to the fact that the intensity of fluorescence emitted by the C-C3N4 is not quenched due to existence of the cupric ions, when gelatin exists in the C-C3N4 solution, the quenching of the fluorescence of the C-C3N4 solution can be caused by existence of an extremely small amount of gelatin, and the concentration of the gelatin and the change value of the fluorescence intensity of the C-C3N4 are in a linear relation. C3N4 (C-C3N4) after energy band regulation and control is used as a fluorescent probe, a fluorescence analysis method is adopted, when a C-C3N4 solution is irradiated by light with the wavelength of 320 nm, an emission peak of the C-C3N4 can be seen at the position of 433 nm, and quantitative analysis of the gelatin in the copper electrolyte is achieved. The detection method is simple, convenient, efficient, high in detection sensitivity and low in detection limit, and has positive significance for effectively regulating and controlling the quality of the copper foil.

Description

Technical Field

[0001] The present invention belongs to the technical field of copper electrolyte additive detection, and specifically relates to a method for accurately analyzing and determining the gelatin concentration in the copper electrolyte using gelatin as a copper electrolyte additive in order to effectively control the quality of electrolytic copper foil. In particular, it relates to a method for using band-regulated C3N4 (C-C3N4) as a fluorescent probe to detect the gelatin content in the copper electrolyte. When gelatin is present, it will cause fluorescence quenching of C-C3N4, and the change in the fluorescence intensity of C-C3N4 is linearly related to the change in the gelatin concentration. Background Art

[0002] In the manufacturing process of electrolytic copper foil, in order to obtain bright and ductile copper foil, it is necessary to add organic matter containing functional groups such as nitrogen and sulfur as additives to the copper electrodeposition solution. Gelatin not only contains functional groups such as nitrogen and sulfur, but also has carboxyl and hydroxyl groups that complex with copper ions. Therefore, gelatin is widely used as an additive in copper electrodeposition solutions.

[0003] Since gelatin is continuously consumed in the manufacturing process of electrolytic copper foil, in the current electrolytic copper foil production process, the gelatin concentration in the copper electrodeposition solution is usually controlled by converting the amount of gelatin added into the amount of electricity consumed. As the quality requirements for electrolytic copper foil continue to increase, the fine control of the gelatin concentration in the copper electrodeposition solution has become increasingly intense. Based on this, a series of analysis and detection technologies such as gel chromatography, liquid chromatography and electrochemical analysis have been established. However, the above analysis methods either require sample pretreatment or require complicated analysis steps, making it difficult to achieve rapid detection of gelatin in the copper electrodeposition solution and monitoring of the copper electrodeposition tank solution during continuous production.

[0004] Among various nanomaterials, g-C3N4 is a metal-free polymer semiconductor material. It exhibits properties similar to those of graphene and is easy to prepare, which has attracted widespread attention. In particular, in the development of non-toxic fluorescence detection, it avoids secondary pollution during the preparation process. Many research reports in existing domestic and foreign literature use g-C3N4 as a fluorescent probe to achieve analytical detection. Although g-C3N4 is used as a fluorescent probe, in order to achieve high-sensitivity detection, it needs to be combined with other co-reactants to further increase the fluorescence intensity and achieve high-sensitivity detection. In addition, due to Cu 2+ The redox potential of g-C3N4 nanosheets is between the conduction band (CB) and the valence band (VB). 2+ When mixed with g-C3N4 nanosheets, CB from g-C3N4 nanosheets to Cu 2+ The photoinduced electron transfer process leads to the fluorescence quenching of g-C3N4 nanosheets.

[0005] It has been reported in the literature that trace amounts of Cu 2+ This can lead to the fluorescence quenching of the g-C3N4 nanosheet solution. This is not only due to the low fluorescence intensity of the g-C3N4 nanosheet solution, but also due to the fact that Cu 2+ The redox potential of g-C3N4 is just between the valence band and conduction band, which causes the fluorescence quenching of g-C3N4. 2+ The presence of will undoubtedly greatly improve the selectivity and speed of gelatin analysis in copper electrolyte. Summary of the invention

[0006] In view of the problems existing in the existing technology for detecting gelatin in copper electrolyte, the purpose of the present invention is to provide a method for detecting the gelatin content in copper electrolyte based on a C3N4 fluorescent probe with energy band regulation.

[0007] The present invention surprisingly found that C3N4 (C-C3N4) based on energy band regulation is different from the previous g-C3N4. Even in the presence of strong acidity and high concentration of copper ions, it also shows extremely strong luminescence intensity, which undoubtedly lays the foundation for using C-C3N4 as a fluorescent probe to analyze and detect the presence of gelatin. At the same time, when gelatin exists in the C-C3N4 solution, the fluorescence of C-C3N4 is quenched. Therefore, the present invention uses C-C3N4 as a fluorescent probe to successfully achieve rapid quantitative analysis of gelatin in copper electrolyte.

[0008] The present invention first provides a preparation method of C3N4 (C-C3N4) based on energy band regulation, which adopts the condensation reaction of melamine and formaldehyde. The amount of formaldehyde used should not be too high, and the mass volume ratio of melamine to formaldehyde is about 10g:1-1.5mL. Too much formaldehyde will affect the reaction of melamine and cyanuric acid. The melamine that has undergone condensation reaction is then reacted with cyanuric acid, and the mass ratio of melamine to cyanuric acid is generally 1:1-1.2. According to this mass ratio, cyanuric acid is in excess, and it can be removed by repeated washing with deionized water after the reaction. The reaction product is calcined to obtain C-C3N4. Compared with g-C3N4, the prepared C-C3N4 has very strong fluorescence and is not affected by the presence of divalent copper ions. Compared with g-C3N4, C-C3N4 shows extremely strong fluorescence ( Figure 1 ), perhaps because the melamine after the condensation reaction with formaldehyde is combined with cyanuric acid, the calcined C-C3N4 contains a large number of carboxyl and carbonyl groups, which effectively regulates the energy levels of the valence band and conduction band of C3N4. The specific steps include: (1) Melamine was dispersed in deionized water, and formaldehyde was added under stirring. The condensation reaction was carried out at room temperature for 2 h, which was recorded as solution A. (2) Dissolve cyanuric acid in 80°C deionized water, referred to as solution B; (3) Solution B was added to solution A, the temperature was raised to 80 °C, stirring was continued for 2 h, centrifuged, washed with deionized water at 80 °C, the product was collected and redispersed in deionized water, allowed to stand at room temperature for 12 h, the supernatant was removed to obtain a flocculent precipitate, and freeze-dried for 48 h to obtain a C-C3N4 precursor; (4) The C-C3N4 precursor was annealed in a tubular furnace at 500°C-600°C under nitrogen conditions for 2 hours to obtain the product C-C3N4.

[0009] Furthermore, in the step (1), the mass volume ratio of melamine to formaldehyde is 10 g:1-1.5 mL; and the mass volume ratio of melamine to deionized water is 1 g:300 mL.

[0010] Furthermore, in step (2), the mass of cyanuric acid is 1-1.2 times the mass of melamine in step (1); and the mass volume ratio of cyanuric acid to deionized water is 1 g:300 mL.

[0011] The band-regulated C3N4 prepared by the present invention is in Cu 2+ In the presence of 2-hydroxy-2-nitropropene, no fluorescence quenching occurs, and the C3N4 can be used as a fluorescent probe for detecting gelatin in copper electrolyte. The maximum excitation wavelength of the band-regulated C3N4 is 320 nm, and the maximum emission wavelength is 433 nm.

[0012] The present invention also provides a method for detecting gelatin content in a copper electrolyte using the above C-C3N4 as a fluorescent probe, comprising the following steps: S1. Mix C-C3N4 with copper sulfate-sulfuric acid solution and disperse them fully by ultrasonic to obtain 0.5 mg / ml C-C3N4 copper sulfate-sulfuric acid solution.

[0013] S2. Mix the C-C3N4 copper sulfate-sulfuric acid solution with the gelatin solution to prepare a series of gelatin standard solutions containing 0.05 mg / ml C-C3N4; detect the fluorescence intensity, draw a curve of the change in fluorescence intensity before and after adding gelatin and the gelatin concentration, and obtain the corresponding linear regression equation.

[0014] S3. Mix the C-C3N4 copper sulfate-sulfuric acid solution with the copper electrolyte to be tested, and make up the volume of the copper sulfate-sulfuric acid solution to obtain a mixed solution containing 0.05 mg / ml C-C3N4.

[0015] S4. Detect the fluorescence intensity of the mixed solution, and substitute the fluorescence intensity value into the linear regression equation obtained in the above step S2 to calculate, so as to obtain the actual gelatin concentration in the copper electrolyte.

[0016] In the above technical solution, the copper sulfate-sulfuric acid solution is a mixed solution containing 150 g / L copper sulfate and 100 g / L sulfuric acid. The copper sulfate-sulfuric acid solution has copper ion and sulfuric acid concentrations similar to those of copper electrolyte in the industrial production of electrolytic copper foil.

[0017] In the above technical solution, the concentrations of gelatin in the gelatin standard solutions of a series of concentrations are 0, 1, 3, 5, 8 and 10 mg / L respectively.

[0018] In the above technical solution, the fluorescence intensity is measured by a fluorescence spectrophotometer, the excitation wavelength is set to 320 nm, and the detection is performed at 433 nm.

[0019] In the above technical solution, the volume ratio of C-C3N4 copper sulfate-sulfuric acid solution to the copper electrolyte to be tested is 1:2.

[0020] The beneficial effects of the present invention are as follows: The fluorescence intensity of the band-regulated C-C3N4 prepared by the present invention is extremely high and is not quenched by the presence of copper ions.

[0021] The present invention selects band-regulated C-C3N4 as a fluorescent probe, and can analyze gelatin in a copper electrodeposition solution without pretreatment. Due to the convenience of the analysis method, it is fully applicable to intermediate control analysis in the copper electrodeposition production process.

[0022] The gelatin detection method of the present invention has the advantages of rapid detection and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The fluorescence emission peak λem = 433 nm and the excitation wavelength λex = 320 nm of 0.05 mg / mL g-C3N4 and 0.05 mg / mL C-C3N4 in 150 g / L copper sulfate and 100 g / L sulfuric acid solution.

[0024] Figure 2 The corresponding emission fluorescence intensity in copper sulfate-sulfuric acid solutions with a C-C3N4 fluorescent probe concentration of 0.05 mg / ml and gelatin concentrations of (a) 0, (b) 1, (c) 3, (d) 5, (e) 8, and (f) 10 mg / L, respectively.

[0025] Figure 3 This is the relationship curve between the fluorescence intensity of C-C3N4 and the gelatin concentration. DETAILED DESCRIPTION

[0026] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following embodiments.

[0027] In the following specific embodiments, the method for detecting gelatin content in copper electrolyte based on C3N4 fluorescent probe regulated by energy band is as follows: In the production process of electrolytic copper foil, the concentration of copper sulfate is generally 150 g / L, and the concentration of sulfuric acid is approximately 100 g / L. Therefore, when preparing the standard solutions of C-C3N4 and gelatin, the present invention uses a mixed solution of 150 g / L copper sulfate and 100 g / L sulfuric acid as the base solution, which is marked as copper sulfate-sulfuric acid solution.

[0028] (1) Prepare a 1000 mg / L gelatin copper sulfate-sulfuric acid solution: Weigh 0.10 g of gelatin and dissolve it in a 100 mL volumetric flask with the above copper sulfate-sulfuric acid solution to obtain a gelatin copper sulfate-sulfuric acid solution with a gelatin concentration of 1000 mg / L. Since gelatin is easily decomposed in acidic solutions, the gelatin solution must be prepared before analysis and cannot be retained.

[0029] (2) Prepare a 0.5 mg / ml C-C3N4 copper sulfate-sulfuric acid solution of the fluorescent probe.

[0030] Take 5.0 mg of C-C3N4 and add it to a 10 ml volumetric flask, make up to volume with copper sulfate-sulfuric acid solution, and fully disperse it using ultrasound to obtain a 0.5 mg / ml C-C3N4 copper sulfate-sulfuric acid solution.

[0031] (3) Preparation of standard solution Take 0, 10, 30, 50, 80 and 100 μl of 1000 mg / L gelatin copper sulfate-sulfuric acid solution respectively and place them in 10 ml volumetric flasks, take 1 ml of C-C3N4 copper sulfate-sulfuric acid solution and add it into the above volumetric flasks, and then make up the volume with copper sulfate-sulfuric acid solution to obtain copper sulfate-sulfuric acid solutions with a C-C3N4 fluorescent probe concentration of 0.05 mg / ml and gelatin concentrations of 0, 1, 3, 5, 8 and 10 mg / L, respectively, which are recorded as gelatin standard solutions.

[0032] (4) Draw a standard curve The fluorescence intensity of the gelatin standard solution prepared in step (3) was detected at 433 nm using a fluorescence spectrophotometer with an excitation wavelength of 320 nm. The corresponding linear regression equation was obtained by recording the curve of the fluorescence intensity change before and after the addition of gelatin and the gelatin concentration.

[0033] (5) Actual sample testing Take 1 ml of C-C3N4 copper sulfate-sulfuric acid solution and place it in a 10 ml volumetric flask, take 2 ml of actual copper electrolyte and add it to a 10 ml volumetric flask, and then make up to volume with copper sulfate-sulfuric acid solution. Detect the fluorescence intensity according to the above step (4), substitute the obtained fluorescence intensity value into the linear regression equation obtained in the above step (4) for calculation, and the gelatin concentration in the actual electrolytic copper solution can be obtained. Example 1

[0034] Preparation of C-C3N4: weigh 1g of melamine and add it to 300ml of deionized water. Add 0.1ml of formaldehyde under stirring and carry out condensation reaction at room temperature for 2h. Dissolve 1g of cyanuric acid in 300ml of deionized water at 80℃ and add it to the melamine solution that has completed the condensation reaction. Heat it to 80℃ and continue stirring for 2h. Centrifuge the product and wash it with deionized water at 80℃ to remove the unreacted product. Re-disperse the product in deionized water and let it stand at room temperature for 12h. Remove the supernatant to obtain a flocculent precipitate. Finally, freeze-dry the precipitate for 48h to obtain the C-C3N4 precursor. Then anneal it in a tubular furnace at 500℃, 550℃, and 600℃ under nitrogen for 2 hours to obtain the product C-C3N4.

[0035] Preparation of g-C3N4. Weigh 10 g of melamine and place it in a sealed porcelain crucible. Then, place the crucible in a high-temperature muffle furnace, heat it to 550 °C at a heating rate of 5 °C / min and keep the temperature for 2 h. After the crucible is cooled naturally to ambient temperature, the obtained product is transferred to an agate mortar for fine grinding. The light yellow powder obtained is g-C3N4.

[0036] 5.0 mg of C-C3N4 powder obtained at different calcination temperatures was uniformly dispersed in copper sulfate-sulfuric acid solution. The copper sulfate-sulfuric acid solution was fixed to volume to obtain 0.5 mg / ml C-C3N4 copper sulfate-sulfuric acid solution. Using a fluorescence spectrophotometer, the excitation wavelength was set to 320 nm, and the fluorescence intensity was detected at 433 nm. The fluorescence curve of C-C3N4 obtained by annealing at 550 ° C for 2 h is shown in FIG. Figure 1 As a comparison, this example also prepared g-C3N4 and tested its fluorescence intensity. Figure 1 As can be seen from the figure, the C-C3N4 prepared by the present invention is not affected by copper ions, and also shows extremely strong luminescence intensity in the presence of strong acidity and high concentration of copper ions. Example 2

[0037] Using the C-C3N4 obtained by annealing at 550°C for 2h in Example 1 as a fluorescent probe, the concentration of gelatin in the copper electrolyte was analyzed and detected. The specific steps are as follows: (1) Preparation of copper sulfate and sulfuric acid solutions with different gelatin concentrations Weigh 0.10 g of gelatin and dissolve it in a 100 mL volumetric flask with copper sulfate-sulfuric acid solution to obtain a copper sulfate-sulfuric acid solution with a gelatin concentration of 1000 mg / L gelatin. Then dilute it with the above copper sulfate and sulfuric acid solutions to obtain copper sulfate and sulfuric acid solutions with gelatin concentrations ranging from 1 to 10 mg / L.

[0038] (2) Preparation of 0.5 mg / ml fluorescent probe C-C3N4 copper sulfate-sulfuric acid solution Take 5.0 mg of C-C3N4 and add it to a 10 ml volumetric flask, make up to volume with copper sulfate-sulfuric acid solution, and fully disperse it using ultrasound to obtain a 0.5 mg / ml C-C3N4 copper sulfate-sulfuric acid solution.

[0039] (3) Preparation of standard solution Take 0, 10, 30, 50, 80 and 100 μl of the 1000 mg / L gelatin copper sulfate-sulfuric acid solution of step (1) and place them in 10 ml volumetric flasks, take 1 ml of C-C3N4 copper sulfate-sulfuric acid solution and add it to the above volumetric flasks, and then make up the volume with copper sulfate-sulfuric acid solution to obtain copper sulfate-sulfuric acid solutions containing C-C3N4 fluorescent probe at a concentration of 0.05 mg / ml and gelatin at concentrations of 0, 1, 3, 5, 8 and 10 mg / L, respectively.

[0040] (4) Drawing of standard curve Use a fluorescence spectrophotometer, set the excitation wavelength to 320 nm, and measure the fluorescence intensity of the standard curve solution prepared in step (3) at 433 nm ( Figure 2 By recording the curve of the change in fluorescence intensity before and after the addition of gelatin and the gelatin concentration, the corresponding linear regression equation was obtained ( Figure 3 ). ΔF = 776.6842 + 520.9474C, R 2 = 0.99599. The linear range of gelatin detection is 1-10 mg / L, and the minimum detection limit is 0.33 mg / L.

[0041] (5) Actual sample testing Take 1 ml of C-C3N4 copper sulfate-sulfuric acid solution and place it in a 10 ml volumetric flask, take 2 ml of actual copper electrodeposition solution (solutions from 5 different copper electrolytic cells were taken in M ​​Company) and add it to a 10 ml volumetric flask, and then make up the volume with copper sulfate-sulfuric acid solution. Follow the above step (4) and substitute the obtained fluorescence intensity value into the linear regression equation in the above step (4) for calculation to obtain the gelatin concentration in the actual electrolytic copper solution. The gelatin concentration of the copper electrolytic cell solution is listed in Table 1. Comparative Example 1

[0042] A specific comparative example of using the g-C3N4 prepared in Example 1 as a fluorescent probe to analyze and detect gelatin in a copper electrolyte. The analysis method is the same as that in Example 1, and the analysis sample is the electrolytic cell solution #1 in Example 1. The results are listed in Table 1. Comparative Example 2

[0043] Preparation of melamine g-C3N4 based on condensation reaction with formaldehyde. Weigh 1g of melamine and add it to 300ml of deionized water. Add 0.1ml of formaldehyde under stirring and carry out condensation reaction at room temperature for 2h. Place it in a sealed porcelain crucible. Subsequently, the crucible is placed in a high-temperature muffle furnace, heated to 550℃ at a heating rate of 5℃ / min and maintained at this temperature for 2h. After the crucible is naturally cooled to ambient temperature, the resulting product is transferred to an agate mortar for fine grinding. The light yellow powder finally obtained is g-C3N4. The analysis method is the same as that in Example 1, and the analysis sample used is the electrolytic cell liquid #2 in Example. The results are listed in Table 1.

[0044] Table 1 Determination results of gelatin in copper electrolytic cell solution (n=3)

[0045] As shown in Table 1, the samples were tested in parallel 3 times, the relative standard deviation was less than 3%, and the spike recovery range was 98.2% to 102%. The above results show that the analysis method of the present invention satisfies the rapid detection of gelatin concentration in copper electrolyte and realizes the effective control of electrolytic copper foil quality.

[0046] The above embodiments are only used to illustrate the present invention, not to limit the present invention. Those skilled in the art may make various corresponding changes without departing from the scope of the present invention. Therefore, all technical solutions formed by equivalent replacement or equivalent modification belong to the protection scope of the present invention.

Claims

1. A fluorescent probe for detecting gelatin in copper electrolyte, characterized in that: The fluorescent probe is band-regulated C3N4, expressed as C-C3N4; the C-C3N4 is in Cu 2+ No fluorescence quenching occurs in the presence of 2. The fluorescent probe for detecting gelatin in copper electrolyte according to claim 1, characterized in that: The maximum excitation wavelength of the C-C3N4 is 320 nm, and the maximum emission wavelength is 433 nm.

3. The method for preparing a fluorescent probe for detecting gelatin in a copper electrolyte according to claim 1 or 2, characterized in that: The steps include: (1) Melamine was dispersed in deionized water, and formaldehyde was added under stirring. The condensation reaction was carried out at room temperature for 2 h, which was recorded as solution A. (2) Dissolve cyanuric acid in 80°C deionized water, referred to as solution B; (3) Solution B was added to solution A, the temperature was raised to 80 °C, stirring was continued for 2 h, centrifuged, washed with deionized water at 80 °C, the product was collected and redispersed in deionized water, allowed to stand at room temperature for 12 h, the supernatant was removed to obtain a flocculent precipitate, and freeze-dried for 48 h to obtain a C-C3N4 precursor; (4) The C-C3N4 precursor was annealed in a tubular furnace at 500°C-600°C under nitrogen conditions for 2 hours to obtain the product C-C3N4.

4. The method for preparing a fluorescent probe for detecting gelatin in a copper electrolyte according to claim 3, characterized in that: In the step (1), the mass volume ratio of melamine to formaldehyde is 10 g:1-1.5 mL; the mass volume ratio of melamine to deionized water is 1 g:300 mL.

5. The method for preparing a fluorescent probe for detecting gelatin in a copper electrolyte according to claim 3, characterized in that: In the step (2), the mass of cyanuric acid is 1-1.2 times the mass of melamine in the step (1); and the mass volume ratio of cyanuric acid to deionized water is 1 g:300 mL.

6. The method for detecting gelatin content in copper electrolyte using the fluorescent probe according to claim 1 or 2, characterized in that: The steps include: S1, mixing C-C3N4 with copper sulfate-sulfuric acid solution, and fully dispersing by ultrasonic wave, so as to obtain 0.5 mg / ml C-C3N4 copper sulfate-sulfuric acid solution; S2, mixing the C-C3N4 copper sulfate-sulfuric acid solution with the gelatin solution to prepare a series of gelatin standard solutions containing 0.05 mg / ml C-C3N4; Detect the fluorescence intensity, draw a curve of the change in fluorescence intensity before and after adding gelatin and the gelatin concentration, and obtain the corresponding linear regression equation; S3, mixing the C-C3N4 copper sulfate-sulfuric acid solution with the copper electrolyte to be tested, and adjusting the volume of the copper sulfate-sulfuric acid solution to obtain a mixed solution containing 0.05 mg / ml C-C3N4; S4. Detect the fluorescence intensity of the mixed solution, and substitute the fluorescence intensity value into the linear regression equation obtained in the above step S2 to calculate, so as to obtain the actual gelatin concentration in the copper electrolyte.

7. The method for detecting gelatin content in copper electrolyte using the fluorescent probe according to claim 6, characterized in that: The copper sulfate-sulfuric acid solution is a mixed solution containing 150 g / L copper sulfate and 100 g / L sulfuric acid.

8. The method for detecting gelatin content in copper electrolyte using the fluorescent probe according to claim 6, characterized in that: The concentrations of gelatin in the gelatin standard solutions of the series of concentrations are 0, 1, 3, 5, 8 and 10 mg / L respectively.

9. The method for detecting gelatin content in copper electrolyte using a fluorescent probe according to claim 6, characterized in that: The fluorescence intensity was measured by a fluorescence spectrophotometer with the excitation wavelength set at 320 nm and detection at 433 nm.

10. The method for detecting gelatin content in copper electrolyte using a fluorescent probe according to claim 6, characterized in that: The volume ratio of C-C3N4 copper sulfate-sulfuric acid solution to the copper electrolyte to be tested is 1:2.

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