Concentration measuring method and concentration measuring device for sulfuric acid and oxidizing agent, and concentration measuring system using the same

Abstract

To provide a concentration measuring method, a concentration measuring device, and a concentration measuring system capable of measuring the concentrations of sulfuric acid and oxidizing agent in electrolytic sulfuric acid solution inline and in real time.SOLUTION: A concentration measuring method according to one aspect of the present invention is a concentration measuring method for measuring peaks of at least one of an oxidizing agent and sulfuric acid using Raman spectroscopy. A concentration measuring device according to another aspect of the present invention measures concentrations of oxidizing agent and sulfuric acid using Raman spectroscopy. Furthermore, a concentration measuring system according to another aspect of the present invention comprises a storage tank for storing sulfuric acid solution, circulation piping for circulating the sulfuric acid solution, and a pump, an electrolytic cell, and a concentration measuring device placed on the path of the circulation piping. The electrolytic cell comprises at least a pair of diamond electrodes to electrolyze the sulfuric acid solution and perform Raman spectroscopic measurement.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for measuring the concentrations of sulfuric acid and an oxidizing agent, a concentration measuring device, and a concentration measuring system using the same. [Background technology]

[0002] Sulfuric acid solutions electrolyzed using diamond electrodes are specifically called electrolytic sulfuric acid solutions, and contain peroxodisulfuric acid, a highly oxidizing agent. Furthermore, peroxodisulfuric acid decomposes depending on the temperature and the oxidation of the treated material, converting into peroxomonosulfuric acid and hydrogen peroxide. Therefore, the electrolytic sulfuric acid solution produced during treatment contains a mixture of three oxidizing agents with different oxidizing powers: peroxodisulfuric acid, peroxomonosulfuric acid, and hydrogen peroxide. While sulfuric acid becomes a highly oxidizing agent when electrolyzed using diamond electrodes, it does not contain heavy metals, so it does not violate environmental regulations and presents few disposal issues, making it a highly valuable substance for industrial use.

[0003] In fact, electrolytic sulfuric acid solutions are beginning to be put to practical use in the photoresist removal process in semiconductor manufacturing, and research results are also being reported for pretreatment in metal plating and the anodization of aluminum alloys, etc. Furthermore, research is also being conducted in areas such as processes for dissolving the resin components of CFRP and cleaning silica stones.

[0004] As a system for generating the electrolytic sulfuric acid solution, for example, Patent Document 1 listed below proposes a circulation system in which a sulfuric acid solution is electrolyzed in an electrode cell having a diamond electrode, the generated electrolytic sulfuric acid solution is sent to a treatment tank through piping, the object to be treated is treated in the treatment tank, and then the solution is returned to the electrolytic tank for electrolysis. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-114880 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, although electrolytic sulfuric acid solution can provide an extremely excellent oxidizing agent, unfortunately it has not yet become widespread as a production technology in various industrial fields where there are various needs.

[0007] One reason for this is that optimal treatment cannot be achieved unless the concentration of the three oxidizers, of which peroxodisulfuric acid has the strongest oxidizing power, is kept constant during treatment depending on the intended use, material, shape, and size of the workpiece, but there is currently no technology to constantly monitor this concentration.For example, when used as a pretreatment for resin plating, if the oxidizer concentration is too high, it can damage the resin substrate itself, while if the oxidizer concentration is low, the treatment takes too long or the treatment effect cannot be achieved.

[0008] Furthermore, there is no feedback technology for determining the oxidant concentration during the treatment and restoring it to the target oxidant concentration if it deviates from the target oxidant concentration.In particular, it is known that the sulfuric acid concentration in the electrolytic sulfuric acid solution changes over time due to factors such as moisture adhering to the workpiece being mixed into the treatment tank, a decrease in the amount of electrolytic sulfuric acid due to adhesion to the workpiece after treatment, and evaporation of moisture from the treatment tank.

[0009] On the other hand, methods for measuring sulfuric acid concentration have been proposed, such as specific gravity, titration, dielectric constant, and ion quantitative measurement. However, all of these methods are difficult to measure inline in real time, and the strong oxidizing power of the electrolytic sulfuric acid solution makes it difficult to use metal sensors, making them difficult to implement.

[0010] In view of the above problems, the present invention aims to provide a concentration measurement method, a concentration measurement device, and a concentration measurement system that can measure the concentrations of sulfuric acid and an oxidizing agent in an electrolytic sulfuric acid solution inline in real time. [Means for solving the problem]

[0011] The present inventors have conducted extensive research into the above-mentioned problems and have discovered that the concentrations of various oxidizing agents are strongly correlated with the Raman peak intensity, leading to the completion of the present invention.

[0012] That is, a concentration measurement method according to one aspect of the present invention uses Raman spectroscopy to measure the peak of at least one of the oxidizing agent and sulfuric acid.

[0013] In this respect, although not limited thereto, it is preferable to compare the peak intensity of sulfuric acid with the peak intensity of the oxidizing agent.

[0014] In this respect, it is preferable, but not limited to, to measure the concentrations of the oxidizing agent and sulfuric acid based on a calibration curve.

[0015] In this respect, although not limited thereto, the oxidizing agent preferably includes at least one of peroxodisulfuric acid, peroxomonosulfuric acid, and aqueous hydrogen peroxide.

[0016] In this respect, the oxidizing agent is peroxodisulfuric acid, but is not limited thereto, and the concentration of peroxodisulfuric acid is adjusted to a wave number of 1075 cm -1 Peak value of 840cm -1 It is preferable to measure based on at least one of the peak values of

[0017] In this respect, the oxidizing agent is peroxomonosulfuric acid, but is not limited thereto, and the concentration of peroxomonosulfuric acid is adjusted to a wave number of 780 cm -1 It is preferable to measure based on the peak value of

[0018] In this respect, the oxidizing agent is hydrogen peroxide, but is not limited thereto, and the concentration of hydrogen peroxide is adjusted to a wave number of 880 cm -1 It is preferable to measure based on the peak value of

[0019] In this respect, although not limited to, the concentration of sulfuric acid is -1It is preferable to measure based on the peak value of

[0020] An apparatus for measuring the concentrations of an oxidizing agent and sulfuric acid according to another aspect of the present invention uses Raman spectroscopy.

[0021] According to another aspect of the present invention, a concentration measurement system includes a storage tank for storing a sulfuric acid solution, a circulation pipe for circulating the sulfuric acid solution in the storage tank, a pump arranged on the path of the circulation pipe, an electrolytic cell, and a concentration measurement device, wherein the electrolytic cell is equipped with at least a pair of diamond electrodes and is configured to electrolyze the sulfuric acid solution, and the concentration measurement device is configured to perform Raman spectroscopy measurement. [Effects of the Invention]

[0022] As described above, the present invention can provide a concentration measurement method, a concentration measurement device, and a concentration measurement system that can measure the concentrations of sulfuric acid and oxidizing agent in an electrolytic sulfuric acid solution inline in real time. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of a concentration measurement system according to an embodiment. [Figure 2] FIG. 1 is a diagram showing a spectrum obtained by Raman spectroscopy of a sulfuric acid solution in an example. [Figure 3] FIG. 1 is a diagram showing a spectrum obtained by Raman spectroscopy of a sulfuric acid solution in an example. [Figure 4] FIG. 1 is a diagram showing changes in peak intensity obtained by Raman spectroscopy of a sulfuric acid solution in an example. [Figure 5] FIG. 1 is a diagram showing changes in peak intensity (calibration curve) obtained by Raman spectroscopy of a sulfuric acid solution in an example. [Figure 6] FIG. 1 is a diagram showing changes in peak intensity (calibration curve) obtained by Raman spectroscopy of a sulfuric acid solution containing peroxodisulfuric acid in an example. [Figure 7]FIG. 1 is a diagram showing changes in peak intensity (calibration curve) obtained by Raman spectroscopy of a sulfuric acid solution containing peroxomonosulfuric acid in an example. [Figure 8] FIG. 2 is a diagram showing the change in peak intensity (calibration curve) obtained by Raman spectroscopy of a sulfuric acid solution containing hydrogen peroxide in an example. BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described. However, the present invention can be embodied in many different forms and is not limited to the specific examples described in the following embodiments and examples.

[0025] (Concentration measurement system) FIG. 1 is a diagram showing an outline of a concentration measurement system S according to this embodiment (hereinafter referred to as "this system"). As shown in this figure, this system S is a concentration measurement system having a storage tank 2 for storing a sulfuric acid solution L, a circulation pipe 3 for circulating the sulfuric acid solution L in the storage tank 2, a pump 4 arranged on the path of the circulation pipe 3, an electrolytic cell 5, and a concentration measurement device 1.

[0026] In the present system S, the electrolytic cell 5 is provided with at least a pair of diamond electrodes and electrolyzes the sulfuric acid solution. The concentration measuring device 1 performs Raman spectroscopy.

[0027] According to this system, the concentrations of sulfuric acid and oxidizing agent in the electrolytic sulfuric acid solution can be measured inline in real time, and details of this will become clear from the description below.

[0028] First, the concentration measuring device 1 of the present system S is a main device of the present system S, and is capable of measuring the concentration of at least one of an oxidizing agent and sulfuric acid, and uses Raman spectroscopy for this concentration measurement. Details of the concentration measuring device 1 will be explained again after explaining the other components of the present system S.

[0029] The storage tank 2 of the present system S stores the sulfuric acid solution L. The storage tank 2 is not limited to any particular material as long as it is not dissolved by the sulfuric acid solution and can stably maintain its structure, but is preferably made of glass or an acid-resistant resin such as PTFE, PFA, or PVC, but is not limited to these.

[0030] Furthermore, the sulfuric acid solution whose concentration is to be measured in this system S contains sulfuric acid and a solvent, i.e., water, and some of the sulfuric acid becomes an oxidizing agent as a result of electrolysis, resulting in an electrolytic sulfuric acid solution containing sulfuric acid and an oxidizing agent, which is used for various industrial applications. In other words, "sulfuric acid solution" includes pure sulfuric acid solution before electrolysis, but can also include "electrolyzed sulfuric acid solution" that contains an oxidizing agent. More specifically, a sulfuric acid solution is a solution containing a solvent and sulfuric acid, and an electrolyzed sulfuric acid solution is a solution containing a solvent, sulfuric acid, and an oxidizing agent.

[0031] In this system S, the oxidant is produced by electrolysis by immersing a pair of diamond electrodes in a sulfuric acid solution and passing an electric current through it. While not limited to this, it preferably contains at least one of peroxodisulfuric acid, peroxomonosulfuric acid, and hydrogen peroxide. First, sulfuric acid is converted into peroxodisulfuric acid by electrolysis, and peroxodisulfuric acid is further decomposed into peroxomonosulfuric acid and hydrogen peroxide depending on the temperature conditions and the oxidation of the workpiece. In other words, the electrolytic sulfuric acid solution contains oxidants such as peroxodisulfuric acid, peroxomonosulfuric acid, and aqueous hydrogen peroxide, in addition to sulfuric acid that remains unelectrolyzed. These reactions are expressed as follows: [ka]

[0032] The circulation pipe 3 of the system S is connected to the storage tank 2 and is used to circulate the sulfuric acid solution L. Circulating the sulfuric acid solution L makes it possible to measure the concentration of at least one of the sulfuric acid and the oxidizing agent. The material of the circulation pipe 3 is not limited, but is not limited to any material as long as it can be circulated without any problems even when it comes into contact with the sulfuric acid solution as described above. Preferably, the material is glass or an acid-resistant resin such as PTFE, PFA, or PVC, but is not limited to these.

[0033] Furthermore, for example, a control valve 31 may be provided on the path of the circulation pipe 3 of the present system S. By providing the control valve 31, it becomes possible to control the flow of the sulfuric acid solution.

[0034] As described above, the pump 4 of the present system S is disposed on the path of the circulation pipe 3 and actually forms the flow of the sulfuric acid solution. The structure of the pump 4 can be exemplified by, but is not limited to, a diaphragm pump.

[0035] As is clear from the above description, the electrolytic cell 5 of the present system S is disposed on the path of the circulation pipe 3 and serves to electrolyze sulfuric acid in the sulfuric acid solution. Specifically, the electrolytic cell 5 has a storage container 51 capable of storing the sulfuric acid solution, and at least a pair of diamond electrodes 52 immersed in the sulfuric acid solution stored in the storage container 51. The material of the storage container 51 is the same as that of the storage tank 2 described above.

[0036] Here, the diamond electrode 52 is an electrode in which the surface of a conductive material is coated with diamond, and is not limited as long as it can be immersed in a sulfuric acid solution and current is passed between the pair of diamond electrodes 52 to efficiently electrolyze sulfuric acid, but for example, it is preferable that it is a flat conductive silicon plate coated with diamond. With such a configuration, the pair of flat electrodes can be held at a predetermined distance, forming a uniform electric field and enabling stable electrolysis.

[0037] Furthermore, as described above, the electrolytic cell 5 of the present system S has at least one pair of diamond electrodes 52. "At least" means that it is possible to provide electrodes other than the pair of diamond electrodes 52. In the present system S, by providing a pair of diamond electrodes 52 and passing a current between these electrodes, sulfuric acid can be electrolyzed into an oxidizing agent, specifically peroxodisulfuric acid, as described above.

[0038] The current value when electrolyzing sulfuric acid is not limited as long as it can electrolyze sulfuric acid, as described above, but the current density is preferably 1 A / dm 2 More than 50A / dm 2 The range is preferably within the range of 5 A / dm 2 More than 30A / dm 2 The range is as follows:

[0039] Furthermore, the present system S is preferably provided with a water supply means 6 connected to the storage tank 2 for adjusting the sulfuric acid concentration and the oxidizing agent concentration in the sulfuric acid solution. Specifically, the water supply means 6 includes a supply pipe 61 and an adjustment valve 62, and by opening the adjustment valve 62, water (pure water) can be supplied into the storage tank 2 and its concentration can be adjusted.

[0040] Furthermore, in the present system S, it is preferable to provide a supply pipe 7 for supplying the electrolytic sulfuric acid solution produced by the electrolytic cell 5 to the non-processing side. It is preferable to provide an adjustment valve 71 on the supply pipe 7. This makes it possible to adjust the amount of electrolytic sulfuric acid solution to be sent to the outside.

[0041] Here, the concentration measuring device 1 of the present system S will be explained again. As described above, the concentration measuring device 1 is capable of measuring the peak of at least one of the oxidizing agent and sulfuric acid using Raman spectroscopy. Here, the "peak" can be the value of the peak intensity itself, but it may also include the value of the peak area. When determining this peak, it is important to use the spectroscopic spectrum, but it is preferable to perform noise removal and baseline correction. By setting a baseline, it becomes possible to determine peak values with higher accuracy and compare peak values with each other. The baseline setting is not limited as long as it allows peak values to be determined with high accuracy, but it is preferable to set a baseline in a region where peaks do not appear stably, for example, at 700 cm -1 From 730cm -1 The lower peak in the region around 1100 cm -1 From 1150cm -1 It is preferable to connect the lower limit peaks of the area around the center with a straight line and set this as the baseline (0 line), but this is not limited to this.

[0042] Furthermore, the configuration of the concentration measurement device 1 of the present system S is not limited to, but preferably includes a light source member 11 that emits Raman light to the electrolytic sulfuric acid solution, a light receiving member 12 that receives the Raman light generated by the electrolytic sulfuric acid solution, and a concentration calculation device 13 that calculates the concentration based on the light received by the light receiving member 12. These components may be provided directly in the circulation pipe 3, or a storage container 14 may be provided separately from the circulation pipe 3 and the above components may be disposed inside this.

[0043] First, the light source member 11 is a member for irradiating light into the sulfuric acid solution, and preferably includes a light source 111 and a light guide member 112. The light source 111 is not limited as long as it has a wavelength that can be used for Raman spectroscopy, but it is preferable that the light source 111 is capable of emitting laser light in a wavelength range of 400 nm to 900 nm, more preferably in a range of 500 nm to 800 nm, and even more preferably 513.5 nm, 532 nm, 633 nm, or 785 nm.

[0044] Furthermore, the light-guiding member 112 is capable of guiding the light emitted by the light source 111 to the sulfuric acid solution, and may be, but is not limited to, an optical system such as a lens or a mirror, or an optical fiber.

[0045] The light receiving member 12 receives Raman light emitted from the sulfuric acid and the oxidizing agent when the light emitted by the light source 111 is incident on them, and guides the light to the concentration calculation device 13. The light receiving member 12 is not limited to any particular type, but preferably has a light receiving element 121.

[0046] Furthermore, the concentration calculation device 13 in the concentration measurement device 1 is a device that can calculate the concentrations of sulfuric acid and the oxidizing agent based on the information received by the light receiving member 12. More specifically, the concentration calculation device 13 can calculate a Raman spectrum based on the intensity of the received light, find each peak based on this Raman spectrum, and find the concentrations of sulfuric acid and the oxidizing agent based on these peaks.

[0047] As described above, the concentration measuring device 1 of the present system S can first measure the concentration of sulfuric acid in a sulfuric acid solution as a relative value or an absolute value. For example, as a method for measuring the concentration of sulfuric acid as an absolute value, a calibration curve is created by performing Raman spectroscopy on a sulfuric acid solution whose concentration has been specified in advance, and the peak obtained as a result of the Raman spectroscopy corresponding to the sulfuric acid measured by the concentration measuring device 1 can be compared with this calibration curve to determine the measured concentration of sulfuric acid.

[0048] In addition, in the Raman spectroscopy performed by the concentration measuring device 1 of the present system S, the concentration of sulfuric acid is measured at a wave number of 3200 cm -1 However, it is preferable to measure based on the peak value at 3200 cm. -1 plus or minus 30cm -1 Since there may be a peak shift of about 3200 cm, it is preferable to adjust the peak position appropriately. -1The peak is thought to be due to OH vibration, but in this system S, it has been confirmed that it is related to the initial concentration of sulfuric acid. Although this principle is only speculation, it is presumed that some kind of interaction occurs between sulfuric acid and water in sulfuric acid, and that this interaction is reflected in the peak value.

[0049] The concentration measuring device 1 of the present system S can also determine the concentration of an oxidizing agent. The method for determining this concentration is similar to that for determining the concentration of sulfuric acid described above, except for the wavenumber range. Specifically, a method for measuring the concentration of an oxidizing agent as an absolute value involves performing Raman spectroscopy on an oxidizing agent solution whose concentration has been specified in advance, creating a calibration curve, and then comparing the peak obtained as a result of the Raman spectroscopy measurement corresponding to the oxidizing agent measured by the concentration measuring device 1 with this calibration curve to determine the concentration of the measured sulfuric acid.

[0050] In addition, when determining the concentration of the oxidant in this system S, if the oxidant is peroxodisulfuric acid, the concentration of peroxodisulfuric acid is calculated at a wavenumber of 1075 cm -1 Peak value of 840cm -1 When the oxidizing agent is peroxomonosulfuric acid, the concentration of peroxomonosulfuric acid is measured based on at least one of the peak values at a wave number of 780 cm. -1 When the oxidizing agent is hydrogen peroxide, the concentration of hydrogen peroxide is measured based on the peak value at a wave number of 880 cm. -1 It is preferable to measure based on the peak value of

[0051] Furthermore, the concentration measuring device 1 of the present system S may be configured to determine the ratio of the sulfuric acid peak to the oxidizing agent peak. Specifically, the sulfuric acid peak value and the oxidizing agent peak value are determined, and the relative values of these are evaluated to determine the concentration ratio of the oxidizing agent.

[0052] Furthermore, when multiple oxidizing agents are used, the ratio of the peaks of the oxidizing agents may be calculated. As described above, sulfuric acid is converted into peroxodisulfuric acid by electrolysis using a diamond electrode, and then further converted into peroxomonosulfuric acid and hydrogen peroxide solution depending on the temperature conditions, etc., so there is an advantage in that by understanding the ratio of these, it is possible to understand the situation in more detail.

[0053] (Concentration measurement method) Here, a concentration measurement method using this system (hereinafter referred to as "this method") will be described. That is, this method uses Raman spectroscopy to measure the peak of at least one of the oxidizing agent and sulfuric acid.

[0054] More specifically, in this method, first, (S1) sulfuric acid is stored in a storage tank 2, and (S2) the sulfuric acid solution is circulated in a circulation pipe 3 using a pump 4.

[0055] After stabilizing the circulation of the sulfuric acid solution, the solution is electrolyzed using diamond electrodes in the electrolytic cell (S3), which decomposes the sulfuric acid into peroxodisulfuric acid, a powerful oxidizing agent.

[0056] Furthermore, (S4) Raman spectroscopy is performed using the concentration measuring device 1 to measure the peak of at least one of the oxidizing agent and sulfuric acid, thereby making it possible to measure the concentration of sulfuric acid.

[0057] As described above, the present invention can provide a concentration measurement method, a concentration measurement device, and a concentration measurement system that can measure the concentrations of sulfuric acid and oxidizing agent in an electrolytic sulfuric acid solution inline in real time. [Example]

[0058] Here, the results of an actual experiment conducted to confirm the effects of the above embodiment will be specifically described. In this example, measurements were performed using an EnSpectrR532 (registered trademark) manufactured by Enspectr Inc. as a Raman spectrometer.

[0059] (Spectral changes due to electrolysis of sulfuric acid 1) First, a pair of diamond electrodes was immersed in 2 L of a 20 wt% sulfuric acid solution and exposed to a current of 7 A / dm 2 The solution was electrolyzed for 6 hours while circulating at a current density of 1000 kJ / cm2, and Raman spectroscopy was performed. The results are shown in Figure 2. This figure confirms that the peaks change due to electrolysis. For example, peaks that are not present or are small at the start of electrolysis (0 min) appear or become large peaks in the spectrum after 4 hours (240 min).

[0060] (Spectral changes due to electrolysis of sulfuric acid 2) Similarly, 7A / dm 2 After that, the polypropylene was immersed in an electrolytic sulfuric acid solution heated to 50°C for 60 minutes. Figure 3 shows the results of Raman spectroscopy at this time.

[0061] According to this figure, a change in the spectrum occurs, which is due to S2O8 2- 840cm, which is thought to be due to -1 While the peaks around 880 cm are reduced, the peak at 880 cm is thought to be due to H2O2. -1 Peak and HSO5 - 780cm, which is thought to be due to -1 It was confirmed that the peak of

[0062] (Confirmation of changes in sulfuric acid peak intensity) Here, 2 L of sulfuric acid solution prepared at 40 wt% is 2 The Raman spectrum of the electrolysis at 3200 cm -1 The changes in the intensity of the nearby peaks were examined, and the results are shown in Figure 4.

[0063] The results confirmed that the intensity of this peak remained constant regardless of the elapsed time. This tendency was also observed in sulfuric acid solutions of other concentrations.

[0064] (Confirmation of peak intensity according to sulfuric acid concentration) On the other hand, sulfuric acid solutions were prepared with concentrations varying from 10% to 90% by 10% increments, and Raman spectroscopy was performed on each solution. -1 The intensity of the nearby peaks was checked, and the results are shown in Figure 5.

[0065] From this result, it was confirmed that the peak intensity is inversely proportional to the sulfuric acid concentration. In other words, by preparing such a calibration curve in advance, it is possible to perform Raman spectroscopy and obtain the peak intensity at 3200 cm -1 It can be seen that the concentration of the sulfuric acid solution can be estimated by measuring the peak intensity around the wavenumber 3200 cm. -1 The peak of is thought to be due to the vibration of OH, but in this example, it was confirmed that this peak intensity depends on the initial concentration, and that there is almost no change in the peak intensity even when the sulfuric acid is subsequently electrolyzed and circulated. This is a very interesting phenomenon.

[0066] (Calibration curve for peroxodisulfate) An evaluation solution was prepared using potassium peroxodisulfate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 96% sulfuric acid manufactured by Kanto Kasei Co., Ltd., and pure water to confirm the possibility of a calibration curve for peroxodisulfate. Specifically, sulfuric acid was first added to pure water to adjust the sulfuric acid concentration, and the peroxodisulfate concentrations were adjusted to 1 g, 10 g, and 20 g in a measuring cylinder. The solutions with each adjusted concentration were measured using a Raman spectrometer, and the results were analyzed at 840 cm -1 The peak intensity was confirmed. The heat generated when sulfuric acid was added to pure water was slowly suppressed by cooling with ice water. The results are shown in Figure 6.

[0067] As shown in this figure, 840 cm -1 The peak intensity of S2O8 2- It was confirmed that the concentration was proportional to the concentration of , and that it functioned as a calibration curve.

[0068] (Calibration curve for peroxomonosulfuric acid) An evaluation solution was prepared using potassium peroxomonosulfate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 96% sulfuric acid manufactured by Kanto Kasei Co., Ltd., and pure water to confirm the possibility of a calibration curve for peroxomonosulfuric acid. Specifically, sulfuric acid was first added to pure water to adjust the sulfuric acid concentration, and the peroxomonosulfuric acid concentration was adjusted to 1 g, 10 g, and 20 g in a measuring cylinder. The solutions with each adjusted concentration were measured using a Raman spectrometer, and the results were analyzed at 780 cm -1 The peak intensity was confirmed. The heat generated when sulfuric acid was added to pure water was slowly suppressed by cooling with ice water. The results are shown in Figure 7.

[0069] As shown in this figure, 780cm -1 The peak intensity of HSO5 - It was confirmed that the concentration was proportional to the concentration of , and that it functioned as a calibration curve.

[0070] (Hydrogen peroxide calibration curve) An evaluation solution was prepared using 30% hydrogen peroxide manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 96% sulfuric acid manufactured by Kanto Kasei Co., Ltd., and pure water to confirm the possibility of a calibration curve for hydrogen peroxide. Specifically, sulfuric acid was first added to pure water to adjust the sulfuric acid concentration, and the hydrogen peroxide concentrations were adjusted to 1 g, 10 g, and 20 g in a measuring cylinder. The solutions with each adjusted concentration were measured using a Raman spectrometer, and the results were analyzed at 880 cm -1 The peak intensity was confirmed. The heat generated when sulfuric acid was added to pure water was slowly suppressed by cooling with ice water. The results are shown in Figure 8.

[0071] As shown in this figure, 880cm -1 It was confirmed that the peak intensity was proportional to the H2O2 concentration, and that it functioned as a calibration curve.

[0072] As described above, these experimental examples have made it possible to create calibration curves for sulfuric acid concentration, peroxodisulfuric acid, peroxomonosulfuric acid, and hydrogen peroxide, respectively, and have confirmed that the unknown concentrations of sulfuric acid, peroxodisulfuric acid, peroxomonosulfuric acid, and hydrogen peroxide can be estimated by creating the calibration curves. [Industrial Applicability]

[0073] The present invention has industrial applicability as a concentration measurement method, a concentration measurement device, and a concentration measurement system. [Explanation of symbols]

[0074] S···Concentration Measurement System L...Sulfuric acid solution 1...Concentration measuring device 11. Light source component 111...Light source 112 Light guide member 12. Parts 121....Photodetector 13...Concentration calculation device 2. Reservoir 3...Circulation piping 31. Control valve 4. Pump 5...Electrolytic cell 51 Storage container 52 Diamond electrode 6...Water supply means 61 Supply piping 62 Regulating valve 7. Supply piping 71. Regulating valve

Claims

1. A concentration measurement method that uses Raman spectroscopy to measure the peak of at least one of an oxidizing agent and sulfuric acid.

2. 2. The concentration measuring method according to claim 1, wherein the peak intensity of the sulfuric acid and the peak intensity of the oxidizing agent are compared.

3. 2. The method for measuring concentrations according to claim 1, wherein the concentrations of the oxidizing agent and the sulfuric acid are measured based on calibration curves.

4. The concentration measuring method according to claim 1 , wherein the oxidizing agent includes at least one of peroxodisulfuric acid, peroxomonosulfuric acid, and hydrogen peroxide solution.

5. The oxidizing agent is peroxodisulfuric acid, and the concentration of the peroxodisulfuric acid is adjusted to a wave number of 1075 cm －１ and a peak value of 840 cm －１ 2. The method for measuring concentration according to claim 1, wherein the concentration is measured based on at least one of the peak values of

6. The oxidizing agent is peroxomonosulfuric acid, and the concentration of the peroxomonosulfuric acid is adjusted to a wave number of 780 cm －１ 2. The method for measuring concentration according to claim 1, wherein the measurement is made based on the peak value of

7. The oxidizing agent is hydrogen peroxide, and the concentration of the hydrogen peroxide is adjusted to a wave number of 880 cm －１ 2. The method for measuring concentration according to claim 1, wherein the measurement is made based on the peak value of

8. The concentration of the sulfuric acid was measured at a wave number of 3200 cm －１ 2. The method for measuring concentration according to claim 1, wherein the measurement is made based on the peak value of

9. An apparatus for measuring the concentration of oxidizing agents and sulfuric acid using Raman spectroscopy.

10. a storage tank for storing a sulfuric acid solution; a circulation pipe for circulating the sulfuric acid solution in the storage tank; A concentration measurement system having a pump, an electrolytic cell, and a concentration measurement device arranged on a path of the circulation piping, The electrolytic cell is provided with at least one pair of diamond electrodes to electrolyze the sulfuric acid solution, The concentration measurement system is a concentration measurement system in which the concentration measurement device performs Raman spectroscopy measurement.

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