JP7480652B2 - Analysis method for glue in electrolyte - Google Patents

Description

The present invention relates to a method for analyzing and measuring the concentration of glue in an electrolyte solution.

In the copper smelting process, to obtain electrolytic copper (copper purity ≧ 99.99%), electrolytic refining is carried out in an electrolyte whose main component is copper sulfate, using crude copper (copper purity ≧ 99%) obtained by dry smelting as the anode and a seed plate (copper purity ≧ 99.99%) as the cathode.

The electrolyte is mainly composed of copper sulfate and is strongly acidic with a pH of less than 0. The concentration of copper sulfate in the electrolyte is so high that it crystallizes out when cooled from the operating temperature of about 50°C to 60°C, for example, about 250 g/L.

It is also known that the electrolyte contains a small amount of glue (also called "gelatin") as another component. Glue is an important additive that is added to maintain the appearance, mechanical strength, and other properties of electrolytic copper in good condition. Therefore, it is important to maintain the concentration of glue in the electrolyte within a specified range during operation.

However, glue is easily decomposed, and the concentration of glue in the electrolyte is extremely low (on the order of ppm (≒mg/L)). As a result, it is difficult to analyze the concentration of glue with high accuracy due to the influence of components in the electrolyte that are more concentrated than glue, such as copper sulfate.

For example, Patent Documents 1 and 2 disclose a technique for analysis using size exclusion chromatography (also called "SEC" or "SEC analysis"), which includes a step of adsorbing glue to an amphiphilic polymer by contacting the polymer with an electrolyte prior to SEC analysis, and then eluting the glue from the polymer. According to this method, the concentration of components other than the glue in the eluent is reduced, reducing the background, thereby improving the accuracy of the analysis of the glue.

The methods disclosed in Patent Documents 1 and 2 are excellent technologies in that they can improve analytical accuracy compared to previous technologies. However, as a means of concentrating glue, which has a very low concentration in the electrolyte, the steps of adsorption and elution using a resin are required, and because the resin is expensive, it is common to use it repeatedly. This means that analytical errors due to deterioration of the resin caused by repeated use are unavoidable, and there are certain limitations to improving analytical accuracy.

JP 2009-192491 A JP 2009-69001 A

The present invention has been proposed in light of these circumstances, and aims to provide a method for effectively and efficiently measuring the concentration of glue in an electrolyte, such as a copper electrolyte.

The inventors of the present invention have conducted extensive research to solve the above-mentioned problems. As a result, they discovered that when analyzing and measuring the concentration of glue in an electrolyte solution using size exclusion chromatography (SEC) or total organic carbon (TOC), a solution in which the glue is effectively concentrated can be obtained by treating the electrolyte solution to be analyzed using an ultrafiltration membrane as a pretreatment, thereby improving the accuracy of analysis using SEC or TOC, and thus completed the present invention.

(1) The first aspect of the present invention is a method for analyzing the concentration of glue in an electrolyte solution by size exclusion chromatography (SEC), which involves concentrating the glue in the electrolyte solution by treating the electrolyte solution with an ultrafiltration membrane prior to the SEC analysis.

(2) The second aspect of the present invention is a method for analyzing the concentration of glue in an electrolyte solution by total organic carbon (TOC), which involves concentrating the glue in the electrolyte solution by treating the electrolyte solution with an ultrafiltration membrane prior to the TOC analysis.

(3) The third invention of the present invention is a method for analyzing glue in an electrolyte according to the first or second invention, wherein the pH of the electrolyte is 0.5 or less.

(4) The fourth invention of the present invention is a method for analyzing glue in an electrolyte solution according to any one of the first to third inventions, in which the electrolyte solution is centrifuged using a volumetric container equipped with the ultrafiltration membrane.

(5) The fifth aspect of the present invention is a method for analyzing glue in an electrolyte solution according to any one of the first to fourth aspects of the present invention, further comprising subjecting the concentrated glue solution obtained by the treatment using the ultrafiltration membrane to a washing treatment.

(6) The sixth aspect of the present invention is a method for analyzing glue in an electrolyte solution according to the first aspect of the present invention, which involves preparing a calibration curve by performing an SEC analysis using an aqueous solution with a known glue concentration, and measuring the concentration of glue in the electrolyte solution based on the calibration curve from the SEC analysis value for a concentrated solution of glue obtained by processing using the ultrafiltration membrane.

(7) The seventh aspect of the present invention is a method for analyzing glue in an electrolyte according to the sixth aspect of the present invention, in which the aqueous solution having a known glue concentration is an electrolyte for preparing a calibration curve having a known glue concentration, and in preparing the calibration curve, the electrolyte for preparing the calibration curve is treated using an ultrafiltration membrane to concentrate the glue in the electrolyte, the resulting concentrated glue solution is washed, and the concentrated solution after the washing treatment is analyzed by SEC to prepare the calibration curve.

(8) The eighth aspect of the present invention is a method for analyzing glue in an electrolyte, which comprises the steps of: preparing a calibration curve by TOC analysis using an aqueous solution of potassium hydrogen phthalate of known concentration in the second aspect of the invention; and measuring the concentration of glue in the electrolyte based on the calibration curve from the TOC analysis value for the concentrated glue solution obtained by processing using the ultrafiltration membrane.

(9) The ninth aspect of the present invention is a method for analyzing glue in an electrolyte solution according to the second aspect of the present invention, which involves preparing a calibration curve by performing a TOC analysis using an aqueous solution with a known glue concentration, and measuring the concentration of glue in the electrolyte solution based on the calibration curve from the TOC analysis value for the concentrated glue solution obtained by processing using the ultrafiltration membrane.

(10) The tenth invention of the present invention is a method for analyzing glue in an electrolyte according to the ninth invention, in which the aqueous solution having a known glue concentration is an electrolyte for preparing a calibration curve having a known glue concentration, and in preparing the calibration curve, the electrolyte for preparing the calibration curve is treated using an ultrafiltration membrane to concentrate the glue in the electrolyte, the resulting concentrated glue solution is washed, and the concentrated solution after the washing treatment is analyzed by TOC to prepare the calibration curve.

The present invention makes it possible to effectively and efficiently measure the concentration of glue in an electrolyte solution.

FIG. 1 is a photograph showing an example of a constant volume container for centrifugation equipped with an ultrafiltration membrane, and showing the appearance when centrifugal separation is performed at a rotation speed of 4000 rpm. 1 is a chart graph showing the results of SEC analysis performed in preparing a calibration curve using aqueous solutions of known glue concentrations in Example 1. FIG. 1 is a diagram showing a calibration curve obtained by SEC analysis of aqueous solutions of known glue concentrations. 1 is a chart graph of an elution curve obtained by SEC analysis in Comparative Example 1. 1 is a chart graph showing the results of SEC analysis performed when preparing a calibration curve using an electrolyte solution having a known glue concentration. FIG. 1 is a diagram showing a calibration curve obtained by SEC analysis using an electrolyte solution with a known glue concentration. FIG. 2 is a graph showing a calibration curve obtained by TOC analysis of an aqueous solution having a known concentration of potassium hydrogen phthalate. FIG. 11 is a graph showing the results of a TOC analysis of the electrolyte in Example 2. FIG. 11 is a graph showing the results of a TOC analysis of the electrolyte in Comparative Example 2.

A specific embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail below, but the present invention is not limited to the following embodiment, and can be implemented with appropriate modifications within the scope that does not change the gist of the present invention. In this specification, the expression "X to Y" (X and Y are arbitrary numbers) means "X or more and Y or less."

The glue analysis method according to the present invention (hereinafter simply referred to as the "analysis method") is a method for analyzing and measuring the concentration of glue, which is a component contained in an electrolyte solution. Specifically, the method for analyzing the glue concentration includes analysis by size exclusion chromatography (SEC) or analysis by total organic carbon (TOC).

The electrolyte to be analyzed contains glue at a ratio on the order of ppm. Specifically, the concentration of glue in the electrolyte is, for example, about 0.01 to 10 ppm. The electrolyte also contains various components with higher concentrations than glue, such as metal ions of copper, nickel, gold, manganese, lead, etc., inorganic acids, organic acids, etc. For example, in the case of a copper electrolyte, the general concentrations are Cu: about 40 to 70 g/L, H ₂ SO ₄ : about 150 to 210 g/L, and further additives such as glue, thiourea, and abiton are contained.

The analytical method of the present invention is a method for analyzing and measuring the concentration of low amounts of glue contained in such electrolyte solutions.

Specifically, this analytical method is characterized by concentrating the glue in the electrolyte by pretreating the electrolyte using an ultrafiltration membrane prior to analysis by SEC or TOC.

This method effectively concentrates the glue in the electrolyte, and the concentrated solution is used for analysis by SEC or TOC, so that the area where the glue is detected can be clearly identified in the chart of the analysis results, and the concentration of the glue can be measured with high accuracy. Furthermore, this pretreatment does not require operations such as polymer adsorption or elution, and it is extremely easy to obtain a concentrated solution of concentrated glue, that is, a solution to be analyzed by SEC or TOC.

In addition, by applying this analysis method, it is possible to effectively control the concentration of glue components in the copper electrolyte used in copper electrolysis operations, for example, and to obtain higher quality electrolytic copper under more precise concentration control than before.

[Analysis by Size Exclusion Chromatography (SEC)]
Size exclusion chromatography (SEC) analysis is a method of separating substances in a column packed with a porous packing material by the size exclusion mechanism between the pores on the packing material surface and high molecular weight molecules. In SEC, high molecular weight molecules with large molecular sizes cannot reach the depths of the porous packing material, so they end up eluting early through a short flow path, while low molecular weight molecules with small molecular sizes can reach the depths, so the flow path becomes longer and they are eluted late. In this way, SEC can separate molecules based on the difference in molecular size (molecular weight). In the analysis method according to the present invention, the high molecular weight molecules are the glue, and the low molecular weight molecules are components other than the glue.

There are various types of packing materials (columns) available commercially for use in SEC, and the analytical method of the present invention is not particularly limited as long as the column can properly analyze and measure the glue concentration.

In glue concentration analysis using SEC, a calibration curve method can be used. Specifically, an elution curve is obtained from the retention time (unit: min) and the elution amount (unit: mV) measured by a UV transmittance meter, and the peak area value on the positive side of the reference (0 mV) is calculated. Meanwhile, a calibration curve is prepared by performing a similar SEC measurement on a glue solution of known concentration. Then, based on the calibration curve prepared, the glue concentration in the glue-containing solution (electrolyte) to be analyzed is measured from the calculated peak area value. The preparation of the calibration curve will be described in detail later.

[Total organic carbon (TOC) analysis]
Total organic carbon (TOC) analysis is an analytical method for quantifying the total amount of organic matter in a sample by measuring the amount of carbon dioxide generated during oxidative decomposition of an organic-containing sample, utilizing the fact that the amount of carbon dioxide generated is proportional to the amount of carbon in the organic matter contained in the oxidatively decomposed sample. Note that in the analytical method according to the present invention, the high molecular weight organic matter in the solution after concentration by ultrafiltration, which will be described later, is the glue, and the low molecular weight organic matter is the components other than the glue.

In glue concentration analysis using TOC, a calibration curve method can be used. Specifically, the measurement time (unit: min) and carbon dioxide detection amount (unit: mV) are obtained using a non-dispersive infrared gas detector or the like, and the peak area value on the positive side of the reference (0 mV) for the carbon dioxide detection amount calculated from the curve obtained from this is calculated. Meanwhile, a calibration curve is prepared by performing a similar TOC measurement on an aqueous potassium hydrogen phthalate solution of known concentration. Then, based on the calibration curve prepared and the calculated peak area value, the glue-derived TOC in the glue-containing solution (electrolyte) to be analyzed is measured. The preparation of the calibration curve will be described in detail later.

[Pretreatment for SEC or TOC analysis (pretreatment using ultrafiltration membrane)]
As described above, for example, in an electrolyte such as a copper electrolyte, in addition to metal compounds such as copper sulfate, additive compounds such as thiourea and avitone are contained, and these compounds are contained in higher concentrations than glue, which is contained in trace amounts (on the order of ppm) in the electrolyte. Therefore, in conventional SEC analysis, it is difficult to quantitatively analyze glue with high accuracy due to the influence of other compound components contained in higher concentrations than glue.

The analytical method according to the present invention is characterized in that the electrolyte to be analyzed is treated with an ultrafiltration membrane as a pretreatment prior to analysis by SEC or TOC, thereby concentrating the glue in the electrolyte.

In this way, by performing pretreatment using an ultrafiltration membrane on the electrolyte to be analyzed, the glue (molecular weight ≧3000) in the electrolyte can be effectively concentrated, making it possible to relatively reduce the influence of other components, and as a result, SEC analysis and TOC analysis can be performed with high accuracy. Furthermore, this type of pretreatment does not require operations such as polymer adsorption and elution, making it possible to concentrate the glue extremely simply and effectively.

(About ultrafiltration membranes)
Ultrafiltration membranes are generally used in pressure filtration, which separates molecules based on their size, and their performance index is expressed by the molecular weight cutoff. Ultrafiltration membranes allow a solution (electrolyte) to flow in from the primary side (inlet side) and allow the filtered solution to flow out from the secondary side (outlet side). This operation provides an on-membrane liquid remaining above the ultrafiltration membrane and an under-membrane liquid that passes through the ultrafiltration membrane and migrates under the membrane.

The ultrafiltration membrane used in the analysis method of the present invention has a molecular weight cutoff of 1000 or more. The molecular weight cutoff of the ultrafiltration membrane is preferably 2000 or more, more preferably 3000 or more. The upper limit of the molecular weight cutoff is not particularly limited, but is preferably 10000 or less, more preferably 5000 or less. Here, the molecular weight cutoff is an indication of the molecular weight at which the membrane rejection rate is 90% when a standard substance with a known molecular weight is passed through it.

In the analytical method according to the present invention, the subject of analysis is an electrolyte solution, and among the components contained in the electrolyte solution, the molecular weight of glue is on the order of tens of thousands to hundreds of thousands, while the molecular weight of components other than glue is at most less than 1000. For example, by processing using an ultrafiltration membrane with a molecular weight cutoff (applicable molecular weight) of 3000, those fractionated as having a molecular weight cutoff greater than 3000 can be clearly regarded as glue in the electrolyte solution, and the glue can be selectively concentrated. In addition, additives that are intentionally added to the electrolyte solution include, for example, thiourea and abitone, and the molecular weights of these compounds are thiourea: approximately 80, and abitone: approximately 300.

Specifically, by subjecting the electrolyte to a pretreatment using an ultrafiltration membrane, it is possible to separate the electrolyte into an above-membrane liquid and an below-membrane liquid, with the glue having a molecular weight larger than the molecular weight cutoff remaining in the above-membrane liquid, and other components other than the glue having a molecular weight smaller than the molecular weight cutoff being separated and transferred to the below-membrane liquid. In this way, the analytical method according to the present invention is a method for measuring the concentration of glue contained in an electrolyte by SEC analysis, and is characterized by using the difference in molecular weight between the glue contained in the electrolyte and the other components contained in the electrolyte as a pretreatment to effectively and efficiently obtain a solution in which the glue is concentrated (also called the "above-membrane liquid" or "glue-concentrated solution").

After pretreating using an ultrafiltration membrane to obtain a concentrated glue solution, the concentrated glue solution is analyzed by SEC or TOC. This allows the glue concentration to be determined from a graph of the results of the SEC or TOC analysis. In particular, by subjecting the concentrated glue solution obtained by pretreating using an ultrafiltration membrane to SEC or TOC analysis, the portion in the chart of the analysis results where glue is detected becomes clear. The concentration of glue can then be measured with high accuracy from the peak area of that portion and a calibration curve obtained by SEC analysis of a glue solution of known concentration in the case of SEC analysis, or from a calibration curve obtained by TOC analysis of an aqueous solution of potassium hydrogen phthalate with a known concentration, for example.

Here, it is preferable that the ultrafiltration membrane is acid-resistant. As mentioned above, the subject of this analysis method is an electrolyte, which is a strongly acidic solution. For example, the pH of a copper electrolyte is ≦0.5. Therefore, by using an acid-resistant ultrafiltration membrane, deterioration caused by contact with an electrolyte can be suppressed, and the glue can be selectively fractionated with higher accuracy to obtain a concentrated solution.

As an example of an ultrafiltration membrane with high acid resistance, "Vivaspin Turbo 15" manufactured by Sartorius is commercially available and can be suitably used. However, it is preferable to use the ultrafiltration membrane only once per analysis, so that a decrease in analytical accuracy due to slight deterioration of the ultrafiltration membrane can be reliably prevented.

(An example of a process using an ultrafiltration membrane: centrifugation process)
As described above, in the analysis method according to the present invention, a solution in which glue is concentrated is obtained by performing a treatment using an ultrafiltration membrane as a pretreatment for SEC analysis or TOC analysis. If an ultrafiltration membrane is used, the specific concentration means is not particularly limited, but an example of the method is a method in which an electrolyte solution to be analyzed is centrifuged using a fixed volume container for centrifugation equipped with an ultrafiltration membrane.

Figure 1 shows an example of a fixed volume container for centrifugation equipped with an ultrafiltration membrane, and is a photograph showing the state when centrifuged at a rotation speed of 4000 rpm. The photograph in Figure 1 shows the state when 15 ml of electrolyte is poured into the ultrafiltration membrane and centrifuged, and shows the state at four points in time: before, 10 minutes, 20 minutes, and 30 minutes after the centrifugation process.

In this way, centrifugal separation using an ultrafiltration membrane is preferable because it allows the glue in the electrolyte to be concentrated more effectively and efficiently, for the following reasons:

That is, there are various types of centrifuge devices used for centrifugation processing, and many types exist that can be installed in test rooms at electrolysis operation sites, for example, meaning that they can be easily used in close proximity to the electrolysis operation site. This shortens the time required from sampling the electrolyte to starting the concentration operation, and even inexperienced workers can complete the pretreatment in, for example, less than 10 minutes.

In addition, when pretreatment using an ultrafiltration membrane is used to concentrate, for example, the glue concentration in the electrolyte solution by 10 times, the time required for the concentration operation to be completed is approximately 30 minutes at a rotation speed of 4000 rpm. Even including the time required for sampling the electrolyte solution, the concentration operation can be completed in a short time of approximately 40 minutes, which is much shorter than the adsorption and elution operations using polymers disclosed in, for example, Patent Documents 1 and 2 mentioned above.

Furthermore, pretreatment by centrifugation using an ultrafiltration membrane can efficiently obtain a glue concentrate, and since low molecular weight components are effectively removed from the solution, it is possible to prevent a decrease in the analytical accuracy of SEC and TOC due to the crystallization of copper sulfate caused by a decrease in liquid temperature.

Here, in the procedure for concentrating the glue in the electrolyte by centrifugation using an ultrafiltration membrane, it is preferable to obtain a concentrated solution in which the glue is concentrated, for example, 10 times by centrifugation, and then add a cleaning solution to the concentrated solution and perform repeated centrifugation operations. More specifically, a cleaning solution is added to the concentrated solution obtained, and centrifugation is performed again using an ultrafiltration membrane, and the resulting solution on the membrane is washed and diluted 10 times, and then another centrifugation operation is performed to wash and dilute the solution to 100 times.

In this way, by washing and diluting the obtained concentrated solution and repeatedly centrifuging it, the glue concentration in the glue concentrate remains 10 times concentrated, and the remaining low molecular weight components can be further reduced by washing and dilution. In other words, the background (other components) that cause a decrease in analytical accuracy in subsequent SEC analysis and TOC analysis can be further reduced.

The more times the process is repeated, the greater the effect will be, but if the balance with the time required is taken into consideration, repeating the process twice, for example, will allow for up to 100 times cleaning and dilution, and will adequately reduce low molecular weight components.

The cleaning solution is not particularly limited as long as it does not contain any of the components in the electrolyte. For example, ultrapure water can be used, but it is particularly preferable to use a solution containing disodium hydrogen phosphate (0.1 mol/L) and potassium dihydrogen phosphate (0.1 mol/L) as the cleaning solution. By using such a cleaning solution for cleaning and dilution, it is possible to reduce noise due to water in the result charts obtained by the subsequent SEC analysis and TOC analysis.

In addition, in the procedure for concentrating glue in an electrolyte solution by centrifugation using an ultrafiltration membrane, it is preferable to wash the fixed-volume container used for centrifugation before use. For example, a fixed-volume container in the delivered state may have deposits that adhered to it during the manufacturing process, and from the viewpoint of enabling more accurate SEC analysis, it is preferable to wash the fixed-volume container before use to remove the deposits.

(Dilution of electrolyte when performing pretreatment using ultrafiltration membrane)
In the analysis method according to the present invention, the subject of analysis is an electrolyte solution, which is generally a strongly acidic solution with a pH of ≦ 0.5. Therefore, in order to suppress deterioration of the ultrafiltration membrane used in the pretreatment of the electrolyte solution, it is preferable to dilute the electrolyte solution by at least about 2 times or more when performing the pretreatment.

To increase the pH of the electrolyte by 1 through dilution, it is necessary to dilute it 10 times, and the higher the dilution rate, the higher the pH can be raised. However, this dilution process is almost the opposite of the process of concentrating glue by pretreatment using an ultrafiltration membrane. For this reason, in order to prevent the labor and time required for the process from becoming too long, it is preferable to dilute the electrolyte by up to about 5 times.

(Glue concentration rate by pretreatment using ultrafiltration membrane)
By the pretreatment using an ultrafiltration membrane, a glue concentrate can be obtained as the liquid on the membrane, and the concentration of the glue is preferably about 10 times.

The effect of components other than glue contained in the electrolyte is gradually reduced as the concentration of glue increases, reaching a plateau when the concentration exceeds 10 times, and at higher concentration rates the effect of components other than glue remains almost the same. For this reason, in order to minimize the effort and enable efficient and highly accurate SEC or TOC analysis, it is preferable to perform pretreatment so that the concentration of glue is about 10 times.

However, depending on the electrolysis operation, the glue content in the electrolyte may be adjusted, and the appropriate concentration rate of the glue may vary. In other words, if the glue content is high, it is not necessary to concentrate it up to 10 times, and conversely, if the glue content is low, even 10 times concentration may not be sufficient. Therefore, it is preferable to adjust and set the concentration rate of the glue appropriately based on the glue content in the electrolyte used in the electrolysis operation.

[About creating a calibration curve]
As described above, in the analysis of the concentration of glue in an electrolyte using SEC or TOC, a calibration curve method can be used.

(When SEC analysis is performed)
Specifically, when measuring the glue concentration of the electrolyte to be analyzed by SEC analysis, a calibration curve is prepared in advance by performing SEC analysis using an aqueous solution with a known glue concentration. Then, the SEC analysis value (the positive peak area value calculated from the elution curve obtained from the retention time and the elution amount in the UV transmittance meter by SEC analysis) of the concentrated glue solution obtained by processing using an ultrafiltration membrane is compared with the prepared calibration curve, and the concentration of glue contained in the electrolyte is measured based on the calibration curve.

An electrolyte solution with a known glue concentration can be used as the aqueous solution with a known glue concentration used to prepare the calibration curve. This electrolyte solution is also referred to as the "electrolyte solution for preparing the calibration curve" with a known glue concentration to distinguish it from the electrolyte solution to be analyzed. In this way, by preparing the calibration curve using the electrolyte solution for preparing the calibration curve, the glue concentration in the electrolyte solution to be analyzed can be approximated to the actual measurement conditions, and the analytical accuracy using the calibration curve method can be improved.

Here, when preparing a calibration curve using the electrolyte for preparing the calibration curve, the electrolyte for preparing the calibration curve is pretreated using an ultrafiltration membrane prior to SEC analysis, in the same manner as the treatment of the electrolyte to be analyzed, to concentrate the glue in the electrolyte. When an electrolyte is used to prepare a calibration curve, the low molecular weight substances contained in the electrolyte at high concentrations will have an effect, and it will be difficult to prepare an appropriate calibration curve even if the glue concentration is known. Therefore, prior to SEC analysis, the electrolyte for preparing the calibration curve is pretreated using an ultrafiltration membrane to obtain a concentrated solution in which the glue is concentrated. This makes it possible to eliminate the effect of low molecular weight substances contained in the electrolyte for preparing the calibration curve, thereby improving the accuracy of the SEC analysis, and to make the calibration curve prepared based on the analysis results more appropriate.

The pretreatment of the electrolyte solution used to prepare the calibration curve using an ultrafiltration membrane can be performed in the same manner as the pretreatment of the electrolyte solution to be analyzed described above, so a detailed explanation will be omitted here.

In addition, it is preferable to obtain a glue concentrate by treating the electrolyte for preparing the calibration curve using an ultrafiltration membrane, and then to perform a washing process on the glue concentrate. The obtained glue concentrate is derived from the "electrolyte" for preparing the calibration curve, and therefore has the electrolyte attached to it. Therefore, by washing the glue concentrate with a washing solution such as water to replace the electrolyte with the washing solution, the attached electrolyte can be effectively removed. In this way, by washing the obtained glue concentrate, the accuracy of the SEC analysis of the glue concentrate after the washing process can be improved, and a more appropriate calibration curve can be prepared from the SEC analysis results. This allows the analysis of the glue concentration in the electrolyte to be analyzed to be more closely similar to the actual measurement conditions, and the analysis accuracy by the calibration curve method can be improved.

(When performing TOC analysis)
When measuring the glue concentration in the electrolyte to be analyzed by TOC analysis, a calibration curve is prepared in advance by performing a similar TOC measurement on an aqueous solution containing potassium hydrogen phthalate of known concentration.Then, the TOC analysis value (the positive peak area value calculated from the curve obtained from the measurement time and the amount of carbon dioxide detected by the non-dispersive infrared gas detector in the TOC analysis) of the glue concentrated solution obtained by the treatment using the ultrafiltration membrane is compared with the prepared calibration curve, and the TOC derived from the glue contained in the electrolyte is measured based on the calibration curve to calculate the concentration.

In addition to creating a calibration curve using a potassium hydrogen phthalate-containing solution, when measuring glue concentration by TOC analysis, a calibration curve can also be created by performing a TOC analysis using a glue-containing solution of known concentration. As described above, the TOC analysis value for the glue concentrate obtained by processing using an ultrafiltration membrane is compared with the created calibration curve, and the TOC derived from the glue contained in the electrolyte is measured based on the calibration curve to calculate the concentration.

When preparing a calibration curve using a solution containing glue with a known concentration, an electrolyte with a known glue concentration (electrolyte for preparing a calibration curve) can be used as the glue-containing solution. By preparing a calibration curve using an electrolyte for preparing a calibration curve, the glue concentration in the electrolyte to be analyzed can be approximated to the conditions of actual measurement, and the analysis accuracy by the calibration curve method can be improved. In addition, when preparing a calibration curve using an electrolyte for preparing a calibration curve, similar to the treatment of the electrolyte to be analyzed, the electrolyte for preparing the calibration curve is pretreated using an ultrafiltration membrane to concentrate the glue in the electrolyte prior to TOC analysis. This eliminates the influence of low molecular weight substances contained in the electrolyte for preparing the calibration curve, improving the accuracy of the TOC analysis, and the calibration curve prepared based on the analysis results can be made more appropriate. Furthermore, it is preferable to perform a washing process on the electrolyte for preparing the calibration curve after obtaining a concentrated solution of glue by treating the electrolyte for preparing the calibration curve using an ultrafiltration membrane.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
The glue analysis method according to the present invention was applied to measure the concentration of glue contained in the copper electrolyte by size exclusion chromatography (SEC).

(Dilution of electrolyte)
Specifically, first, 15 ml of ultrapure water was added to 15 ml of the electrolyte solution (pH ≦ 0.5) to be analyzed, thereby diluting the electrolyte solution by two times.

(Pretreatment using ultrafiltration membrane)
Next, the diluted electrolyte was divided into two portions ([a] and [b]) of 15 ml each, and 15 ml of the diluted electrolyte [a] was placed in a fixed volume vessel (capacity above the membrane: 17 ml) equipped with an ultrafiltration membrane, and centrifugal separation was performed at a rotation speed of 4000 rpm. Here, the ultrafiltration membrane used was one made of PES (polyethersulfone) with a molecular weight cutoff of 3000 ("Vivaspin Turbo 15", manufactured by Sartorius). The centrifugal separation was performed until the electrolyte above the membrane (above the membrane) was 1.5 ml (below the membrane: 13.5 ml) (the processing time was about 30 minutes).

Next, 15 ml of diluted electrolyte [b] was added to the 1.5 ml of the resulting membrane-above liquid, and the mixture was again placed in a volumetric container equipped with an ultrafiltration membrane and centrifuged at a rotation speed of 4000 rpm. The centrifugation was continued until the electrolyte on the membrane (above membrane liquid) reached 1.5 ml (below membrane liquid was 13.5 ml), resulting in a concentrated liquid (1.5 ml) that was 10 times concentrated as the membrane-above liquid.

(Washing treatment for concentrated solution)
Next, 13.5 ml of ultrapure water was added to 1.5 ml of the obtained concentrated solution, and the solution was placed in a fixed volume container equipped with an ultrafiltration membrane, and a cleaning process was performed by centrifugation at a rotation speed of 4000 rpm. Furthermore, 13.5 ml of ultrapure water was added to 1.5 ml of the membrane liquid obtained by the cleaning process by centrifugation, and the solution was again placed in a fixed volume container equipped with an ultrafiltration membrane, and a cleaning process was performed by centrifugation at a rotation speed of 4000 rpm. As a result, a concentrated solution (1.5 ml) after the cleaning process was obtained as the membrane liquid.

(SEC Analysis)
Next, the resulting concentrate was subjected to SEC analysis.

- Preparation of calibration curve First, aqueous solutions with glue concentrations of 0 mg/L, 1 mg/L, 5 mg/L, and 10 mg/L were prepared, and SEC analysis was performed using a high-performance liquid chromatograph (Tosoh Corporation, HLC-8020) using a size exclusion column. Based on this analysis, an elution curve (see FIG. 2) was obtained from the retention time (unit: min) and the elution amount (unit: mV) measured by a UV transmittance meter, and the peak area (area of the shaded area in FIG. 2) on the positive side of the reference (0 mV) was calculated, plotted on a graph showing the relationship of the area to the glue concentration, and a calibration curve was prepared from the approximation line. Note that FIG. 2 is a graph of an elution curve showing the results of SEC analysis for an electrolyte solution with a glue concentration of 10 mg/L.

Figure 3 is a graph showing a calibration curve obtained by SEC analysis of an aqueous solution with a known glue concentration as described above. Based on this calibration curve, for example, if the peak area of glue detected in the elution curve obtained by SEC analysis of the electrolyte to be analyzed (the area on the positive side of the reference (0 mV)) is about 2500 (white diamond point in Figure 3), the glue concentration of the electrolyte to be analyzed can be determined to be 7 mg/L.

・SEC analysis of concentrated solution (measurement of glue concentration)
Next, the concentrate obtained through the above-mentioned pretreatment was subjected to SEC analysis to measure the glue concentration. Specifically, the SEC analysis was performed using a high-performance liquid chromatograph (HLC-8020, manufactured by Tosoh Corporation) using a size exclusion crumb. Based on this analysis, an elution curve was obtained from the retention time (unit: min) and the elution amount (unit: mV) measured by a UV transmittance meter, and the peak area on the positive side of the reference (0 mV) was calculated.

Specifically, in the chart graph of the elution curve obtained by SEC analysis, a portion that was clearly more positive (+) than the reference (0 mV) was confirmed in the retention time range of 23 to 27 minutes, which corresponds to the molecular weight of glue (the positive side portion indicated by diagonal lines, as in Figure 2). From this, the peak area of the portion on the positive side of the reference was calculated, and the glue concentration could be measured from this peak area based on the prepared calibration curve.

The reason why the positive side of the reference for calculating the peak area was clearly identified in this way is thought to be because pretreatment (centrifugation) using an ultrafiltration membrane was performed prior to SEC analysis, which allowed components other than glue contained in the electrolyte to be separated and removed, concentrating the glue and effectively reducing the background in the SEC analysis.

In addition, in the chart, a sudden negative (-) swing was observed in the retention time range of approximately 27 to 28 minutes, and then a positive swing was observed again in the retention time range of 28 minutes or more. This is presumably due to the influence of components with a molecular weight of ≦3000, which is also seen in the comparative example described below. However, because pretreatment using an ultrafiltration membrane significantly reduced components with a molecular weight of ≦3000, this is thought not to have had a significant effect on the glue concentration measurement.

[Comparative Example 1]
The concentration of glue contained in the copper electrolyte solution was measured by SEC analysis using the same copper electrolyte solution as in Example 1. However, in Comparative Example 1, the SEC analysis was performed without pretreatment using an ultrafiltration membrane, i.e., without concentrating the electrolyte solution.

Figure 4 is a chart graph of the elution curve obtained by SEC analysis in Comparative Example 1.

The chart indicated by the dashed line in Figure 4 is a chart obtained when glue was dissolved in pure water (dissolved at the same concentration as the copper electrolyte to be analyzed) and the solution was analyzed by SEC without pretreatment using an ultrafiltration membrane or concentration. Since no pretreatment was performed, the peak of the measurement results is formed near the retention time of 27 minutes (molecular weight ≒ 3000). Therefore, it can be seen from this chart that the glue, which originally had a molecular weight distribution in the range of tens of thousands to hundreds of thousands, has decomposed and now has a distribution with a peak at a molecular weight of 3000. This is thought to be because there are no other components other than glue, i.e., there is no influence from other components, so the glue was correctly detected.

In contrast, the chart shown by the solid line in Figure 4 is the result of SEC analysis of copper electrolyte that was not pretreated using an ultrafiltration membrane. In the range of retention times from 23 to 27 minutes, there are some areas that show negative values due to the influence of components other than glue contained in the copper electrolyte, and the positive areas are also unclear. This is thought to be because the influence of components other than glue was too great, i.e., the concentration of components other than glue in the copper electrolyte used in the SEC analysis was too high, and these components acted as a background, making it impossible to clearly observe the glue peak.

In addition, in the range of retention times of 27 minutes or more, as seen in the examples, the chart swung significantly to the negative side due to the influence of molecules with a molecular weight of 3000 or the crystallization of copper sulfate components, and at retention times of 28 minutes or more, it swung significantly to the positive side, making it difficult to measure the concentration.

[Example of preparation of a calibration curve using an electrolyte for preparing a calibration curve]
Unlike the example of preparing a calibration curve shown in Example 1, an example of preparing a calibration curve using an electrolyte solution (electrolyte solution for preparing a calibration curve) with a known glue concentration will be shown.

That is, first, electrolyte solutions with glue concentrations of 0 mg/L, 1 mg/L, 5 mg/L, and 10 mg/L were prepared, and 15 mL of the electrolyte solution was placed in a volumetric vessel equipped with an ultrafiltration membrane and centrifuged at a rotation speed of 4000 rpm. The ultrafiltration membrane used was made of PES with a molecular weight cutoff of 3000 ("Vivaspin Turbo 15", manufactured by Sartorius). The centrifugation process was continued until the electrolyte solution on the membrane (above-membrane solution) reached 1.5 mL (below-membrane solution was 13.5 mL).

Next, since the electrolyte was attached to the liquid above the membrane captured by the ultrafiltration membrane, the electrolyte was removed by performing a cleaning process using water as a cleaning solution on the liquid above the membrane (concentrated glue solution).

The glue concentrate obtained after the washing process was then subjected to SEC analysis using a high-performance liquid chromatograph (Tosoh Corporation, HLC-8020) with a size exclusion column.

Based on the SEC analysis, an elution curve (see Figure 5) was obtained from the retention time (unit: min) and the elution amount (unit: mV) measured by a UV transmittance meter. In the elution curve chart, the peak area (area of the shaded area in Figure 5) to the left of the downward peak (peak indicated by "Z" in Figure 5) occurring around retention times of 27 to 28 minutes and on the positive side of the reference (0 mV) was calculated and plotted on a graph showing the relationship of the area to the glue concentration, and a calibration curve was created from the approximation line. Note that Figure 5 is a chart of an elution curve showing the results of SEC analysis of an electrolyte solution with a glue concentration of 10 mg/L.

Comparing the chart in Figure 5 with the chart in Figure 2, which shows the results of the SEC analysis measured to create the calibration curve in Example 1, the phenomenon in which the chart in Figure 2 suddenly swings into the negative region in the range of retention times of 27 minutes or more was not observed in Figure 5. In other words, it can be seen that the method shown in Figure 5 can eliminate and reduce the effects of chart swing. From this, it can be seen that by creating a calibration curve as shown in this test example, a more appropriate calibration curve can be created, and the analytical accuracy of the glue concentration in the electrolyte can be improved.

Figure 6 is a graph showing a calibration curve obtained by SEC analysis of an electrolyte solution with a known glue concentration as described above. Based on this calibration curve, for example, if the peak area of glue detected in the elution curve obtained by SEC analysis of the electrolyte solution being analyzed (similar to Figure 5, the area of the positive peak to the left of the downward peak at retention times around 27 to 28 minutes in the chart) is about 2500 (white diamond point in Figure 6), the glue concentration of the electrolyte solution being analyzed can be determined to be 7 mg/L.

[Example 2]
The glue analysis method according to the present invention was applied to measure the concentration of glue contained in the copper electrolyte by total organic carbon (TOC) analysis.

(Dilution of electrolyte)
Specifically, first, 15 ml of ultrapure water was added to 15 ml of the electrolyte solution (pH ≦ 0.5) to be analyzed, thereby diluting the electrolyte solution by two times.

(Pretreatment using ultrafiltration membrane)
Next, the diluted electrolyte was divided into two portions ([c] and [d]) of 15 ml each, and 15 ml of the diluted electrolyte [c] was placed in a fixed volume vessel (capacity above the membrane: 17 ml) equipped with an ultrafiltration membrane, and centrifugal separation was performed at a rotation speed of 4000 rpm. Here, the ultrafiltration membrane used was one made of PES (polyethersulfone) with a molecular weight cutoff of 3000 ("Vivaspin Turbo 15", manufactured by Sartorius). The centrifugal separation was performed until the electrolyte above the membrane (above the membrane) was 1.5 ml (below the membrane: 13.5 ml) (the processing time was about 30 minutes).

Next, 15 ml of diluted electrolyte [d] was added to the 1.5 ml of the obtained liquid on the membrane, and the mixture was again placed in a volumetric container equipped with an ultrafiltration membrane and centrifuged at a rotation speed of 4000 rpm. The centrifugation was continued until the electrolyte on the membrane (liquid on the membrane) reached 1.5 ml (liquid below the membrane was 13.5 ml), thereby obtaining a concentrated liquid (1.5 ml) that was 10 times concentrated as the liquid on the membrane.

(Washing treatment for concentrated solution)
Next, 13.5 ml of ultrapure water was added to 1.5 ml of the obtained concentrated solution, and the solution was placed in a fixed volume container equipped with an ultrafiltration membrane, and a cleaning process was performed by centrifugation at a rotation speed of 4000 rpm. Furthermore, 13.5 ml of ultrapure water was added to 1.5 ml of the membrane liquid obtained by the cleaning process by centrifugation, and the solution was again placed in a fixed volume container equipped with an ultrafiltration membrane, and a cleaning process was performed by centrifugation at a rotation speed of 4000 rpm. As a result, a concentrated solution (1.5 ml) after the cleaning process was obtained as the membrane liquid.

(TOC analysis)
Next, the resulting concentrated liquid was subjected to TOC analysis.

Preparation of calibration curve First, aqueous solutions of potassium hydrogen phthalate with concentrations of 0 mg/L, 2.125 mg/L, 10.625 mg/L, 21.25 mg/L, 42.5 mg/L, and 106.25 mg/L (equivalent to 0 mg/L, 1 mg/L, 5 mg/L, 10 mg/L, 20 mg/L, and 50 mg/L in TOC) were prepared, and TOC analysis was performed using a total organic carbon meter (TOC-V CPH, manufactured by Shimadzu Corporation). Based on this analysis, the measurement time (unit: min) and the amount of carbon dioxide detected (unit: mV) measured using a non-dispersive infrared gas detector were plotted on a graph showing the relationship between the area and TOC, and a calibration curve was prepared from the approximation line.

Figure 7 is a graph showing a calibration curve obtained by TOC analysis of an aqueous solution with a known potassium hydrogen phthalate concentration as described above. Based on this calibration curve, for example, if the amount of carbon dioxide detected from glue by TOC analysis in the electrolyte being analyzed is about 50 (the open diamond point in Figure 7), the TOC derived from glue in the electrolyte being analyzed can be determined to be 3.6 mg/L.

- TOC analysis of concentrated liquid (measurement of glue concentration)
Next, the TOC analysis was performed on the concentrated solution obtained through the above-mentioned pretreatment to measure the glue concentration. Specifically, the TOC analysis was performed using a total organic carbon meter (TOC-V CPH, manufactured by Shimadzu Corporation). Based on this analysis, the peak area value on the positive side of the standard (0 mV) for the carbon dioxide detection amount was calculated from the measurement time (unit: min) and the carbon dioxide detection amount (unit: mV) measured by a non-dispersive infrared gas detector. Note that FIG. 8 is a graph showing the results of the TOC analysis of the electrolyte in Example 2.

As a result, the TOC analysis value in the electrolyte was 3.5 mg/L. This analysis result does not include organic carbon derived from other additives such as thiourea and abiton contained in the copper electrolyte; in other words, the organic carbon derived from the glue alone was detected, without any organic carbon derived from other additives.

[Comparative Example 2]
The copper electrolyte solution in Example 2 was used as the analysis target, and the concentration of glue contained in the copper electrolyte solution was measured by TOC analysis. However, in Comparative Example 2, pretreatment using an ultrafiltration membrane was not performed, that is, the electrolyte solution was not concentrated, and the solution was diluted 10 times with pure water and subjected to TOC analysis. FIG. 9 is a graph showing the results of the TOC analysis of the electrolyte solution in Comparative Example 2.

As a result, the TOC analysis value in the electrolyte was 270 mg/L. In the analysis of Comparative Example 2, organic carbon derived from other additives, such as thiourea and abiton, contained in the copper electrolyte was also detected, making it difficult to detect only organic carbon derived from the glue.

Claims (9)

1. A method for analyzing the concentration of glue in an electrolyte solution by size exclusion chromatography (SEC), comprising:
Prior to the SEC analysis, the electrolyte is treated with an ultrafiltration membrane to concentrate the glue in the electrolyte;
The glue concentrate obtained by the treatment using the ultrafiltration membrane is further subjected to a washing treatment.
Method for analyzing glue in electrolyte. A method for analyzing the concentration of glue contained in an electrolyte solution based on total organic carbon (TOC), comprising the steps of:
Prior to the TOC analysis, the electrolyte is treated with an ultrafiltration membrane to concentrate the glue in the electrolyte;
The glue concentrate obtained by the treatment using the ultrafiltration membrane is further subjected to a washing treatment.
Method for analyzing glue in electrolyte. The pH of the electrolyte is 0.5 or less.
A method for analyzing glue in an electrolyte solution according to claim 1 or 2. The electrolyte is centrifuged using a volumetric container equipped with the ultrafiltration membrane.
A method for analyzing glue in an electrolyte solution according to any one of claims 1 to 3. A calibration curve was created by performing SEC analysis using an aqueous solution with a known glue concentration.
The concentration of glue contained in the electrolyte is measured based on the analytical value by the SEC for the concentrated glue solution obtained by the treatment using the ultrafiltration membrane, based on the calibration curve.
A method for analyzing glue in an electrolyte according to claim 1. The aqueous solution having a known glue concentration is an electrolyte solution for preparing a calibration curve having a known glue concentration,
When preparing the calibration curve,
The electrolyte solution for preparing the calibration curve is subjected to a process using an ultrafiltration membrane to concentrate the glue in the electrolyte solution, and the resulting concentrated solution of glue is subjected to a washing process;
A calibration curve is prepared by performing an SEC analysis using the concentrated solution after the washing treatment.
The method for analyzing glue in an electrolyte according to claim 5 . A calibration curve was created by performing TOC analysis using an aqueous solution of potassium hydrogen phthalate with a known concentration.
The concentration of glue contained in the electrolyte is measured based on the TOC analysis value of the glue concentrate obtained by the treatment using the ultrafiltration membrane and the calibration curve.
The method for analyzing glue in an electrolyte according to claim 2. A calibration curve was created by performing TOC analysis using an aqueous solution with a known glue concentration.
The concentration of glue contained in the electrolyte is measured based on the TOC analysis value of the glue concentrate obtained by the treatment using the ultrafiltration membrane and the calibration curve.
The method for analyzing glue in an electrolyte according to claim 2. The aqueous solution having a known glue concentration is an electrolyte solution for preparing a calibration curve having a known glue concentration,
When preparing the calibration curve,
The electrolyte solution for preparing the calibration curve is subjected to a process using an ultrafiltration membrane to concentrate the glue in the electrolyte solution, and the resulting concentrated solution of glue is subjected to a washing process;
A calibration curve is prepared by performing TOC analysis using the concentrated liquid after the washing treatment.
The method for analyzing glue in an electrolyte according to claim 8 .

Images