Recovery method, analysis method, and recovery device for metal impurities

Abstract

To recover metal impurities in an organic solvent safely and easily while reducing the occurrence of contamination.SOLUTION: Disclosed is a recovery method for metal impurities for recovering metal impurities from an organic solvent, the recovery method including: a step for preparing a diluent by diluting an organic solvent with water; and a step for passing the prepared diluent as a sample liquid through an adsorbent 12 so as to capture metal impurities in the sample liquid on the adsorbent 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recovering and analyzing metal impurities, and a recovery device. [Background technology]

[0002] Highly purified organic solvents are used in the manufacturing process of electronic devices such as semiconductors. Metal impurities contained in organic solvents, even in trace amounts, can have a significant effect on the characteristics of the device, so their concentration must be strictly controlled. For this reason, there is a demand for highly accurate analysis of trace amounts of metal impurities in organic solvents.

[0003] As a method for analyzing metal impurities in an organic solvent, a method is generally known in which a sample liquid sampled in a bottle is directly introduced into an analyzer such as an inductively coupled plasma mass spectrometer (ICP-MS) for analysis. On the other hand, when it is required to perform high-precision analysis even when the metal impurity concentration in the organic solvent is so low that it is below the detection limit of the analyzer, there is also a method in which the sample liquid sampled in a bottle is heated and concentrated, and the metal impurities in the concentrated sample liquid are analyzed (for example, see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-141721 A [Patent Document 2] JP 2002-5799 A [Patent Document 3] International Publication No. 2020 / 071481 Summary of the Invention [Problem to be solved by the invention]

[0005] However, sampling of sample liquid into bottles not only entails the risk of contamination depending on the working environment and the proficiency of the worker, but also raises safety concerns for the worker and the surrounding environment due to leakage. In addition, if the sampling location is far from the location of the subsequent process (heat concentration, analysis, etc.), the bottle needs to be transported, but if the sample liquid is an organic solvent, there may be restrictions on the transportation. In addition, in the method of concentrating the sample liquid by heating, there is a limit to the concentration rate by heating, and a large amount of sample liquid needs to be sampled to obtain sufficient sensitivity. In addition, the heat concentration of the sample liquid is performed in an open environment, so in this case too, the risk of contamination is high.

[0006] Therefore, an object of the present invention is to recover metal impurities in an organic solvent safely and simply while suppressing the occurrence of contamination. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the method for recovering metal impurities of the present invention is a method for recovering metal impurities in an organic solvent, and includes the steps of: diluting the organic solvent with ultrapure water to prepare a diluted solution; and passing the prepared diluted solution as a sample solution through an adsorbent to capture the metal impurities in the sample solution in the adsorbent.

[0008] In addition, the method for analyzing metal impurities of the present invention includes a step of quantifying the metal impurities recovered by the above-mentioned method for recovering metal impurities, and a step of calculating the concentration of the metal impurities in the organic solvent based on the quantification result and the dilution ratio of the dilution solution.

[0009] In addition, the metal impurity recovery device of the present invention is a metal impurity recovery device that recovers metal impurities in an organic solvent, and has an adsorbent that captures the metal impurities in the organic solvent, and a sample liquid passing means that dilutes the organic solvent with ultrapure water to prepare a diluted liquid, and passes the prepared diluted liquid through the adsorbent as a sample liquid.

[0010] According to such a metal impurity recovery method, analysis method, and recovery device, sampling of the sample liquid into a bottle becomes unnecessary, and the occurrence of various problems associated with the sampling can be suppressed. In addition, when preparing the dilution liquid, it becomes possible to reduce the concentration of the organic solvent to a safe concentration (for example, a concentration that is not a hazardous material under the Fire Service Act, or a concentration that does not affect the human body or the environment even if the liquid leaks to the outside). Therefore, in addition to eliminating concerns about leakage, it is possible to increase reliability in terms of safety. Effect of the Invention

[0011] As described above, according to the present invention, metal impurities in an organic solvent can be recovered safely and simply while suppressing the occurrence of contamination. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of an impurity recovery device according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a schematic configuration diagram of an impurity recovery device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Configurations common to the following embodiments are denoted by the same reference numerals in the drawings, and duplicated descriptions are omitted as appropriate. In this specification, a dilution liquid of the present invention is exemplified by diluting an organic solvent with ultrapure water, but the present invention is not limited thereto, and water having a lower purity than ultrapure water may be used as a dilution medium. In addition, in this specification, a method of preparing a dilution liquid is exemplified by adding ultrapure water to an organic solvent, but the present invention is not limited thereto, and an organic solvent may be added to ultrapure water.

[0014] (First embodiment) 1 is a schematic diagram of an impurity recovery device according to a first embodiment of the present invention. Note that the configuration of the impurity recovery device shown in the figure is merely an example, and it goes without saying that it can be modified as necessary, for example, by adding valves or measuring instruments.

[0015] The impurity recovery device 10 collects metal impurities in an organic solvent supplied through the raw solution supply line L1. The organic solvent to be collected is not particularly limited, but examples thereof include various organic solvents such as alcohols (isopropyl alcohol, methanol, ethanol, etc.), ketones (cyclohexanone, methyl isobutyl ketone, acetone, methyl ethyl ketone, etc.), alkenes (2,4-diphenyl-4-methyl-1-pentene, 2-phenyl-1-propene, etc.), esters (propylene glycol monomethyl ether acetate, isopropyl acetate, etc.), aromatics, and amines (N-methylpyrrolidone, etc.), as well as mixtures thereof.

[0016] The impurity recovery device 10 has a sampling line L11 and an impurity collection kit 11 removably attached to the sampling line L11. The sampling line L11 is connected to the raw liquid supply line L1 via an on-off valve V1. The impurity collection kit 11 has a concentration column 12 and an integrating flow meter 13. The concentration column 12 captures and concentrates metal impurities in the sample liquid supplied through the sampling line L11, and is composed of a resin container and an ion exchanger (adsorbent) filled in the container. The integrating flow meter 13 has a function of measuring the total amount of sample liquid passing through the concentration column 12. The impurity collection kit 11 may be provided with a sealing means for sealing the inside so as to prevent contamination when removed from the sampling line L11 and to reduce the risk of leakage. The impurity collection kit 11 may also be provided with an exhaust means such as a duct or an introduction means for introducing an inert gas or the like so as to prevent the inside from becoming an organic solvent vapor atmosphere.

[0017] Examples of the ion exchanger packed in the concentration column 12 include ion exchange resins, ion adsorption membranes (porous membranes having ion exchange ability), and monolithic organic porous ion exchangers. Among these, the monolithic organic porous ion exchanger is preferably used. The monolithic organic porous ion exchanger is a monolithic organic porous body, that is, a porous body having a large number of communicating holes between the skeletons formed by organic polymers, in which ion exchange groups are introduced into the skeleton of the porous body that serves as a flow path for the reaction solution. The monolithic organic porous ion exchanger allows liquid to pass at a high spatial velocity compared to general granular ion exchange resins, and the required time can be significantly reduced. In addition, the captured metal impurities are easily eluted into the eluent for quantitative analysis, and the amount of eluent used can be reduced, so the amount of sample liquid passed can also be reduced. Furthermore, the eluent recovered after passing through the monolithic organic porous ion exchanger is in an acid-added state, so that the eluted metal impurities do not adhere to a recovery container such as a bottle, and therefore it is excellent in storage (keeping). In this respect, the monolithic organic porous ion exchanger is also advantageous. As the monolithic organic porous ion exchanger, at least one of a monolithic organic porous cation exchanger and a monolithic organic porous anion exchanger can be used depending on the type of metal element to be captured. Specific examples of the monolithic organic porous ion exchanger will be described later.

[0018] Although details will be described later, in this embodiment, the organic solvent stock solution (hereinafter also simply referred to as "stock solution") itself flowing through the stock solution supply line L1 is not used, but rather a diluted solution obtained by diluting the organic solvent stock solution with ultrapure water is supplied to the concentration column 12 as the sample solution and passed through the concentration column 12. As a configuration for this purpose (sample solution passing means), the impurity recovery device 10 has an ultrapure water addition line L21 in addition to the above-mentioned sampling line L11. The ultrapure water addition line L21 connects the ultrapure water supply line L2, which circulates ultrapure water, and the sampling line L11, and is provided to prepare a diluted solution by adding ultrapure water to the stock solution flowing through the sampling line L11. An opening / closing valve V2 is provided downstream of the ultrapure water addition line L21.

[0019] The impurity recovery device 10 also has an agitation means 14 and a diluent flowmeter 15 provided in the sampling line L11, and an ultrapure water flowmeter 21 and a purification means 22 provided in the ultrapure water addition line L21. The agitation means 14 has a function of mixing the ultrapure water added to the sampling line L11 with the stock solution. The agitation means 14 is not particularly limited, but is preferably one that does not require electrical equipment because of the risk of the organic solvent igniting, and for example, a static mixer or a long tube is used. The agitation means 14 does not necessarily have to be provided. The diluent flowmeter 15 and the ultrapure water flowmeter 21 are used to calculate the dilution ratio of the diluent, and have the function of measuring the flow rate of the diluent flowing through the sampling line L11 and the flow rate of the ultrapure water flowing through the ultrapure water addition line L21, respectively. The purification means 22 has a function of removing metal impurities from the ultrapure water to be added. For example, an ion exchanger similar to that filled in the concentration column 12 can be used as the purification means 22. Depending on the purity of the ultrapure water to be added, the purification means 22 may not necessarily be provided. Also, a check valve may be provided between the ultrapure water flowmeter 21 and the purification means 22 in the ultrapure water adding line L21.

[0020] In this embodiment, the integrating flowmeter 13 is used to measure the total amount of sample liquid passing through the concentration column 12, but the method of measuring the total amount of sample liquid passing through the concentration column 12 is not limited to this. For example, instead of the integrating flowmeter 13, a diluent flowmeter 15 may be used, and its measured value may be integrated by a separately provided computing device. If the flow rate of the diluent is constant, the total amount of sample liquid passing through the concentration column 12 can be calculated from the flow rate and the time the sample liquid passes through the concentration column 12. Therefore, instead of the integrating flowmeter 13, a flowmeter (e.g., a float type flowmeter) that does not require an electrical device may be provided. Alternatively, the total amount of sample liquid passing through the concentration column 12 can be calculated from the total amount of stock solution flowing into the sampling line L11 and the total amount of ultrapure water added thereto. Therefore, a flow meter for measuring the flow rate of the raw liquid flowing into the sampling line L11 may be installed upstream of the connection between the sampling line L11 and the ultrapure water addition line L21, and the measurement value of this flow meter and the measurement value of the ultrapure water flow meter 21 may be integrated by a separately provided calculation device.

[0021] Here, a method for recovering metal impurities in an organic solvent using the above-mentioned impurity recovery apparatus 10 and a method for analyzing the thus recovered metal impurities will be described. Note that the metal impurities referred to here include not only those in the form of ions or particles, but also those present in the form of compounds or complexes.

[0022] First, the organic solvent stock solution is diluted with ultrapure water to prepare a diluted solution. Specifically, the on-off valve V1 of the sampling line L11 is opened, a part of the stock solution flowing through the stock solution supply line L1 is supplied to the sampling line L11, and the on-off valve V2 of the ultrapure water addition line L21 is opened. As a result, a part of the ultrapure water flowing through the ultrapure water supply line L2 flows into the ultrapure water addition line L21, and after metal impurities such as metal ions are removed by the purification means 22, it is added to the stock solution flowing through the sampling line L11. Then, the stock solution and the ultrapure water are mixed by the stirring means 14, and a diluted solution of the organic solvent is prepared. At this time, the opening degree of at least one of the on-off valves V1 and V2 is adjusted as necessary to adjust at least one of the flow rate of the stock solution flowing into the sampling line L11 and the flow rate of the ultrapure water flowing into the ultrapure water addition line L21, thereby adjusting the dilution ratio of the diluted solution. The dilution ratio of the diluent can be calculated from the measurement value of the diluent flowmeter 15 (preferably, its moving average value) and the measurement value of the ultrapure water flowmeter 21 (preferably, its moving average value).

[0023] The diluted solution thus prepared is passed through the concentration column 12 as a sample solution, and metal impurities in the sample solution are captured and concentrated by the ion exchanger in the concentration column 12. The passing speed at this time is not particularly limited, but is preferably 2000 h at spatial velocity (SV). -1 It is preferable that the temperature is less than 1000h. -1 It is more preferable that the temperature is less than 200 h. -1 It is particularly preferable that the linear velocity (LV) is 1000 m / h or less, and more preferably 500 m / h or less. The liquid passing time (concentration time) at this time depends on the type of ion exchanger packed in the concentration column 12 and the above-mentioned liquid passing speed, but is not particularly limited as long as the metal impurities to be analyzed are concentrated to a degree that allows them to be quantified with sufficient accuracy. In order to calculate the content of the metal impurities in the sample liquid from the results of the quantitative analysis described later, the total amount of the sample liquid passed through the concentration column 12 is required, and the total amount of the sample liquid passed through the concentration column 12 is measured by the integrating flow meter 13.

[0024] After that, when a predetermined liquid passing time has elapsed, the on-off valve V1 of the sampling line L11 and the on-off valve V2 of the ultrapure water addition line L21 are closed (preferably in this order) to stop the passage of the sample liquid into the concentration column 12. Then, the impurity collection kit 11 is removed from the sampling line L11, preferably with the inside sealed to prevent contamination from the outside. At this time, water (ultrapure water) may be supplied from the ultrapure water addition line L21 through the sampling line L11, and the inside may be replaced with the water before the impurity collection kit 11 is removed.

[0025] Next, a replacement fluid is passed through the concentration column 12 of the removed impurity collection kit 11, and the sample liquid remaining in the concentration column 12, particularly in the ion exchanger, is replaced with the replacement fluid. This makes it possible to prevent the eluent (aqueous solution containing an acid) used in the elution process described below from coming into contact with an organic solvent, thereby ensuring safety. This replacement process may be performed at the site where the impurity collection device 10 is installed, or at a location away from the site.

[0026] As the replacement fluid, at least one of water and gas is used. The water used here is preferably as pure as possible, that is, the water with the metal impurity concentration reduced as much as possible is preferable. Specifically, the metal impurity concentration is preferably reduced to less than 10 ng / L, more preferably less than 1 ng / L, and particularly preferably less than 0.1 ng / L. The gas used here is preferably a high-purity gas with a purity of 99.9% or more, more preferably 99.99% or more. The type of high-purity gas is not particularly limited, and for example, an inert gas (nitrogen, argon, helium, etc.) or oxygen can be used. Note that air can also be used as the high-purity gas if the metal impurities are sufficiently removed.

[0027] During the passage of the sample liquid, the amount of metal impurities captured by the ion exchanger gradually decreases along the direction of the passage of the liquid. Therefore, it is preferable that the direction of the replacement fluid is the same as the direction of the passage of the sample liquid. This allows metal impurities captured by the ion exchanger to be recaptured downstream even after they are desorbed, and prevents them from being discharged from the concentration column 12. When ultrapure water is used as the replacement fluid, its flow rate is not particularly limited, but is preferably at least 20,000 h SV. -1 It is preferable that the temperature is 100 to 4000 h or less. -1 It is more preferable that the LV is 1000 m / h or less, and more preferably 1 to 80 m / h. The time for which the replacement fluid is passed depends on the type and flow rate of the ion exchanger packed in the concentration column 12, but is not particularly limited as long as the sample liquid remaining in the ion exchanger can be replaced with the replacement fluid.

[0028] Next, an eluent is passed through the concentration column 12, and the metal impurities captured by the ion exchanger in the concentration column 12 are eluted into the eluent and recovered. This elution process may be performed on-site where the impurity recovery device 10 is installed, or may be performed at a location away from the site.

[0029] The eluent used here is an aqueous solution containing an acid. The acid contained in the eluent may be either an inorganic acid or an organic acid, and examples of inorganic acids include nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid. Among these, nitric acid, sulfuric acid, and hydrochloric acid are preferred because they facilitate the elution of ionic metal impurities and can be prepared with high purity. The acid concentration in the eluent is not particularly limited, but is preferably 0.1 to 3.0N. In addition, the eluent is preferably one in which the concentration of each metal impurity is 100ng / L or less, more specifically, nitric acid or hydrochloric acid in which the concentration of each metal impurity is 100ng / L or less is more preferred, and nitric acid or hydrochloric acid in which the concentration of each metal impurity is 10ng / L or less is particularly preferred.

[0030] The amount of eluent passed through is not particularly limited as long as the concentration of metal impurities in the recovered eluent is higher than the detection limit of an analysis device described later, but as described later, it is preferable that it is as small as possible. Note that the amount of eluent passed through (amount of recovered liquid) is necessary to calculate the content of metal impurities in the sample liquid, similar to the total amount of sample liquid passed through the concentration column 12. For this purpose, for example, a method using a recovery container with a measuring function or a method of passing the entire amount of eluent measured in advance is used.

[0031] Thereafter, the metal impurities in the collected eluent are quantified, and the metal impurity concentration in the sample liquid is calculated from the obtained metal concentration. Then, the metal impurity concentration in the raw solution is calculated based on the calculated metal impurity concentration and the dilution ratio of the diluted solution. This quantitative analysis may be performed at the site where the impurity collection device 10 is installed, or at a location away from the site. The quantitative analysis may also be performed at a location different from the above-mentioned replacement process and elution process.

[0032] For the quantitative determination of metal impurities, for example, an inductively coupled plasma mass spectrometer (ICP-MS), an inductively coupled plasma atomic emission spectrometer (ICP-AES), an atomic absorption spectrometer, an ion chromatograph analyzer, etc. can be used. The type of metal impurity element to be analyzed here is not particularly limited, and for example, at least one of Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Sr, Mo, Ag, Cd, In, Sn, Sb, Ba, W, Au, Pt, and Pb can be analyzed. The metal impurity concentration in the sample liquid can be calculated as a value obtained by dividing the obtained metal concentration by the concentration factor of the eluent (the value obtained by dividing the total amount of the sample liquid passed by the amount of the eluent recovered), and the metal impurity concentration in the original solution can be calculated as a value obtained by dividing the obtained metal concentration by the dilution factor of the dilution liquid.

[0033] According to the above-mentioned calculation method, even if the metal impurity concentration in the stock solution is so low as to be below the detection limit of the analysis device, the metal impurity concentration in the stock solution can be obtained by increasing the concentration ratio of the eluent until the metal impurity concentration in the eluent is equal to or higher than the detection limit. Therefore, it is preferable that the concentration ratio of the eluent is as high as possible, and therefore, if the total amount of sample liquid passed is the same, it is preferable that the amount of recovered eluent is as small as possible. In other words, if metal impurities can be recovered with a smaller amount of eluent, it is possible to measure (evaluate) even lower concentrations of metal impurities in the stock solution without increasing the total amount of sample liquid passed. From this viewpoint, it is preferable that the direction of passage of the eluent to the concentration column 12 is opposite to the direction of passage of the sample liquid. In other words, as described above, the amount of metal impurities captured in the ion exchanger gradually decreases along the direction of passage of the sample liquid, but by passing the eluent in the opposite direction, it is possible to recover such metal impurities with a smaller amount of eluent.

[0034] Thus, according to the present embodiment, in order to concentrate and collect the metal impurities in the target organic solvent, a method is used in which the organic solvent is diluted with water (ultrapure water) to prepare a diluted solution, and the diluted solution is passed through the concentration column 12 as a sample liquid. Therefore, sampling of the sample liquid in a bottle is not required, and the work for concentrating the metal impurities is not performed in an open environment. As a result, the risk of contamination can be reduced and the concentration efficiency can be increased compared to the method of concentrating the sample liquid by heating. In addition, the ion exchanger packed in the concentration column 12 generally has a faster ion exchange rate when in contact with water than when in contact with an organic solvent. Therefore, the passing speed of the sample liquid through the concentration column 12 can be increased, and the passing time at that time, i.e., the time required for concentrating the metal impurities, can be shortened.

[0035] In addition, when preparing the diluted solution, it is possible to reduce the concentration of the organic solvent to a safe concentration (for example, a concentration that is not a hazardous material under the Fire Service Act, or a concentration that does not affect the human body or the environment even if the diluted solution leaks to the outside). Therefore, there is no concern about leakage due to sampling into a bottle, and it is possible to safely recover metal impurities in the target organic solvent. In addition, since the diluted solution prepared in this way is used as the sample liquid, if the organic solvent is flammable, it is necessary to install the raw solution supply line L1 in the dangerous place A, while it is possible to install the impurity collection kit 11 including the concentration column 12 in the non-hazardous place B. That is, it is no longer necessary to install the integrating flowmeter 13 of the impurity collection kit 11 in the dangerous place A, and it is no longer necessary to install the diluted solution flowmeter 15 in the dangerous place A. Therefore, it is no longer necessary to use expensive flowmeters 13 and 15 that correspond to explosion-proof specifications, and this does not lead to an increase in the cost of the impurity collection device 10. The hazardous location referred to here is a location where an explosive atmosphere is present or may be present due to the leakage of flammable gas or vapor of a flammable liquid into the atmosphere, and where the use of equipment conforming to a specified explosion-proof standard is mandatory. The concentration of the organic solvent in the dilution liquid is not particularly limited, but is preferably less than the concentration (predetermined value) that is subject to the regulation of the law on hazardous materials. For example, in the case of a saturated monohydric alcohol with 1 to 3 carbon atoms, it is less than 60% by weight, which is classified as a non-hazardous material under the Fire Service Act.

[0036] Furthermore, according to this embodiment, another problem that occurs when an organic solvent stock solution itself is passed through an ion exchanger, particularly a monolithic organic porous ion exchanger, can be avoided. That is, when an organic solvent is passed through a monolithic organic porous ion exchanger in a water-wet state, the monolithic organic porous ion exchanger shrinks (or swells), while when water is passed through a monolithic organic porous ion exchanger wetted with an organic solvent, the monolithic organic porous ion exchanger may swell (or shrink). Due to this property, when a monolithic organic porous ion exchanger in a water-wet state is filled in a concentration column and an organic solvent is passed through as a sample liquid, a gap may be generated between the concentration column and the monolithic organic porous ion exchanger. As a result, sufficient contact with the organic solvent may be hindered, and the capture performance of the monolithic organic porous ion exchanger for metal impurities may be reduced. In addition, the monolithic organic porous ion exchanger may deteriorate due to repeated swelling and shrinkage caused by repeated use. In contrast, in this embodiment, a diluted solution obtained by diluting the organic solvent with ultrapure water is used as the sample liquid, rather than the organic solvent stock solution itself. Therefore, the shrinkage of the monolithic organic porous ion exchanger is suppressed, and the occurrence of the above-mentioned problems can be minimized.

[0037] In the illustrated embodiment, the impurity collection kit 11 including the concentration column 12 and the integrating flow meter 13 is removably attached to the sampling line L11, but only the concentration column 12 may be removably attached to the sampling line L11. That is, after passing the sample liquid, only the concentration column 12 may be removed from the sampling line L11 (optionally after replacing the inside with water) and the remaining sample liquid may be replaced with a replacement fluid.

[0038] Here, two types of monolithic organic porous ion exchangers will be described as specific examples of monolithic organic porous ion exchangers that are preferably used as an adsorbent packed in the concentration column 12. One is a first monolithic organic porous ion exchanger described in paragraphs

[0019] to

[0028] of JP 2010-234357 A, and the other is a second monolithic organic porous ion exchanger described in paragraphs

[0052] to

[0061] of the same publication. Hereinafter, the monolithic organic porous ion exchanger will be simply referred to as a "monolith ion exchanger", and the monolithic organic porous material will also be simply referred to as a "monolith". In addition, a monolithic organic porous intermediate, which is an intermediate (precursor) in the production of a monolith, will also be simply referred to as a "monolith intermediate".

[0039] The first monolith ion exchanger is obtained by introducing ion exchange groups into a monolith, and has a continuous macropore structure in which bubble-like macropores overlap each other, and these overlapping parts form openings (mesopores) with an average diameter of 30 to 300 μm, preferably 30 to 200 μm, and particularly preferably 35 to 150 μm, in a water-wet state.

[0040] The method for producing the first monolith ion exchanger is composed of the following four steps, as described in paragraphs

[0029] to

[0051] of JP 2010-234357 A. (1) First, a mixture of an oil-soluble monomer not containing an ion exchange group, a surfactant, and water is stirred to prepare a water-in-oil emulsion. Then, the water-in-oil emulsion is polymerized to obtain a first monolith intermediate having a continuous macropore structure with a total pore volume of 5 to 16 ml / g. (2) A mixture is prepared that includes a vinyl monomer, a crosslinking agent having at least two vinyl groups in one molecule, an organic solvent that dissolves the vinyl monomer and the crosslinking agent but does not dissolve the polymer produced by polymerization of the vinyl monomer, and a polymerization initiator. (3) This mixture is left to stand and polymerized in the presence of the first monolith intermediate obtained in (1) above to obtain a first monolith having a thicker skeleton than the first monolith intermediate. (4) Thereafter, an ion exchange group is introduced into the first monolith thus obtained to produce a first monolith ion exchanger.

[0041] On the other hand, the second monolith ion exchanger is a bicontinuous structure consisting of a three-dimensionally continuous skeleton having a thickness of 1 to 60 μm and three-dimensionally continuous pores having a diameter of 10 to 100 μm between the skeletons, the skeleton being made of an aromatic vinyl polymer containing 0.3 to 5.0 mol % of crosslinked structural units among all structural units having ion exchange groups introduced therein. The second monolith ion exchanger has a total pore volume of 0.5 to 5 ml / g, an ion exchange capacity per volume in a water-wet state of 0.3 to 5 mg equivalent / ml, and ion exchange groups are uniformly distributed in the porous ion exchanger.

[0042] The second monolith ion exchanger is manufactured through the following four steps as described in paragraphs

[0062] to

[0083] of JP 2010-234357 A. First, a mixture of an oil-soluble monomer not containing an ion exchange group, a surfactant, and water is stirred to prepare a water-in-oil emulsion. Then, the water-in-oil emulsion is polymerized to obtain a second monolith intermediate having a continuous macropore structure with a total pore volume of more than 16 ml / g and less than 30 ml / g. (2) A mixture is prepared consisting of an aromatic vinyl monomer, a crosslinker having at least two or more vinyl groups in one molecule and 0.3 to 5 mol % relative to the total oil-soluble monomer, an organic solvent that dissolves the aromatic vinyl monomer and the crosslinker but does not dissolve the polymer produced by polymerization of the aromatic vinyl monomer, and a polymerization initiator. (3) This mixture is left to stand and polymerized in the presence of the second monolith intermediate obtained in (1) above to obtain a second monolith having a bicontinuous structure. (4) Thereafter, ion exchange groups are introduced into the second monolith thus obtained to produce a second monolith ion exchanger.

[0043] Second Embodiment 2 is a schematic diagram of an impurity recovery device according to a second embodiment of the present invention. This embodiment differs from the first embodiment in that the replacement process and the elution process are performed at the site where the impurity recovery device is installed. The following mainly describes such differences. Note that the various modified examples described in the first embodiment are also applicable to this embodiment, and therefore overlapping descriptions will be omitted.

[0044] In this embodiment, the concentration column 12 is configured to be able to be supplied with a replacement fluid and an eluent. Specifically, a replacement fluid line L12 and an eluent line L13 are connected to the concentration column 12. The replacement fluid line L12 functions as a replacement fluid supplying means for supplying a replacement fluid to the concentration column 12 in order to replace the sample liquid remaining in the concentration column 12, particularly in the ion exchanger, with the replacement fluid. The eluent line L13 functions as an eluent supplying means for supplying an eluent to the concentration column 12 in order to elute metal impurities captured by the ion exchanger in the concentration column 12 into the eluent and recover them. Accordingly, the concentration column 12 and the integrating flow meter 13 do not need to be removable from the sampling line L11. Note that the eluent line L13 is provided with an integrating flow meter (not shown) or an instantaneous flow meter and a calculation device (neither of which are shown) for integrating the measured value of the instantaneous flow meter in order to measure the amount of eluent passing through (amount of recovered liquid). Alternatively, similarly to the elution process of the first embodiment, a recovery container with a measuring function may be provided downstream of the eluent line L13, and the entire amount of the eluent measured in advance may be passed through.

[0045] Thus, in this embodiment, the process from passing the sample liquid through the concentration column 12 to recovering the eluent can be continuously performed online at the site where the impurity recovery device 10 is installed. Therefore, this embodiment is advantageous over the first embodiment in that at least the replacement process is performed at the site where the impurity recovery device 10 is installed, and therefore it is not necessary to transport the concentration column 12 in which the sample liquid containing the organic solvent remains inside. In addition, a quantitative analysis device such as ICP-MS may be connected downstream of the eluent line L13, and thus the quantification of the metal impurities in the eluent may also be performed online. Furthermore, such a series of processes may be automated by a control means such as a controller, and in this case, the control means may perform calculations of the metal impurity concentration in the raw liquid based on the measurement results of the flow meters 13, 15, and 21 and the analysis results of the quantitative analysis device.

[0046] The replacement fluid line L12 may be omitted in a portion downstream of the concentration column 12 so that only the replacement fluid is supplied to the concentration column 12. Similarly, the eluent line L13 may be omitted in a portion downstream of the concentration column 12 so that only the eluent is supplied to the concentration column 12. Alternatively, the replacement fluid line L12 and the eluent line L13 may each be connected to the sampling line L11 upstream of the concentration column 12. On the other hand, the ultrapure water of the replacement fluid may be supplied from the ultrapure water addition line L21. In either case, the replacement fluid and the eluent can be discharged through the sampling line L11. Also, the eluent line L13 may be omitted, so that only the replacement process is performed at the site where the impurity recovery device 10 is installed, and the elution process is performed at a location away from the site.

[0047] (Example) Next, the effects of the present invention will be described with reference to specific examples.

[0048] In this example, a test device simulating the impurity recovery device shown in FIG. 2 was used to recover and analyze metal impurities in an organic solvent, and the recovery rate of each metal element was calculated.

[0049] Specifically, first, the dilution liquid obtained by diluting the stock solution of the organic solvent with ultrapure water was passed through a concentration column as a sample solution, and the metal elements contained in the sample solution were captured and concentrated by the ion exchanger in the concentration column. A monolithic organic porous cation exchanger was used as the ion exchanger packed in the concentration column. As the stock solution of the organic solvent, isopropyl alcohol (IPA) adjusted so that the concentrations of the metal elements Li, Na, Mg, Al, K, Ca, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr, Ag, Cd, In, Ba, and Pb were 100 ng / L, respectively, was used, and it was diluted two-fold with ultrapure water. That is, the opening degree of each opening and closing valve was adjusted so that the measured values ​​of the dilution liquid flow meter and the ultrapure water flow meter were 10 mL / min and 5 mL / min, respectively. Then, the dilution liquid was passed through the concentration column for 150 h. -1A 600 mL volume of the liquid was passed through the tube at an SV of 100° C. A long tube was used as the stirring means, but the test apparatus in this example was not provided with a purification means.

[0050] Next, the concentration column was filled with ultrapure water as a replacement fluid for 150 h. -1 After passing 50 mL of water through the SV, high-purity nitrogen gas was supplied at a flow rate of 4 L / min to replace the sample liquid remaining in the concentration column with the replacement fluid. Note that the replacement fluid was supplied to the concentration column through the sampling line in all cases.

[0051] Next, the eluent was passed through the concentration column through the sampling line, and the metal elements in the sample solution captured by the ion exchanger in the concentration column were eluted into the eluent and collected. -1 50mL was passed through the eluent at an SV of 1000. Thereafter, the content of each metal element (amount of each metal) in the recovered eluent was measured using ICP-MS, and the metal concentration in the sample solution was calculated by dividing the obtained metal concentration by the concentration ratio of the eluent (600mL / 50mL=12 times in this embodiment). Furthermore, the metal concentration in the stock solution was calculated by dividing the calculated metal concentration by the dilution ratio of the dilution solution (2 times in this embodiment). Then, the metal concentration in the stock solution was measured separately, and the recovery rate, which is the ratio (percentage) of the calculated value to the measured value, was calculated. Table 1 shows the calculation results of the recovery rate of each metal element in the stock solution.

[0052] [Table 1]

[0053] Table 1 shows that the recovery rates for all the analyzed metal elements were in the range of 100±35%. Therefore, it was confirmed that metal impurities can be recovered with a high recovery rate even when the sample solution is not an undiluted organic solvent solution itself, but a diluted solution obtained by diluting the organic solvent solution with ultrapure water. [Explanation of symbols]

[0054] 10. Impurity recovery device 11 Impurity Collection Kit 12 Concentration column 13 Integrating flow meter 14 Mixing means 15 Diluent flow meter 21 Ultrapure water flow meter 22 Purification means L1 Raw solution supply line L2 Ultrapure water supply line L11 Sampling Line L12 Replacement fluid supply line L13 Eluent supply line L21 Ultrapure water addition line A Dangerous area B Non-hazardous area

Claims

1. A method for recovering metal impurities in an organic solvent, comprising the steps of: diluting the organic solvent with water to prepare a diluted solution; and passing the prepared dilution liquid through an adsorbent as a sample liquid, thereby capturing the metal impurities in the sample liquid in the adsorbent.

2. a step of flowing at least one of water and gas as a replacement fluid through the adsorbent after the sample liquid has been passed through the adsorbent, thereby replacing the sample liquid remaining in the adsorbent with the replacement fluid; 2. The method for recovering metal impurities according to claim 1, further comprising the step of passing an eluent through the adsorbent after the replacement fluid has been passed through, and eluting the metal impurities captured by the adsorbent into the eluent and recovering them.

3. 3. The method for recovering metal impurities according to claim 1, wherein the step of preparing the diluted solution comprises diluting the organic solvent with water so that the concentration of the organic solvent in the diluted solution is less than a predetermined value.

4. 3. The method for recovering metal impurities according to claim 1, wherein the adsorbent is a monolithic organic porous ion exchanger.

5. 3. The method for recovering metal impurities according to claim 1, wherein the organic solvent is an alcohol.

6. A step of quantifying the metal impurities recovered by the method for recovering metal impurities according to claim 1 or 2; and calculating a concentration of the metal impurity in the organic solvent based on the result of the quantification and the dilution ratio of the diluted solution.

7. 7. The method for analyzing metal impurities according to claim 6, wherein the steps of preparing the dilute solution, capturing the metal impurities, and quantifying the metal impurities are carried out online continuously.

8. A metal impurity recovery apparatus for recovering metal impurities in an organic solvent, comprising: an adsorbent that captures the metal impurities in the organic solvent; a sample liquid passing means for diluting the organic solvent with water to prepare a diluted liquid, and passing the prepared diluted liquid through the adsorbent as a sample liquid.

9. a replacement fluid supply means for supplying at least one of water and gas as a replacement fluid to the adsorbent; 9. The apparatus for recovering metal impurities according to claim 8, further comprising: an eluent supplying means for supplying an eluent to said adsorbent.

10. 10. The apparatus for recovering metal impurities according to claim 8 or 9, wherein the adsorbent is a monolithic organic porous ion exchanger.

Images