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

Abstract

Disclosed is a recovery method for metal impurities for recovering metal impurities from an organic solvent, and this recovery method includes: 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.

Description

METHOD FOR RECOVERING METAL IMPURITIES, ANALYZING METHOD, AND RECOVERY APPARATUS

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

[0002] Highly purified organic solvents are used in the manufacturing processes of electronic devices such as semiconductors. Metal impurities contained in organic solvents, even in trace amounts, can have a significant impact on device characteristics, so their concentrations must be strictly controlled. This requires highly accurate analysis of trace amounts of metal impurities in organic solvents.

[0003] A commonly known method for analyzing metal impurities in organic solvents is to introduce a sample liquid sampled in a bottle directly into an analytical device such as an inductively coupled plasma mass spectrometer (ICP-MS) for analysis. On the other hand, when high-precision analysis is required even for low concentrations of metal impurities in an organic solvent that are below the detection limit of the analytical device, 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 (see, for example, Patent Documents 1 to 3).

[0004] JP 2001-141721 A JP 2002-5799 A International Publication No. 2020 / 071481

[0005] However, sampling sample liquids into bottles poses a risk of contamination depending on the working environment and the level of operator proficiency, as well as safety concerns for the operator and the surrounding environment due to leakage. Furthermore, if the sampling location is far from the location of subsequent processes (such as thermal concentration and analysis), the bottles must be transported. This transportation may also be restricted if the sample liquid is an organic solvent. Furthermore, methods that heat-concentrate sample liquids have limitations on the concentration factor achieved by heating, requiring the sampling of large amounts of sample liquid to achieve sufficient sensitivity. Furthermore, the thermal concentration of sample liquids is performed in an open environment, which also increases the risk of contamination.

[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.

[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 results and the dilution ratio of the diluted solution.

[0009] Furthermore, the metal impurity recovery device of the present invention is a metal impurity recovery device that recovers metal impurities in an organic solvent, and includes 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] These metal impurity recovery methods, analysis methods, and recovery devices eliminate the need for sampling sample liquids into bottles, thereby preventing the occurrence of various problems associated with this. Furthermore, when preparing a diluted solution, it is possible to reduce the concentration of the organic solvent to a safe level (e.g., a level that is not considered a hazardous substance under the Fire Service Act or a level that will not harm humans or the environment even if the liquid leaks outside). Therefore, in addition to eliminating concerns about leakage, safety reliability can be improved.

[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.

[0012] 1 is a schematic diagram of an impurity recovery device according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram of an impurity recovery device according to a second embodiment of the present invention.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components common to the following embodiments are denoted by the same reference numerals in the drawings, and redundant description will be omitted where appropriate. In this specification, a dilution liquid of the present invention is exemplified by a solution obtained by diluting an organic solvent with ultrapure water. However, the present invention is not limited to this, and water having a lower purity than ultrapure water may be used as the dilution medium. Furthermore, in this specification, a method of preparing a dilution liquid is exemplified by adding ultrapure water to an organic solvent. However, the present invention is not limited to this, and an organic solvent may be added to ultrapure water.

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

[0015] The impurity recovery device 10 recovers metal impurities from the organic solvent supplied through the raw solution supply line L1. The organic solvent to be recovered 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 includes 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 includes 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. The concentration column 12 is composed of a resin container and an ion exchanger (adsorbent) filled in the container. The integrating flow meter 13 functions to measure 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 interior 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 to prevent the interior from becoming an organic solvent vapor atmosphere.

[0017] Examples of ion exchangers packed into the concentration column 12 include ion exchange resins, ion adsorption membranes (porous membranes with ion exchange capacity), and monolithic organic porous ion exchangers. Among these, monolithic organic porous ion exchangers are preferred. Monolithic organic porous ion exchangers are monolithic organic porous materials, i.e., porous materials with ion exchange groups incorporated into the skeleton of a monolithic organic porous material, i.e., a porous material formed from an organic polymer, with numerous interconnecting pores serving as flow paths for the reaction solution. Compared to typical granular ion exchange resins, monolithic organic porous ion exchangers enable liquid flow at higher spatial velocities, significantly shortening the required time. Furthermore, since the trapped metal impurities are easily eluted into the eluent used for quantitative analysis, the amount of eluent used can be reduced, thereby reducing the amount of sample liquid flow. Furthermore, the eluent recovered after passing through the monolithic organic porous ion exchanger is in an acid-containing state, preventing the eluted metal impurities from adhering to the collection container, such as a bottle, making it easy to store. These advantages also make monolithic organic porous ion exchangers 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 monolithic organic porous ion exchangers will be described later.

[0018] As will be described in detail later, in this embodiment, instead of the organic solvent stock solution (hereinafter simply referred to as "stock solution") itself flowing through the stock solution supply line L1, 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. To achieve this (sample solution passing means), the impurity recovery device 10 has an ultrapure water addition line L21 in addition to the sampling line L11 described above. The ultrapure water addition line L21 connects the ultrapure water supply line L2, which circulates ultrapure water, with 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 on-off valve V2 is provided downstream of the ultrapure water addition line L21.

[0019] The impurity recovery apparatus 10 also includes an agitator 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 agitator 14 functions to mix the ultrapure water added to the sampling line L11 with the stock solution. The agitator 14 is not particularly limited, but due to the risk of organic solvents igniting, it is preferable to use a device that does not require electrical equipment, such as a static mixer or a long tube. The agitator 14 is not necessarily required. The diluent flowmeter 15 and the ultrapure water flowmeter 21 are used to calculate the dilution ratio of the diluent and function to measure 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 functions to remove metal impurities from the ultrapure water being added. The purification means 22 can be, for example, an ion exchanger similar to that packed in the concentration column 12. Depending on the purity of the ultrapure water to be added, the purifying means 22 may not necessarily be provided. Also, a check valve may be provided in the ultrapure water adding line L21 between the ultrapure water flow meter 21 and the purifying means 22.

[0020] In this embodiment, an integrating flow meter 13 is used to measure the total amount of sample liquid passing through the concentration column 12. However, the method for measuring the total amount of sample liquid passing through the concentration column 12 is not limited to this. For example, a diluent flow meter 15 may be used instead of the integrating flow meter 13, and its measured values ​​may be integrated by a separately provided computing device. Furthermore, 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, a flow meter (e.g., a float-type flow meter) that does not require electrical equipment may be provided instead of the integrating flow meter 13. 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 point of the sampling line L11 with the ultrapure water addition line L21, and the measured value of this flow meter and the measured value of the ultrapure water flow meter 21 may be integrated by a separately provided calculation device.

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

[0022] First, a stock solution of organic solvent is diluted with ultrapure water to prepare a diluted solution. Specifically, the on-off valve V1 of the sampling line L11 is opened, a portion 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 portion of the ultrapure water flowing through the ultrapure water supply line L2 flows into the ultrapure water addition line L21, where metal impurities such as metal ions are removed by the purification means 22 and the ultrapure water is added to the stock solution flowing through the sampling line L11. The stock solution and ultrapure water are then mixed by the stirring means 14 to prepare a diluted solution of the organic solvent. At this time, the opening 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 (preferably, its moving average value) of the diluent flow meter 15 and the measurement value (preferably, its moving average value) of the ultrapure water flow meter 21 .

[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 in space velocity (SV). －１ It is preferable that the time is 1000 h or less. －１ More preferably, it is 200 h or less. －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 liquid passing speed described above, but is not particularly limited as long as the metal impurities to be analyzed are concentrated to an extent that they can be quantified with sufficient accuracy. Note that, in order to calculate the content of metal impurities in the sample liquid from the results of the quantitative analysis described below, the total amount of sample liquid passed through the concentration column 12 is required, and therefore, when the sample liquid is passed through, the total amount of sample liquid passed through the concentration column 12 is measured by the integrating flow meter 13.

[0024] After that, when a predetermined liquid flow 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 that order) to stop the flow of the sample liquid into the concentration column 12. The impurity collection kit 11 is then removed from the sampling line L11, preferably with the interior 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 interior may be replaced with that 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 to replace the sample liquid remaining in the concentration column 12, particularly in the ion exchanger, with the replacement fluid. This prevents the eluent (aqueous solution containing an acid) used in the elution process described below from coming into contact with the organic solvent, thereby ensuring safety. This replacement process may be performed on-site where the impurity collection device 10 is installed, or at a location remote from the site.

[0026] At least one of water and gas is used as the replacement fluid. The water used here is preferably as pure as possible, i.e., water with a metal impurity concentration as low as possible is preferred. 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 examples include inert gases (nitrogen, argon, helium, etc.) and oxygen. Air can also be used as the high-purity gas as long as the metal impurities have been sufficiently removed.

[0027] When the sample liquid is passed through the ion exchanger, the amount of metal impurities captured by the ion exchanger gradually decreases along the flow direction. Therefore, it is preferable that the direction of flow of the replacement fluid is the same as the direction of flow of the sample liquid. This allows metal impurities captured by the ion exchanger to be recaptured downstream even after they are desorbed, preventing 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 20,000 h at SV. －１ It is preferable that the time is 100 to 4000 h or less. －１ Alternatively, the LV is preferably 1000 m / h or less, and more preferably 1 to 80 m / h. The time for which the replacement fluid is allowed to flow 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 remote 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 enable the preparation of high-purity eluates. The acid concentration in the eluent is not particularly limited, but is preferably 0.1 to 3.0 N. Furthermore, the eluent preferably has a metal impurity concentration of 100 ng / L or less. Specifically, nitric acid or hydrochloric acid having a metal impurity concentration of 100 ng / L or less is more preferred, and nitric acid or hydrochloric acid having a metal impurity concentration of 10 ng / 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 analytical device described below, but as described below, it is preferable that it be as small as possible. Note that the amount of eluent passed through (amount of recovered liquid) is necessary for calculating 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 in which the entire amount of eluent measured in advance is passed through may be used.

[0031] Thereafter, the metal impurities in the recovered eluent are quantified, and the metal impurity concentration in the sample solution is calculated from the obtained metal concentration. The metal impurity concentration in the raw solution is then calculated based on the calculated metal impurity concentration and the dilution ratio of the diluted solution. This quantitative analysis may be performed on-site where the impurity recovery device 10 is installed, or may be performed at a location remote from the site. Furthermore, the quantitative analysis may be performed at a location different from the location where the substitution process and elution process are performed.

[0032] For the quantification 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, or the like can be used. The type of metal impurity element to be analyzed 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 solution can be calculated by dividing the obtained metal concentration by the concentration factor of the eluent (the total volume of the sample solution divided by the volume of the eluent recovered), and the metal impurity concentration in the stock solution can be calculated by dividing the calculated value by the dilution factor of the dilution solution.

[0033] According to the above-described calculation method, even if the metal impurity concentration in the raw solution is low and below the detection limit of the analytical instrument, the metal impurity concentration in the raw solution can be determined by increasing the concentration factor of the eluent until the metal impurity concentration in the eluent is equal to or greater than the detection limit. Therefore, it is preferable to use as high a concentration factor as possible for the eluent. Therefore, it is preferable to minimize the amount of eluent recovered for the same total amount of sample solution. In other words, if metal impurities can be recovered with a smaller amount of eluent, it becomes possible to measure (evaluate) even lower concentrations of metal impurities in the raw solution without increasing the total amount of sample solution. From this perspective, it is preferable that the direction of flow of the eluent through the concentration column 12 is opposite to the direction of flow of the sample solution. As described above, the amount of metal impurities captured by the ion exchanger gradually decreases along the flow direction of the sample solution. However, by passing the eluent in the opposite direction, it becomes possible to recover such metal impurities with a smaller amount of eluent.

[0034] As described above, according to this embodiment, in order to concentrate and collect metal impurities in a target organic solvent, a diluted solution is prepared by diluting the organic solvent with water (ultrapure water), and this diluted solution is passed through the concentration column 12 as a sample solution. This eliminates the need to sample the sample solution in a bottle, and the work of concentrating the metal impurities does not have to be performed in an open environment. As a result, the risk of contamination can be reduced and the concentration efficiency can be improved compared to methods that concentrate sample solutions by heating. Furthermore, the ion exchanger packed in the concentration column 12 generally exhibits a faster ion exchange rate when in contact with water than when in contact with an organic solvent. This allows the sample solution to pass through the concentration column 12 at a higher rate, thereby shortening the time required for passing the sample solution through the concentration column 12, i.e., the time required for concentrating the metal impurities.

[0035] Furthermore, when preparing the diluted solution, it is possible to reduce the concentration of the organic solvent to a safe concentration (e.g., a concentration that is not considered a hazardous substance under the Fire Service Act or a concentration that will not affect humans or the environment even if the organic solvent leaks outside). This eliminates the risk of leakage associated with sampling into a bottle and enables the safe recovery of metal impurities in the target organic solvent. Furthermore, since the diluted solution prepared in this manner is used as the sample solution, if the organic solvent is flammable, the raw solution supply line L1 must be installed in a hazardous location A, while the impurity collection kit 11 including the concentration column 12 can be installed in a non-hazardous location B. In other words, it is no longer necessary to install the integrating flow meter 13 of the impurity collection kit 11 in the hazardous location A, and it is also no longer necessary to install the diluent flow meter 15 in the hazardous location A. This eliminates the need to use expensive explosion-proof flow meters 13 and 15, which does not increase the cost of the impurity collection device 10. The term "hazardous location" as used herein refers to a location where an explosive atmosphere exists or is likely to exist due to the leakage of flammable gas or vapor of a flammable liquid into the atmosphere, and where the use of equipment that complies with specified explosion-proof standards is mandatory. The concentration of the organic solvent in the diluted solution is not particularly limited, but is preferably less than the concentration (predetermined value) that is subject to regulation under laws and regulations regarding hazardous materials. For example, in the case of a saturated monohydric alcohol having 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, this embodiment can avoid another problem that occurs when an undiluted organic solvent is passed through an ion exchanger, particularly a monolithic organic porous ion exchanger. Specifically, when an organic solvent is passed through a water-wetted monolithic organic porous ion exchanger, the monolithic organic porous ion exchanger shrinks (or swells). On the other hand, 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 water-wetted monolithic organic porous ion exchanger is packed in a concentration column and an organic solvent is passed through the concentration column, gaps may form between the concentration column and the monolithic organic porous ion exchanger. This may prevent sufficient contact with the organic solvent, potentially reducing the monolithic organic porous ion exchanger's ability to capture metal impurities. Furthermore, repeated swelling and shrinkage during repeated use of the monolithic organic porous ion exchanger may cause deterioration of the monolithic organic porous ion exchanger. In contrast, in this embodiment, a diluted solution prepared by diluting the undiluted organic solvent with ultrapure water is used as the sample solution, rather than the undiluted organic solvent itself. Therefore, 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 through the concentration column 12, 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 suitable for use 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, a monolithic organic porous ion exchanger will be simply referred to as a "monolith ion exchanger," and a monolithic organic porous material will also be simply referred to as a "monolith." Furthermore, 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 portions 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 a first monolith ion exchanger, as described in paragraphs

[0029] to

[0051] of Japanese Patent Application Laid-Open No. 2010-234357, consists of the following four steps: (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. The water-in-oil emulsion is then 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 consisting of a vinyl monomer, a crosslinker having at least two vinyl groups per molecule, an organic solvent that dissolves the vinyl monomer and the crosslinker but not the polymer produced by polymerization of the vinyl monomer, and a polymerization initiator. (3) This mixture is allowed 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) Then, ion exchange groups are introduced into the first monolith thus obtained to produce a first monolith ion exchanger.

[0041] The second monolithic ion exchanger is a bicontinuous structure consisting of a three-dimensionally continuous skeleton with a thickness of 1 to 60 μm, which is 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, and three-dimensionally continuous pores with a diameter of 10 to 100 μm between the skeletons. The second monolithic 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 equivalents / ml, and ion exchange groups uniformly distributed throughout the porous ion exchanger.

[0042] As described in paragraphs

[0062] to

[0083] of Japanese Patent Application Laid-Open No. 2010-234357, the second monolith ion exchanger is produced through the following four steps: (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. The water-in-oil emulsion is then polymerized to obtain a second monolith intermediate having a continuous macropore structure with a total pore volume exceeding 16 ml / g and not exceeding 30 ml / g. (2) A mixture is prepared comprising an aromatic vinyl monomer, a crosslinker having at least two vinyl groups per molecule and 0.3 to 5 mol% of the total oil-soluble monomer, an organic solvent that dissolves the aromatic vinyl monomer and the crosslinker but not the polymer produced by polymerization of the aromatic vinyl monomer, and a polymerization initiator. (3) This mixture is allowed to stand and polymerized in the presence of the second monolith intermediate obtained in (1) above to obtain a second monolith with a co-continuous structure. (4) Then, ion exchange groups are introduced into the second monolith thus obtained to produce a second monolith ion exchanger.

[0043] Second Embodiment Fig. 2 is a schematic diagram of an impurity recovery apparatus according to a second embodiment of the present invention. This embodiment differs from the first embodiment in that the substitution process and elution process are performed on-site where the impurity recovery apparatus is installed. The following description will focus on these differences. Note that the various modifications described in the first embodiment are also applicable to this embodiment, and redundant description will be omitted.

[0044] In this embodiment, a substitution fluid and an eluent can be supplied to the concentration column 12. Specifically, a substitution fluid line L12 and an eluent line L13 are connected to the concentration column 12. The substitution fluid line L12 functions as a substitution fluid supply means for supplying a substitution fluid to the concentration column 12 in order to replace the sample liquid remaining in the concentration column 12, particularly the ion exchanger, with the substitution fluid. The eluent line L13 functions as an eluent supply 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 detachable from the sampling line L11. The eluent line L13 is provided with an integrating flow meter (not shown) or an instantaneous flow meter and a computing device (neither of which are shown) for integrating the measured value to measure the flow rate of the eluent (recovery volume). Alternatively, similar to the elution process of the first embodiment, a collection container with a measuring function may be provided downstream of the eluent line L13, and the entire amount of 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 performed continuously 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, eliminating the need to transport the concentration column 12 containing the sample liquid containing the organic solvent remaining therein. A quantitative analyzer such as an ICP-MS may be connected downstream of the eluent line L13, thereby enabling the quantification of metal impurities in the eluent to be performed online. Furthermore, this series of processes may be automated by a control means such as a controller. In this case, the control means may even calculate the concentration of metal impurities in the raw solution based on the measurement results of the flow meters 13, 15, and 21 and the analysis results of the quantitative analyzer.

[0046] The replacement fluid line L12 may be omitted from its portion downstream of the concentrator column 12 so that it only supplies replacement fluid to the concentrator column 12. Similarly, the eluent line L13 may be omitted from its portion downstream of the concentrator column 12 so that it only supplies eluent to the concentrator 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 concentrator column 12. On the other hand, ultrapure water, which is one of the replacement fluids, may be supplied from the ultrapure water addition line L21. In either case, the replacement fluid and eluent can be discharged through the sampling line L11. Alternatively, the eluent line L13 may be omitted, so that only the replacement process is performed on-site where the impurity recovery device 10 is installed, and the elution process is performed at a location remote from the site.

[0047] EXAMPLES 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, a dilution obtained by diluting a stock solution of 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 organic solvent, isopropyl alcohol (IPA) adjusted to a concentration of 100 ng / L for each 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 was used, and this was diluted two-fold with ultrapure water. Specifically, the openings of each on-off valve were adjusted so that the measured values ​​of the dilution flow meter and ultrapure water flow meter were 10 mL / min and 5 mL / min, respectively. The dilution was then passed through the concentration column for 150 h. －１ 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, ultrapure water was used as a replacement fluid in the concentration column for 150 h. －１ After passing 50 mL of water through the concentration column at an SV of 1000 psi, 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, an 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 50 mL of the solution was passed through the eluent at an SV of 0.01. 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 factor of the eluent (600 mL / 50 mL = 12 times in this example). Furthermore, the metal concentration in the stock solution was calculated by dividing the calculated metal concentration by the dilution factor of the diluted solution (2 times in this example). 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]

[0053] Table 1 shows that the recovery rates for all of the metal elements analyzed were in the range of 100±35%. Therefore, it was confirmed that metal impurities can be recovered with a high recovery rate even when a diluted solution prepared by diluting an organic solvent with ultrapure water is used as the sample solution, rather than the undiluted organic solvent itself.

[0054] 10 Impurity recovery device 11 Impurity collection kit 12 Concentration column 13 Integrating flow meter 14 Stirring means 15 Dilution liquid flow meter 21 Ultrapure water flow meter 22 Purification means L1 Stock 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 Hazardous 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 diluted solution as a sample solution through an adsorbent, thereby capturing the metal impurities in the sample solution in the adsorbent.

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

3. The recovery method according to claim 1 or 2, wherein the preparing step includes 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. The recovery method according to claim 1 or 2, wherein the adsorbent is a monolithic organic porous ion exchanger.

5. The method according to claim 1 or 2, wherein the organic solvent is an alcohol.

6. A method for analyzing metal impurities, comprising the steps of: quantifying the amount of the metal impurities recovered by the recovery method according to claim 1 or 2; and calculating the concentration of the metal impurities in the organic solvent based on the results of the quantification and the dilution ratio of the dilution solution.

7. The analytical method according to claim 6, wherein the preparing step, the capturing step, and the quantifying step are carried out continuously online.

8. A metal impurity recovery device for recovering metal impurities in an organic solvent, comprising: an adsorbent for capturing the metal impurities in the organic solvent; and 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. The recovery apparatus according to claim 8, further comprising: a replacement fluid supplying means for supplying at least one of water and gas as a replacement fluid to said adsorbent; and an eluent supplying means for supplying an eluent to said adsorbent.

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

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