Method and apparatus for recovering metal impurity

Abstract

To stably and satisfactorily recover metal impurities in an organic solvent.SOLUTION: A method for recovering metal impurities for recovering metal impurities in an organic solvent includes the steps of: passing the organic solvent as a sample liquid through an adsorbent, and capturing the metal impurities in a sample liquid in the adsorbent; flowing at least one of water and gas as a substitution fluid in the adsorbent after having passed the sample liquid therethrough, and substituting a sample liquid remaining in the adsorbent with the substitution fluid; and passing an eluent through the adsorbent after having flowed the substitution fluid therein, eluting the metal impurities captured in the adsorbent in the eluent and recovering the metal impurities, wherein the adsorbent is composed of a sintered body of mixed powder containing dry gel powder and thermoplastic resin powder having at least any one of an ionic exchange group and a chelate group.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for recovering metal impurities. [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. In particular, there is a demand for highly accurate analysis even when the metal impurity concentration in an organic solvent is so low that it is below the detection limit of analytical equipment such as an inductively coupled plasma mass spectrometry (ICP-MS).

[0003] As a method for analyzing such low-concentration metal impurities, a method is known in which a sample liquid sampled in a bottle is heated and concentrated to increase the concentration of metal impurities in the sample liquid, and then the metal impurities in the concentrated sample liquid are analyzed (see, for example, Patent Documents 1 and 2). However, in this method, there is a limit to the concentration rate by heating, and a large amount of sample liquid needs to be sampled in order to obtain sufficient sensitivity. In addition, since the heat concentration of the sample liquid is performed in an open environment, the risk of contamination increases. In response to this, Patent Document 3 describes a method for concentrating and collecting metal impurities in a sample liquid, in which the sample liquid is passed through an ion exchanger such as a monolithic organic porous ion exchanger, and the metal impurities are captured and concentrated by the ion exchanger. This concentration method is preferably used in the field of ultrapure water production because of its high concentration efficiency and low risk of contamination in the concentration process, and it is considered that this method can also be applied to organic solvents. [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. 2019 / 221186 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if a concentration method using an ion exchanger, particularly a monolithic organic porous ion exchanger, is applied to an organic solvent, metal impurities in the organic solvent cannot be recovered well, and the analytical accuracy may be reduced due to the following reasons. That is, a monolithic organic porous ion exchanger shrinks (or swells) when an organic solvent is passed through it in a water-wet state, and may swell (or shrink) when water is passed through it in a wet state with an organic solvent. Due to such properties, if a monolithic organic porous ion exchanger is repeatedly used to recover metal impurities in an organic solvent, washing with ultrapure water or the like is performed between recovery steps, resulting in repeated swelling and shrinkage. As a result, the monolithic organic porous ion exchanger may deteriorate and its capture performance may gradually decrease.

[0006] Therefore, an object of the present invention is to stably and satisfactorily recover metal impurities in an organic solvent. [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 passing an organic solvent as a sample liquid through an adsorbent and capturing the metal impurities in the sample liquid in the adsorbent, 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 liquid through the adsorbent after the replacement fluid has been passed through, thereby eluting the metal impurities captured by the adsorbent into the elution liquid and recovering them, wherein the adsorbent is a porous molded body made of a sintered body of a mixed powder containing a dry gel powder having at least one of an ion exchange group and a chelating group, and a thermoplastic resin powder.

[0008] 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 includes an adsorbent that captures metal impurities in an organic solvent, a sample liquid passing means for passing an organic solvent as a sample liquid through the adsorbent, a replacement fluid supply means for supplying at least one of water and gas as a replacement fluid to the adsorbent, and an elution liquid passing means for passing an elution liquid through the adsorbent, wherein the adsorbent is a porous molded body made of a sintered body of a mixed powder containing a dry gel powder having at least one of an ion exchange group and a chelating group, and a thermoplastic resin powder.

[0009] According to such a method and apparatus for recovering metal impurities, by using a porous molded body that is less susceptible to the effects of swelling and shrinkage as the adsorbent, it is possible to maintain good capture performance even with repeated use. Effect of the Invention

[0010] As described above, according to the present invention, metal impurities in an organic solvent can be stably and satisfactorily recovered. [Brief description of the drawings]

[0011] [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

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Configurations common to the following embodiments will be denoted by the same reference numerals in the drawings, and duplicated descriptions will be omitted as appropriate.

[0013] (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.

[0014] The impurity recovery device 10 collects metal impurities from the organic solvent flowing 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.

[0015] The impurity recovery device 10 has a sampling line L11 and an impurity collection kit 11 provided on the sampling line L11. The sampling line L11 is connected to the raw liquid supply line (solvent supply line) L1 via an on-off valve V1, and the impurity collection kit 11 has a concentration column 12 and an integrating flow meter 13. The sampling line L11 functions as a sample liquid passing means for extracting a part of the organic solvent flowing through the raw liquid supply line L1 as a sample liquid and passing the extracted sample liquid through the concentration column 12. The concentration column 12 captures and concentrates metal impurities in the sample liquid thus extracted, and is composed of a resin or metal container and a porous molded body (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. Instead of the integrating flow meter 13, a combination of an instantaneous flow meter and a calculation device that accumulates the measured value may be used.

[0016] The porous molded body packed in the concentration column 12 is a sintered body of a mixed powder containing a dry gel powder having at least one of an ion exchange group and a chelating group and a thermoplastic resin powder. Such a porous molded body is less susceptible to swelling and shrinkage than a monolithic organic porous ion exchanger because the sintered part (porous structure) of the thermoplastic resin powder serving as the support has the property of only slightly swelling and shrinking when moistened. Therefore, as shown in the examples described later, it is advantageous in that it has excellent resistance to deterioration with repeated use. The detailed configuration of the porous molded body will be described later, but specific examples include the metal ion removal filters "SCP series" and "APP series" manufactured by 3M Japan Ltd.

[0017] The impurity recovery device 10 also has a fluid supply line L12 and a supply source of a replacement fluid and an eluent (both not shown). The fluid supply line L12 is connected to the sampling line L11 (specifically, the upstream side of the impurity collection kit 11) via an on-off valve V2, and the supply sources of the replacement fluid and the eluent are connected to the upstream side of the fluid supply line L12 in a switchable manner. Therefore, the fluid supply line L12, together with the sampling line L11, functions as a replacement fluid supply means for supplying a replacement fluid to the concentration column 12, and also functions as an eluent passing means for supplying and passing the eluent.

[0018] 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.

[0019] First, an organic solvent is passed through the concentration column 12 as a sample liquid. Specifically, the on-off valve V1 of the sampling line L11 is opened, and a part of the organic solvent flowing through the raw liquid supply line L1 is passed through the concentration column 12 as a sample liquid. In this way, metal impurities in the sample liquid are captured and concentrated by the porous body 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 temperature is less than 1000h. -1 It is more preferable that the temperature is less than 200 h. -1It 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 porous body 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 liquid passing amount of the sample liquid to the concentration column 12 is required, and at this time, the total liquid passing amount is measured by the integrating flow meter 13. After that, when a predetermined liquid passing time has elapsed, the opening and closing valve V1 is closed to stop the passage of the sample liquid to the concentration column 12.

[0020] Next, a replacement process is performed to flow a replacement fluid into the concentration column 12. Specifically, the on-off valve V2 of the fluid supply line L12 is opened, and the connection source of the fluid supply line L12 is switched to the replacement fluid supply source. In this way, the replacement fluid is supplied from the replacement fluid line L12 through the sampling line L11 to the concentration column 12, and the sample liquid remaining in the concentration column 12, particularly in the porous molded body, 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 later from coming into contact with an organic solvent, ensuring safety.

[0021] At least one of water and gas is used as the replacement fluid. 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.

[0022] During the passage of the sample liquid, the amount of metal impurities captured in the porous body 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 the metal impurities captured in the porous body to be recaptured downstream even after they are desorbed, and prevents them from being discharged from the concentration column 12. When 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 porous body packed in the concentration column 12, but is not particularly limited as long as the sample liquid remaining in the porous body can be replaced with the replacement fluid.

[0023] When the inside of the concentration column 12 has been sufficiently replaced with the replacement fluid, the supply of the replacement fluid to the concentration column 12 is stopped to terminate the replacement process. Then, the connection source of the fluid supply line L12 is switched from the replacement fluid supply source to the elution fluid supply source, and an elution process is performed in which the elution fluid is passed through the concentration column 12. In this way, the elution fluid is supplied from the fluid supply line L12 through the sampling line L11 to the concentration column 12, and the metal impurities captured in the porous body in the concentration column 12 are eluted into the elution fluid and collected in a collection container installed downstream of the sampling line L11.

[0024] 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.

[0025] The amount of the eluent passed through is not particularly limited as long as the metal impurity concentration 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 the liquid passed through (recovered amount) at this time is necessary to calculate the content of metal impurities in the sample liquid, like the total amount of the sample liquid passed through the concentration column 12, so it is measured by an integrating flow meter 13 during the elution process or measured by a recovery container with a measuring function.

[0026] 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. 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 to quantify the metal impurities. There is no particular limitation on the type of metal impurity element to be analyzed here, 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 (a value obtained by dividing the total amount of the sample liquid passed by the amount of the eluent recovered). The quantitative analysis described above may be performed on-site where the impurity recovery device 10 is installed, or may be performed at a location away from the site.

[0027] According to the above-mentioned calculation method, even if the metal impurity concentration in the organic solvent is so low as to be below the detection limit of the analysis device, the metal impurity concentration in the organic solvent 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 passing is the same, it is preferable that the amount of eluent recovered is as small as possible. In other words, if the 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 organic solvent without increasing the total amount of sample liquid passing. 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 porous molded body 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.

[0028] Thus, according to this embodiment, a porous molded body made of a sintered body of a mixed powder containing a dry gel powder having at least one of an ion exchange group and a chelating group and a thermoplastic resin powder is used as an adsorbent for capturing metal impurities in a sample liquid. Since such a porous molded body is not easily affected by swelling and shrinkage, it can maintain its capturing performance well even with repeated use, as shown in the examples described later. As a result, it is possible to stably and satisfactorily recover metal impurities in an organic solvent.

[0029] The impurity collection kit 11 (or at least the concentration column 12) may be removably attached to the sampling line L11. Therefore, after stopping the passage of the sample liquid to the concentration column 12, the impurity collection kit 11 (or at least the concentration column 12) may be removed from the sampling line L11, and the above-mentioned replacement process and elution process may be performed, for example, at a location other than the site where the impurity recovery device 10 is installed. For this purpose, the impurity collection kit 11 may be provided with a sealing means for sealing the inside so that contamination or leakage does not occur when the impurity collection kit 11 is removed from the sampling line L11. In addition, at this time, the replacement process and the elution process may be performed at the same location or at different locations. That is, the replacement process and the elution process may both be performed at a location other than the site where the impurity recovery device 10 is installed, or the replacement process may be performed at a location other than the site where the impurity recovery device 10 is installed, and the elution process may be performed at a location still other than the site where the impurity recovery device 10 is installed.

[0030] Here, the detailed configuration of the porous body packed in the concentration column 12 will be described.

[0031] The porous molded body described above is a molded body made of a sintered body of a mixed powder containing a dry gel powder and a thermoplastic resin powder. This porous molded body can be said to be a molded body in which the dry gel powder is dispersed and fixed in a porous structure formed by sintering the thermoplastic resin powder, and can also be said to be a molded body in which the dry gel powder is bound to each other by the thermoplastic resin powder. Therefore, the porous molded body is not easily disintegrated even if a dimensional change occurs due to swelling of the dry gel powder, and can maintain a strength sufficient for self-supporting.

[0032] The dry gel powder is a powder that swells and gels by absorbing water, and can be obtained, for example, by drying hydrogel particles. The drying method is not particularly limited, and for example, hot air drying, stirring drying, vacuum drying, etc. can be used. The moisture content of the dry gel powder is preferably 10% by mass or less, more preferably 5% by mass or less.

[0033] The dry gel powder has at least one of an ion exchange group and a chelating group. Examples of the ion exchange group include a sulfonic acid group, a carboxylic acid group, a tertiary amine group, and a quaternary amine group. Examples of the chelating group include a polyamine, an aminophosphate group, an iminodiacetic acid group, a urea group, a thiol group, and a dithiocarbamic acid group.

[0034] The dry gel powder may contain an organic polymer as a main component. Examples of such organic polymers include polystyrene, acrylic resin, polyvinyl alcohol, cellulose, and polyamide. The main component means a component with a content of 80% by mass or more (preferably 90% by mass or more, and more preferably 95% by mass or more). These organic polymers may have the above-mentioned functional groups, and may be crosslinked with a crosslinking agent such as divinylbenzene. The dry gel powder may further contain an inorganic material. Examples of such inorganic materials include silica gel, alumina gel, and sucmetite. These inorganic materials may be modified to have the above-mentioned functional groups.

[0035] The water absorption rate of the dry gel powder is preferably 30% by mass or more, and more preferably 40% by mass or more. This allows the water to be efficiently removed even if the liquid to be treated contains a small amount of water, and allows the metal ions in the liquid to be more effectively removed. The water absorption rate of the dry gel powder is preferably 90% by mass or less, and more preferably 60% by mass or less. This allows the strength of the porous molded body to be further improved.

[0036] The thermoplastic resin powder is a powder made of a resin material mainly composed of a thermoplastic resin, and can be fused together by sintering to form a porous structure. The content of the thermoplastic resin in the thermoplastic resin powder is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total amount of the thermoplastic resin powder. The thermoplastic resin powder may contain other components other than the thermoplastic resin, such as a plasticizer such as a stearate salt, talc, silica, an antioxidant, etc.

[0037] The thermoplastic resin contained in the thermoplastic resin powder is preferably at least one of ultra-high molecular weight polyethylene and polyamide.

[0038] The weight average molecular weight of ultra-high molecular weight polyethylene is 7.5 x 10 5 g / mol or more 5×10 7 g / mol or less, more preferably 1.0×10 6 g / mol or more 1.2×10 7 The melting point of the ultra-high molecular weight polyethylene is not particularly limited and may be, for example, 130 to 135° C. The melt index of the ultra-high molecular weight polyethylene is preferably 1.0 g / 10 min or less (ASTM D1238, 190° C., load 21.6 kg) or less, and more preferably 0.5 g / 10 min or less.

[0039] As the polyamide, for example, semicrystalline polyamide fine particles having a melting point of 150° C. to 200° C. can be suitably used. In addition, as such a polyamide, it is preferable that the average number of carbon atoms per monomer unit is 10 or more.

[0040] The average particle size d1 of the thermoplastic resin powder is not particularly limited and may be, for example, 0.5 μm or more and 1000 μm or less, or 1 μm or more and 100 μm or less. When the average particle size d1 of the thermoplastic resin powder is large, the gaps in the porous molded body tend to increase and the liquid permeability tends to improve, and when the average particle size d1 is small, the porous molded body tends to become denser and the strength tends to be further improved.

[0041] The thermoplastic resin powder is preferably a non-spherical resin powder. The thermoplastic resin powder may have a shape in which small spherical particles are aggregated like a bunch of grapes, or may have a confetti-like shape in which multiple protrusions are formed on spherical particles. By using a non-spherical thermoplastic resin powder, it is possible to further improve resistance to dimensional changes during swelling. In addition, the thermoplastic resin powder is preferably a porous powder. The bulk density of the thermoplastic resin powder is, for example, 0.1 to 0.7 g / cm. 3 and may be 0.2 to 0.6 g / cm 3 may be also possible.

[0042] The ratio d2 / d1 of the average particle diameter d2 of the dry gel powder to the average particle diameter d1 of the thermoplastic resin powder is preferably 1.3 or more, whether the main component of the resin material constituting the thermoplastic resin powder is ultra-high molecular weight polyethylene or polyamide. This prevents the fixed dry gel powder from being detached even if a dimensional change occurs due to swelling of the dry gel powder, and reduces the possibility of the porous molded body collapsing. In addition, when the main component is ultra-high molecular weight polyethylene, the ratio d2 / d1 is preferably 13 or less, more preferably 10 or less, and when the main component is polyamide, it is preferably 50 or less, more preferably 25 or less.

[0043] The ratio (d3-d2) / d1 of the difference between the average particle diameter d2 of the dry gel powder and the average particle diameter d3 of the dry gel powder when it absorbs water and swells, relative to the average particle diameter d1 of the thermoplastic resin powder, is preferably 4 or less, more preferably 2 or less, when the resin material constituting the thermoplastic resin powder is mainly composed of ultra-high molecular weight polyethylene, and is preferably 4 or less, more preferably 3 or less, when the resin material is mainly composed of polyamide. This suppresses the detachment of the fixed dry gel powder even when a dimensional change occurs due to the swelling of the dry gel powder, and reduces the possibility of the porous molded body collapsing. In addition, the ratio (d3-d2) / d1 is preferably 0.2 or more, more preferably 0.3 or more, in both cases where the main component is ultra-high molecular weight polyethylene and polyamide. The average particle diameter d2 of the dry gel powder is not particularly limited as long as the ratios d2 / d1 and (d3-d2) / d1 are within the above ranges, but may be, for example, 0.1 μm or more and 500 μm or less, and preferably 1 μm or more and 200 μm or less.

[0044] The above-mentioned dry gel powder and thermoplastic resin powder are mixed, filled in a mold according to the desired shape of the porous molded body, and sintered. Examples of the shape of the porous molded body include a disk type, a hollow cylinder type, a bell type, a cone type, and a hollow star type. The mixed powder can be sintered under conditions that cause fusion of the thermoplastic resin powder. The mixed powder can be sintered at a temperature equal to or higher than the melting point of the thermoplastic resin contained in the thermoplastic resin powder. The sintering temperature may be, for example, 140°C or higher, and preferably 150°C or higher. The sintering temperature may be, for example, 200°C or lower, or 180°C or lower. The sintering time is not particularly limited, and may be, for example, 5 to 120 minutes, or 10 to 60 minutes.

[0045] In the mixed powder, the content of the dry gel powder is preferably 10 parts by mass or more and 900 parts by mass or less, more preferably 25 parts by mass or more and 300 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin powder. The mixed powder may further contain components other than the dry gel powder and the thermoplastic resin powder, such as activated carbon, heavy metal reduction medium, arsenic removal medium, antimicrobial medium, ion exchange medium, iodine, resin, fiber, gas adsorption medium, etc., as additives. The content of such additives is preferably 20% by mass or less, more preferably 5% by mass or less, based on the total amount of the mixed powder.

[0046] 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 it is provided with a configuration for reducing the amount of organic solvent discarded in the recovery of metal impurities. The following description will focus on such differences.

[0047] In the first embodiment, the sample liquid passed through the concentration column 12 is discharged directly to the outside through the sampling line L11 and discarded, but from the viewpoint of reducing the amount of waste, it may be returned to the raw liquid supply line L1 without being discharged to the outside. To achieve this, the impurity recovery device 10 of this embodiment has a return line L13, a liquid delivery pump 14, and a purification member 15.

[0048] The return line L13 is provided to connect the downstream side of the impurity collection kit 11 and the raw solution supply line L11 in the sampling line L11, and to return the sample liquid passed through the concentration column 12 to the raw solution supply line L1. The return line L13 is connected to the sampling line L11 via the on-off valve V4 on the upstream side of the on-off valve V3 provided in the sampling line L11. The liquid delivery pump 14 has a function of pressurizing the sample liquid returned to the raw solution supply line L11. Note that a check valve may be provided instead of or in addition to the liquid delivery pump 14. The purification member 15 has a function of removing impurities (such as fine particles) other than metal impurities contained in the sample liquid. The purification member 15 is not particularly limited as long as it is used for purifying an organic solvent, and for example, an ion exchanger (such as an ion exchange resin or a monolithic organic porous ion exchanger) or a filtration membrane (such as a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane)) can be used alone or in combination.

[0049] With this configuration, in this embodiment, when the sample liquid starts to pass through the concentration column 12, the on-off valve V3 of the sampling line L11 is closed and the on-off valve V4 of the return line L13 is opened at the same time. As a result, the sample liquid passed through the concentration column 12 is returned to the raw solution supply line L1 through the return line L13 without being discharged to the outside. After the sample liquid passes through the concentration column 12, the on-off valve V3 of the sampling line L11 is opened and the on-off valve V4 of the return line L13 is closed, and the replacement process and elution process are performed in the same procedure as in the first embodiment.

[0050] (Example) Next, the effects of the present invention will be described with reference to specific examples.

[0051] In this example, the recovery of metal impurities in an organic solvent was performed twice in succession using a test device simulating the impurity recovery device shown in Figure 1, and the change in the capture performance of the metal impurities by the porous molded body was examined. In the first recovery, each metal element in the eluent was quantified, and the recovery rate was calculated.

[0052] Specifically, first, a sample liquid was passed through a concentration column, and the metal elements contained in the sample liquid were captured and concentrated by the porous body in the concentration column. The sample liquid that had passed through the concentration column was then recovered, and the amount of each metal element captured by the porous body in the sample liquid was examined based on the content of each metal element in the recovered liquid. Isopropyl alcohol (IPA) adjusted to a concentration of 100 ng / L for each of the metal elements Li, Na, Al, K, Ca, Mn, Ni, Zn, and Sr was used as the sample liquid, and it was left for 200 h. -1 The concentration column was filled with a porous body, which was a metal ion removal filter "SCP series" manufactured by 3M Japan Ltd. The content of each metal element (amount of each metal) in the recovered liquid was measured using ICP-MS.

[0053] Next, ultrapure water was supplied to the concentration column as a replacement fluid, and the sample liquid remaining in the concentration column was replaced with the replacement fluid. Then, an eluent was passed through the concentration column, and the metal elements in the sample liquid captured in the concentration column were eluted into the eluent and collected. 2N nitric acid was used as the eluent, and it was left for 345 h. -1 200 mL of the solution was passed through the eluent at an SV of 1000. Thereafter, the content of each metal element (amount of each metal) in the collected 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 (in this embodiment, 1014 mL / 200 mL = 5.1 times). Then, the metal concentration in the sample solution was measured separately, and the recovery rate, which is the ratio (percentage) of the calculated value to the measured value, was calculated.

[0054] After that, the porous body in the concentration column was washed with ultrapure water, and the sample liquid was again passed through the concentration column under the same conditions and procedures as described above, except that the amount of liquid passed was changed to 553 mL, and the extent to which each metal element in the sample liquid was captured by the porous body was investigated.

[0055] In addition, as a comparative example, the same measurement was carried out in the same manner as in the example, using the same test equipment as in the example, except that the concentration column was packed with a monolithic organic porous cation exchanger. -1 500 mL of the eluent was passed through the column at 100°C for 200 h. -1 The eluent was concentrated 10-fold at 50 mL / min.

[0056] Table 1 shows the results of measuring the content of each metal element in the sample liquid and the recovered liquid in the examples and comparative examples.

[0057] [Table 1]

[0058] From the results in Table 1, it was confirmed that in the Comparative Example, a decrease in capture performance was observed in the second run compared to the first run for almost all of the metal elements analyzed, whereas in the Examples, good capture performance was obtained in both the first and second runs. This is believed to be because the porous molded body used in the Examples is less susceptible to the effects of swelling and shrinkage and has excellent resistance to deterioration with repeated use compared to the monolithic organic porous ion exchanger used in the Comparative Example. It was also confirmed that the Examples were good in pure performance comparison, without the case where only a specific metal element (i.e., Fe) was not sufficiently captured, as was seen in the Comparative Example.

[0059] Table 2 shows the calculation results of the recovery rates of Fe, Li, and Mn in the sample solutions in the examples and comparative examples.

[0060] [Table 2]

[0061] According to Table 2, in the examples, the recovery rates for all metal elements were in the range of 100±20%, confirming that metal impurities can be recovered at high recovery rates regardless of the type of metal element. On the other hand, the comparative examples were unable to achieve a high recovery rate for a specific metal element (i.e., Fe), and therefore were confirmed to be unsuitable for the analysis of organic solvents containing trace amounts of such metal elements. [Explanation of symbols]

[0062] 10 Impurity recovery device 11 Impurity Collection Kit 12 Concentration column 13 Integrating flow meter 14 Liquid delivery pump 15 Purification means L1 Raw solution supply line L11 Sampling Line L12 Fluid supply line L13 Return Line V1~V4 Opening and closing valves

Claims

1. A method for recovering metal impurities in an organic solvent, comprising the steps of: passing the organic solvent as a sample liquid through an adsorbent and capturing the metal impurities in the sample liquid on the adsorbent; 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; and passing an eluent through the adsorbent after the replacement fluid has been passed through the adsorbent, and eluting the metal impurities captured by the adsorbent into the eluent and recovering the metal impurities, The method for recovering metal impurities, wherein the adsorbent is a porous molded body made of a sintered body of a mixed powder containing a dry gel powder having at least one of an ion exchange group and a chelating group and a thermoplastic resin powder.

2. the dry gel powder comprises a strongly acidic cation exchange resin; 2. The method for recovering metal impurities according to claim 1, wherein the thermoplastic resin powder comprises ultra-high molecular weight polyethylene.

3. 3. The method for recovering metal impurities according to claim 1, wherein the step of passing the sample liquid includes extracting a portion of the organic solvent supplied to a use point through a solvent supply line as the sample liquid and passing the portion through the adsorbent.

4. 4. The method for recovering metal impurities according to claim 3, wherein the step of passing the sample liquid includes passing the sample liquid that has been passed through the adsorbent through a purification member to purify it, and returning the purified sample liquid to the solvent supply line.

5. 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 passing the organic solvent as a sample liquid through the adsorbent; a replacement fluid supply means for supplying at least one of water and gas as a replacement fluid to the adsorbent; and an eluent passing means for passing an eluent through the adsorbent, The apparatus for recovering metal impurities, wherein the adsorbent is a porous molded body made of a sintered body of a mixed powder containing a dry gel powder having at least one of an ion exchange group and a chelating group and a thermoplastic resin powder.

6. the dry gel powder comprises a strongly acidic cation exchange resin; 6. The apparatus for recovering metal impurities according to claim 5, wherein the thermoplastic resin powder comprises ultra-high molecular weight polyethylene.

7. 7. The metal impurity recovery device according to claim 5, wherein the sample liquid passing means is connected to a solvent supply line that supplies the organic solvent to a use point, and has a sampling line that extracts a portion of the organic solvent flowing through the solvent supply line as the sample liquid and passes the sample liquid through the adsorbent.

8. a return line that connects the downstream side of the adsorbent in the sampling line to the solvent supply line and returns the sample liquid that has passed through the adsorbent to the solvent supply line; 8. The apparatus for recovering metal impurities according to claim 7, further comprising a purification member provided in the return line for purifying the sample liquid returned to the solvent supply line.

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