Electrophoresis apparatus and electrophoresis method

Abstract

To provide a concentration and separation technique with further improved efficiency and further improved extendability of an apparatus.SOLUTION: An electrophoresis apparatus concentrates and separates a desired substance by moving ions along an electrophoresis path, which is provided in an electrophoresis medium and to which an electric field is applied, using an ion aqueous solution of a substance being the target of concentration and separation. The electrophoresis path is formed in the electrophoresis medium, which is composed of an insulator having a thermal conductivity of 30 W / mK or more and formed into a rectangular parallelepiped in a plate shape having a predetermined thickness, length, and width, so as to penetrate along a longitudinal direction of the electrophoresis medium in a flat plate shape. The electrophoresis apparatus further includes cooling means that forcibly cools the insulator from the outside, and counterflow generating means that generates a flow in a direction opposite to a movement direction of ions moving in the electrophoresis path with respect to the ion aqueous solution.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electrophoresis device and an electrophoresis method. [Background technology]

[0002] The majority of naturally occurring elements have multiple isotopes, and by enriching and separating these isotopes, they can be used as tracers, medical testing reagents, nuclear fuel, and other raw materials.

[0003] The most commonly used technique for isotope enrichment and separation is the centrifugation method, which separates elements that form gaseous compounds by centrifugal separation. However, there are many elements that do not form gaseous compounds, and centrifugation cannot be used for these elements.

[0004] Therefore, as a technology for enriching and separating isotopes from these gaseous elements that do not contain compounds, mass spectrometry has been proposed, in which ionized elements are accelerated in a vacuum through an electric field, and the curvature of the magnetic field varies depending on the mass, thereby enriching and separating them.However, because this method requires a large amount of electricity, the separated isotopes are expensive and not cost-effective.

[0005] In addition, electrophoresis has been proposed, which focuses on the migration speed of ions in a solution under an electric field, and separates and concentrates each ion based on the product of the difference in migration speed and the migration distance. However, since it takes a long time to achieve a high degree of enrichment, the separated isotopes are expensive, and the cost-effectiveness is poor.

[0006] In addition, lithium hydroxide (LiOH) is used to adjust the pH of the primary cooling water in PWRs (Pressurized Water Reactors), but natural lithium (Li) contains 7.5% 6 Li and 92.5% 7 Li is present, 6 Li acts as a neutron absorber, 6 Li is separated and removed 7Li must be enriched and separated. 6 Li and 7 Currently, the mercury amalgamation method, which utilizes a countercurrent exchange reaction between an aqueous LiOH solution and lithium amalgam (an alloy of lithium and mercury), is used to separate Li. However, because the use of mercury causes environmental pollution, an alternative Li separation technology to the mercury amalgamation method is desired.

[0007] Under these circumstances, the present inventors have proposed a multi-channel counter current electrophoresis (MCCCE) method, which introduces a countercurrent flow in which a solution flows in the opposite direction to the migration direction of ions, thereby achieving a concentration and separation function equivalent to that achieved when the migration distance is longer, even in a short migration path, and by forming multiple migration paths consisting of thin cylindrical capillaries in an insulator with high thermal conductivity to create multi-channels, it becomes possible to concentrate and separate large amounts of material, thereby significantly improving the concentration and separation function (e.g., Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6207148 [Patent Document 2] Patent No. 6425958 Summary of the Invention [Problem to be solved by the invention]

[0009] However, even this MCCCE method is still not sufficient in terms of efficiency for isotope enrichment and separation and the expandability of the equipment.

[0010] Therefore, an object of the present invention is to provide a concentration and separation technology that achieves further improvements in efficiency and expandability of the device. [Means for solving the problem]

[0011] The invention described in claim 1 is An electrophoresis device that concentrates and separates a desired substance by using an aqueous ion solution of the substance to be concentrated and separated and moving the ions along a migration path provided in a migration medium and to which an electric field is applied, comprising: the migration path is formed in a plate-like shape in a migration medium made of a flat insulator having a thermal conductivity of 30 W / mK or more and a predetermined thickness, length, and width, and penetrates the migration medium in a longitudinal direction of the migration medium; Furthermore, a cooling means for forcibly cooling the insulator from the outside; The electrophoresis apparatus is characterized by being provided with a countercurrent generating means for generating a flow in the aqueous ionic solution in a direction opposite to the direction of movement of ions moving in the migration path.

[0012] The invention described in claim 2 is 2. The electrophoretic device according to claim 1, wherein the migration medium is configured by providing a plurality of migration paths in a single insulator.

[0013] The invention described in claim 3 is 2. The electrophoretic device according to claim 1, wherein the migration medium is formed by laminating a plurality of insulators, each having one migration path, in a thickness direction.

[0014] The invention described in claim 4 is 4. The electrophoretic device according to claim 1, wherein the electrophoretic medium is made of a sintered body of boron nitride (BN).

[0015] The invention described in claim 5 is 5. The electrophoresis device according to claim 4, wherein the sintered body of boron nitride (BN) is impregnated with a resin.

[0016] The invention described in claim 6 is 6. The electrophoresis device according to claim 5, wherein the resin is a cyanoacrylate resin.

[0017] The invention described in claim 7 is 4. The electrophoresis apparatus according to claim 1, wherein the countercurrent generating means generates a pulsating flow to generate a countercurrent flow.

[0018] The invention described in claim 8 is 8. The electrophoresis apparatus according to claim 7, wherein the pulsating flow is generated using a tubing pump.

[0019] The invention described in claim 9 is An electrophoresis method for concentrating and separating a desired substance by using an aqueous ion solution of the substance to be concentrated and separated, and moving the ions along a migration path provided in a migration medium and to which an electric field is applied, comprising the steps of: a countercurrent generating means is used to generate a flow in the aqueous ionic solution in the migration path at a speed corresponding to the migration speed of the ions in a direction opposite to the direction of migration of the ions; This electrophoresis method is characterized by applying an electric field to a flat migration path formed in a migration medium composed of a flat insulator having a thermal conductivity of 30 W / mK or more and a predetermined thickness, length, and width, the flat migration path being formed so as to penetrate the insulator in the longitudinal direction, thereby causing the ions passing through the migration path to migrate and be concentrated and separated.

[0020] The invention described in claim 10 is 10. The electrophoresis method according to claim 9, wherein a plurality of the migration paths are provided, and concentration and separation are carried out in each of the migration paths.

[0021] The invention described in claim 11 is 11. The electrophoresis method according to claim 9, wherein a pulsating flow is generated in the countercurrent generating means.

[0022] The invention described in claim 12 is 12. The electrophoresis method according to claim 11, wherein the pulsating flow is generated by a tubing pump.

[0023] The invention described in claim 13 is 11. The electrophoresis method according to claim 9, wherein the substance to be enriched and separated is an isotope element.

[0024] The invention described in claim 14 is 14. The electrophoresis method according to claim 13, wherein the isotope element is lithium (Li). [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a concentration and separation technique that achieves further improvements in efficiency and scalability of the device. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic vertical cross-sectional view of an electrophoretic device according to an embodiment of the present invention. [Figure 2] 1A and 1B are a schematic front view and a schematic plan view, respectively, of a migration medium in an electrophoretic device according to an embodiment of the present invention. [Figure 3] FIG. 1 is a schematic longitudinal sectional view showing the configuration of a conventional MCCCE electrophoresis device. [Figure 4] FIG. 1A is a schematic front view of a migration medium in a conventional MCCCE electrophoresis device, and FIG. 1B is a schematic plan view of the migration medium. [Figure 5] This is a diagram explaining the velocity distribution of Hagen-Poiseuille flow. [Figure 6] FIG. 1 is a diagram illustrating the relationship between the temperature distribution and the concentration of an aqueous ionic solution in a conventional MCCCE electrophoresis device and an MCCCE electrophoresis device according to an embodiment of the present invention. [Figure 7] FIG. 1 is a diagram illustrating the relationship between yield and speed range in a conventional MCCCE electrophoresis device and an MCCCE electrophoresis device according to an embodiment of the present invention. [Figure 8] FIG. 1 is a diagram illustrating the relationship between the separation factor and the applied voltage in an MCCCE electrophoresis device with a cylindrical migration path. [Figure 9] FIG. 1 is a diagram illustrating the relationship between the separation factor and the applied voltage in an MCCCE electrophoresis device with a flat-plate migration path. [Figure 10] FIG. 1 is a diagram illustrating the change in Li concentration near the outlet of the LiCl solution in an MCCCE electrophoresis device with a flat-plate migration path. DETAILED DESCRIPTION OF THE INVENTION

[0027] [1] How this invention came to be First, the process leading to the completion of the present invention will be described.

[0028] 1. Basic Concept of the MCCCE Act First, the basic concept of the MCCCE method will be explained.

[0029] As described above, electrophoresis is a technique for enriching and separating ions by focusing on the migration speed of ions in a solution to which an electric field is applied, and separating each ion based on the product of the difference in migration speed and the migration distance. However, since the difference in mobility between isotopes is basically small, in order to enrich and separate isotopes, it is necessary to apply a high electric field to increase the migration distance and increase the difference in migration distance. However, when a high electric field is applied and a large current is passed, a large amount of Joule heat is generated, which causes turbulence such as convection in the solution and disrupts the migration of ions. Therefore, even if the migration distance is extended, there is a risk that the enrichment and separation of isotopes may not be sufficient.

[0030] Therefore, in the MCCCE method, by flowing the solution in the opposite direction to the ion migration (countercurrent flow) and making the flow rate approximately the same as the ion migration rate, it is possible to achieve a substantially long-distance migration in a short migration path, thereby improving the efficiency of concentration and separation. Furthermore, by providing multiple migration paths (channels) (multi-channeling) and performing concentration and separation while applying countercurrent flow in each migration path, large-volume processing is possible, resulting in even more efficient concentration and separation.

[0031] 2. Points to consider in the MCCCE method In the above-mentioned MCCCE method, the migration velocity ν E is given by the product of the electric field E and the mobility μ (ν E = μE), but the mobility μ is highly dependent on temperature. Therefore, in order to improve the performance of the MCCCE method, specifically to improve the concentration (separation factor) and efficiency, it is necessary to minimize the temperature distribution within the migration path and between the migration paths, thereby reducing the temperature dependency of the mobility μ and achieving uniformity in temperature, thereby achieving the migration velocity ν E It is necessary to ensure uniformity.

[0032] And the countercurrent velocity ν CC has a velocity distribution that is hydrodynamically determined by the shape of the migration path and the viscosity of the solution. Therefore, in order to improve the performance of the MCCCE method, it is necessary to control the migration velocity v E and countercurrent velocity ν CC The difference between (ν E -ν CC ) should be kept small, and its variance should be reduced to ensure uniformity of the migration velocity and countercurrent velocity, thereby increasing the difference in relative migration distance between isotopes.

[0033] 3. Problems with the conventional MCCCE method However, in the case of conventional MCCCE devices, which have a large number of thin cylindrical migration paths on a cylindrical BN plate serving as the migration medium, Joule heat generated within the migration path causes a widening of the temperature distribution within the migration path, and temperature distributions occur depending on the position of the migration path. As a result, it is not easy to optimize the temperature distribution within the migration path, the temperature distribution between the migration paths, and each of these temperature distributions to achieve uniformity in migration speed and countercurrent speed. Furthermore, it was found that these two temperature distributions limit performance improvement and make scalability difficult.

[0034] 4. MCCCE method according to the present invention Therefore, the inventors conducted various experiments and studies and found that when the MCCCE method is applied to an MCCCE device equipped with a planar migration path instead of the conventional cylindrical migration path, the temperature distribution within the migration path, the temperature distribution between the migration paths, and each of the temperature distributions can be optimized, and the uniformity of the migration velocity and countercurrent velocity can be sufficiently achieved, thereby enabling sufficient isotope enrichment and separation, and greatly improving the efficiency and scalability of isotope enrichment and separation.The completion of this invention is expected to be a major step toward practical enrichment using the MCCCE method.

[0035] [2] Implementation form Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In this embodiment, an aqueous LiCl solution is used as an ionic solution, and the concentration and separation of two isotopes contained in the aqueous LiCl solution is described. 6 Li and 7 The explanation is given using the example of enrichment and separation with Li, 48 Ca and 40 It can also be applied to the enrichment and separation of isotopes in aqueous solutions of other ions, such as Ca.

[0036] 1. Electrophoresis Device According to the Present Embodiment (1) Overall structure First, the overall configuration of the electrophoretic device according to this embodiment will be described.

[0037] Fig. 1 is a schematic vertical cross-sectional view illustrating the configuration of an electrophoretic device according to the present embodiment, and Fig. 2 is (a) a schematic front view and (b) a schematic plan view of a migration medium in the electrophoretic device according to the present embodiment.

[0038] 1 and 2, 1 denotes an electrophoresis device, 11 denotes a case, 12 denotes a migration medium, and 13 denotes a flat-plate migration path (channel). In FIG. 1, A and B denote the inlet and outlet, respectively, of a LiCl solution (aqueous ionic solution), C and D denote the inlet and outlet, respectively, of a hydrochloric acid solution added to compensate for H and Cl released outside the system during electrophoresis, E denotes the cathode, F denotes the anode, and G denotes an ion-exchange membrane. In FIG. 2, h denotes the thickness of the migration medium, d denotes the thickness of the migration path, L denotes the length of the migration path, w denotes the width of the migration path, y denotes the thickness direction of the migration medium, and z denotes the flow direction of the LiCl solution.

[0039] As shown in Fig. 1, the case 11 is formed in a rectangular parallelepiped shape, and a flat-plate-shaped migration medium 12 is disposed in the center. Inside the migration medium 12, a migration path (channel) 13 is formed in a flat plate shape with a thickness d × length L × width w. The inside of the case 11 is filled with a LiCl solution to be concentrated and separated. An anode F and a cathode E are disposed opposite each other with a predetermined distance between them, sandwiching the migration medium 12 between them.

[0040] In addition, from the viewpoint of more effectively removing heat from the migration medium 12, it is preferable that the case 11 is formed using an insulating material with high thermal conductivity, but this may be appropriately selected taking into account cost and effectiveness, and for example, acrylic resin or the like may be used.

[0041] With the case 11 filled with LiCl solution, the LiCl solution is allowed to flow from the inlet A to the outlet B. This causes the LiCl solution to start moving in the z direction (from the bottom to the top of the page) through the migration path 13.

[0042] After that, when a predetermined voltage is applied between the anode F and the cathode E, an electric field is applied to the migration medium 12 (more precisely, the migration path 13), and the migration path 13 to which the electric field is applied is filled with LiCl in the LiCl solution. + moves from the anode F side to the cathode E side, from the top to the bottom of the paper. + The flow direction of the LiCl solution is opposite to that of the LiCl solution.+ The flow of the LiCl solution acts as a countercurrent to the flow of the eluate, and as described above, a substantially long distance migration can be achieved in a short migration path, thereby enabling efficient concentration and separation.

[0043] In this case, the width w of the planar migration path 13 is much larger than the thickness d, so that the temperature distribution within the migration path and between the migration paths can be reduced compared to an MCCCE device equipped with a conventional cylindrical migration path, thereby reducing the temperature dependence of mobility and achieving temperature uniformity, thereby enabling more efficient isotope enrichment and separation. Furthermore, the planar migration path allows for easier expansion of the MCCCE device than a cylindrical migration path.

[0044] That is, by providing a plurality of migration paths 13 (multi-channeling) and performing concentration and separation in each migration path, it is possible to increase the throughput while suppressing the generation of turbulence and maintaining a laminar flow state. This multi-channeling can be achieved by forming a migration medium by providing a plurality of migration paths in a single insulator, or by stacking multiple insulators each having a single migration path in the thickness direction, which makes it easy to expand the MCCCE device.

[0045] (2) Each component Next, each of the components constituting the electrophoretic device according to the present embodiment will be described.

[0046] (a) Electrophoresis medium In this embodiment, the migration medium 12 in which the flat migration path 13 is formed is made of an insulating material with high thermal conductivity, specifically, a material with thermal conductivity of 30 W / mK or more, more preferably 50 W / mK or more, such as boron nitride (BN), and is formed into a flat plate having a predetermined thickness, length, and width. By forming the migration path 13 in such a migration medium 12 with high thermal conductivity, even when a high electric field is applied to the migration path 13, the generated Joule heat can be sufficiently removed, the generation of turbulence in the migration path 13 can be suppressed, and the generation of disturbances in the migration of ions can be suppressed.

[0047] As mentioned above, a sintered body such as BN is used for the electrophoretic medium 12. However, during sintering, voids (pores) are inevitably formed, and the ionic solution may penetrate into these voids (pores), reducing the insulating properties of the electrophoretic medium and causing the applied voltage to become unstable.

[0048] Furthermore, there is a risk that the hydrochloric acid passing through the pores of the electrophoretic medium 12 may come into contact with the copper plate arranged as a cooling means, causing copper to dissolve into the LiCl solution. The dissolved copper then deposits in the electrophoretic medium, reducing the insulating properties of the electrophoretic medium. Furthermore, if the ion exchange membrane G is an anion exchange membrane, the copper deposits on the ion exchange membrane G, causing it to lose its function as an ion exchange membrane.

[0049] Therefore, it is preferable to seal the voids (pores) of the sintered body that will serve as the migration medium in advance with a resin such as cyanoacrylate resin by using a method such as vacuum impregnation or pressure impregnation. This makes it possible to maintain high insulation properties and prevent copper elution, thereby enabling stable voltage application and maintaining the functionality of the ion exchange membrane.

[0050] (b)Migration path As described above, in this embodiment, the migration path 13 is formed in a flat plate shape with a thickness d, a width w, and a length L so as to penetrate longitudinally through the above-mentioned flat plate-shaped migration medium 12. Here, as described above, by setting the width w much larger than the thickness d, it is possible to optimize the temperature distribution within the migration path and the temperature distribution between the migration paths, thereby achieving uniformity in the migration speed and countercurrent speed, and enabling efficient isotope enrichment and separation.

[0051] Specifically, for example, in each experiment described below, a migration path 13 having a thickness (d) of 1 mm, a width (w) of 50 mm, and a length (L) of 50 mm was formed on a 5 mm x 50 mm x 50 mm flat migration medium (BN plate) 12. By increasing the thickness d, width w, and length L, the amount of LiCl solution passing through the migration path 13 can be increased, enabling large-scale concentration and separation. However, this also makes it more likely that turbulence will occur within the migration path 13, making it difficult to maintain a laminar flow state.

[0052] (c) Countercurrent generation means As mentioned above, the flow of LiCl solution from inlet A to outlet B is + The flow is countercurrent to the direction of movement of the particles, so the migration speed is slow. 7 Li + and fast migration speed 6 Li + By substantially increasing the difference between the migration distances of the two, it is possible to efficiently concentrate and separate the two.

[0053] In this case, it is preferable to add pulsation to the countercurrent flow to form a pulsating flow, which allows a countercurrent flow that is not a Hagen-Poiseuille flow to be formed even in the thickness direction d of the migration path 13, thereby enabling concentration and separation with a more uniform velocity distribution without position dependency (high velocity at the center and low velocity at the periphery).

[0054] It is preferable to use a tubing pump for liquid transfer when forming a pulsating flow, and among tubing pumps, it is preferable to use the "Smoothflow Pump" ("Smoothflow" is a registered trademark) manufactured by Takumina Corporation, which allows the liquid transfer rate and pulse period to be changed independently. By providing such a counterflow generating means, 7 Li and 6 The separation factor of Li can be steadily set to 1.03 (3%) to 1.04 (4%), which is comparable to the separation factor in the mercury amalgamation method.

[0055] (d) Cooling means In this embodiment, a cooling means such as a copper plate is provided on the outer periphery of the case 11 in contact with the migration medium 12 to cool the migration medium 12. This suppresses the temperature rise of the LiCl solution passing through the electric field, thereby suppressing the generation of turbulence and enabling stable concentration and separation.

[0056] (e) Ion exchange membrane In this embodiment, an ion exchange membrane G is provided below the inlet A for the LiCl solution. Either an anion exchange membrane or a cation exchange membrane may be used as the ion exchange membrane, and an appropriate membrane may be selected taking into consideration the advantages and disadvantages of each ion exchange membrane.

[0057] That is, when a cation exchange membrane is used as the ion exchange membrane, the Li in the LiCl solution flowing in from the inlet A of the LiCl solution is + 80-95% of the cations in the LiCl solution pass through the cation exchange membrane and escape from the system. + As a result, the concentration of Li + However, the copper dissolved in the LiCl solution is prevented from depositing on the ion exchange membrane, which prevents the efficiency of concentration and separation from decreasing.

[0058] In contrast, when an anion exchange membrane is used, Li + However, copper eluted into the LiCl solution may precipitate and accumulate on the ion exchange membrane, which may result in a decrease in the efficiency of concentration and separation.

[0059] For example, when a cation exchange membrane is used as the ion exchange membrane, the LiCl in the LiCl solution flowing in from the inlet A of the LiCl solution is + 80-95% of the cations in the LiCl solution pass through the cation exchange membrane and escape from the system. + As a result, the concentration of Li +The concentration becomes low, and the efficiency of concentration and separation decreases.

[0060] In contrast, when an anion exchange membrane is used, Li + Since the escape of the ions to the outside of the system is prevented, the efficiency of concentration and separation is not reduced, and more efficient concentration and separation can be performed.

[0061] 2. Electrophoresis Method According to the Present Embodiment Next, an electrophoresis method performed using the above-described electrophoresis apparatus will be described.

[0062] First, the case 11 is filled with a LiCl solution and hydrochloric acid. Then, the LiCl solution is flowed from the inlet A to the outlet B, and simultaneously, a predetermined voltage is applied between the cathode E and the anode F. This applies an electric field to the flat-plate migration path 13, and the LiCl solution flows in the flat-plate migration path 13 against the flow of the LiCl solution. + begins to move from the cathode E side (top of the paper) toward the anode F side (bottom of the paper).

[0063] In this way, the flow of LiCl solution is countercurrent, and Li + By moving in the flat electrophoresis track 13, 6 Li + and 7 Li + The difference in migration distance between 6 Li + is on the upstream side of the counterflow, and has low mobility 7 Li + became unevenly distributed downstream, 6 Li and 7 By continuing this operation for a predetermined time, 6 The LiCl solution with increased Li enrichment (separation factor) is placed on the cathode E side. 7 A LiCl solution with an increased Li enrichment (separation factor) can be extracted from the anode F side.

[0064] 3. Theoretical consideration of the superiority over the conventional MCCCE method Next, the superiority of the MCCCE method according to this embodiment over the conventional MCCCE method will be theoretically considered.

[0065] (1) Temperature distribution in the migration path In electrophoresis, the temperature (T) distribution in the migration path is given by solving the heat conduction equation shown in the following formula (1) using the boundary conditions of the migration path shape.

[0066]

number

[0067] where J is the heat flow rate (W / m 2 ), λ is the thermal conductivity (W / mK), and gradT is the temperature gradient.

[0068] (a) Temperature distribution in a conventional MCCCE electrophoresis device Fig. 3 is a schematic longitudinal cross-sectional view showing the configuration of a conventional MCCCE electrophoresis device, and Fig. 4 is (a) a schematic front view and (b) a schematic plan view of the migration medium in the conventional MCCCE electrophoresis device. In Fig. 3, reference numeral 14 denotes a cooling means provided on the outer peripheral side of the migration medium 12. In each experiment described below, the migration medium 12 is, for example, a 20 mm thick cylindrical BN plate with 0.8 mm diameter cylindrical holes arranged at 4 mm intervals as migration paths 13.

[0069] In the case of the cylindrical migration path 13 shown in Figures 3 and 4, focusing on one migration path 13, assuming its radius to be a, and determining the temperature at a certain position (radius r) within the migration path 13, the temperature T(r) can be expressed as a function of radius r, as shown in the following equation (2).

[0070]

number

[0071] Here, T0 is the initial temperature (the temperature at the start of concentration separation), T mis the temperature rise determined by Joule heat, and ρ is the power density (W / m 3 ), λ W is the thermal conductivity of water (W / mK).

[0072] On the other hand, if the radius of the migration medium (BN plate) 12 on which a plurality of similar cylindrical migration paths 13 are provided is A (mm), the position (radius) of the migration paths 13 is R (m), and it is approximated that the heat generated in the migration paths 13 is uniformly distributed within the migration medium (BN plate) 12, T0 shown in the above equation can be expressed as the following equation (3), which shows that T0 depends on the position R of the migration path 13.

[0073]

number

[0074] In the above equation, ρ aν is the power density (W / m) averaged over the migration medium (BN plate) of the power generated in the migration path. 3 ), λ BN is the thermal conductivity of the migration medium, T BN is the temperature rise of the electrophoretic medium determined by Joule heat, T c is the temperature at the periphery of the migration medium.

[0075] At this time, since the mobility depends on the temperature as described above, in the case of a conventional cylindrical migration path, the temperature rise T determined by Joule heat in one migration path 13 m and the temperature rise T determined by Joule heat in the migration medium 12. BN The shape of the device needs to be optimized so that the size of the T BN corresponds to the difference in the optimal countercurrent velocity for each migration lane, so in reality, T m and T BN It is inevitable that there will be a difference of about 10°C between

[0076] (b) Temperature distribution in the MCCCE electrophoresis device according to the present embodiment In contrast, in the case of the MCCCE electrophoresis device according to the present embodiment, which includes the flat-plate migration path 13 shown in FIGS. 1 and 2, as described above, the temperature distribution can be considered to be uniform in the width direction, where the width is much larger than the thickness. Therefore, the temperature distribution in the flat-plate migration path 13 depends on the thickness y direction of the migration medium 12, and the temperature T(y) can be expressed by the following equation (4):

[0077]

number

[0078] From the above formula (4), in the case of the MCCCE electrophoresis device according to the present embodiment, the temperature rise T m is the power density ρ in the migration path 13 and the thermal conductivity λ of water. W Although the formula is almost the same as equation (2), the thermal conductivity (λ W ) changes from 4 in equation (2) to 2.

[0079] In the above, the influence of the side edges of the migration path is ignored, but in reality, it is known that if the migration path is 50 mm wide, the influence of the edges can be ignored.

[0080] (2) Countercurrent velocity distribution (a) Velocity distribution in a conventional MCCCE electrophoresis device In conventional MCCCE electrophoresis devices, the countercurrent flow (flow of ionic solution) in the cylindrical migration channel is known to be a laminar flow called Hagen-Poiseuille flow, based on the Reynolds number obtained from the size of the device and the migration velocity of the ionic solution. The velocity distribution of this Hagen-Poiseuille flow is shown in Figure 5.

[0081] As shown in FIG. 5, in the case of a cylindrical migration path 13, the velocity distribution ν(r) in the migration path 13 can be expressed as a quadratic function in which the velocity at the wall surface (the surface of the migration medium 12) is 0 and the velocity at the center of the migration path is maximum, specifically, as shown in the following equation (5). The maximum velocity at the center of the migration path 13 is the average velocity ν av It turns out that it is twice as large.

[0082]

number

[0083] Now, if we convert the velocity distribution ν(r) as a function of position into the distribution of yield Y per unit velocity (dY / dν), we get (dY / dν)=2πr, (dν / dr)=[(4ν0 / a 2 )·r], it can be seen that (dY / dν) is a constant, as shown in the following equation (6).

[0084]

number

[0085] (b) Velocity distribution in the MCCCE electrophoresis device according to this embodiment In contrast, in the case of the MCCCE electrophoresis device according to the present embodiment, which includes the flat-plate type migration path 13 shown in FIG. 2, the velocity distribution in the migration path 13 is such that the width w is much larger than the thickness d, and the wall where the velocity is zero is only in the thickness direction. Considering that there is essentially no boundary in the width direction and the temperature distribution is uniform, the velocity distribution ν(y) in the migration path 13 can be expressed as in the following equation (7) by substituting the migration path radius a with the migration path thickness d and the axial direction r with the thickness direction y in equation (5). The maximum velocity at the center of the migration path is the average velocity ν av It turns out that it is 1.5 times larger than the

[0086]

number

[0087] Similarly, if we convert the velocity distribution ν(y) as a function of position into the distribution of yield Y per unit velocity (dY / dν), we get (dY / dy)=1, (dν / dy)=[(3ν0 / a 2 )·y], it can be expressed as in the following equation (8), which shows that (dY / dν) is not a constant but is related to ν.

[0088]

number

[0089] FIG. 6 shows how the flow rate relates to the concentration of the ionic aqueous solution in the conventional MCCCE electrophoresis device and the MCCCE electrophoresis device according to the present embodiment. In FIG. 6, the vertical axis represents the yield, while the horizontal axis represents the flow rate, with the average flow rate v av represents the flow velocity when is set to 1. The thin solid line represents the results for a conventional MCCCE electrophoresis device (cylindrical migration path), and the thick dashed line represents the results for the MCCCE electrophoresis device (flat migration path) according to the present embodiment.

[0090] As shown in FIG. 6, in the case of a conventional MCCCE electrophoresis device (cylindrical migration path), (dY / dν) is a constant as shown in Equation (6), and therefore, 0 to 2.0 (2ν av ) yields are uniformly around 1%.

[0091] The yield Y is calculated by multiplying the above equation (6) by ν to obtain the initial velocity v E to maximum speed v m By integrating up to this, it can be shown as in the following equation (9).

[0092]

number

[0093] On the other hand, in the case of the MCCCE electrophoresis device (flat-plate type electrophoresis track) according to the present embodiment, (dY / dν) is related to ν as shown in formula (8), so that the maximum velocity of 1.5ν av The yield increased significantly at 1.5ν, reaching a yield of 10%. av It can be seen that a high yield can be obtained by taking out the crystals near the temperature.

[0094] The yield Y is calculated by multiplying the above equation (8) by ν to obtain the initial velocity v E to maximum speed v m By integrating up to this, it can be expressed as the following equations (10) and (11).

[0095]

number

[0096]

number

[0097] The yield Y and velocity width (v m -v E ) is shown in Figure 7. From Figure 7, it can be seen that the yield in the flat migration path is an order of magnitude higher than that in the cylindrical migration path. This result is thought to be due to the fact that the countercurrent velocity in the flat migration path is more uniform than that in the cylindrical migration path. [Example]

[0098] In the following examples, the superiority of an MCCCE electrophoresis device with a planar migration path over a conventional MCCCE electrophoresis device with a cylindrical migration path was confirmed through an experiment in which an aqueous LiCl solution was concentrated and separated.

[0099] Here, the conventional MCCCE electrophoresis device with cylindrical migration paths was used, which had the cylindrical migration medium and migration paths shown in Fig. 4 and the configuration shown in Fig. 3. Specifically, a cylindrical BN plate (80 mm diameter × 20 mm thickness) was used as the migration medium, and cylindrical migration paths with 0.8 mm diameter were arranged at 4 mm intervals in a 40 mm diameter section.

[0100] On the other hand, as the MCCCE electrophoresis device with a flat-plate migration path according to this embodiment, an electrophoresis device with the configuration shown in Fig. 1 was used, which includes the flat-plate migration medium and migration path shown in Fig. 2. Specifically, a resin-impregnated flat BN plate (thickness 5 mm × width 50 mm × length 50 mm) was used as the migration medium, and a migration path with a thickness of 1 mm × width 50 mm × length 50 mm was formed.

[0101] In all the MCCCE electrophoresis devices, the countercurrent velocity (ie, the inflow velocity of the LiCl solution) was set to 0.39 mm / sec, and a cation exchange membrane was used as the ion exchange membrane.

[0102] The experiment was carried out by varying the applied voltage. + Ion electrophoresis is carried out, 7 Li and 6 The separation factor of Li, i.e., (after electrophoresis [ 7 Li / 6 Li]) / (before electrophoresis [ 7 Li0 / 6 Li0]) was obtained.

[0103] Figure 8 shows the results for the MCCCE electrophoresis device with a cylindrical migration path, and Figure 9 shows the results for the MCCCE electrophoresis device with a flat migration path. In Figures 8 and 9, the vertical axis represents the separation factor [( 7 Li / 6 Li) / ( 7 Li0 / 6 Li0)], and the horizontal axis is the applied voltage (V).

[0104] From FIG. 8, it can be seen that in the case of an MCCCE electrophoresis device with a cylindrical migration path, the maximum separation factor was approximately 1.03, or 3%, and that the separation factor fluctuated significantly after the applied voltage exceeded 280 V.

[0105] In contrast, in the case of the MCCCE electrophoresis device with a flat-plate migration path, as shown in Figure 9, the maximum separation factor was just under 1.05, i.e., just under 5%, and no significant fluctuations in the separation factor were observed even after the applied voltage exceeded 280 V, and the separation factor increased even at 350 V or higher.

[0106] The change in Li concentration near the outlet of the LiCl solution in an MCCCE electrophoresis device with a flat-plate migration path is shown in Figure 10. In Figure 10, the vertical axis represents the Li concentration (mg / L) and the horizontal axis represents the applied voltage (V).

[0107] As can be seen from Figure 10, in the case of an MCCCE electrophoresis device with a flat-plate migration path, the Li concentration decreases exponentially as the applied voltage increases. The higher the rate of change in yield with respect to voltage, the higher the separation factor. Therefore, by using an MCCCE electrophoresis device with a flat-plate migration path, in which the separation factor and the change in yield with respect to voltage show consistent behavior, further improvements can be expected in the future through parameter investigations.

[0108] Further investigation revealed that when a flat-plate type MCCCE electrophoresis device is used, it is possible to achieve an extremely high separation factor of approximately 1.13 (13%).

[0109] Such high separation factors are currently 7 This separation factor far exceeds that of the mercury amalgamation method, which is the only Li enrichment and separation technology currently used (approximately 1.02 to 1.07). By using a planar MCCCE electrophoresis device, a high separation factor can be achieved without causing environmental pollution. 7 It is clear that efficient enrichment and separation of Li can be expected.

[0110] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiments within the scope of the same or equivalent to the present invention. [Explanation of symbols]

[0111] 1. Electrophoresis apparatus 11 cases 12 Running medium 13 Swimming channel 14 Cooling means A Inlet for LiCl solution (ionic aqueous solution) B. Outlet for LiCl solution (ionic aqueous solution) C Hydrochloric acid solution inlet D Hydrochloric acid solution outlet E cathode F Anode G. Ion exchange membrane L length of the migration path d Thickness of the migration path h Thickness of the electrophoresis medium w Width of the migration path y: thickness direction of the electrophoretic medium z Flow direction of the solution

Claims

1. An electrophoresis device that concentrates and separates a desired substance by using an aqueous ion solution of the substance to be concentrated and separated and moving the ions along a migration path provided in a migration medium and to which an electric field is applied, comprising: the migration path is formed in a plate-like shape in a migration medium made of a plate-like insulator having a thermal conductivity of 30 W / mK or more and a predetermined thickness, length, and width, and penetrates the migration medium along the length direction of the migration medium; Furthermore, a cooling means for forcibly cooling the insulator from the outside; An electrophoresis apparatus comprising a countercurrent generating means for generating a flow in the aqueous ionic solution in a direction opposite to the direction of movement of ions in the migration path.

2. 2. The electrophoretic device according to claim 1, wherein the electrophoretic medium is configured by providing a plurality of electrophoretic paths in a single insulator.

3. 2. The electrophoretic device according to claim 1, wherein the electrophoretic medium is formed by laminating a plurality of insulators, each having one electrophoretic path, in the thickness direction.

4. 4. The electrophoretic device according to claim 1, wherein the electrophoretic medium is made of a sintered body of boron nitride (BN).

5. 5. The electrophoretic device according to claim 4, wherein the sintered body of boron nitride (BN) is impregnated with a resin.

6. 6. An electrophoretic device according to claim 5, wherein the resin is a cyanoacrylate resin.

7. 4. An electrophoresis apparatus according to claim 1, wherein the countercurrent generating means generates a pulsating flow to generate a countercurrent flow.

8. 8. The electrophoresis apparatus according to claim 7, wherein the pulsating flow is generated using a tubing pump.

9. An electrophoresis method for concentrating and separating a desired substance by using an ion aqueous solution of the substance to be concentrated and separated, and moving the ions along a migration path provided in a migration medium and to which an electric field is applied, comprising the steps of: a countercurrent generating means is used to generate a flow in the aqueous ionic solution in the migration path at a speed corresponding to the migration speed of the ions in a direction opposite to the direction of migration of the ions; An electrophoresis method comprising: applying an electric field to a flat migration path formed in a migration medium composed of a flat insulator having a thermal conductivity of 30 W / mK or more and a predetermined thickness, length, and width, the flat migration path being formed so as to penetrate the insulator in the longitudinal direction; thereby causing the ions passing through the migration path to migrate and be concentrated and separated.

10. 10. The electrophoresis method according to claim 9, wherein a plurality of the migration paths are provided, and concentration and separation are carried out in each of the migration paths.

11. 11. The electrophoresis method according to claim 9, wherein a pulsating flow is generated in the countercurrent generating means.

12. 12. The electrophoresis method according to claim 11, wherein the pulsating flow is generated by a tubing pump.

13. 11. The electrophoresis method according to claim 9, wherein the substance to be enriched and separated is an isotope element.

14. 14. The electrophoresis method according to claim 13, wherein the isotope element is lithium (Li).

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