Extraction agent selection support device, extraction agent selection support method, and program

Abstract

To support selection of an extracting agent in a solvent extracting method.SOLUTION: An extracting agent selection support device, which supports selection of an extracting agent in a solvent extracting method, comprises: a molecular information obtaining part that obtains molecular information about diluent molecules and a plurality of extracting agent molecules which become candidates; an extracting agent candidate selecting part that calculates a binding energy value of a complex structure constituted of the plurality of extracting agent molecules and metallic ions to be extracted, and narrows down the extracting agent molecules which become candidates on the basis of the calculated binding energy value; a molecular dynamics calculating part that performs molecular dynamics calculation in a three-dimensional model including an organic phase and a water phase in a case where each of the narrowed-down extracting agent molecules is used, so as to calculate pressure tensor in an interface between the organic phase and the water phase; and an interface tension calculating part that calculates interface tension in the interface on the basis of the calculated pressure tensor of each of the narrowed-down extracting agent molecules.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an extractant selection support device, an extractant selection support method, and a program.

Background Art

[0002] One method for selectively extracting metal ions contained in an aqueous solution is the solvent extraction method (SX: Solvent Extraction). In the solvent extraction method, two immiscible phases are used, and a combination of an organic phase (organic solvent) and an aqueous phase (aqueous solution) is widely used. Metal ions bind to an extractant added to the organic phase near the two-phase interface and move into the organic phase. Therefore, the stability of the interface (phase separation property) greatly affects the extraction equilibrium and extraction rate of metal ions.

[0003] The phase separation property changes depending on the combination of the organic solvent (also called a diluent) and the extractant, and the specific gravity, interfacial tension, and viscosity of the diluent have a great influence. It is also related to the temperature of the system. In particular, when the interfacial tension is large, the phase separation property is good.

[0004] It is known that extractant molecules selectively bind to specific metal ions. This means that the bound state is stable, so the binding energy value serves as an index when selecting an extractant suitable for the intended use. The binding energy value can be calculated from quantum chemical calculations or molecular mechanics calculations.

[0005] Therefore, a method for selecting an extractant used for solvent extraction based on the interfacial tension has been studied. For example, Patent Document 1 discloses an apparatus for measuring the interfacial tension by the centrifugal liquid membrane method, which comprises measuring an ultrathin film in a phase-separated state.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, when experimentally measuring the interfacial tension and selecting an extractant using the above-described conventional technology, there is a problem that it takes time and cost as the number of candidate extractants increases.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to assist in the selection of an extractant in a solvent extraction method.

Means for Solving the Problems

[0009] To achieve the above object, an extractant selection support device according to an aspect of the present invention is an extractant selection support device for assisting in the selection of an extractant in a solvent extraction method, a molecular information acquisition unit that acquires molecular information of a diluent molecule and a plurality of candidate extractant molecules; an extractant candidate selection unit that calculates a binding energy value of a complex structure composed of the plurality of extractant molecules and a metal ion to be extracted, and narrows down candidate extractant molecules based on the calculated binding energy value; a molecular dynamics calculation unit that performs molecular dynamics calculation in a three-dimensional model including an organic phase and an aqueous phase when each of the narrowed-down extractant molecules is used, and calculates a pressure tensor at the interface between the organic phase and the aqueous phase; and an interfacial tension calculation unit that calculates an interfacial tension at the interface based on the pressure tensor calculated for each of the narrowed-down extractant molecules.

Advantages of the Invention

[0010] It is possible to assist in the selection of an extractant in a solvent extraction method.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0012] Hereinafter, embodiments of the present invention (the present embodiments) will be described with reference to the drawings.

[0013] (Functional Configuration of Extractant Selection Support Device) FIG. 1 is a diagram showing an example of the functional configuration of an extractant selection support device.

[0014] The extractant selection support device 1 according to the present embodiment is a device that supports the selection of an extractant in the solvent extraction method. Specifically, the extractant selection support device 1 includes a molecular information acquisition unit 11, an extractant candidate selection unit 12, a molecular dynamics calculation unit 13, an interfacial tension calculation unit 14, a display unit 15, and an extractant selection unit 16.

[0015] The molecular information acquisition unit 11 acquires molecular information of diluent molecules and a plurality of extractant molecules as candidates. The molecular information is information indicating the chemical structure of the molecule, and includes data such as the number and type of atoms constituting the molecule, and data indicating the relationship between atoms. The data indicating the relationship between atoms is data including the size of the atoms, the angle of the bond with the bonded atoms, and the like.

[0016] The extractant candidate selection unit 12 calculates the binding energy values of complex structures composed of each of a plurality of extractant molecules as candidates and the metal ions to be extracted, and narrows down the extractant molecules as candidates based on the calculated binding energy values. Note that the information indicating the metal ions to be extracted may be set in advance or may be obtained by the molecular information acquisition unit 11.

[0017] Specifically, the extractant candidate selection unit 12 models the complex structure of the extractant molecule and the metal ion based on the molecular information of the extractant molecule. Then, the extractant candidate selection unit 12 calculates the binding energy value of the complex structure. Here, the extractant candidate selection unit 12 may create a plurality of complex structures for each extractant molecule, and in that case, it may be determined to one complex structure based on the attributes such as the number of molecules and shape of the complex structure and the binding energy value. For example, the extractant candidate selection unit 12 may determine the complex structure with the lowest binding energy value, that is, the most stable complex structure.

[0018] Then, the extractant candidate selection unit 12 narrows down the extractant molecules as candidates based on the binding energy values of the complex structures calculated for each extractant molecule. For example, the extractant candidate selection unit 12 may narrow down to the extractant molecules constituting the complex structure with the binding energy value below the threshold.

[0019] The molecular dynamics calculation unit 13 generates a three-dimensional model of a system having an organic phase and an aqueous phase for each of the narrowed-down extractant molecules, performs molecular dynamics calculation in the generated three-dimensional model, and calculates the pressure tensor. The three-dimensional model is data indicating the arrangement of each molecule. The organic phase contains diluent molecules and extractant molecules, and the aqueous phase contains water molecules (counter ions if necessary).

[0020] Specifically, for each of the narrowed-down extractant molecules, the molecular dynamics calculation unit 13 generates, as a three-dimensional model, data indicating the arrangement of each molecule in a system having an organic phase and an aqueous phase based on the molecular information acquired by the molecular information acquisition unit 11. Here, the molecular dynamics calculation unit 13 generates a three-dimensional model in which each molecule is randomly arranged and dispersed in space. Then, the molecular dynamics calculation unit 13 performs molecular dynamics calculations to calculate the pressure tensor for each of the narrowed-down extractant molecules.

[0021] Based on the pressure tensor calculated for each of the narrowed-down extractant molecules, the interfacial tension calculation unit 14 calculates the interfacial tension at the interface between the two phases.

[0022] The display unit 15 displays, on a screen such as a display, information indicating the interfacial tension when each of the narrowed-down all extractant molecules is used. Note that the display unit 15 may display on another device, such as a terminal operated by the user.

[0023] Based on the value of the interfacial tension, the extractant selection unit 16 selects an optimal extractant. Further, the display unit 15 may display information indicating the selected extractant.

[0024] (Operation of the extractant selection support device) Next, the operation of the extractant selection support device 1 will be described with reference to the drawings. FIG. 2 is a flowchart showing an example of the flow of the extractant selection support process.

[0025] In response to a user's operation, the molecular information acquisition unit 11 acquires the molecular information of the diluent molecules and a plurality of candidate extractant molecules (step S11).

[0026] Next, the extractant candidate selection unit 12 selects one from the candidate extractant molecules (step S12), and calculates the binding energy value of the complex structure composed of the metal ion and the selected extractant (step S13). As described above, here, the extractant candidate selection unit 12 may create a plurality of complex structures for each extractant molecule. In that case, it may be determined to one complex structure based on the attributes such as the number of molecules and shape of the complex structure and the binding energy value. For example, the extractant candidate selection unit 12 may determine to the complex structure with the lowest binding energy value, that is, the most stable complex structure.

[0027] Regarding the plurality of complex structures, the modeled results may be displayed on the display unit 15 to accept the user's selection. Thereby, the user can select an appropriate complex structure with reference to the information indicating the complex structure.

[0028] Then, the extractant candidate selection unit 12 determines whether the binding energy value is less than or equal to the threshold value (step S14). Here, the reference value is a value set in advance as an acceptable binding energy value as an extractant.

[0029] If the extractant candidate selection unit 12 determines that the binding energy value is not less than or equal to the threshold value (step S14: NO), it returns to the process of step S12 to select an unselected extractant molecule. Also, if the extractant candidate selection unit 12 determines that the binding energy value is less than or equal to the threshold value (step S14: YES), the molecular dynamics calculation unit 13 generates a three-dimensional model of the system having an organic phase and an aqueous phase based on the molecular information of the diluent molecule and the selected extractant molecule (step S15). Here, the molecular dynamics calculation unit 13 may perform a structure optimization calculation by molecular mechanics (MM) calculation, molecular dynamics (MD) calculation, quantum chemistry (QM) calculation, or the like.

[0030] Next, the molecular dynamics calculation unit 13 calculates the pressure tensor at the interface by molecular dynamics calculation (step S16). The pressure tensor is represented as a tensor (Pxx, Pyy, Pzz) by the XYZ axes defined in advance in the space where the diluent molecules exist.

[0031] Specifically, the molecular dynamics calculation unit 13 executes a temperature increase calculation to simulate a state in which the temperature is gradually increased to room temperature in the generated three-dimensional model. Next, the molecular dynamics calculation unit 13 performs an NVT calculation to simulate such that the number of atoms, volume, and temperature are each maintained at specified values. Subsequently, the molecular dynamics calculation unit 13 performs an NPT calculation to simulate such that the number of atoms, pressure, and temperature are each maintained at specified values, and calculates the pressure tensor at the interface based on the data of the last 0.1 ns in the NPT calculation.

[0032] Next, the interfacial tension calculation unit 14 calculates the interfacial tension based on the pressure tensor (step S17). Specifically, the interfacial tension calculation unit 14 calculates the interfacial tension σ by the following formula (1).

[0033] σ = (L / 2) × {Pzz - (1 / 2) × (Pxx + Pyy)} ··· (1) Here, (Pxx, Pyy, Pzz) is the pressure tensor, and L is the cell size in the normal direction of the interface.

[0034] Next, the extractant selection support device 1 determines whether all extractants have been calculated (step S18). When the extractant selection support device 1 determines that there is an extractant that has not been calculated (step S18: NO), it returns to step S12, selects one from the extractants that have not been calculated yet, and executes the process.

[0035] When the extractant selection support device 1 determines that all extractants have been calculated (step S18: YES), the display unit 15 displays the calculation result of the interfacial tension (step S19).

[0036] Subsequently, the extractant selection unit 16 selects an extractant, and the display unit 15 displays information indicating the selected extractant (step S20). Specifically, the extractant selection unit 16 stores in advance information serving as a criterion for selecting an extractant based on surface tension, and selects an extractant based on the information. For example, the extractant selection unit 16 may select an extractant having a value of surface tension close to a reference value (for example, 20 [mN / m]). Further, the extractant selection unit 16 may select one extractant, or may select a plurality of extractants, and may also be determined based on the ranking of recommended extractants as a criterion.

[0037] Note that the extractant selection support device 1 may not include the extractant selection unit 16, and may not execute the processes of step S19 and step S20. In that case, the user may select an extractant based on the calculated result of the displayed surface tension.

[0038] Next, the hardware configuration of the extractant selection support device 1 will be described. FIG. 3 is a diagram showing an example of the hardware configuration of the extractant selection support device.

[0039] The extractant selection support device 1 is configured by a computer, and includes, for example, a CPU (Central Processing Unit) 101, a main storage device 102, an auxiliary storage device 103, an input device 104, a display device 105, a communication interface device 106, and a drive device 107. These devices are connected by a bus.

[0040] The CPU 101 is a main control unit that controls the operation of the extractant selection support device 1, and realizes various functions described later by reading and executing a program stored in the main storage device 102.

[0041] The main storage device 102 reads and stores a program from the auxiliary storage device 103 when the extractant selection support device 1 is started. The auxiliary storage device 103 stores the installed program, and also stores files, data, etc. necessary for various functions described later.

[0042] The input device 104 is a device for inputting various types of information, and is realized by, for example, a keyboard, a pointing device, or the like. The display device 105 is for displaying various types of information, and is realized by, for example, a display or the like. The communication interface device 106 includes a LAN card or the like and is used for connection to other devices or the like.

[0043] The program according to the present embodiment is at least a part of various programs for controlling the extractant selection support device 1. The program is provided, for example, by distribution of the storage medium 108 or download from a network. The storage medium 108 recording the program can use various types of storage media, such as a storage medium that optically, electrically, or magnetically records information, such as a CD-ROM, a flexible disk, a magneto-optical disk, or a semiconductor memory that electrically records information, such as a ROM or a flash memory.

[0044] Also, when the storage medium 108 recording the program is set in the drive device 107, the program is installed from the storage medium 108 via the drive device 107 into the auxiliary storage device 103. The program downloaded from the network is installed into the auxiliary storage device 103 via the communication interface device 106.

[0045] (Example) An example of the extractant selection support device 1 according to the present embodiment will be described. The metal ion to be extracted is Co 2+ , the diluent molecule is cyclohexane (C6H 12 ), and the candidate extractant molecules are (a) LIX63, (b) Versatic Acid 10 (VA10), (c) TNOA ((CH3(CH2)7)3N), (d) TBP (tributyl phosphate), and (e) PC-88A. The results of the implementation are shown below.

[0046] FIG. 4 is a diagram showing an example of a three-dimensional model. The three-dimensional model generated by the molecular dynamics calculation unit 13 may be arranged such that, for example, boxes 20 including an organic phase 21 and an aqueous phase 22 are arranged side by side in the XY direction. Further, the length Lx in the X direction and the length Ly in the Y direction of the box 20 are, for example, 50 angstroms each, and the length Lz in the Z direction of the box 20 is, for example, 100 angstroms.

[0047] The molecular dynamics calculation unit 13 generates, for example, two phases in the box 20: an organic phase in which about 25 extractant molecules are arranged in a box containing about 600 diluent molecules (cyclohexane), and an aqueous phase containing about 4300 water molecules.

[0048] FIG. 5 is a diagram showing an example of a molecular model of an extractant. (a) is a molecular model of the extractant molecule LIX63, (b) is a molecular model of the extractant molecule VA10, (c) is a molecular model of the extractant molecule TNOA, (d) is a molecular model of the extractant molecule TBP, and (c) is a molecular model of the extractant molecule PC-88A, illustrating the molecular information (information indicating the arrangement of each atom and the relationship of bonds) acquired by the molecular information acquisition unit 11.

[0049] FIG. 6 is a diagram showing an example of an interfacial tension calculation result screen. The interfacial tension calculation result screen 30 is an example of a screen displayed by the display unit 15 in step S19 of the extractant selection support process. On the interfacial tension calculation result screen 30, the name of each extractant and the interfacial tension calculated for each extractant are displayed in association with each other.

[0050] Further, in step S20 of the extractant selection support process, the display unit 15 displays information indicating the extractant selected by the extractant selection unit 16. For example, the extractant selection unit 16 selects TBP having a value close to a reference value (for example, 20 [mN / m]). The display unit 15 may display the selected TBP on the interfacial tension calculation result screen 30 in a different character color from the others.

[0051] According to the extractant selection support device 1 according to the present embodiment, the interfacial tension is calculated by molecular dynamics calculation and used as an index of phase separability, thereby enabling efficient selection of the extractant.

[0052] Further, the extractant selection support device 1 models the complex structure of each of a plurality of extractant molecules and a metal ion, and calculates the binding energy value of the complex structure. Then, the extractant selection support device 1 narrows down the extractant molecules to be candidates based on the calculated binding energy value, thereby accurately reducing the number of extractant molecules to be calculated by molecular dynamics calculation and reducing the calculation cost. In particular, it is known that extractant molecules selectively bind to specific metal ions. This means that the bound state is stable, so the binding energy value becomes an index when selecting an extractant suitable for the purpose of use. Therefore, the extractant molecules can be appropriately narrowed down based on the binding energy value.

[0053] The extractant candidate selection unit 12 may narrow down to extractant molecules whose calculated binding energy value is equal to or less than a threshold value. Thereby, the extractant molecules can be appropriately narrowed down.

[0054] The extractant selection support device 1 may further include an extractant selection unit 16 that selects an extractant based on the calculated interfacial tension. Thereby, the variation among users in the selection of the extractant can be suppressed, and selection based on a uniform criterion becomes possible.

[0055] Further, the extractant selection unit 16 may select an extractant having an interfacial tension value close to a preset reference value. If an extractant with too large an interfacial tension is selected, it is too stable to mix, so the interface is not activated. Conversely, if the interfacial tension is too small, it is not stable and will mix and not separate into two phases. Therefore, it is possible to support the selection of an appropriate extractant based on a reference value considering such a trade-off.

[0056] Further, the molecular dynamics calculation unit 13 may generate a three-dimensional model in which extractant molecules are randomly arranged by performing a structure optimization calculation. As a result, in creating the three-dimensional model, it is not necessary to specify the arrangement of all molecules, so the generation of the three-dimensional model can be realized by a simple operation.

[0057] Further, the molecular dynamics calculation unit 13 may calculate the pressure tensor by performing at least any one of a temperature increase calculation, an NVT calculation, and an NPT calculation. This makes it possible to attempt calculations for a large number of candidates, reducing costs and labor.

[0058] The extractant selection support device 1 may further include a display unit 15 that associates and displays the name indicating the extractant for each of the candidate extractant molecules and the information indicating the calculated interfacial tension. This makes it possible to present information to support the selection to the user.

[0059] As described above, the present invention has been described based on the present embodiment, but the present invention is not limited to the requirements shown in the above embodiment. Regarding these points, it can be changed without departing from the gist of the present invention, and can be appropriately determined according to the application form.

Industrial Applicability

[0060] The present invention can be applied to the selection of an extractant when selectively extracting metal ions contained in an aqueous solution by a solvent extraction method.

Explanation of Signs

[0061] 1 Extractant selection support device 11 Molecular information acquisition unit 12 Extractant candidate selection unit 13 Molecular dynamics calculation unit 14 Interfacial tension calculation unit 15 Display unit 16 Extractant selection unit 20 Box 21 Organic phase 22 Aqueous phase 30 Interface Tension Calculation Result Screen 101 CPU 102 Main Memory Device 103 Auxiliary Memory Device 104 Input Device 105 Display Device 106 Communication Interface Device 107 Drive Device 108 Memory Medium

Claims

1. An extractant selection support device for supporting the selection of an extractant in a solvent extraction method, comprising: a molecular information acquisition unit that acquires molecular information of diluent molecules and a plurality of candidate extractant molecules; an extractant candidate selection unit that calculates a binding energy value of a complex structure composed of the plurality of extractant molecules and a metal ion to be extracted, and narrows down candidate extractant molecules based on the calculated binding energy value; a molecular dynamics calculation unit that performs molecular dynamics calculations on a three-dimensional model including an organic phase and an aqueous phase when each of the narrowed-down extractant molecules is used, and calculates a pressure tensor at the interface between the organic phase and the aqueous phase; an interfacial tension calculation unit that calculates an interfacial tension at the interface based on the pressure tensors calculated for each of the narrowed-down extractant molecules. Extractant selection support device.

2. The extractant candidate selection unit narrows down to extractant molecules constituting the complex structure in which the calculated binding energy value is equal to or less than a threshold value. The extractant selection support device according to claim 1.

3. Further comprising an extractant selection unit that selects an extractant based on the calculated interfacial tension. The extractant selection support device according to claim 1 or 2.

4. The extractant selection unit selects the extractant having an interfacial tension close to a preset reference value. The extractant selection support device according to claim 3.

5. The molecular dynamics calculation unit generates the three-dimensional model in which the extractant molecules are randomly arranged by a structure optimization calculation. The extractant selection support device according to any one of claims 1 to 4.

6. The molecular dynamics calculation unit calculates the pressure tensor by performing at least any one of a temperature increase calculation, an NVT calculation, and an NPT calculation. The extractant selection support device according to any one of claims 1 to 5.

7. Further comprising a display unit that associates and displays the name indicating the extractant for each of the candidate extractant molecules and the information indicating the calculated interfacial tension. The extractant selection support device according to any one of claims 1 to 6.

8. A method executed by a computer for supporting the selection of an extractant in a solvent extraction method, comprising: a step of acquiring molecular information of diluent molecules and a plurality of candidate extractant molecules; Calculating the binding energy value of the complex structure composed of the plurality of extractant molecules and the metal ions to be extracted, and narrowing down the candidate extractant molecules based on the calculated binding energy value; Performing molecular dynamics calculations on a three-dimensional model including an organic phase and an aqueous phase when each of the narrowed-down extractant molecules is used, and calculating the pressure tensor at the interface between the organic phase and the aqueous phase; Calculating the interfacial tension at the interface based on the pressure tensor calculated for each of the narrowed-down extractant molecules. An extractant selection support method.

9. A computer for supporting the selection of an extractant in a solvent extraction method, Obtaining the molecular information of diluent molecules and a plurality of candidate extractant molecules; Calculating the binding energy value of the complex structure composed of the plurality of extractant molecules and the metal ions to be extracted, and narrowing down the candidate extractant molecules based on the calculated binding energy value; Performing molecular dynamics calculations on a three-dimensional model including an organic phase and an aqueous phase when each of the narrowed-down extractant molecules is used, and calculating the pressure tensor at the interface between the organic phase and the aqueous phase; Calculating the interfacial tension at the interface based on the pressure tensor calculated for each of the narrowed-down extractant molecules. A program for causing the above to be executed.

Images