Chip structure and method for separating rare earth ions by microfluidic counter-current chromatography

Abstract

The application relates to a chip structure and a method for separating rare earth ions by microfluid reverse flow extraction chromatography, and belongs to the technical field of microfluid extraction and separation. The process for separating a plurality of coexisting complex systems of rare earth ions is simple, the separation flow is short, the separation efficiency between the rare earth ions is high, and the product purity of the component effluent is high. The chip structure comprises an extraction module composed of a microchannel and three gradient elution modules. An aqueous phase feed liquid containing a plurality of rare earth element ions is contacted with an extractant in the microchannel in parallel flow countercurrent contact, so that the plurality of rare earth element ions are separated by step-by-step extraction and separation in groups. Three gradient elution modules are used to separately elute the rare earth ions loaded in the organic phase after the extraction in groups. A gradient elution liquid with continuously increasing hydrochloric acid concentration is used for step-by-step gradient elution. The organic phase is countercurrently contacted with the gradient elution liquid in the microchannel, so that the plurality of rare earth element ions loaded in the organic phase after the extraction in groups are separated by step-by-step gradient elution again.

Description

Technical Field

[0001] The present invention relates to the technical field of microfluid extraction and separation, and in particular to a chip structure and method for microfluid countercurrent extraction chromatography grouping separation of rare earth ions. Background Art

[0002] The 14 lanthanide rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) have similar outer electron shell structures and chemical properties, making their separation extremely difficult. Currently, solvent extraction is the most commonly used method for separating these 14 lanthanide rare earth elements. This method is based on the "tetrad effect," a phenomenon in which the chemical properties of lanthanide rare earth ions gradually change as their 4f outer electron shells become filled to 1 / 4, 1 / 2, 3 / 4, and finally completely. This method repeatedly separates the 14 rare earth elements into separate groups. Generally, with Nd / Pm, Gd, and Ho / Er as the dividing points (Gd is the common point), each four elements are grouped together, namely La-Ce-Pr-Nd, Pm-Sm-Eu-Gd, Gd-Tb-Dy-Ho, and Er-Tm-Yb-Lu. The relationship between their liquid-liquid partition coefficient and atomic number constitutes four characteristic curves.

[0003] In industry, rare earth extraction and separation process design typically takes into account the thermodynamic differences in the extraction equilibrium of rare earth ions, as described above, due to the "quadruple effect." This approach exploits differences in the complex stability constants of complexes formed between organic extractants and rare earth ions of varying ionic radii to achieve mutual separation of rare earth ions. To obtain a single, high-purity rare earth product, a multi-step, cascade fractionation extraction process using a multi-stage mixer-settler tank is often required. For example, in the P507-chlorinated rare earth system, which is commonly used for rare earth extraction, the initial separation is typically performed between Nd / Sm. The acidity of the hydrochloric acid wash or stripping solution is then adjusted to group the ions between Dy / Ho, followed by further grouping between Gd / Tb / Dy. The acidity of the hydrochloric acid wash or stripping solution is then adjusted again for further refinement within each group. Separation of difficult-to-separate heavy rare earth groups may even require a change of extractant, making the entire process extremely complex, inefficient, and lengthy. In practice, achieving effective group separation often requires continuous extraction in dozens or even hundreds of mixer-settler tanks. The higher the purity requirement of rare earth products, the more cascade separation stages of mixing and clarification tanks are required, which occupies a large area and has high maintenance costs.

[0004] Research reports indicate that the kinetic separation coefficient for rare earth extraction is higher than the thermodynamic equilibrium separation coefficient. Yukinor Minagawa et al. separated Pr and Nd based on differences in extraction rates, achieving a separation coefficient of 5.0, while the conventional Pr / Nd thermodynamic equilibrium separation coefficient is only about 1.4. Abdul Azis et al. also achieved kinetically enhanced rare earth separation by adding a certain concentration of aminocarboxylic acid complexing agent (such as DTPA) to a rare earth aqueous solution and exploiting the differences in the rates at which rare earth ions form complexes with the aminocarboxylic acid complexing agent or the dissociation rates of the complexes. The study found that the kinetic separation coefficients for Y / Er and Y / Tm were 1.53 times and 3.72 times the thermodynamic equilibrium separation coefficients, respectively. However, current research on the separation of rare earth ions using kinetic methods has mostly focused on the separation of only two rare earth ions, and has been unable to achieve the simultaneous separation of multiple rare earth ions under conditions where multiple rare earth ions coexist.

[0005] Microfluidic extraction, an emerging process intensification method, has demonstrated significant advantages in the field of rare earth extraction and separation. Compared with traditional stirred-mixing and settling tanks, microfluidic extraction's most significant advantages lie in the significantly reduced characteristic mixing and reaction times within the microchannels, which are related to the diffusion mass transfer rate. Furthermore, the mass transfer and reaction processes at the microscopic interfaces are controllable. By designing appropriate channel structure, flow patterns, and fluid flow parameters within the channels, the reaction and separation processes can be precisely controlled. Furthermore, because the droplet dispersion behavior within the microchannel reactor can be manipulated, the trade-off between efficient droplet dispersion and rapid coalescence, which is difficult to overcome in traditional stirred extraction, is avoided, effectively preventing emulsification and solvent loss that often occur in traditional stirred extraction processes. For separating rare earth elements with very similar properties and structures, microfluidic extraction can achieve an extremely large dispersed phase surface area, short mass transfer distances within the microchannels, and rapid interface turnover. Consequently, microfluidic extractions reach equilibrium extremely quickly (typically, reaching equilibrium takes only seconds or even fractions of a second). However, to date, most of the research reports on microfluidic extraction and separation of rare earths have focused on the separation of rare earth elements in pairs, and it is impossible to achieve the simultaneous group separation of multiple rare earth element ions under the conditions of coexistence of multiple rare earth element ions.

[0006] The principle of chromatographic gradient elution separation is to use an eluent with continuously changing concentration or polarity to continuously elute and separate multiple target components with different capacity factors, so that each effluent component has a suitable capacity factor and all components can be optimally separated in the shortest time. Liu Chenming et al. used gradient elution high performance liquid chromatography to separate a mixture containing five organic acids at the same time. First, a mixture containing formic acid, acetic acid, lactic acid, succinic acid and propionic acid was pumped into the resin column so that it was co-adsorbed on the resin column. Then, using an eluent composed of a mixture of acetonitrile and potassium dihydrogen phosphate, the relative content ratio of acetonitrile and potassium dihydrogen phosphate was controlled to change gradiently over time, so that the formic acid, acetic acid, lactic acid, succinic acid and propionic acid adsorbed on the resin stationary phase were separated. Liu Anxi et al. loaded a resin Cl-P204 column with the extractant P204 adsorbed onto it. A mixture containing five rare earth ions, La, Ce, Nd, Sm, and Eu, was then pumped into the column for adsorption. The adsorbed rare earth ions were then eluted with aqueous hydrochloric acid at concentrations increasing over time from 0.1 mol / L to 1.0 mol / L. Different elution times yielded effluents containing different rare earth ions: La, Ce, Nd, Sm, and Eu. However, this method is incapable of grouping and separating complex systems containing fourteen lanthanide rare earth ions simultaneously. Separation of adjacent heavy rare earth elements, which share very similar physicochemical properties, is particularly challenging. Traditional gradient elution separations of rare earth ions using resin stationary phase columns require increasing the column diameter ratio and number of columns as the number of coexisting rare earth ions in the aqueous feed increases. This, coupled with the complex process parameters required to manipulate these parameters, results in low separation efficiency for complex systems containing multiple rare earth ions.

[0007] Therefore, it is necessary to study a new chip structure and method for microfluidic countercurrent extraction chromatography group separation of rare earth ions to address the shortcomings of the existing technology and to solve or alleviate one or more of the above problems. Summary of the Invention

[0008] In view of this, the present invention provides a chip structure and method for group separation of rare earth ions by microfluidic countercurrent extraction chromatography. By bringing an aqueous phase liquid containing multiple rare earth element ions into countercurrent contact with an organic extractant in a microchannel in parallel flow, the multiple rare earth element ions can be grouped and extracted and separated step by step according to the "quadruple group effect". Then, three groups of gradient elution modules are used to perform step-by-step gradient elution on the rare earth ions that have been grouped and extracted into the loaded organic phase to achieve group elution and separation. This method has a simple process for group separation of complex systems with multiple rare earth coexistence, a short separation process, a high separation efficiency between rare earth ions, and a high purity of the component effluent products.

[0009] In one aspect, the present invention provides a chip structure for separating rare earth ions by microfluidic countercurrent extraction chromatography. The chip structure comprises an extraction module, a first gradient elution module, a second gradient elution module, and a third gradient elution module. The first gradient elution module, the second gradient elution module, and the third gradient elution module are sequentially arranged in three directions around the periphery of the extraction module and interwoven to form a "half-cross" planar grid structure.

[0010] The extraction module, the first gradient elution module, the second gradient elution module and the third gradient elution module are all microchannel reactors in the shape of a parallelogram consisting of four microchannels;

[0011] The extraction module and any gradient elution module are interwoven and connected in such a way that the two share a microchannel at the connecting edge; the rare earth ion aqueous phase feed solution in the extraction module and the extractant in the corresponding gradient elution module flow in counter-current contact in the shared microchannel;

[0012] The rare earth ion aqueous phase feed liquid in the extraction module flows in the following manner: it is pumped in from the aqueous phase feed liquid inlet, then flows sequentially through the microchannels on three sides, namely, the microchannel shared by the extraction module and the first gradient elution module, the microchannel shared by the extraction module and the second gradient elution module, and the microchannel shared by the extraction module and the third gradient elution module, and finally is discharged and collected from the aqueous phase feed liquid outlet; the aqueous phase feed liquid inlet and the aqueous phase feed liquid outlet are respectively arranged at the two ends of the fourth side of the extraction module; the fourth side refers to the fourth side of the parallelogram-shaped extraction module excluding the aforementioned three microchannels shared with the gradient elution module, and the fourth side does not pass through the aqueous phase feed liquid;

[0013] The extractant in any gradient elution module flows in the following manner: it is pumped in from the extractant inlet, then flows sequentially through the microchannel shared by the gradient elution module and the extraction module, as well as the second and third microchannels sequentially connected to the shared microchannel, and finally discharged and collected from the extractant outlet; the extractant inlet and the extractant outlet are respectively located at the ends of the fourth side of the gradient elution module; the fourth side is the fourth side of the gradient elution module excluding the microchannel shared with the extraction module and the second and third microchannels sequentially flowing through the extractant, and the fourth side does not flow through the extractant;

[0014] The second microchannel and the third microchannel are both structures with an eluent inlet and an eluent outlet at both ends; the eluent in the second microchannel and the eluent in the third microchannel flow in a countercurrent contact flow with the extractant flowing through.

[0015] The reverse contact flow in the present invention specifically refers to reverse relative movement in the form of parallel flow.

[0016] In any of the above aspects and possible implementation manners, further provided is an implementation manner, wherein the structural parameters of the microchannels constituting the extraction module, the first gradient elution module, the second gradient elution module or the third gradient elution module include that the cross section of the microchannels is circular, the diameter of the cross section is 0.05 mm to 2.0 mm, and the length of the microchannels is 10 mm to 200 mm.

[0017] In any of the above aspects and possible implementation manners, further provided is an implementation manner, wherein the aqueous phase feed liquid outlet is connected with a step component collector, and a component effluent storage tank is arranged at the outlet of the step component collector.

[0018] In any of the above aspects and possible implementation manners, further provided is an implementation manner, wherein the elution liquid inlets of the second microchannels and the third microchannels are respectively connected with corresponding elution liquid storage tanks through elution liquid pipelines, and a metering syringe pump is arranged on the elution liquid pipeline.

[0019] The elution liquid outlets of the second microchannels and the third microchannels are respectively connected with corresponding step component collectors, and the outlet of the step component collector is connected with a component effluent storage tank.

[0020] In any of the above aspects and possible implementation manners, further provided is an implementation manner, wherein the extractant outlet of any gradient elution module is connected with the inlet of an extractant back-extraction regenerator through an extractant pipeline, the outlet of the extractant back-extraction regenerator is connected with the inlet of an oil-water phase separator, the outlet of the oil-water phase separator is connected with the extractant inlet of the gradient elution module, and a metering syringe pump is arranged in the connecting pipeline between the oil-water phase separator and the extractant inlet.

[0021] In any of the above aspects and possible implementation manners, further provided is an implementation manner, wherein the elution liquid is an aqueous hydrochloric acid solution with a concentration gradient change, the concentration of the hydrochloric acid in the elution liquid increases by 0.1 mol / L per minute, and the concentration of the hydrochloric acid in the elution liquid changes in a range of 0.1 mol / L to 6 mol / L.

[0022] In any of the above aspects and possible implementation manners, further provided is an implementation manner, wherein the extractant includes a solute and a solvent.

[0023] The solute is any one or a combination of two or more of 2-ethylhexyl phosphoric acid mono(2-ethylhexyl) ester, di(2-ethylhexyl) phosphoric acid ester, di(2,4,4-trimethylpentyl) phosphinic acid, bis(2-ethylhexyl) phosphinic acid, tributyl phosphate, dimethylheptyl methylphosphonate, a secondary carbon primary amine and naphthenic acid.

[0024] The solvent is kerosene or an alkane containing 6 to 12 carbon atoms.

[0025] The molar concentration of the solute in the extractant is 0-1.0 mol / L.

[0026] According to the above aspects and any possible implementation, an implementation is further provided, wherein the rare earth ion aqueous solution is an aqueous solution containing three or more elements of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y;

[0027] The total concentration of rare earth elements contained in the rare earth ion aqueous phase feed liquid is 50-1000 mg / L, and the initial pH is 2-5.

[0028] In another aspect, the present invention provides a method for separating rare earth ions by grouping through microfluidic countercurrent extraction and chromatography, wherein the method is implemented using any of the above-described chip structures for separating rare earth ions by grouping through microfluidic countercurrent extraction and chromatography; the method comprises:

[0029] The rare earth ion aqueous phase feed liquid is pumped into the aqueous phase feed liquid inlet and flows along the three microchannels of the extraction module in sequence to complete the extraction of the rare earth ion aqueous phase feed liquid. The aqueous phase feed liquid then flows out from the aqueous phase feed liquid outlet and is collected to obtain an enriched solution containing different rare earth ions.

[0030] The extractant overflowing from the upper layer of the oil-water phase separator and regenerated by stripping is pumped into the extractant inlets of the first gradient elution module, the second gradient elution module, and the third gradient elution module, respectively, so as to flow in countercurrent contact with the rare earth ion aqueous phase feed liquid in the microchannels shared by the extraction module and the three gradient elution modules, and then flows out from the respective extractant outlets for collection to obtain three gradients of extract-enriched liquid; the extracted enriched liquid is recycled after stripping and regeneration; the three shared microchannels are the first microchannels of the respective gradient elution modules, which are sequentially connected to the second microchannel and the third microchannel;

[0031] Gradient eluents with varying concentrations are pumped into the eluent inlets of the second microchannel and the third microchannel of the first gradient elution module, the second gradient elution module and the third gradient elution module respectively. After the eluents come into reverse contact with the extractant in the microchannels, they are discharged and collected from the eluent outlets of the microchannels to obtain two gradient eluent enrichment liquids of each gradient elution module.

[0032] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the rare earth ion aqueous phase feed liquid is pumped at a speed of 0.1 to 10 mL / min;

[0033] The flow rate of the extractant in the first gradient elution module, the second gradient elution module and the third gradient elution module is 0.1 to 10 mL / min;

[0034] The flow rate of the gradient eluent in the second microchannel of the first gradient elution module, the second gradient elution module, and the third gradient elution module is 0.1 to 5 mL / min; the flow rate of the gradient eluent in the third microchannel of the first gradient elution module, the second gradient elution module, and the third gradient elution module is 1 to 10 mL / min;

[0035] The gradient eluent pumped into the second microchannel of the first gradient elution module changes in concentration within a gradient range of 0.5 to 1.5 mol / L; the gradient eluent pumped into the third microchannel changes in concentration within a gradient range of 2.0 to 6.0 mol / L;

[0036] The gradient eluent pumped into the second microchannel of the second gradient elution module changes in concentration within a gradient range of 1.5 to 2.5 mol / L; the gradient eluent pumped into the third microchannel changes in concentration within a gradient range of 2.5 to 6.0 mol / L;

[0037] The gradient eluent pumped into the second microchannel of the third gradient elution module changes gradually within the concentration range of 4.0 to 6.0 mol / L; the gradient eluent pumped into the third microchannel changes gradually within the concentration range of 5.0 to 6.0 mol / L.

[0038] According to the above aspects and any possible implementation, an implementation is further provided, wherein the flow rate of the gradient eluent in the second microchannel of the first gradient elution module, the second gradient elution module, and the third gradient elution module is 0.1 to 1.0 mL / min; the flow rate of the gradient eluent in the third microchannel of the first gradient elution module, the second gradient elution module, and the third gradient elution module is 2 to 5 mL / min, 3 to 7 mL / min, and 5 to 8 mL / min, respectively;

[0039] The gradient eluent pumped into the second microchannel of the first gradient elution module changes in concentration within a gradient range of 0.5 to 1.5 mol / L; the gradient eluent pumped into the third microchannel changes in concentration within a gradient range of 2.0 to 6.0 mol / L;

[0040] The gradient eluent pumped into the second microchannel of the second gradient elution module changes in concentration within a gradient range of 1.5 to 2.5 mol / L; the gradient eluent pumped into the third microchannel changes in concentration within a gradient range of 2.5 to 6.0 mol / L;

[0041] The gradient eluent pumped into the second microchannel of the third gradient elution module changes gradually within the concentration range of 4.0 to 6.0 mol / L; the gradient eluent pumped into the third microchannel changes gradually within the concentration range of 5.0 to 6.0 mol / L.

[0042] Compared with the prior art, one of the above technical solutions has the following advantages or beneficial effects: the present invention utilizes the differences in extraction and stripping rates of different rare earth ions, first extracting and separating them in groups according to the "quadrant effect" in a microchannel reactor of an "extraction module" connected end to end, and then, in a microchannel reactor of a "gradient elution module" connected end to end, using a gradient eluent with a hydrochloric acid concentration that continuously increases with time to perform step-by-step elution and stripping separation on the organic phase loaded with rare earth ions according to the "quadrant effect", so that the rare earth ions that have been grouped in the extraction unit and enter the organic phase are further eluted and separated in groups in the elution unit. The process is simple, the separation process is short, the efficiency of group separation between rare earth ions is high, and the purity of the component effluent product is high;

[0043] Another technical solution among the above technical solutions has the following advantages or beneficial effects: the present invention can realize the rapid grouping and separation of any multiple rare earth ions in a mixed aqueous solution containing at least three or more rare earth element ions of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y by adjusting the process parameters and adjusting the combination mode of the basic functional units of the chip module. The separation time is short, the combination mode of the basic functional units of the chip module and the process parameters of the operation process can be flexibly adjusted, and the universality is high. Compared with the existing process technology of cascade extraction and separation of complex systems of multiple rare earth ions coexisting in mixing and settling tanks, significant progress has been made.

[0044] Of course, any product implementing the present invention does not necessarily need to achieve all of the above-mentioned technical effects at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 This is a schematic diagram of the chip structure for the microfluidic countercurrent extraction chromatography grouped separation of rare earth ions provided in Example 1 of the present invention. The planar square formed by four end-to-end double Y-shaped microchannel reactors in the figure is the basic structural unit of the chip module. Within the dotted box in the figure, the "half-cross" planar grid configuration formed by a group of microchannel reactor "extraction module" parallelogram basic units and three groups of microchannel reactor "gradient elution module" parallelogram basic units on three adjacent sides is the basic functional unit of the chip module.

[0047] Figure 2It is a gradient eluent feeding system supporting the chip structure for the microfluidic countercurrent extraction chromatography group separation of rare earth ions provided in Example 1 of the present invention;

[0048] Figure 3 This is a schematic diagram of a step-by-step component collector H and an effluent storage tank G supporting the chip structure for the microfluidic countercurrent extraction chromatography grouping separation of rare earth ions provided in Example 1 of the present invention;

[0049] Figure 4 This is a schematic diagram of the extractant stripping regenerators E1, E2, E3 and the oil-water phase separators F1, F2, F3 supporting the chip structure for the microfluidic countercurrent extraction chromatography grouping separation of rare earth ions provided in Example 1 of the present invention;

[0050] Figure 5 It is an extended combination of the chip structure for grouping and separating rare earth ions using microfluidic countercurrent extraction chromatography provided in Example 2 of the present invention, and is composed of two basic functional units of microfluidic countercurrent extraction chromatography chip modules; the two basic functional units of the microfluidic countercurrent extraction chromatography chip modules in the figure share the same set of gradient eluent feed system, the same set of extractant stripping regenerator and oil-water phase separator.

[0051] Among them, in the figure:

[0052] 1: extraction module; 2: first gradient elution module; 3: second gradient elution module; 4: third gradient elution module; a, aqueous phase feed liquid inlet; b, aqueous phase feed liquid outlet; c1, d1: gradient eluent inlet of the first gradient elution module; c2, d2: gradient eluent outlet of the first gradient elution module; e1, f1: gradient eluent inlet of the second gradient elution module; e2, f2: gradient eluent outlet of the second gradient elution module; g1, h1: gradient eluent inlet of the third gradient elution module; g2, h2: gradient eluent outlet of the third gradient elution module Gradient eluent outlet; I-1, II-1, III-1: extractant inlet; I-2, II-2, III-2: extractant outlet; A1, A2, A3, B1, B2, B3: gradient eluent storage tanks; J1, J2, J3, K1, K2, K3: gradient eluent preparation tanks; C: concentrated hydrochloric acid storage tank; D: pure water storage tank; E1, E2, E3: extractant stripping regenerator; F1, F2, F3: oil-water phase separator; G: component effluent storage tank for the step component collector; H: step component collector; L: injection pump. DETAILED DESCRIPTION

[0053] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0054] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0055] In light of the existing challenges, the present invention aims to provide a chip structure and method for the grouped separation of rare earth ions using microfluidic countercurrent extraction chromatography. This method offers significant advantages in grouping and separating complex systems containing multiple rare earth elements. The method features a simple process, a short separation flow, high efficiency in grouping rare earth ions, and high purity of the component effluent products.

[0056] The chip structure and method for grouping and separating rare earth ions by microfluidic countercurrent extraction chromatography described in the present invention are based on the "quadruple group effect" for grouping and separating a system in which multiple rare earth element ions coexist. Four double Y-shaped microchannel reactors connected end to end are arranged to form a parallelogram-configured microchip "extraction module" functional unit. An aqueous phase feed liquid containing multiple rare earth element ions and an organic extractant are contacted with each other in parallel and countercurrent flow in the microchannel, which can realize the grouped and step-by-step extraction and separation of multiple rare earth element ions in a mixed aqueous solution containing more than three rare earth element ions according to the "quadruple group effect"; then, a parallelogram-configured "gradient elution module" functional unit with the same layout is used to step-by-step gradient elution of the rare earth ions that have been grouped and extracted into a loaded organic phase using a gradient eluent with a hydrochloric acid concentration that continuously increases over time. The organic phase and the gradient eluent are in countercurrent contact in the microchannel, which can realize the grouped elution and separation of the multiple rare earth element ions that have been grouped and extracted into the loaded organic phase again according to the "quadruple group effect". The microfluidic countercurrent extraction chromatography chip module basic functional unit, consisting of a microchannel reactor "extraction module" parallelogram basic unit and three adjacent microchannel reactor "gradient elution module" parallelogram basic units, and its corresponding extended combination, can achieve group extraction and group elution chromatographic separation of multiple rare earth element ions in mixed rare earth aqueous solutions according to the "quadrant effect." To achieve the above objectives and methods, the present invention provides the following technical solutions:

[0057] In a first aspect, the present invention provides a chip structure for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography.

[0058] According to a specific embodiment of the present invention, the chip module is composed of a planar grid structure formed by interweaving multiple groups of double Y-type microchannel reactors connected end to end. The basic structural unit of the planar grid structure chip module is composed of a group (i.e., four) of double Y-type microchannel reactors connected end to end in a parallelogram configuration. The basic structural units of the chip module share a set of double Y-type microchannel reactors on one side of the parallelogram configuration. The double Y-type microchannel reactor includes a microchannel with a circular cross section, a circular cross section diameter of 0.05mm to 2.0mm, and a length of 10mm to 200mm, and also includes a Y-type structure microchannel inlet and outlet located on both sides of the microchannel. The inlet and outlet of the Y-type structure microchannel are respectively composed of two microchannels with a circular cross section, a circular cross section diameter of 0.1mm to 2.0mm, and a length of 1mm to 5mm to form a Y-type structure.

[0059] The basic functional unit of the chip module consists of four parts: extraction module 1, first gradient elution module 2, second gradient elution module 3, and third gradient elution module 4, forming a "semi-cross" plane grid configuration. The extraction module 1 is located at the center of the "semi-cross" plane grid configuration, and the first gradient elution module 2, second gradient elution module 3, and third gradient elution module 4 are located above, to the right, and below the extraction module 1 at the center of the "semi-cross" plane grid configuration.

[0060] The extraction module 1 consists of four double-Y-shaped microchannel reactors connected end-to-end in a parallelogram configuration. An aqueous liquid inlet a is located at the left inlet of the double-Y-shaped microchannels on the upper side of the parallelogram. An aqueous liquid outlet b is located at the left outlet of the double-Y-shaped microchannels on the lower side of the parallelogram. This aqueous liquid outlet b is connected to a step-by-step component collector, which has a component effluent storage tank at its outlet.

[0061] The first gradient elution module 2, the second gradient elution module 3, and the third gradient elution module 4 are each composed of four double-Y-shaped microchannel reactors connected end to end in a parallelogram configuration. The double Y-shaped microchannel on the lower side of the parallelogram of the first gradient elution module 2 and the double Y-shaped microchannel on the upper side of the parallelogram of the extraction module 1 share the same double Y-shaped microchannel; the double Y-shaped microchannel on the left side of the parallelogram of the second gradient elution module 3 and the double Y-shaped microchannel on the right side of the parallelogram of the extraction module 1 share the same double Y-shaped microchannel; and the double Y-shaped microchannel on the upper side of the parallelogram of the third gradient elution module 4 and the double Y-shaped microchannel on the lower side of the parallelogram of the extraction module 1 share the same double Y-shaped microchannel.

[0062] The upper inlet of the double Y-shaped microchannel on the left side of the parallelogram of the first gradient elution module 2 is provided with a gradient eluent inlet c1, and the lower outlet is provided with a gradient eluent outlet c2; the right inlet of the double Y-shaped microchannel on the upper side of the parallelogram of the first gradient elution module 2 is provided with a gradient eluent inlet d1, and the left outlet is provided with a gradient eluent outlet d2; the lower inlet of the double Y-shaped microchannel on the right side of the parallelogram of the first gradient elution module 2 is provided with an organic extractant inlet I-1, and the upper outlet is provided with an organic extractant outlet I-2. The right inlet of the double Y-shaped microchannel on the upper side of the parallelogram of the second gradient elution module 3 is provided with a gradient eluent inlet e1, and the left outlet is provided with a gradient eluent outlet e2; the lower inlet of the double Y-shaped microchannel on the right side of the parallelogram of the second gradient elution module 3 is provided with a gradient eluent inlet f1, and the upper outlet is provided with a gradient eluent outlet f2; the left inlet of the double Y-shaped microchannel on the lower side of the parallelogram of the second gradient elution module 3 is provided with an organic extractant inlet II-1, and the right outlet is provided with an organic extractant outlet II-2. The lower inlet of the double Y-shaped microchannel on the right side of the parallelogram of the third gradient elution module 4 is provided with a gradient eluent inlet g1, and the upper outlet is provided with a gradient eluent outlet g2; the left inlet of the double Y-shaped microchannel on the lower side of the parallelogram of the third gradient elution module 4 is provided with a gradient eluent inlet h1, and the right outlet is provided with a gradient eluent outlet h2; the upper inlet of the double Y-shaped microchannel on the left side of the parallelogram of the third gradient elution module 4 is provided with an organic extractant inlet III-1, and the lower outlet is provided with an organic extractant outlet III-2.

[0063] The gradient eluent inlet c1 on the upper side of the double Y-shaped microchannel on the left side of the parallelogram of the first gradient elution module 2, the gradient eluent inlet e1 on the right side of the double Y-shaped microchannel on the upper side of the parallelogram of the second gradient elution module 3, and the gradient eluent inlet g1 on the lower side of the double Y-shaped microchannel on the right side of the parallelogram of the third gradient elution module 4 are connected to the gradient eluent storage tanks A1, A2, and A3 respectively through pipes, and a metering injection pump is configured in each of the three inlet pipes; the gradient eluent inlet d1 on the right side of the double Y-shaped microchannel on the upper side of the parallelogram of the first gradient elution module 2, the gradient eluent inlet f1 on the lower side of the double Y-shaped microchannel on the right side of the parallelogram of the second gradient elution module 3, and the gradient eluent inlet h1 on the left side of the double Y-shaped microchannel on the lower side of the parallelogram of the third gradient elution module 4 are connected to the gradient eluent storage tanks B1, B2, and B3 respectively through pipes, and a metering injection pump is configured in each of the three inlet pipes. The gradient eluent storage tanks A1, A2, A3 and B1, B2, B3 are connected to the gradient eluent preparation tanks J1, J2, J3 and K1, K2, K3, respectively. The gradient eluent preparation tanks J1, J2, J3 and K1, K2, K3 are each equipped with a concentrated hydrochloric acid storage tank C and a pure water storage tank D, which are connected by pipes, and each pipe is equipped with a metering infusion pump.

[0064] The gradient eluent outlet c2 on the lower side of the double Y-shaped microchannel on the left side of the parallelogram of the first gradient elution module 2, the gradient eluent outlet e2 on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the second gradient elution module 3, and the gradient eluent outlet g2 on the upper side of the double Y-shaped microchannel on the right side of the parallelogram of the third gradient elution module 4 are respectively connected to the step component collector, and the outlets of the step component collector are respectively provided with component effluent storage tanks; the gradient eluent outlet d2 on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the first gradient elution module 2, the gradient eluent outlet f2 on the upper side of the double Y-shaped microchannel on the right side of the parallelogram of the second gradient elution module 3, and the gradient eluent outlet h2 on the right side of the double Y-shaped microchannel on the lower side of the parallelogram of the third gradient elution module 4 are respectively connected to the step component collector, and the outlets of the step component collector are respectively provided with component effluent storage tanks.

[0065] The extractant outlet I-2 on the upper side of the double Y-shaped microchannel on the right side of the parallelogram of the first gradient elution module 2 is connected to the extractant stripping regenerator E1 through a pipeline, and the outlet of the extractant stripping regenerator E1 is connected to the oil-water phase separator F1. The upper outlet of the oil-water phase separator F1 is connected to the extractant inlet I-1 on the lower side of the double Y-shaped microchannel on the right side of the parallelogram of the first gradient elution module 2 through a pipeline, and a metering injection pump is configured in the pipeline; the extractant outlet II-2 on the right side of the double Y-shaped microchannel on the lower side of the parallelogram of the second gradient elution module 3 is connected to the extractant stripping regenerator E2 through a pipeline, and the outlet of the extractant stripping regenerator E2 is connected to the oil-water phase separator F2, the upper outlet of the oil-water phase separator F2 is connected to the extractant inlet II-1 on the left side of the double Y-shaped microchannel on the lower side of the parallelogram of the second gradient elution module 3 by a pipeline, and a metering injection pump is configured in the pipeline; the extractant outlet III-2 on the lower side of the double Y-shaped microchannel on the left side of the parallelogram of the third gradient elution module 4 is connected to the extractant stripping regenerator E3 by a pipeline, and the outlet of the extractant stripping regenerator E3 is connected to the oil-water phase separator F3, and the upper outlet of the oil-water phase separator F3 is connected to the extractant inlet III-1 on the upper side of the double Y-shaped microchannel on the left side of the parallelogram of the third gradient elution module 4 by a pipeline, and a metering injection pump is configured in the pipeline.

[0066] According to a specific embodiment of the present invention, the basic functional unit of the chip module and the peripheral supporting gradient eluent feeding system, step component collector and effluent storage tank, extractant stripping regenerator and oil-water phase separator constitute a complete separation system.

[0067] In a second aspect, the present invention provides a method for separating rare earth ions by microfluidic countercurrent extraction chromatography, comprising the following steps:

[0068] ① An aqueous phase feed liquid containing at least three or more rare earth element ions of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y is pumped into the extraction module 1 from the aqueous phase feed liquid inlet a on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the extraction module 1 at a feed rate of 0.1 to 10 mL / min. Then, at the aqueous phase feed liquid outlet b on the left side of the double Y-shaped microchannel on the lower side of the parallelogram of the extraction module 1, a step component collector is used to continuously collect the effluent flowing out of the b port in different time periods in batches, and the collection time of each batch is independently selected from 0.5 to 5 minutes to obtain enriched solutions containing different rare earth ions; the total rare earth concentration contained in the aqueous phase feed liquid is 50 to 1000 mg / L, and the initial pH is 2 to 5.

[0069] ② The extractant overflowing from the upper layer of the oil-water phase separator F1 after back extraction and regeneration is pumped into the microchannel shared by the extraction module 1 and the first gradient elution module 2 from the extractant inlet I-1 on the lower side of the double Y-shaped microchannel on the right side of the parallelogram of the first gradient elution module 2, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the gradient eluent inlet c1 on the upper side of the double Y-shaped microchannel on the left side of the parallelogram of the first gradient elution module 2, and then countercurrently contacts with the gradient eluent pumped from the gradient eluent inlet d1 on the right side of the double Y-shaped microchannel on the upper side of the parallelogram of the first gradient elution module 2, and finally flows out from the extractant outlet I-2 on the upper side of the double Y-shaped microchannel on the right side of the parallelogram of the first gradient elution module 2. The extractant is recycled after stripping and regeneration; the flow rate of the extractant at the I-1 inlet on the lower side of the first gradient elution module 2 is controlled to be 0.1~10mL / min; the flow rate of the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 is controlled to be 0.1~5mL / min, preferably 0.1~1.0mL / min; the flow rate of the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 is controlled to be 1~10mL / min, preferably 2~5mL / min; the hydrochloric acid concentration in the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 is continuously increased in the range of 0.5~1.5mol / L; the hydrochloric acid concentration in the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 is continuously increased in the range of 2.0~6.0mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration by 0.1mol / L per minute;

[0070] ③ The extractant overflowing from the upper layer of the oil-water phase separator F2 after back extraction and regeneration is pumped into the microchannel shared by the extraction module 1 and the second gradient elution module 3 from the extractant inlet II-1 on the left side of the double Y-shaped microchannel on the lower side of the parallelogram of the second gradient elution module 3, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped into the gradient eluent inlet e1 on the right side of the double Y-shaped microchannel on the upper side of the parallelogram of the second gradient elution module 3, and then countercurrently contacts with the gradient eluent pumped into the gradient eluent inlet f1 on the lower side of the double Y-shaped microchannel on the right side of the parallelogram of the second gradient elution module 3, and finally flows out from the extractant outlet II-2 on the right side of the double Y-shaped microchannel on the lower side of the parallelogram of the second gradient elution module 3. The extractant is recycled after stripping and regeneration; the flow rate of the extractant at the II-1 inlet on the left side of the second gradient elution module 3 is controlled to be 0.1~10mL / min; the flow rate of the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is controlled to be 0.1~5mL / min, preferably 0.1~1.0mL / min; the flow rate of the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is controlled to be 1~10mL / min, preferably 3~7mL / min; the hydrochloric acid concentration in the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is continuously increased in the range of 1.5~2.5mol / L; the hydrochloric acid concentration in the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is continuously increased in the range of 2.5~6.0mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration by 0.1mol / L per minute;

[0071] ④ The extractant overflowing from the upper layer of the oil-water phase separator F3 after stripping and regeneration is pumped into the microchannel shared by the extraction module 1 and the third gradient elution module 4 from the extractant inlet III-1 on the upper side of the double Y-shaped microchannel on the left side of the parallelogram of the third gradient elution module 4, and countercurrently contacts with the aqueous phase liquid pumped from the aqueous phase liquid inlet a on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the gradient eluent inlet g1 on the lower side of the double Y-shaped microchannel on the right side of the parallelogram of the third gradient elution module 4, and then countercurrently contacts with the gradient eluent pumped from the gradient eluent inlet h1 on the left side of the double Y-shaped microchannel on the lower side of the parallelogram of the third gradient elution module 4, and finally flows out from the extractant outlet III-2 on the lower side of the double Y-shaped microchannel on the left side of the parallelogram of the third gradient elution module 4. The extractant is recycled after back extraction and regeneration; the flow rate of the extractant at the III-1 inlet on the upper side of the third gradient elution module 4 is controlled to be 0.1~10mL / min; the flow rate of the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 is controlled to be 0.1~5mL / min, preferably 0.1~1.0mL / min; the flow rate of the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 is controlled to be 1~10mL / min, preferably 5~8mL / min; the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases in the range of 4.0~6.0mol / L; the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases in the range of 5.0~6.0mol / L; the rate of change of the hydrochloric acid concentration is a continuous change with the hydrochloric acid concentration increasing by 0.1mol / L per minute.

[0072] The purpose of optimizing the gradient eluent flow rate in steps ②, ③, and ④ is to control the volume flow rate ratio of the oil-water phase in the microchannel and improve the separation degree of the components to be separated; when the hydrochloric acid concentration in the gradient eluent continuously increases within the said range, gradient elution is performed with the preferred eluent flow rate, which can further increase the rate difference of elution and stripping of different components, obtain a higher separation factor, and have a higher purity of the components flowing out of the eluent.

[0073] ⑤ Use a step component collector to continuously collect in batches the effluent flowing out from the lower gradient eluent outlet c2 of the double Y-shaped microchannel on the left side of the parallelogram of the first gradient elution module 2 in step ②, the gradient eluent outlet e2 on the left side of the double Y-shaped microchannel on the upper side of the parallelogram of the second gradient elution module 3 in step ③, and the gradient eluent outlet g2 on the upper side of the double Y-shaped microchannel on the right side of the parallelogram of the third gradient elution module 4 in step ④ in different time periods, and the collection time of each batch is independently selected from 0.5 to 5 minutes to obtain enriched solutions containing different rare earth ions;

[0074] ⑥ Use a step component collector to continuously collect in batches the effluents flowing out from the left side gradient eluent outlet d2 of the double Y-shaped microchannel on the upper side parallelogram of the first gradient elution module 2 in step ②, the upper side gradient eluent outlet f2 of the double Y-shaped microchannel on the right side parallelogram of the second gradient elution module 3 in step ③, and the right side gradient eluent outlet h2 of the double Y-shaped microchannel on the lower side parallelogram of the third gradient elution module 4 in step ④ in different time periods. The collection time of each batch is independently selected from 0.5 to 5 minutes to obtain enriched solutions containing different rare earth ions.

[0075] According to a specific embodiment of the present invention, the countercurrent contact mode of the water-oil two-phase flow in the microchannel described in steps ②, ③ and ④ is: the water-oil two-phase flow moves relative to each other in the opposite direction in the parallel flow pattern for countercurrent contact.

[0076] According to a specific embodiment of the present invention, the solute of the extractant is any one or a combination of at least two of 2-ethylhexyl mono(2-ethylhexyl) phosphate, di(2-ethylhexyl) phosphate, di(2,4,4-trimethylpentyl)phosphinic acid, bis(2-ethylhexyl)phosphinic acid, tributyl phosphate, dimethylheptyl methylphosphate, secondary carbon primary amine, and cycloalkane acid. The solvent of the extractant is an alkane or kerosene, wherein the alkane is an alkane containing 6 to 12 carbon atoms. The molar concentration of the extractant, that is, the molar concentration of the solute in the alkane or kerosene solution, is greater than 0 and less than or equal to 1.0 mol / L.

[0077] According to a specific embodiment of the present invention, the gradient eluent is prepared by mixing concentrated hydrochloric acid and pure water, and the hydrochloric acid concentration changes at a rate of 0.1 mol / L per minute. The hydrochloric acid concentration in the gradient eluent increases continuously within a range of 0.1 to 6 mol / L. Preferably, in step ②, the hydrochloric acid concentration in the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 continuously increases within the range of 0.5 to 1.5 mol / L; in step ②, the hydrochloric acid concentration in the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 continuously increases within the range of 2.0 to 6.0 mol / L; in step ③, the hydrochloric acid concentration in the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 continuously increases within the range of 1.5 to 2.5 mol / L; in step ③, the hydrochloric acid concentration in the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 continuously increases within the range of 2.5 to 6.0 mol / L; in step ④, the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases within the range of 4.0 to 6.0 mol / L; in step ④, the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases within the range of 5.0 to 6.0 mol / L.

[0078] According to a specific embodiment of the present application, the step component collector rotates at a constant speed for continuous batch collection, wherein the time interval of the step component collector rotating at a constant speed is 0.5-5 min.

[0079] According to a specific embodiment of the present application, the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography can be used alone, or the basic functional unit of the chip module can be a repeating unit for extended combination use; the basic functional unit of the chip module can share the same set of peripheral supporting gradient eluent feeding system, extractant back-extraction regenerator and oil-water phase separator, or each can independently use its own supporting gradient eluent feeding system, extractant back-extraction regenerator and oil-water phase separator system.

[0080] Example 1:

[0081] A chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in Figure 1 The basic structure unit of the chip module is a planar quadrilateral surrounded by four double-Y microchannel reactors connected head to tail. The microchannel has a diameter of 0.2 mm and a length of 100 mm, and the Y-shaped structure at both ends of the microchannel has a diameter of 0.2 mm and a length of 2 mm. The chip module is composed of a group of microchannel reactors "extraction module" parallelogram basic unit and three groups of microchannel reactors "gradient elution module" parallelogram basic unit adjacent to three sides, forming a "half-cross" planar grid configuration. The supporting Figure 1 A gradient eluent feeding system for the basic functional unit of the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in Figure 2 A gradient eluent feeding system for the basic functional unit of the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in Figure 1 A step component collector H and an effluent storage tank G for the basic functional unit of the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in Figure 3 A step component collector H and an effluent storage tank G for the basic functional unit of the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in Figure 1 An extractant back-extraction regenerator E1, E2, E3 and an oil-water phase separator F1, F2, F3 for the basic functional unit of the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in Figure 4 An extractant back-extraction regenerator E1, E2, E3 and an oil-water phase separator F1, F2, F3 for the basic functional unit of the chip structure for separating rare earth ions by microfluidic counter-current extraction chromatography, as shown in

[0082] The above chip module is used to separate a mixed aqueous solution containing La, Nd, Sm, Gd, Tb, Ho, Lu and Y eight rare earth element ions; wherein the total concentration of rare earth elements in the mixed aqueous solution is 500 mg / L, the initial pH of the mixed aqueous solution is 2.0; the extractant used is 2-ethylhexyl phosphoric acid mono(2-ethylhexyl) ester dissolved in kerosene, and the molar concentration of 2-ethylhexyl phosphoric acid mono(2-ethylhexyl) ester in kerosene is 0.5 mol / L.

[0083] The specific method steps are as follows:

[0084] ① A mixed aqueous solution containing eight rare earth element ions, La, Nd, Sm, Gd, Tb, Ho, Lu, and Y, was pumped into the extraction module 1 from the aqueous phase feed liquid inlet a at a feed rate of 1.0 mL / min. Then, at the aqueous phase feed liquid outlet b, a stepping component collector was used to continuously collect the effluent flowing out of port b at different time periods in batches. Each batch of collection lasted for 4 minutes to obtain enriched solutions containing Y and Lu, respectively. The relative purity of Y was 99.4%, and the relative purity of Lu was 99.3%.

[0085] ② The extractant overflowing from the upper layer of the oil-water phase separator F1 after stripping and regeneration is pumped into the shared microchannel from the extractant inlet I-1 of the first gradient elution module 2, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet c1 of the first gradient elution module 2, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet d1 of the first gradient elution module, and finally flows out from the extractant outlet I-2 of the first gradient elution module 2. The outflowing extractant is recycled after stripping and regeneration; the extractant at the inlet I-1 on the lower side of the first gradient elution module 2 is The flow rate of the agent was controlled at 1.0 mL / min; the flow rate of the eluent at the c1 inlet on the left side of the first gradient elution module 2 was controlled at 0.5 mL / min; the flow rate of the eluent at the d1 inlet on the upper side of the first gradient elution module 2 was controlled at 3 mL / min; the hydrochloric acid concentration in the eluent at the c1 inlet on the left side of the first gradient elution module 2 was continuously increased within the range of 0.5 to 1.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 was continuously increased within the range of 2.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration was a continuous change of the hydrochloric acid concentration by 0.1 mol / L per minute;

[0086] ③ The extractant overflowing from the upper layer of the oil-water phase separator F2 after stripping and regeneration is pumped into the microchannel shared by the extraction module 1 and the second gradient elution module 3 from the extractant inlet II-1 of the second gradient elution module 3, and countercurrently contacts with the aqueous phase feed liquid pumped in from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped in from the eluent inlet e1 of the second gradient elution module 3, and then countercurrently contacts with the gradient eluent pumped in from the eluent inlet f1 of the second gradient elution module 3, and finally flows out from the extractant outlet II-2 of the second gradient elution module 3, and the outflowing extractant is recycled after stripping and regeneration; the left side of the second gradient elution module 3 The flow rate of the extractant at the side II-1 inlet is controlled to be 1.0 mL / min; the flow rate of the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is controlled to be 0.3 mL / min; the flow rate of the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is controlled to be 5 mL / min; the hydrochloric acid concentration in the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is continuously increased in the range of 1.5 to 2.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is continuously increased in the range of 2.5 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration is a continuous change with the hydrochloric acid concentration increasing by 0.1 mol / L per minute;

[0087] ④ The extractant overflowing from the upper layer of the oil-water phase separator F3 after stripping and regeneration is pumped into the microchannel shared by the extraction module 1 and the third gradient elution module 4 from the extractant inlet III-1 of the third gradient elution module 4, and is countercurrently contacted with the aqueous phase feed liquid pumped in from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacted with the gradient eluent pumped in from the eluent inlet g1 of the third gradient elution module 4, and then countercurrently contacted with the gradient eluent pumped in from the eluent inlet h1 of the third gradient elution module 4, and finally flows out from the extractant outlet III-2 of the third gradient elution module 4, and the outflowing extractant is recycled after stripping and regeneration; the extractant on the third gradient elution module 4 is countercurrently contacted with the gradient eluent pumped in from the eluent inlet g1 of the third gradient elution module 4, and then countercurrently contacted with the gradient eluent pumped in from the eluent inlet h1 of the third gradient elution module 4. The flow rate of the extractant at the side III-1 inlet is controlled to be 1.0 mL / min; the flow rate of the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 is controlled to be 0.1 mL / min; the flow rate of the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 is controlled to be 6 mL / min; the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases within the range of 4.0 to 6.0 mol / L; the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases within the range of 5.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration by 0.1 mol / L per minute;

[0088] ⑤ Use a step component collector to continuously collect in batches the effluent flowing out from the eluent outlet c2 of the first gradient elution module 2 in step ②, the eluent outlet e2 of the second gradient elution module 3 in step ③, and the eluent outlet g2 of the third gradient elution module 4 in step ④ in different time periods, with each batch collection time being 4 minutes; an enriched solution containing La and Nd, respectively, is obtained from outlet c2, with a relative purity of La of 99.8% and a relative purity of Nd of 96.6%; an enriched solution containing Sm and Gd, respectively, is obtained from outlet e2, with a relative purity of Sm of 98.9% and a relative purity of Gd of 97.7%; an enriched solution containing Tb and Ho, respectively, is obtained from outlet g2, with a relative purity of Tb of 97.5% and a relative purity of Ho of 93.3%;

[0089] ⑥ Use a step component collector to continuously collect in batches the effluent flowing out from the eluent outlet d2 of the first gradient elution module 2 in step ②, the eluent outlet f2 of the second gradient elution module 3 in step ③, and the eluent outlet h2 of the third gradient elution module 4 in step ④ in different time periods, and the collection time for each batch is 4 minutes; an enriched solution containing Sm and Gd, respectively, is obtained from outlet d2, with a relative purity of Sm of 99.1% and a relative purity of Gd of 92.6%; an enriched solution containing Tb and Ho, respectively, is obtained from outlet f2, with a relative purity of Tb of 99.5% and a relative purity of Ho of 91.3%; an enriched solution containing Y and Lu, respectively, is obtained from outlet h2, with a relative purity of Y of 92.8% and a relative purity of Lu of 94.2%.

[0090] Example 2:

[0091] A chip structure extension combination for microfluidic countercurrent extraction chromatography group separation of rare earth ions, such as Figure 5 As shown, it is composed of two basic functional units of microfluidic countercurrent extraction chromatography chip modules on the left and right. The two basic functional units of microfluidic countercurrent extraction chromatography chip modules on the left and right share the same set of gradient eluent feeding system, the same set of extractant stripping regenerator and oil-water phase separator. The microchannel diameter of the double Y-type microchannel reactor of the microfluidic countercurrent extraction chromatography chip module on the right is 0.2mm, the length is 100mm, and the inlet and outlet diameters of the Y-type structures at both ends of the microchannel are 0.2mm and 2mm respectively. The microchannel diameter of the double Y-type microchannel reactor of the microfluidic countercurrent extraction chromatography chip module on the left is 0.5mm, the length is 200mm, and the inlet and outlet diameters of the Y-type structures at both ends of the microchannel are 0.5mm and 5mm respectively.

[0092] The above-mentioned chip module expansion combination is used to separate a mixed aqueous solution containing fifteen rare earth element ions including La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y; wherein the total rare earth concentration in the mixed aqueous solution is 1000 mg / L, and the initial pH of the mixed aqueous solution is 3.0; the extractant used in gradient elution modules 2 and 3 is 2-ethylhexyl mono(2-ethylhexyl) phosphate, which is dissolved in kerosene, and the molar concentration of the extractant in kerosene is 1.0 mol / L; the extractant used in gradient elution module 4 is di(2,4,4-trimethylpentyl)phosphinic acid dissolved in kerosene, and the molar concentration of di(2,4,4-trimethylpentyl)phosphinic acid in kerosene is 1.0 mol / L.

[0093] The specific steps are as follows:

[0094] ① A mixed aqueous solution containing fifteen rare earth element ions of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y was pumped into the mixed aqueous solution from the aqueous phase feed inlet a of the extraction module 1 at a feed rate of 0.1 mL / min, and then the aqueous phase raffinate flowing out of the aqueous phase feed outlet b of the extraction module 1 was pumped into the aqueous phase feed inlet a by a metering injection pump. Finally, at the aqueous phase feed outlet b of the extraction module 1, a stepping component collector was used to continuously collect the effluent flowing out of the b port at different time periods in batches. The collection time for each batch was 5 min, and enriched solutions containing Tm, Yb, and Lu were obtained, respectively. The relative purity of Tm was 99.7%, the relative purity of Yb was 93.1%, and the relative purity of Lu was 90.9%;

[0095] ② The extractant overflowing from the upper layer of the oil-water phase separator F1 after back extraction and regeneration is pumped into the microchannel shared by the extraction module 1 and the first gradient elution module 2 from the extractant inlet I-1 of the first gradient elution module 2 on the right, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet c1 of the first gradient elution module 2, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet d1 of the first gradient elution module 2, and finally flows out from the extractant outlet I-2 of the first gradient elution module 2 on the right. The outflowing extractant is recycled after back extraction and regeneration; the operation of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the left is the same as the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the right. Unit operation; the extractant flow rate of the I-1 inlet on the lower side of the first gradient elution module 2 of the left and right microfluidic countercurrent extraction chromatography chip modules is controlled to be 0.1 mL / min; the flow rate of the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 is controlled to be 0.1 mL / min; the flow rate of the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 is controlled to be 2 mL / min; the hydrochloric acid concentration in the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 is continuously increased in the range of 0.5 to 1.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 is continuously increased in the range of 2.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration by 0.1 mol / L per minute;

[0096] ③ The extractant overflowing from the upper layer of the oil-water phase separator F2 after back extraction and regeneration is pumped into the microchannel shared by the extraction module 1 and the second gradient elution module 3 from the extractant inlet II-1 of the second gradient elution module 3 on the right, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped into the eluent inlet e1 of the second gradient elution module 3, and then countercurrently contacts with the gradient eluent pumped into the eluent inlet f1 of the second gradient elution module 3, and finally flows out from the extractant outlet II-2 of the second gradient elution module 3 on the right. The outflowing extractant is recycled after back extraction and regeneration; the operation of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the left is the same as that of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the right. Operation of functional units; the flow rate of the extractant at the II-1 inlet on the left side of the second gradient elution module 3 of the basic functional unit of the left and right microfluidic countercurrent extraction chromatography chip modules is controlled to 0.1 mL / min; the flow rate of the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is controlled to 0.1 mL / min; the flow rate of the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is controlled to 3 mL / min; the hydrochloric acid concentration in the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 continuously increases in the range of 1.5 to 2.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 continuously increases in the range of 2.5 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration continuously changes by increasing the hydrochloric acid concentration by 0.1 mol / L per minute;

[0097] ④ The extractant overflowing from the upper layer of the oil-water phase separator F3 after back extraction and regeneration is pumped into the microchannel shared by the extraction module 1 and the third gradient elution module 4 from the extractant inlet III-1 of the third gradient elution module 4 on the right, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet g1 of the third gradient elution module 4, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet h1 of the third gradient elution module 4, and finally flows out from the extractant outlet III-2 of the third gradient elution module 4 on the right. The outflowing extractant is recycled after back extraction and regeneration; the operation of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the left is the same as that of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the right. Operation of this functional unit; the flow rate of the extractant at the upper side III-1 inlet of the third gradient elution module 4 of the basic functional unit of the left and right microfluidic countercurrent extraction chromatography chip modules is controlled to 0.1mL / min; the flow rate of the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 is controlled to 0.1mL / min; the flow rate of the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 is controlled to 5mL / min; the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases in the range of 4.0 to 6.0mol / L; the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases in the range of 5.0 to 6.0mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration increasing by 0.1mol / L per minute;

[0098] ⑤ Use a step component collector to continuously collect the effluent from the outlet c2 of the first gradient elution module 2 in step ②, the outlet e2 of the second gradient elution module 3 in step ③, and the outlet g2 of the third gradient elution module 4 in step ④ in different time periods in batches. The collection time of each batch is 5 minutes; the enriched solution containing La and Ce is obtained from the outlet c2, and the relative purity of La is 99.8% and the relative purity of Ce is 95.5%; the enriched solution containing Pr and Nd is obtained from the outlet e2, and the relative purity of Pr is 98.2% and the relative purity of Nd is 91.1%. From outlet g2, enriched solutions containing Sm and Eu were obtained, with the relative purity of Sm being 99.5% and the relative purity of Eu being 93.3%; from outlet c2, enriched solutions containing Gd and Tb were obtained, with the relative purity of Gd being 99.8% and the relative purity of Tb being 96.2%; from outlet e2, enriched solutions containing Dy and Y were obtained, with the relative purity of Dy being 98.9% and the relative purity of Y being 94.0%; from outlet g2, enriched solutions containing Ho and Er were obtained, with the relative purity of Ho being 98.7% and the relative purity of Er being 95.3%;

[0099] ⑥ Use a step component collector to continuously collect the effluent from the outlet d2 of the first gradient elution module 2 in step ②, the outlet f2 of the second gradient elution module 3 in step ③, and the outlet h2 of the third gradient elution module 4 in step ④ in different time periods in batches, with each batch collection time being 5 minutes; from outlet d2, enriched solutions containing Ce and Pr were obtained, with a relative purity of Ce of 99.1% and a relative purity of Pr of 92.6%; from outlet f2, enriched solutions containing Nd and Sm were obtained, with a relative purity of Nd of 99.0% and a relative purity of Sm of 93.7%. ; Enriched solutions containing Eu and Gd were obtained from outlet h2, with the relative purity of Eu being 98.8% and the relative purity of Gd being 95.2%; enriched solutions containing Tb and Dy were obtained from outlet d2, with the relative purity of Tb being 99.8% and the relative purity of Dy being 95.5%; enriched solutions containing Y and Ho were obtained from outlet f2, with the relative purity of Y being 98.9% and the relative purity of Ho being 95.9%; enriched solutions containing Er and Tm were obtained from outlet h2, with the relative purity of Er being 99.0% and the relative purity of Tm being 96.9%.

[0100] Example 3:

[0101] use Figure 1 The chip module described separates a mixed aqueous solution containing four rare earth element ions: La, Gd, Ho, and Lu. The total rare earth concentration in the mixed aqueous solution is 1000 mg / L, and the initial pH of the mixed aqueous solution is 3.0. The extractant used is di(2-ethylhexyl) phosphate dissolved in n-heptane, with a molar concentration of di(2-ethylhexyl) phosphate in n-heptane of 0.5 mol / L. The microchannel of the dual-Y-shaped microchannel reactor, the basic functional unit of the microfluidic countercurrent extraction chromatography chip module, is 0.8 mm in diameter and 50 mm in length. The inlet and outlet of the Y-shaped structure at both ends of the microchannel are 0.8 mm in diameter and 3 mm in length.

[0102] The specific steps are as follows:

[0103] ① A mixed aqueous solution containing four rare earth element ions, La, Gd, Ho, and Lu, was pumped into the aqueous phase feed liquid inlet a of the extraction module 1 at a feed rate of 10.0 mL / min. Then, at the aqueous phase feed liquid outlet b of the extraction module 1, a stepping component collector was used to continuously collect the effluent flowing out of port b in batches at different time periods. Each collection time was 0.5 min to obtain an enriched solution containing Lu, with a relative purity of Lu of 99.2%;

[0104] ② The extractant overflowing from the upper layer of the oil-water phase separator F1 after stripping and regeneration is pumped into the microchannel shared by the extraction module 1 and the first gradient elution module 2 from the extractant inlet I-1 of the first gradient elution module 2, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet c1 of the first gradient elution module 2, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet d1 of the first gradient elution module 2, and finally flows out from the extractant outlet I-2 of the first gradient elution module 2. The outflowing extractant is recycled after stripping and regeneration; the extractant outlet I-2 on the lower side of the first gradient elution module 2 is used for recycling. The flow rate of the extractant at the inlet 1 is controlled to be 5.0 mL / min; the flow rate of the gradient eluent at the inlet c1 on the left side of the first gradient elution module 2 is controlled to be 5.0 mL / min; the flow rate of the gradient eluent at the inlet d1 on the upper side of the first gradient elution module 2 is controlled to be 5.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the inlet c1 on the left side of the first gradient elution module 2 is continuously increased in the range of 0.5 to 1.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the inlet d1 on the upper side of the first gradient elution module 2 is continuously increased in the range of 2.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration by 0.1 mol / L per minute;

[0105] ③ The extractant overflowing from the upper layer of the oil-water phase separator F2 after stripping and regeneration is pumped from the extractant inlet II-1 of the second gradient elution module 3 into the microchannel shared by the extraction module 1 and the second gradient elution module 3, and is countercurrently contacted with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacted with the gradient eluent pumped from the eluent inlet e1 of the second gradient elution module 3, and then countercurrently contacted with the gradient eluent pumped from the eluent inlet f1 of the second gradient elution module 3, and finally flows out from the extractant outlet II-2 of the second gradient elution module 3. The outflowing extractant is recycled after stripping and regeneration; the left side I of the second gradient elution module 3 The flow rate of the extractant at the I-1 inlet is controlled to be 5.0 mL / min; the flow rate of the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is controlled to be 5.0 mL / min; the flow rate of the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is controlled to be 7.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 continuously increases within the range of 1.5 to 2.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 continuously increases within the range of 2.5 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration continuously changes by increasing the hydrochloric acid concentration by 0.1 mol / L per minute;

[0106] ④ The extractant overflowing from the upper layer of the oil-water phase separator F3 after stripping and regeneration is pumped from the extractant inlet III-1 of the third gradient elution module 4 into the microchannel shared by the extraction module 1 and the third gradient elution module 4, and is countercurrently contacted with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacted with the gradient eluent pumped from the eluent inlet g1 of the third gradient elution module 4, and then countercurrently contacted with the gradient eluent pumped from the eluent inlet h1 of the third gradient elution module 4, and finally flows out from the extractant outlet III-2 of the third gradient elution module 4. The outflowing extractant is recycled after stripping and regeneration; the extractant outlet III-2 of the upper side of the third gradient elution module 4 is used for recycling; The flow rate of the extractant at the II-1 inlet is controlled to be 5.0 mL / min; the flow rate of the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 is controlled to be 5.0 mL / min; the flow rate of the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 is controlled to be 8.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases within the range of 4.0 to 6.0 mol / L; the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases within the range of 5.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration continuously changes by increasing the hydrochloric acid concentration by 0.1 mol / L per minute;

[0107] ⑤ Use a step component collector to continuously collect the effluents flowing out from the eluent outlet c2 of the first gradient elution module 2 in step ②, the eluent outlet e2 of the second gradient elution module 3 in step ③, and the eluent outlet g2 of the third gradient elution module 4 in step ④ in different time periods in batches, with each batch collection time being 3 minutes; from outlet c2, enriched solutions containing La and Gd, respectively, are obtained, with the relative purity of La being 98.9% and the relative purity of Gd being 95.3%; from outlet e2, enriched solutions containing Gd and Ho, respectively, with the relative purity of Gd being 99.5% and the relative purity of Ho being 94.4%; from outlet g2, enriched solutions containing Ho and Lu, respectively, are obtained, with the relative purity of Ho being 99.6% and the relative purity of Lu being 93.3%;

[0108] ⑥ Use a step component collector to continuously collect in batches the effluent flowing out from the eluent outlet d2 of the first gradient elution module 2 in step ②, the eluent outlet f2 of the second gradient elution module 3 in step ③, and the eluent outlet h2 of the third gradient elution module 4 in step ④ in different time periods, and the collection time of each batch is 3 minutes; enriched solutions containing Gd and Ho, respectively, are obtained from outlet d2, and the relative purity of Gd is 97.0%, and the relative purity of Ho is 91.2%; enriched solutions containing Ho and Lu, respectively, are obtained from outlet f2, and the relative purity of Ho is 99.5%, and the relative purity of Lu is 90.8%; an enriched solution containing Lu is obtained from outlet h2, and the relative purity of Lu is 94.9%.

[0109] Example 4:

[0110] use Figure 1 The chip module described separates a mixed aqueous solution containing four rare earth element ions: Er, Tm, Yb, and Lu. The total rare earth concentration in the mixed aqueous solution is 50 mg / L, and the initial pH of the mixed aqueous solution is 4.0. The extractant used is bis(2-ethylhexyl)phosphinic acid dissolved in n-heptane, with a molar concentration of bis(2-ethylhexyl)phosphinic acid in n-heptane of 1.0 mol / L. The microchannel of the dual-Y-shaped microchannel reactor, the basic functional unit of the microfluidic countercurrent extraction chromatography chip module, is 1.0 mm in diameter and 200 mm in length. The inlet and outlet of the Y-shaped structure at both ends of the microchannel are 1.0 mm in diameter and 5 mm in length.

[0111] The specific steps are as follows:

[0112] ① A mixed aqueous solution containing four rare earth element ions, Er, Tm, Yb, and Lu, was pumped into the extraction module 1 from the aqueous phase feed liquid inlet a at a feed rate of 5.0 mL / min. Then, at the aqueous phase feed liquid outlet b of the extraction module 1, a stepping component collector was used to continuously collect the effluent flowing out of port b at different time periods in batches. Each collection time was 5 minutes to obtain an enriched solution containing Lu, and the relative purity of Lu was 99.6%;

[0113] ② The extractant overflowing from the upper layer of the oil-water phase separator F1 after stripping and regeneration is pumped into the microchannel shared by the extraction module 1 and the first gradient elution module 2 from the extractant inlet I-1 of the first gradient elution module 2, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet c1 of the first gradient elution module 2, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet d1 of the first gradient elution module 2, and finally flows out from the extractant outlet I-2 of the first gradient elution module 2. The outflowing extractant is recycled after stripping and regeneration; the extractant outlet I-2 on the lower side of the first gradient elution module 2 is used for recycling. The flow rate of the extractant at the inlet 1 is controlled to be 2.5 mL / min; the flow rate of the gradient eluent at the inlet c1 on the left side of the first gradient elution module 2 is controlled to be 1.0 mL / min; the flow rate of the gradient eluent at the inlet d1 on the upper side of the first gradient elution module 2 is controlled to be 2.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the inlet c1 on the left side of the first gradient elution module 2 is continuously increased within the range of 0.5 to 1.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the inlet d1 on the upper side of the first gradient elution module 2 is continuously increased within the range of 2.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration is a continuous change with the hydrochloric acid concentration increasing by 0.1 mol / L per minute;

[0114] ③ The extractant overflowing from the upper layer of the oil-water phase separator F2 after stripping and regeneration is pumped from the extractant inlet II-1 of the second gradient elution module 3 into the microchannel shared by the extraction module 1 and the second gradient elution module 3, and is countercurrently contacted with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacted with the gradient eluent pumped from the eluent inlet e1 of the second gradient elution module 3, and then countercurrently contacted with the gradient eluent pumped from the eluent inlet f1 of the second gradient elution module 3, and finally flows out from the extractant outlet II-2 of the second gradient elution module 3. The outflowing extractant is recycled after stripping and regeneration; the left side I of the second gradient elution module 3 The flow rate of the extractant at the I-1 inlet is controlled to be 2.5 mL / min; the flow rate of the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 is controlled to be 1.0 mL / min; the flow rate of the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 is controlled to be 3.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the e1 inlet on the upper side of the second gradient elution module 3 continuously increases within the range of 1.5 to 2.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the f1 inlet on the right side of the second gradient elution module 3 continuously increases within the range of 2.5 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration continuously changes by increasing the hydrochloric acid concentration by 0.1 mol / L per minute;

[0115] ④ The extractant overflowing from the upper layer of the oil-water phase separator F3 after stripping and regeneration is pumped from the extractant inlet III-1 of the third gradient elution module 4 into the microchannel shared by the extraction module 1 and the third gradient elution module 4, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet g1 of the third gradient elution module 4, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet h1 of the third gradient elution module 4, and finally flows out from the extractant outlet III-2 of the third gradient elution module 4. The outflowing extractant is recycled after stripping and regeneration; the extractant outlet III-1 on the upper side of the third gradient elution module 4 is used for recycling; The flow rate of the extractant at the II-1 inlet is controlled to be 2.5 mL / min; the flow rate of the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 is controlled to be 1.0 mL / min; the flow rate of the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 is controlled to be 5.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases within the range of 4.0 to 6.0 mol / L; the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases within the range of 5.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration continuously changes by increasing the hydrochloric acid concentration by 0.1 mol / L per minute;

[0116] ⑤ Use a step component collector to continuously collect the effluents flowing out from the eluent outlet c2 of the first gradient elution module 2 in step ②, the eluent outlet e2 of the second gradient elution module 3 in step ③, and the eluent outlet g2 of the third gradient elution module 4 in step ④ in different time periods in batches, with each batch collection time being 5 minutes; from outlet c2, enriched solutions containing Er and Tm, respectively, are obtained, with the relative purity of Er being 99.4% and the relative purity of Tm being 92.5%; from outlet e2, enriched solutions containing Tm and Yb, respectively, are obtained, with the relative purity of Tm being 99.7% and the relative purity of Yb being 97.4%; from outlet g2, enriched solutions containing Yb and Lu, respectively, are obtained, with the relative purity of Yb being 99.6% and the relative purity of Lu being 94.7%;

[0117] ⑥ Use a step component collector to continuously collect in batches the effluent flowing out from the eluent outlet d2 of the first gradient elution module 2 in step ②, the eluent outlet f2 of the second gradient elution module 3 in step ③, and the eluent outlet h2 of the third gradient elution module 4 in step ④ in different time periods, and the collection time of each batch is 5 minutes; enriched solutions containing Tm and Yb, respectively, are obtained from outlet d2, with a relative purity of Tm of 99.0% and a relative purity of Yb of 94.2%; enriched solutions containing Yb and Lu, respectively, are obtained from outlet f2, with a relative purity of Yb of 99.6% and a relative purity of Lu of 92.6%; an enriched solution containing Lu is obtained from outlet h2, with a relative purity of Lu of 95.5%.

[0118] Example 5:

[0119] A chip structure extension combination for microfluidic countercurrent extraction chromatography group separation of rare earth ions, such as Figure 5 As shown, it is composed of two basic functional units of microfluidic countercurrent extraction chromatography chip modules on the left and right. The two basic functional units of microfluidic countercurrent extraction chromatography chip modules on the left and right share the same set of gradient eluent feed system, but each uses its own extractant stripping regenerator and oil-water phase separator system. The microchannel diameter of the double Y-type microchannel reactor of the microfluidic countercurrent extraction chromatography chip module on the right is 0.5mm, the length is 200mm, and the inlet and outlet diameters of the Y-type structures at both ends of the microchannel are 0.5mm and 5mm respectively. The microchannel diameter of the double Y-type microchannel reactor of the microfluidic countercurrent extraction chromatography chip module on the left is 0.3mm, the length is 200mm, and the inlet and outlet diameters of the Y-type structures at both ends of the microchannel are 0.3mm and 5mm respectively.

[0120] The above chip module expansion combination is used to separate a mixed aqueous solution containing fourteen rare earth element ions of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; wherein the total concentration of rare earth elements in the mixed aqueous solution is 1000 mg / L, and the initial pH of the mixed aqueous solution is 4.0-4.5; the gradient elution modules 2 and 3 of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module located on the right are used as the extractant of a mixture of 2-ethylhexyl mono(2-ethylhexyl) phosphate and a secondary carbon primary amine, which is dissolved in kerosene, and the molar concentration of 2-ethylhexyl mono(2-ethylhexyl) phosphate in kerosene is 1.0 mol / L, and the molar concentration of the secondary carbon primary amine in kerosene is 0.2 mol / L; the microfluidic countercurrent extraction chromatography chip module located on the right The extractant used in the gradient elution module 4 of the basic functional unit of the block is bis(2-ethylhexyl)phosphinic acid dissolved in kerosene, and the molar concentration of bis(2-ethylhexyl)phosphinic acid in kerosene is 1.0 mol / L; the extractant used in the first and second gradient elution modules is a mixture of bis(2-ethylhexyl)phosphinic acid and cycloalkane acid, dissolved in kerosene, and the molar concentration of bis(2-ethylhexyl)phosphinic acid in kerosene is 1.0 mol / L, and the molar concentration of cycloalkane acid in kerosene is 0.2 mol / L; the extractant used in the third gradient elution module 4 is a mixture of di(2,4,4-trimethylpentyl)phosphinic acid and cycloalkane acid, dissolved in kerosene, and the molar concentration of di(2,4,4-trimethylpentyl)phosphinic acid in kerosene is 1.0 mol / L, and the molar concentration of cycloalkane acid in kerosene is 0.5 mol / L.

[0121] The specific steps are as follows:

[0122] ① A mixed aqueous solution containing fourteen rare earth element ions of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu was pumped into the aqueous phase feed inlet a of the extraction module 1 at a feed rate of 0.5 mL / min. Then, the aqueous phase raffinate flowing out of the aqueous phase feed outlet b of the extraction module 1 was pumped into the aqueous phase feed inlet a by a metering injection pump. Finally, at the aqueous phase feed outlet b, a stepping component collector was used to continuously collect the effluent flowing out of the b port at different time periods in batches. The collection time for each batch was 5 min, and enriched solutions containing Yb and Lu were obtained, respectively. The relative purity of Yb was 99.3%, and the relative purity of Lu was 99.9%.

[0123] ② The extractant overflowing from the upper layer of the oil-water phase separator F1 of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the right and regenerated by back extraction is pumped into the microchannel shared by the extraction module 1 and the first gradient elution module 2 from the extractant inlet I-1 of the first gradient elution module 2, and countercurrently contacts with the aqueous phase feed liquid pumped from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet c1 of the first gradient elution module 2, and then countercurrently contacts with the gradient eluent pumped from the eluent inlet d1 of the first gradient elution module 2, and finally flows out from the extractant outlet I-2 of the first gradient elution module 2. The outflowing extractant is recycled after back extraction and regeneration; the operation of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the left is the same as that located at Operation of the basic functional units of the microfluidic countercurrent extraction chromatography chip module on the right; the flow rate of the extractant at the I-1 inlet on the lower side of the first gradient elution module 2 is controlled at 0.5 mL / min; the flow rate of the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 is controlled at 1.0 mL / min; the flow rate of the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 is controlled at 2.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the c1 inlet on the left side of the first gradient elution module 2 continuously increases within the range of 0.5 to 1.5 mol / L; the hydrochloric acid concentration in the gradient eluent at the d1 inlet on the upper side of the first gradient elution module 2 continuously increases within the range of 2.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration continuously changes with the hydrochloric acid concentration increasing by 0.1 mol / L per minute;

[0124] ③The oil-water separator F2 upper overflowed extractant after back extraction regeneration of the right microfluidic countercurrent extraction chromatography chip module basic functional unit is pumped into the microchannel shared by the extraction module 1 and the second gradient elution module 3 from the extractant inlet II-1 of the second gradient elution module 3, and is countercurrently contacted with the aqueous phase feed from the aqueous phase feed inlet a of the extraction module 1, and then is countercurrently contacted with the gradient elution liquid from the elution liquid inlet e1 of the second gradient elution module 3, and then is countercurrently contacted with the gradient elution liquid from the elution liquid inlet f1 of the second gradient elution module 3, and finally flows out from the extractant outlet II-2 of the second gradient elution module 3, and the outflowing extractant is regenerated by back extraction and then recycled; the operation of the microfluidic countercurrent extraction chromatography chip module basic functional unit on the left is the same as that of the microfluidic countercurrent extraction chromatography chip module basic functional unit on the right; the extractant flow rate of the left II-1 inlet of the second gradient elution module 3 is controlled to be 0.5 mL / min; the gradient elution liquid flow rate of the upper e1 inlet of the second gradient elution module 3 is controlled to be 1.0 mL / min; the gradient elution liquid flow rate of the right f1 inlet of the second gradient elution module 3 is controlled to be 3.0 mL / min; the concentration of hydrochloric acid in the gradient elution liquid of the upper e1 inlet of the second gradient elution module 3 is continuously increased in the range of 1.5-2.5 mol / L; the concentration of hydrochloric acid in the gradient elution liquid of the right f1 inlet of the second gradient elution module 3 is continuously increased in the range of 2.5-6.0 mol / L; the change rate of the concentration of hydrochloric acid is 0.1 mol / L per minute;

[0125] ④ The extractant overflowing from the upper layer of the oil-water phase separator F3 of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the right and regenerated by back extraction is pumped into the microchannel shared by the extraction module 1 and the third gradient elution module 4 from the extractant inlet III-1 of the third gradient elution module 4, and countercurrently contacts with the aqueous phase feed liquid pumped in from the aqueous phase feed liquid inlet a of the extraction module 1, and then countercurrently contacts with the gradient eluent pumped in from the eluent inlet g1 of the third gradient elution module 4, and then countercurrently contacts with the gradient eluent pumped in from the eluent inlet h1 of the third gradient elution module 4, and finally flows out from the extractant outlet III-2 of the third gradient elution module 4. The outflowing extractant is recycled after back extraction and regeneration; the operation of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the left is the same as that located at Operation of the basic functional unit of the microfluidic countercurrent extraction chromatography chip module on the right; the flow rate of the extractant at the III-1 inlet on the upper side of the third gradient elution module 4 is controlled to 0.5 mL / min; the flow rate of the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 is controlled to 1.0 mL / min; the flow rate of the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 is controlled to 5.0 mL / min; the hydrochloric acid concentration in the gradient eluent at the g1 inlet on the right side of the third gradient elution module 4 continuously increases within the range of 4.0 to 6.0 mol / L; the hydrochloric acid concentration in the gradient eluent at the h1 inlet on the lower side of the third gradient elution module 4 continuously increases within the range of 5.0 to 6.0 mol / L; the rate of change of the hydrochloric acid concentration is a continuous change of the hydrochloric acid concentration by 0.1 mol / L per minute;

[0126] ⑤ Use a step component collector to continuously collect the effluent from the outlet c2 of the first gradient elution module 2 in step ②, the outlet e2 of the second gradient elution module 3 in step ③, and the outlet g2 of the third gradient elution module 4 in step ④ in different time periods in batches, and the collection time of each batch is 5 minutes; from the outlet c2, enriched solutions containing La and Ce are obtained, with the relative purity of La being 99.8% and the relative purity of Ce being 95.3%; from the outlet e2, enriched solutions containing Pr and Nd are obtained, with the relative purity of Pr being 99.0% and the relative purity of Nd being 92.2%; from the outlet Port g2 obtained enriched solutions containing Sm and Eu, with a relative purity of Sm of 99.2% and a relative purity of Eu of 92.8%; outlet c2 obtained enriched solutions containing Gd and Tb, with a relative purity of Gd of 99.8% and a relative purity of Tb of 95.5%; outlet e2 obtained enriched solutions containing Dy and Ho, with a relative purity of Dy of 98.9% and a relative purity of Ho of 94.2%; outlet g2 obtained enriched solutions containing Er and Tm, with a relative purity of Er of 98.8% and a relative purity of Tm of 95.8%;

[0127] ⑥ Use a step component collector to continuously collect the effluent from the outlet d2 of the first gradient elution module 2 in step ②, the outlet f2 of the second gradient elution module 3 in step ③, and the outlet h2 of the third gradient elution module 4 in step ④ in different time periods in batches, with each batch collection time being 5 minutes; an enriched solution containing Ce and Pr, respectively, is obtained from outlet d2, with a relative purity of Ce of 99.1% and a relative purity of Pr of 92.6%; an enriched solution containing Nd and Sm, respectively, is obtained from outlet f2, with a relative purity of Nd of 99.2% and a relative purity of Sm of 94.5%; Enriched solutions containing Eu and Gd were obtained from outlet h2, with the relative purity of Eu being 99.3% and the relative purity of Gd being 96.1%; enriched solutions containing Tb and Dy were obtained from outlet d2, with the relative purity of Tb being 99.7% and the relative purity of Dy being 96.7%; enriched solutions containing Ho and Er were obtained from outlet f2, with the relative purity of Ho being 98.9% and the relative purity of Er being 96.9%; enriched solutions containing Tm and Yb were obtained from outlet h2, with the relative purity of Tm being 99.0% and the relative purity of Yb being 96.2%.

[0128] The above describes in detail the chip structure and method for the microfluidic countercurrent extraction chromatography group separation of rare earth ions provided in the examples of this application. The description of the above examples is intended only to facilitate understanding of the method and core concept of this application. Furthermore, those skilled in the art will appreciate that variations in the specific implementation and scope of application may occur based on the concepts of this application. In summary, this description should not be construed as limiting this application.

Claims

1. A chip structure for separating rare earth ions by microfluidic countercurrent extraction chromatography, characterized in that: The chip structure includes an extraction module, a first gradient elution module, a second gradient elution module, and a third gradient elution module; the first gradient elution module, the second gradient elution module, and the third gradient elution module are sequentially arranged in three directions around the periphery of the extraction module and interwoven to form a "half-cross" plane grid structure; The extraction module, the first gradient elution module, the second gradient elution module and the third gradient elution module are all microchannel reactors in the shape of a parallelogram consisting of four microchannels; The extraction module and any gradient elution module are interwoven and connected in such a way that the two share a microchannel at the connecting edge; the rare earth ion aqueous phase feed solution in the extraction module and the extractant in the corresponding gradient elution module flow in counter-current contact in the shared microchannel; The rare earth ion aqueous phase feed liquid in the extraction module flows in the following manner: it is pumped in from the aqueous phase feed liquid inlet, then flows sequentially through the microchannels on three sides, namely, the microchannel shared by the extraction module and the first gradient elution module, the microchannel shared by the extraction module and the second gradient elution module, and the microchannel shared by the extraction module and the third gradient elution module, and finally discharged and collected from the aqueous phase feed liquid outlet; the aqueous phase feed liquid inlet and the aqueous phase feed liquid outlet are respectively arranged at the two ends of the fourth side of the extraction module; The extractant in any gradient elution module flows in the following manner: it is pumped in from the extractant inlet, then flows sequentially through the microchannel shared by the gradient elution module and the extraction module, and the second microchannel and the third microchannel sequentially connected to the shared microchannel, and finally discharged and collected from the extractant outlet; the extractant inlet and the extractant outlet are respectively located at the two ends of the fourth side of the gradient elution module; The second microchannel and the third microchannel are both structures with an eluent inlet and an eluent outlet at both ends; the eluent in the second microchannel and the eluent in the third microchannel flow in a countercurrent contact flow with the extractant flowing through.

2. The chip structure for separating rare earth ions by microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The structural parameters of the microchannel constituting the extraction module, the first gradient elution module, the second gradient elution module or the third gradient elution module include: the cross section of the microchannel is circular, the diameter of the cross section is 0.05mm~2.0mm, and the length of the microchannel is 10mm~200mm.

3. The chip structure for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The aqueous phase liquid outlet is connected to a step component collector, and a component effluent liquid storage tank is provided at the outlet of the step component collector.

4. The chip structure for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The eluent inlets of the second microchannel and the third microchannel are respectively connected to corresponding eluent storage tanks via eluent pipelines; a metering injection pump is provided on the eluent pipeline; The eluent outlets of the second microchannel and the third microchannel are respectively connected to corresponding step component collectors, and the outlets of the step component collectors are connected to the component effluent storage tank.

5. The chip structure for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The extractant outlet of any gradient elution module is connected to the inlet of the extractant stripping regenerator through an extractant pipeline, the outlet of the extractant stripping regenerator is connected to the inlet of the oil-water phase divider, and the outlet of the oil-water phase divider is connected to the extractant inlet of the gradient elution module; a metering injection pump is configured in the connecting pipeline between the oil-water phase divider and the extractant inlet.

6. The chip structure for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The eluent is a hydrochloric acid aqueous solution with a concentration gradient; the eluent gradient changes in a manner that the hydrochloric acid concentration increases by 0.1 mol / L per minute; the hydrochloric acid concentration in the eluent changes in a range of 0.1 to 6 mol / L.

7. The chip structure for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The extractant includes a solute and a solvent; The solute is any one or a combination of two or more of 2-ethylhexyl mono(2-ethylhexyl) phosphate, di(2-ethylhexyl) phosphate, di(2,4,4-trimethylpentyl)phosphinic acid, bis(2-ethylhexyl)phosphinic acid, tributyl phosphate, dimethylheptyl methylphosphate, secondary carbon primary amine and cyclohexane acid; The solvent is kerosene or an alkane containing 6 to 12 carbon atoms; The molar concentration of the solute in the extractant is 0-1.0 mol / L.

8. The chip structure for grouping and separating rare earth ions by microfluidic countercurrent extraction chromatography according to claim 1, characterized in that: The rare earth ion aqueous phase liquid comprises three or more rare earth elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y; The total concentration of rare earth elements contained in the rare earth ion aqueous phase feed liquid is 50-1000 mg / L, and the initial pH is 2-5.

9. A method for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography, characterized in that: The method is implemented by using the chip structure for grouping and separating rare earth ions using microfluidic countercurrent extraction chromatography according to any one of claims 1 to 8; the method comprises: The rare earth ion aqueous phase feed liquid is pumped into the aqueous phase feed liquid inlet and flows along the three microchannels of the extraction module in sequence to complete the extraction of the rare earth ion aqueous phase feed liquid. The aqueous phase feed liquid then flows out from the aqueous phase feed liquid outlet and is collected to obtain an enriched solution containing different rare earth ions. The extractant overflowing from the upper layer of the oil-water phase separator and regenerated by stripping is pumped into the extractant inlets of the first gradient elution module, the second gradient elution module, and the third gradient elution module, respectively, so as to flow in countercurrent contact with the rare earth ion aqueous phase in the microchannels shared by the extraction module and the three gradient elution modules, and then flows out from the respective extractant outlets for collection to obtain three gradients of extractant enriched liquid; the discharged extractant enriched liquid is recycled after stripping and regeneration; Gradient eluents with varying concentrations are pumped into the eluent inlets of the second microchannel and the third microchannel of the first gradient elution module, the second gradient elution module and the third gradient elution module respectively. After the eluents come into reverse contact with the extractant in the microchannels, they are discharged and collected from the eluent outlets of the microchannels to obtain two gradient eluent enrichment liquids of each gradient elution module.

10. The method for separating rare earth ions by grouping using microfluidic countercurrent extraction chromatography according to claim 9, characterized in that: The pumping speed of the rare earth ion aqueous phase liquid is 0.1 to 10 mL / min; The flow rate of the extractant in the first gradient elution module, the second gradient elution module and the third gradient elution module is 0.1 to 10 mL / min; The flow rate of the gradient eluent in the second microchannel of the first gradient elution module, the second gradient elution module, and the third gradient elution module is 0.1 to 5 mL / min; the flow rate of the gradient eluent in the third microchannel of the first gradient elution module, the second gradient elution module, and the third gradient elution module is 1 to 10 mL / min; The gradient eluent pumped into the second microchannel of the first gradient elution module changes in concentration within a gradient range of 0.5 to 1.5 mol / L; the gradient eluent pumped into the third microchannel changes in concentration within a gradient range of 2.0 to 6.0 mol / L; The gradient eluent pumped into the second microchannel of the second gradient elution module changes in concentration within a gradient range of 1.5 to 2.5 mol / L; the gradient eluent pumped into the third microchannel changes in concentration within a gradient range of 2.5 to 6.0 mol / L; The gradient eluent pumped into the second microchannel of the third gradient elution module changes gradually within the concentration range of 4.0 to 6.0 mol / L; the gradient eluent pumped into the third microchannel changes gradually within the concentration range of 5.0 to 6.0 mol / L.

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