Method for separating and purifying scandium based on modified graphene oxide layered membrane
By using modified graphene oxide layered membranes for complexation and impurity removal, combined with electrodialysis and monovalent cation selective anolyte membranes, the problems of high scandium resource loss and low separation accuracy in existing scandium separation and purification technologies have been solved, achieving efficient and low-cost preparation of high-purity scandium solutions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINGMEN GEM NEW MATERIAL CO LTD
- Filing Date
- 2026-06-17
- Publication Date
- 2026-07-24
AI Technical Summary
Existing scandium separation and purification technologies suffer from problems such as high scandium resource loss, large equipment footprint, significant safety and environmental hazards, low separation accuracy, poor resin material stability, and severe interference from impurity ions, making it difficult to prepare high-purity scandium-rich solutions.
Modified graphene oxide layered membranes were used for complexation and impurity removal and electrodialysis treatment. By combining monovalent cation selective anolyte membranes and modified graphene oxide layered membranes, efficient separation of scandium ions and impurity ions was achieved. The separation effect was improved by controlling the interlayer spacing and functional group modification.
The preparation of high-purity scandium-rich solutions has been achieved, with iron removal rates of over 93%, aluminum removal rates of over 91%, sodium removal rates of over 83%, and scandium recovery rates of over 96%, thereby reducing production costs and environmental pressure.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrometallurgical technology and relates to a method for separating and purifying scandium based on a modified graphene oxide layered membrane. Background Technology
[0002] Scandium, as a rare and dispersed metal, possesses unique physicochemical properties such as high melting point, low density, excellent electrical and thermal conductivity, and stable chemical activity. It has irreplaceable application value in high-tech fields such as aerospace, high-end ceramics, semiconductor materials, new energy alloys, and photocatalysis, making it a key strategic resource for the development of high-end new materials industries. Industrially, scandium is often found as a byproduct of minerals such as bauxite, ilmenite, and rare earth ores. Scandium-containing leaching solutions obtained through acid and alkali leaching processes are complex, generally containing high-valence metal impurities such as iron, aluminum, titanium, and calcium, as well as monovalent inorganic salt impurities such as sodium and chloride ions. These impurity ions have similar physicochemical properties to scandium ions and exhibit strong interference, making the purification of scandium-containing leaching solutions extremely difficult and severely restricting the industrial-scale preparation of high-purity scandium oxide and scandium-based high-end materials.
[0003] Currently, the mainstream industrial technologies for scandium separation and purification mainly include chemical precipitation, solvent extraction, and conventional ion exchange resin adsorption. Chemical precipitation removes impurities by adjusting the pH of the feed solution to hydrolyze and precipitate metal ions. However, this process is prone to co-precipitation of scandium ions with impurity hydroxides during impurity removal, resulting in significant scandium resource loss, low scandium recovery rates, and the generation of large amounts of heavy metal hazardous waste, leading to significant environmental pressure and difficulty in ensuring product purity. Solvent extraction is currently the most widely used scandium extraction process, relying on organic extractants such as P507 and TBP to separate scandium from some impurities. However, this method has significant technical shortcomings: the multi-stage extraction process is cumbersome, requires large equipment footprint, and the organic extractants are prone to emulsification, volatilization, and degradation, increasing production costs and generating large amounts of organic waste liquid, posing serious safety and environmental hazards. Furthermore, the high content of monovalent salt impurities such as sodium and chloride ions in the feed solution continuously interferes with the extraction equilibrium, significantly reducing the selectivity and separation accuracy of scandium extraction, making it difficult to directly prepare high-purity scandium-rich solutions.
[0004] Conventional ion exchange resin adsorption methods can achieve scandium ion adsorption and separation through the coordination of resin functional groups. However, commercial chelating resins suffer from disordered pore structure and poor adsorption selectivity. Coexisting impurity ions in the feed solution can compete for resin adsorption sites, resulting in decreased scandium adsorption capacity and insufficient separation purity. Furthermore, the resin materials have poor acid and alkali resistance, and functional groups are easily detached and the framework is easily damaged after repeated regeneration and use, resulting in short cycle life and high operating costs. In addition, most existing purification processes lack targeted desalination pretreatment steps, and residual monovalent anions and cations in scandium-containing feed solutions cannot be effectively removed, continuously interfering with subsequent scandium adsorption and separation processes, becoming a key technical bottleneck limiting the preparation of high-purity scandium. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for separating and purifying scandium based on a modified graphene oxide layered membrane. This invention achieves efficient separation of scandium ions from impurity ions by using a specially modified graphene oxide layered membrane for adsorption and filtration after complexation and electrodialysis to remove impurities, thereby obtaining a high-purity scandium-rich solution.
[0006] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for separating and purifying scandium based on a modified graphene oxide layered membrane, the method comprising the following steps: Provides modified graphene oxide layered films and scandium-containing solutions; After adjusting the pH of the scandium-containing solution, a complexing agent is added to carry out a complexation reaction, resulting in the first scandium-removed solution. The first purified scandium solution after the complexation reaction was subjected to electrodialysis using a monovalent cation-selective anolyte membrane to obtain a second purified scandium solution. After adsorption and filtration of the second scandium solution using a modified graphene oxide layered membrane, the modified graphene oxide layered membrane is rinsed with an acid solution to obtain a scandium-rich solution.
[0007] This invention pre-adjusts the pH of the scandium-containing solution and performs a complexation and impurity removal treatment to remove most of the impurities (such as Fe). 3+ Al 3+ Ca 2+ Ti 4+ (etc.), scandium is basically not lost, and then a monovalent cation selective anolyte membrane is used to directionally remove Na from the solution. + Using modified graphene oxide layered films to precisely trap Sc 3+ , to achieve Sc 3+ With efficient separation of impurity ions, Sc 3+ The scandium-rich solution can be obtained by rinsing the modified graphene oxide layered film with an acid solution.
[0008] Preferably, the modified graphene oxide layered film is prepared by the following method: Graphene oxide is mixed with a solvent to obtain a graphene oxide dispersion. The graphene oxide dispersion is then heat-treated to obtain a pretreated graphene oxide dispersion. The pretreated graphene oxide dispersion, diamine monomer, and amino acid are mixed and subjected to a modification reaction to obtain a modified graphene oxide dispersion. The modified graphene oxide dispersion is coated onto a substrate surface and vacuum-dried to obtain the modified graphene oxide layered film.
[0009] Graphene oxide possesses a unique two-dimensional layered structure, controllable interlayer spacing, abundant oxygen-containing functional groups, and excellent physicochemical stability. This invention first partially reduces graphene oxide through heat treatment, removing unstable oxygen-containing functional groups from its surface, reducing steric hindrance and electrostatic repulsion between layers, and allowing for tighter layer stacking. Then, diamines and amino acids are introduced. The amino groups at both ends of the diamine react chemically with carboxyl or epoxy groups on adjacent graphene layers to form covalent bonds, thereby locking the diamine molecules between graphene layers. Amino acids contain both amino and carboxyl groups, and can react with graphene like diamines, while also introducing new specific adsorption sites between layers. The amino groups on amino acids can attack the epoxy groups on graphene, undergoing nucleophilic substitution reactions, thus grafting onto the graphene surface or edges. By synergistically controlling the interlayer spacing of graphene oxide through heat treatment, diamines, and amino acids, graphene oxide can be obtained with properties similar to Sc... 3+ Channels with highly matched particle size trap Sc 3+ Simultaneously, impurity ions flow out of the membrane, achieving Sc 3+ Efficient separation from impurity ions.
[0010] Preferably, the solvent includes water.
[0011] Preferably, the mass concentration of the graphene oxide dispersion is 0.5 g / L to 2 g / L, for example: 0.5 g / L, 0.8 g / L, 1 g / L, 1.5 g / L or 2 g / L, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0012] Preferably, the heat treatment temperature is 140℃~170℃, for example: 140℃, 145℃, 150℃, 160℃ or 170℃, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0013] Preferably, the heat treatment time is 2h to 4h, for example: 2h, 2.5h, 3h, 3.5h or 4h, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0014] Preferably, the diamine monomer includes any one or a combination of at least two of ethylenediamine, hexamethylenediamine, or m-phenylenediamine. Typical but non-limiting combinations include combinations of ethylenediamine and m-phenylenediamine, combinations of ethylenediamine and hexamethylenediamine, or combinations of hexamethylenediamine and m-phenylenediamine.
[0015] Preferably, the mass ratio of graphene oxide to diamine monomer in the pretreated graphene oxide dispersion is 1:(0.1~1), for example: 1:0.1, 1:0.2, 1:0.5, 1:0.8 or 1:1, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0016] Preferably, the amino acid includes any one or a combination of at least two of serine, alanine, or lysine. Typical but non-limiting combinations include combinations of serine and lysine, serine and alanine, or alanine and lysine.
[0017] Preferably, the mass ratio of graphene oxide to amino acids in the pretreated graphene oxide dispersion is 1:(0.1~0.5), for example: 1:0.1, 1:0.2, 1:0.3, 1:0.4 or 1:0.5, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0018] Preferably, the pH of the modification reaction is 4.5 to 6, for example: 4.5, 4.8, 5, 5.5 or 6, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0019] Preferably, the temperature of the modification reaction is 55℃~70℃, for example: 55℃, 58℃, 60℃, 65℃ or 70℃, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0020] Preferably, the modification reaction time is 4h to 6h, for example: 4h, 4.5h, 5h, 5.5h or 6h, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0021] Preferably, the vacuum drying temperature is 60℃~80℃, for example: 60℃, 65℃, 70℃, 75℃ or 80℃, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0022] Preferably, the pH of the scandium-containing solution is adjusted to be 2 to 3.2, for example: 2, 2.4, 2.8, 3 or 3.2, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0023] Preferably, the complexing agent comprises EDTA and / or citric acid.
[0024] Preferably, the temperature of the complexation reaction is 25℃~35℃, for example: 25℃, 28℃, 30℃, 32℃ or 35℃, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0025] Preferably, the complexation reaction time is 60 min to 120 min, for example: 60 min, 80 min, 90 min, 100 min or 120 min, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0026] Preferably, the complexation reaction is followed by a settling and filtration process.
[0027] Preferably, the monovalent cation-selective anode membrane comprises a sulfonamide-modified cation exchange membrane and / or a polypyrrole-modified cation exchange membrane.
[0028] This invention uses a monovalent cation-selective anolyte membrane to construct an electrodialysis system, which can remove Na+. + While eliminating monovalent salt impurities, it efficiently retains trivalent scandium ions, achieving scandium pre-enrichment. This avoids scandium loss during desalination and eliminates competition from monovalent metal ions for adsorption sites on the subsequent modified graphene oxide membrane. At the same time, the membrane is resistant to contamination by trace amounts of organic complexing agents and has low operating energy consumption, significantly improving the subsequent scandium adsorption and separation efficiency and the purity of the scandium-rich solution.
[0029] Preferably, the monovalent cation-selective anolyte membrane and the homogeneous anion exchange membrane are alternately arranged for electrodialysis treatment.
[0030] Preferably, the voltage of the electrodialysis treatment is 5V~10V, for example: 5V, 6V, 8V, 9V or 10V, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0031] Preferably, the current density of the electrodialysis treatment is 10 mA / cm². 2 ~25mA / cm 2 For example: 10mA / cm 2 12mA / cm 2 15mA / cm 2 20mA / cm 2 Or 25mA / cm 2 The term "etc." is not limited to the listed values; it also applies to other unlisted values within the range.
[0032] Preferably, during the electrodialysis process, the feed rate of the first scandium solution for impurity removal is 20L / h to 30L / h, for example: 20L / h, 22L / h, 25L / h, 28L / h or 30L / h, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0033] Preferably, during the adsorption filtration process, the flow rate of the second scandium solution is 0.5 BV / h to 2 BV / h, for example: 0.5 BV / h, 0.8 BV / h, 1 BV / h, 1.5 BV / h or 2 BV / h, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0034] Preferably, the acid solution includes nitric acid solutions with a concentration of 3 mol / L to 5 mol / L, such as 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0035] Preferably, during the rinsing process, the flow rate of the acid solution is 0.3 BV / h to 0.8 BV / h, for example: 0.3 BV / h, 0.4 BV / h, 0.6 BV / h, 0.7 BV / h or 0.8 BV / h, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0036] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0037] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention achieves efficient separation of scandium ions and impurity ions by complexation and electrodialysis, followed by adsorption and filtration using a specially modified graphene oxide layered membrane, and can produce a high-purity scandium-rich solution.
[0038] (2) The method for separating and purifying scandium based on modified graphene oxide layered membrane described in this invention can achieve an iron removal rate of over 93%, an aluminum removal rate of over 91%, a sodium removal rate of over 83%, and a scandium recovery rate of over 96%. Detailed Implementation
[0039] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0040] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values 1 and 2 are listed, and the maximum range values 3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.
[0041] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.
[0042] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art can understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology.
[0043] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined according to its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order in which they are written or in any order that does not conflict with the technology.
[0044] The modified graphene oxide layered films used in the embodiments and comparative examples of this invention were prepared by the following method: Graphene oxide was mixed with deionized water to obtain a 1 g / L graphene oxide dispersion. The graphene oxide dispersion was then heat-treated at 150 °C for 3 h to obtain a pretreated graphene oxide dispersion. The pretreated graphene oxide dispersion, ethylenediamine monomer and lysine were mixed at a mass ratio of 1:0.5:0.3, the pH was adjusted to 5, and the modification reaction was carried out at 65℃ for 5 h to obtain the modified graphene oxide dispersion. The modified graphene oxide dispersion was spin-coated onto the substrate surface and vacuum dried at 70°C to obtain the modified graphene oxide layered film.
[0045] The monovalent cation-selective anolyte used in the embodiments and comparative examples of this invention is a polypyrrole-modified cation exchange membrane, which is prepared by the following method: Homogeneous cation exchange membranes (CEMs) were cut into 10cm × 30cm pieces and soaked in deionized water for 24 hours. Afterward, they were removed and immersed in a 10% sulfuric acid solution for 4 hours to allow for hydrogenation. The CEMs were then repeatedly rinsed with deionized water to remove residual ions. Under constant temperature conditions of 40℃, the treated CEMs were immersed in 500mL of a 0.2mol / L modified pyrrole solution. Simultaneously, 50mL of a 0.08mol / L hydrochloric acid solution was added as a protic acid catalyst, and 50mL of a 0.8mol / L ferric chloride solution was slowly added dropwise as an oxidant for the pyrrole polymerization reaction. After the addition was complete, the membrane was allowed to stand for 6 hours to allow the pyrrole to fully undergo oxidative polymerization. During this process, the membrane gradually changed from an initial pale yellow to dark green and finally to black. Once the monovalent selective cation exchange membrane was prepared, the membrane was removed and repeatedly rinsed with deionized water to remove residual polypyrrole and oxidant. It was then placed in deionized water for later use.
[0046] The homogeneous cation exchange membrane described in this invention is a Fumasep FKE homogeneous cation exchange membrane, and the homogeneous anion exchange membrane is an HP-AM homogeneous anion exchange membrane.
[0047] The mass concentrations of various ions in the scandium-containing solutions used in the embodiments and comparative examples of this invention are as follows: Sc 3+ 10g / L, Fe 3+ 635mg / L, Al 3+ 573 mg / L, Na + : 80mg / L.
[0048] Example 1 This embodiment provides a method for separating and purifying scandium based on a modified graphene oxide layered membrane, the method comprising the following steps: After adjusting the pH of the scandium-containing solution to 2.5, citric acid (the molar concentration of citric acid and impurity cations is 2.5:1) is added, and a complexation reaction is carried out at 30°C for 80 min. After standing for 30 min, the solution is filtered to obtain the first scandium-removed solution. The electrodialysis unit uses 10 homogeneous anion exchange membranes, 11 monovalent cation selective anolyse membranes, and PP separators arranged alternately. The controlled voltage is 8V, and the current density is 15mA / cm². 2 The first scandium solution after the complexation reaction was subjected to electrodialysis at a feed rate of 25 L / h to obtain the second scandium solution. The flow rate of the second scandium removal solution was controlled at 1 BV / h. After the second scandium removal solution was adsorbed and filtered using a modified graphene oxide layered membrane, the modified graphene oxide layered membrane was rinsed with a nitric acid solution with a molar concentration of 4 mol / L at a flow rate of 0.5 BV / h to obtain a scandium-rich solution.
[0049] Example 2 This embodiment provides a method for separating and purifying scandium based on a modified graphene oxide layered membrane, the method comprising the following steps: After adjusting the pH of the scandium-containing solution to 2, EDTA (the molar concentration of EDTA and impurity cations is 1.2:1) is added, and a complexation reaction is carried out at 35°C for 60 min. After standing for 30 min, the solution is filtered to obtain the first scandium-removed solution. The electrodialysis unit uses 10 homogeneous anion exchange membranes, 11 monovalent cation selective anolyse membranes, and PP separators arranged alternately. The controlled voltage is 5V, and the current density is 10mA / cm². 2 The first scandium solution after the complexation reaction was subjected to electrodialysis at a feed rate of 20 L / h to obtain the second scandium solution. The flow rate of the second scandium removal solution was controlled at 0.5 BV / h. After the second scandium removal solution was adsorbed and filtered using a modified graphene oxide layered membrane, the modified graphene oxide layered membrane was rinsed with a nitric acid solution with a molar concentration of 3 mol / L at a flow rate of 0.3 BV / h to obtain a scandium-rich solution.
[0050] Example 3 This embodiment provides a method for separating and purifying scandium based on a modified graphene oxide layered membrane, the method comprising the following steps: After adjusting the pH of the scandium-containing solution to 3.2, EDTA (the molar concentration of EDTA and impurity cations was 1.2:1) was added, and a complexation reaction was carried out at 25°C for 120 min. After standing for 30 min, the solution was filtered to obtain the first scandium-removed solution. The electrodialysis unit uses 10 homogeneous anion exchange membranes, 11 monovalent cation selective anolyse membranes, and PP separators arranged alternately. The controlled voltage is 10V, and the current density is 25mA / cm². 2 The first scandium solution after the complexation reaction was subjected to electrodialysis at a feed rate of 30 L / h to obtain the second scandium solution. The flow rate of the second scandium removal solution was controlled at 2 BV / h. After the second scandium removal solution was adsorbed and filtered using a modified graphene oxide layered membrane, the modified graphene oxide layered membrane was rinsed with a nitric acid solution with a molar concentration of 3 mol / L at a flow rate of 0.8 BV / h to obtain a scandium-rich solution.
[0051] Example 4 The only difference between this embodiment and Embodiment 1 is that the current density for electrodialysis is 5 mA / cm². 2 Other conditions and parameters are exactly the same as in Example 1.
[0052] Example 5 The only difference between this embodiment and Embodiment 1 is that the current density for electrodialysis is 30 mA / cm². 2 Other conditions and parameters are exactly the same as in Example 1.
[0053] Example 6 The only difference between this embodiment and Embodiment 1 is that the flow rate of the second scandium solution used for impurity removal is 0.2 BV / h during the adsorption filtration process. All other conditions and parameters are exactly the same as in Embodiment 1.
[0054] Example 7 The only difference between this embodiment and Embodiment 1 is that the flow rate of the second scandium solution used for impurity removal is 2.5 BV / h during the adsorption filtration process. All other conditions and parameters are exactly the same as in Embodiment 1.
[0055] Comparative Example 1 The only difference between this comparative example and Example 1 is that an unmodified graphene oxide layered film is used; all other conditions and parameters are exactly the same as in Example 1.
[0056] Comparative Example 2 The only difference between this comparative example and Example 1 is that a common homogeneous cation exchange membrane is used; all other conditions and parameters are exactly the same as in Example 1.
[0057] Performance testing: The scandium-rich solutions obtained in the examples and comparative examples were tested and the scandium recovery rate was calculated. The test results are shown in Table 1. Table 1 As shown in Table 1, and based on Examples 1 to 7, the method for separating and purifying scandium using modified graphene oxide layered membranes described in this invention achieves an iron removal rate of over 82%, an aluminum removal rate of over 80%, a sodium removal rate of over 82%, and a scandium recovery rate of over 88%. By adjusting the conditions, the iron removal rate can reach over 93%, the aluminum removal rate over 91%, the sodium removal rate over 83%, and the scandium recovery rate over 96%.
[0058] A comparison of Examples 1 and 4-5 shows that in the method for separating and purifying scandium based on modified graphene oxide layered membranes described in this invention, the current density of the electrodialysis treatment affects the separation effect. The current density of the electrodialysis treatment should be controlled at 10 mA / cm². 2 ~25mA / cm 2 The separation effect is relatively good. However, if the current density of electrodialysis is too high, concentration polarization will intensify, and a small amount of Sc will be separated. 3+ Accompanied by Na +When the scandium permeates the membrane element, the scandium recovery rate decreases slightly. If the current density of the electrodialysis treatment is too low, the driving force for ion migration is insufficient, the sodium salt is not completely removed, and the competitive adsorption of impurities causes a significant decrease in purity and recovery rate.
[0059] A comparison of Examples 1 and 6-7 shows that in the method for separating and purifying scandium based on modified graphene oxide layered membranes described in this invention, the flow rate of the second scandium removal solution affects the separation effect during the adsorption and filtration process. Controlling the flow rate of the second scandium removal solution between 0.5 BV / h and 2 BV / h yields better separation results. If the flow rate of the second scandium removal solution is too fast, the contact time between the feed solution and the adsorption sites on the membrane surface is insufficient, and some Scandium is lost. 3+ As the scandium permeates the membrane, the recovery rate decreases. If the flow rate of the second scandium removal solution is too slow, the processing efficiency decreases, and some impurity ions remain on the membrane surface, resulting in a decrease in the purity of the scandium-rich solution.
[0060] A comparison of Example 1 and Comparative Example 1 shows that the modified graphene oxide layered film of the present invention, which uses heat treatment, diamine, and amino acids to synergistically regulate the interlayer spacing, can obtain a film similar to Sc 3+ Channels with highly matched particle size trap Sc 3+ Simultaneously, impurity ions flow out of the membrane, achieving Sc 3+ The high efficiency of separation from impurity ions is hampered by the uncontrollable interlayer spacing of the unmodified graphene oxide film, severe co-adsorption of impurities, and significantly low product purity and scandium recovery rate.
[0061] As can be seen from the comparison between Example 1 and Comparative Example 2, the present invention uses a monovalent cation selective anolyte membrane to directionally remove Na from the solution. + This significantly reduces the pressure of subsequent adsorption and filtration processes and noticeably improves the purity of the prepared scandium-rich solution; ordinary general-purpose cation exchange membranes cannot separate valence states, and a large amount of Sc... 3+ Take it easy + Scandium is lost as it migrates into the concentrated aqueous phase, resulting in a significant deterioration in scandium recovery and product purity.
[0062] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A method for separating and purifying scandium based on a modified graphene oxide layered membrane, characterized in that, The method includes the following steps: Provides modified graphene oxide layered films and scandium-containing solutions; After adjusting the pH of the scandium-containing solution, a complexing agent is added to carry out a complexation reaction, resulting in the first scandium-removed solution. The first purified scandium solution after the complexation reaction was subjected to electrodialysis using a monovalent cation-selective anolyte membrane to obtain a second purified scandium solution. After adsorption and filtration of the second scandium solution using a modified graphene oxide layered membrane, the modified graphene oxide layered membrane is rinsed with an acid solution to obtain a scandium-rich solution.
2. The method as described in claim 1, characterized in that, The modified graphene oxide layered film was prepared by the following method: Graphene oxide is mixed with a solvent to obtain a graphene oxide dispersion, and the graphene oxide dispersion is heat-treated to obtain a pretreated graphene oxide dispersion. The pretreated graphene oxide dispersion, diamine monomer, and amino acid were mixed and modified to obtain a modified graphene oxide dispersion. The modified graphene oxide dispersion was coated onto the substrate surface and then vacuum dried to obtain the modified graphene oxide layered film.
3. The method as described in claim 2, characterized in that, The solvent includes water; Preferably, the mass concentration of the graphene oxide dispersion is 0.5 g / L to 2 g / L; Preferably, the heat treatment temperature is 140℃~170℃; Preferably, the heat treatment time is 2h to 4h.
4. The method as described in claim 2 or 3, characterized in that, The diamine monomer includes any one or a combination of at least two of ethylenediamine, hexamethylenediamine, or m-phenylenediamine; Preferably, the mass ratio of graphene oxide to diamine monomer in the pretreated graphene oxide dispersion is 1:(0.1~1); Preferably, the amino acid includes any one or a combination of at least two of serine, alanine, or lysine; Preferably, the mass ratio of graphene oxide to amino acids in the pretreated graphene oxide dispersion is 1:(0.1~0.5); Preferably, the pH of the modification reaction is 4.5-6; Preferably, the temperature of the modification reaction is 55℃~70℃; Preferably, the modification reaction takes 4 to 6 hours. Preferably, the vacuum drying temperature is 60℃~80℃.
5. The method according to any one of claims 1-4, characterized in that, The pH of the scandium-containing solution is adjusted to 2-3.2; Preferably, the complexing agent comprises EDTA and / or citric acid.
6. The method according to any one of claims 1-5, characterized in that, The temperature of the complexation reaction is 25℃~35℃; Preferably, the complexation reaction takes 60 min to 120 min; Preferably, the complexation reaction is followed by a settling and filtration process.
7. The method according to any one of claims 1-6, characterized in that, The monovalent cation-selective anode membrane includes a sulfonamide-modified cation exchange membrane and / or a polypyrrole-modified cation exchange membrane; Preferably, the monovalent cation-selective anolyte membrane and the homogeneous anion exchange membrane are alternately arranged for electrodialysis treatment.
8. The method according to any one of claims 1-7, characterized in that, The voltage for the electrodialysis treatment is 5V~10V; Preferably, the current density of the electrodialysis treatment is 10 mA / cm². 2 ~25mA / cm 2 ; Preferably, during the electrodialysis process, the feed rate of the first scandium solution for impurity removal is 20 L / h to 30 L / h.
9. The method according to any one of claims 1-8, characterized in that, During the adsorption filtration process, the flow rate of the second scandium solution for impurity removal is 0.5 BV / h to 2 BV / h.
10. The method according to any one of claims 1-9, characterized in that, The acid solution includes a nitric acid solution with a concentration of 3 mol / L to 5 mol / L; Preferably, during the rinsing process, the flow rate of the acid solution is 0.3 BV / h to 0.8 BV / h.