A gallium extraction material, a preparation method of the gallium extraction material, and a method for extracting gallium
By using covalent organic framework adsorbents supported on phenolic hydroxyl groups and pyridine rings in coal-based resources, the problems of low efficiency and poor selectivity of gallium extraction materials in strongly acidic solutions have been solved, achieving efficient separation and stable recovery of gallium and promoting the green and economical utilization of gallium resources.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-05
Smart Images
Figure CN122145745A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of non-ferrous metal metallurgy technology, and more specifically, relates to a gallium extraction material, a method for preparing the gallium extraction material, and a method for extracting gallium. Background Technology
[0002] Gallium, a scarce strategic rare metal, possesses unique physicochemical properties and occupies an irreplaceable position in high-tech fields such as semiconductor chips, optoelectronic displays, aerospace, new energy batteries, and fiber optic communications. It is a key basic material supporting the development of the country's high-tech industries. However, gallium rarely forms independent deposits in nature; it mainly occurs as a by-product in mineral resources such as coal-series resources (coal gangue, fly ash, etc.), bauxite, and zinc ore. Among these, coal-series resources are an important potential reserve of gallium.
[0003] my country possesses abundant gallium reserves in its coal-series resources, accounting for over 60% of the country's total gallium reserves, making it a core source for gallium resource recycling. Efficiently recovering gallium from coal-series solid waste not only enables the resource-efficient utilization of this rare metal and effectively alleviates my country's high dependence on imported gallium resources, but also promotes the green disposal of coal-series solid waste. However, after leaching coal-series resources with strong acid, the leachate is highly acidic and contains a large number of coexisting impurity ions such as aluminum, iron, and silicon, posing a significant challenge to the efficient separation and recovery of gallium. Existing adsorption materials used for gallium extraction still have many technical shortcomings and cannot meet the needs of practical industrial applications.
[0004] For example, Chinese patent application No. 202511734947.X, with a publication date of February 13, 2026, discloses a method for deep separation and extraction of gallium. This patent uses 2,5-diacenic oxytetraphenyl aldehyde and its linker tetra(4-aminophenyl)methane as raw materials to synthesize a gallium-selective covalent organic framework adsorbent. The synthesized adsorbent is added to a gallium-containing solution system with a certain alkalinity and reacted at a certain temperature for a period of time to achieve efficient adsorption, separation, and extraction of gallium. However, this adsorbent is only suitable for enriching gallium in highly alkaline environments. The amylopectin (-C(NH2)=NOH) in the adsorbent hydrolyzes and loses the NH2OH fragment under high acidity, heating, or prolonged immersion, resulting in structural damage and a direct reduction in adsorption sites. The stronger the acidity, the more easily the N on the amylopectin is protonated and becomes positively charged, thus increasing its affinity for Ga. 3+ Its chelating ability is greatly reduced, making it unsuitable for gallium extraction in acidic systems.
[0005] However, gallium in coal-series resources is often associated with elements such as aluminum, iron, and lithium. Acid leaching can simultaneously dissolve multiple valuable metals, achieving comprehensive recovery. Therefore, acid leaching is commonly used to treat coal-series resources in industrial practice. However, alkaline leaching also presents several problems: Firstly, gallium in fly ash is mostly found in the aluminum-silicon glass phase and mullite lattice, disrupting the silicon-aluminum network structure and destabilizing the mullite lattice structure, requiring large amounts of alkaline reagents, resulting in high costs. Secondly, coal-series resources have a high silicon content, with large amounts of silicon dissolving to form silicate solutions. However, these solutions are extremely unstable and easily convert to silica gel during subsequent processing, making solid-liquid separation difficult and increasing processing costs. Acid leaching has a natural advantage in separating silicon and aluminum because acid dissolves aluminum and gallium, while silicon remains insoluble in the slag, avoiding the silica gel problem. Finally, alkali is corrosive to equipment, especially during high-temperature alkaline fusion processes.
[0006] Existing technologies have made various attempts to recover gallium from coal-bearing resources or similar media. However, when dealing with gallium-containing solutions that are strongly acidic and contain multiple ions, the adsorbent materials used in these methods still suffer from problems such as low gallium extraction efficiency, poor selectivity, and insufficient chemical stability.
[0007] Therefore, there is an urgent need to develop a novel adsorption material suitable for strongly acidic, low-concentration, and complex impurity systems, which also possesses high selectivity, high adsorption capacity, and high chemical stability. Achieving efficient separation and recovery of gallium from coal-based resources is of significant practical importance and industrial application value for promoting the high-quality development of coal-based solid waste resource utilization and the rare metal recycling industry. Summary of the Invention
[0008] 1. The problem to be solved
[0009] One objective of this invention is to provide a gallium extraction material that addresses the technical problems of low efficiency, poor selectivity, and environmental unfriendliness in the extraction of gallium ions from acidic gallium-containing solutions. Furthermore, this invention provides a method for preparing the aforementioned gallium extraction material and a method for extracting gallium using the aforementioned gallium extraction material.
[0010] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a gallium extraction material, wherein the gallium extraction material is a covalent organic framework (COF) adsorbent material, which is prepared by a Schiff base condensation reaction of an aldehyde monomer and an amino monomer, wherein the covalent organic framework adsorbent material contains phenolic hydroxyl groups and pyridine rings.
[0011] Using the above technical solution, the covalent organic framework adsorbent material simultaneously loads phenolic hydroxyl groups and pyridine functional groups, which coordinate spatially to form gallium ion-specific recognition sites. In strongly acidic systems and systems with multiple metal ions, pyridine nitrogen achieves initial anchoring by coordinating with gallium ions through lone pair electrons; the phenolic hydroxyl group deprotonates under acidic conditions to form a phenoloxy anion, which forms a strong oxygen coordination bond with gallium ions, achieving targeted recognition of gallium ions. The structural design of this gallium extraction material requires no additional post-modification steps, effectively avoiding problems such as pore blockage and active site dispersion that may result from post-modification.
[0012] As one possible implementation, the aldehyde monomer is 2,4,6-tricarboxymethyl phloroglucinol, and the amino monomer is 2,5-diaminopyridine. The covalent organic framework formed has a large number of phenolic hydroxyl groups loaded on it, which is beneficial to improve the adsorption rate of gallium.
[0013] As one possible implementation, the molar ratio of 2,4,6-tricarboxymethyl phloroglucinol to 2,5-diaminopyridine is 1:(0.5~5). By precisely controlling the molar ratio of 2,4,6-tricarboxymethyl phloroglucinol to 2,5-diaminopyridine, and utilizing the reversibility of dynamic covalent chemistry, the final COF material structure, crystallinity, porosity, and most importantly, the surface and interface chemical properties can be "tailored," thereby obtaining a COF containing both unreacted phenolic hydroxyl groups and pyridine rings.
[0014] The second aspect of the present invention provides a method for preparing the above-mentioned gallium extraction material, comprising the following steps: S1. The aldehyde monomer and the amine monomer are uniformly dispersed in an organic solvent to obtain a mixture; S2. The mixture obtained in step S1 is subjected to at least one liquid nitrogen freeze-thaw process, and then sealed under vacuum; S3. The mixture in the sealed state of step S2 is placed in a gradient magnetic field generator to carry out Schiff base polycondensation reaction. After the reaction is completed, the reaction product is filtered, washed and dried to obtain gallium extraction material. The magnetic field strength of the gradient magnetic field generator is 0.01~1.0 T.
[0015] Using the above technical solution, in the preparation of the adsorbent material, i.e., the gallium extraction material, phenolic hydroxyl groups and pyridine functional groups are precisely loaded onto the COF framework through a one-step Schiff base reaction. A covalent organic framework (COF) adsorbent material is prepared using a gradient magnetic field combined with a Schiff base condensation reaction as the gallium extraction material. In the COF framework, the pyridine ring provides abundant nitrogen coordination sites, which, together with the hydroxyl group, construct nitrogen-hydroxyl coordinated coordination centers. Under the synergistic effect of the gradient magnetic field and solvothermal external field, the gradient magnetic field induces the monomers to oriented, reducing defects such as crystal bond breakage and pore blockage, optimizing pore size regularity, and further improving the utilization rate of active sites and the stability of the material for recycling. This allows for high-capacity and high-selectivity adsorption of gallium ions in complex leaching systems with high acidity and coexistence of multiple metal ions.
[0016] As one possible implementation, in step S1, the organic solvent is a mixed solution of N,N-dimethylformamide, 1,4-dioxane, and glacial acetic acid, wherein the volume fractions of the three components are: 1-8 parts of N,N-dimethylformamide; 0.5 to 3 parts of 1,4-dioxane; 0.01~0.5 parts of glacial acetic acid.
[0017] When using the above technical solution, the N,N-dimethylformamide-1,4-dioxane-glacial acetic acid mixed solvent system significantly improves the monomer reactivity and material crystallinity regularity, and reduces the risk of impurity residue.
[0018] As one possible implementation, in step S1, the total volume of the organic solvent is 2~10 ml, preferably 2~6 ml.
[0019] As one possible implementation, in step S1, the aldehyde monomer and the amine monomer are uniformly dispersed in an organic solvent using ultrasonic dispersion treatment, wherein the ultrasonic dispersion treatment time is 5~40 min.
[0020] As one possible implementation, step S2 involves the following steps: the mixture obtained in step S1 is placed in a sealable hard glass tube, and liquid nitrogen is used to freeze the mixture inside the tube until it is completely solidified. Subsequently, a vacuum is applied to the glass tube. At this point, due to the solidification of the solution, the solvent vapor pressure is extremely low, allowing for the safe extraction of gases from the gas phase. After the vacuum treatment, the mixture is allowed to thaw naturally at room temperature. During the thawing process, as the solid melts, the gases dissolved in the solution (due to the vacuum treatment) will escape. The mixture obtained in step S1 is subjected to 1 to 6 cycles of liquid nitrogen freezing-thawing to ensure thorough removal of dissolved gases.
[0021] As one possible implementation, in the liquid nitrogen freeze-thaw process, the liquid nitrogen freezes the mixture in the tube for 5 to 30 minutes.
[0022] As one possible solution, after the liquid nitrogen freezing-thawing cycle is completed, the tube is evacuated and then the hard glass tube is sealed with a flame.
[0023] As one possible implementation scheme, in step S3, the reaction conditions for the Schiff base polycondensation reaction are: constant temperature reaction at 80~160℃ for 36~120 h.
[0024] As one possible implementation, in step S3, the reaction product is filtered and washed sequentially with anhydrous ethanol and acetone.
[0025] As one possible implementation, in step S3, the drying process is vacuum drying, with a drying temperature of 60~130℃ and a drying time of 6~48 h.
[0026] A third aspect of the present invention provides a method for extracting gallium in an acidic gallium-containing solution using the above-mentioned gallium extraction material, comprising the steps of: adding the above-mentioned gallium extraction material to the acidic gallium-containing solution to undergo an adsorption reaction, thereby adsorbing gallium ions in the acidic gallium-containing solution.
[0027] As one possible implementation, the hydrogen ion concentration in the acidic gallium-containing solution is 0.01~3 mol / L. The acidic gallium-containing solution includes a gallium-containing leaching solution obtained from coal-based resources under acidic leaching solution treatment, wherein the coal-based resources include one or more of coal gangue and fly ash. The acidic leaching solution includes a mixed acid system of one or more of hydrochloric acid solution, sulfuric acid solution, nitric acid solution, and perchloric acid solution.
[0028] As one possible implementation, the adsorption reaction temperature is 25~80℃, and the adsorption reaction time is 1~48 h.
[0029] As one possible approach, the solid-liquid ratio of the gallium extraction material to the acidic gallium-containing solution is 0.5~5 g / L.
[0030] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention addresses the core challenges of low adsorption capacity and poor selectivity of existing gallium extraction materials in complex acidic leachates. By targeting molecular design, gallium ion-specific recognition functional groups are introduced into a covalent organic framework to construct a novel adsorption material integrating structure and function. This material can achieve precise capture and efficient separation of gallium ions in strongly acidic and multi-ion coexistence environments, significantly improving the separation purity and deep recovery efficiency of gallium. At the same time, the rigid framework structure endows the material with excellent stability for recycling.
[0031] (2) The method for preparing gallium extraction materials of the present invention utilizes the synergistic effect of gradient magnetic field synergistic preparation process and specific mixed solvent system to significantly shorten the reaction cycle and reduce energy consumption, while giving the material excellent stability for recycling. This provides a green and economical technical path for the efficient recovery of acidic gallium-containing solutions, such as coal-associated gallium.
[0032] (3) The gallium extraction material of this invention uses a bifunctionalized COF material as its core, namely, bifunctionalization with the synergistic effect of phenolic hydroxyl groups and pyridine rings. Through precise design and directional functional group modification, the specific recognition sites of gallium ions (phenolic hydroxyl groups and pyridine rings) are loaded into the COF framework constructed by Schiff base condensation reaction, thereby constructing a stable two-dimensional rigid topological structure with uniformly distributed adsorption sites. The gallium extraction material of this invention exhibits excellent gallium recognition and separation performance in complex leaching systems with strong acidity and coexistence of multiple metal ions, enabling efficient extraction and deep enrichment of gallium resources. In particular, it provides a green and economical new technology approach for the efficient and selective recovery of gallium from coal-based resources, which has important practical significance for promoting the high-quality development of strategic metal resource utilization and related industries. Attached Figure Description
[0033] Figure 1 This is the reaction structure for preparing the gallium extraction material of the present invention.
[0034] Figure 2 The image shows the XRD pattern of the gallium-extracted material in Example 2 of this invention.
[0035] Figure 3 The image shows the infrared spectrum of the gallium extraction material in Example 2 of this invention. Detailed Implementation
[0036] In a specific implementation, addressing the technical problems of low efficiency, poor selectivity, and environmental unfriendliness in existing gallium extraction processes from coal-based resource leachates, a gallium extraction material, a method for preparing the gallium extraction material, and a method for extracting gallium are provided. This method uses a bifunctionalized COF material as its core. Through precise design and directional modification, specific recognition sites for gallium ions are loaded into a COF framework constructed by Schiff base condensation reaction, thereby constructing a stable two-dimensional rigid topological structure with uniformly distributed adsorption sites.
[0037] The present invention will be further described below with reference to specific embodiments.
[0038] Example 1 The method for preparing a gallium extraction material according to this embodiment includes the following steps: S1. Add 2,4,6-tricarboxymethyl phloroglucinol and 2,5-diaminopyridine to a hard glass tube at a molar ratio of 1:0.5. Then, add 2 ml of a mixed solution of N,N-dimethylformamide, 1,4-dioxane and glacial acetic acid to the system at a volume ratio of 1:0.5:0.01. After sonicating for 5 min to disperse evenly, a mixed solution is obtained.
[0039] S2. Place the mixture obtained in step S1 into a sealable hard glass tube and perform a liquid nitrogen freeze-thaw process. The steps are as follows: Freeze the mixture in the tube with liquid nitrogen until it is completely solidified for 5 minutes; then evacuate the glass tube. At this time, due to the solidification of the solution, the solvent vapor pressure is extremely low, and the gas in the gas phase can be safely extracted; after evacuation, allow it to thaw naturally at room temperature. During the thawing process, as the solid melts, the gas dissolved in the solution (due to the vacuum treatment) will escape. Subsequently, evacuate the tube and seal it with a flame.
[0040] S3. The mixture in the sealed state from step S2 is placed in a gradient magnetic field generator for Schiff base polycondensation reaction. Specifically, the sealed mixture is fixed in a gradient magnetic field generator with a magnetic field strength of 0.01 T and simultaneously placed in a constant temperature oven, heated to 80°C, and reacted at a constant temperature for 36 h. After the reaction, the mixture is filtered and washed sequentially with anhydrous ethanol and acetone, and then vacuum dried at 60°C for 6 h to obtain the gallium extraction material of this embodiment.
[0041] In this embodiment, the gallium extraction material is a covalent organic framework (COF) adsorbent, prepared by a Schiff base condensation reaction involving the covalent bonding of an aldehyde monomer (2,4,6-tricarboxymethyl phloroglucinol) and an amino monomer (2,5-diaminopyridine). The adsorbent framework contains phenolic hydroxyl groups and pyridine rings. The specific synthetic route is as follows: Figure 1 As shown.
[0042] The method for extracting gallium from an acidic gallium-containing solution using the gallium extraction material of this embodiment comprises the following steps: adding the gallium extraction material synthesized in this embodiment to a coal-based gallium-containing leaching system (the acid leaching solution is hydrochloric acid solution) with a hydrogen ion concentration of 0.5 g / L at a solid-liquid ratio of 0.01 mol / L, and adsorbing at a constant temperature of 25°C for 1 h to achieve efficient and selective separation and extraction of gallium ions by the bifunctional COF material. In this embodiment, the initial mass concentration of gallium ions in the coal-based gallium-containing leaching system is 100 mg / L, and the remaining concentration after adsorption is 4.6 mg / L, that is, the adsorption rate of gallium reaches 95.4%.
[0043] Example 2 The method for preparing a gallium extraction material according to this embodiment includes the following steps: S1. Add 2,4,6-tricarboxymethyl phloroglucinol and 2,5-diaminopyridine to a hard glass tube at a molar ratio of 1:5. Then, add 6 ml of a mixed solution of N,N-dimethylformamide, 1,4-dioxane and glacial acetic acid to the system at a volume ratio of 8:3:0.5. After sonication for 40 min, a uniformly dispersed mixture is obtained.
[0044] S2. Place the mixture obtained in step S1 into a sealable hard glass tube and perform six liquid nitrogen freeze-thaw cycles. One of the liquid nitrogen freeze-thaw cycles involves freezing the mixture in the tube with liquid nitrogen until it is completely solidified for 30 minutes. Then, a vacuum is applied to the glass tube. At this point, due to the solidification of the solution, the solvent vapor pressure is extremely low, allowing for safe extraction of the gas phase. After vacuuming, allow it to thaw naturally at room temperature. During thawing, as the solid melts, the gas dissolved in the solution (due to the vacuum) will escape. Finally, the tube is evacuated and sealed with a flame.
[0045] S3. The mixture in the sealed state from step S2 is placed in a gradient magnetic field generator for Schiff base polycondensation reaction. Specifically, the sealed mixture is fixed in a gradient magnetic field generator with a magnetic field strength of 1.0 T and simultaneously placed in a constant temperature oven, heated to 160°C and reacted at a constant temperature for 120 h. After the reaction, the mixture is filtered and washed sequentially with anhydrous ethanol and acetone, and then vacuum dried at 130°C for 48 h to obtain the gallium extraction material of this embodiment.
[0046] In this embodiment, the gallium extraction material is a covalent organic framework (COF) adsorbent, prepared by a Schiff base condensation reaction involving the covalent bonding of an aldehyde monomer (2,4,6-tricarboxymethyl phloroglucinol) and an amino monomer (2,5-diaminopyridine). The adsorbent framework contains phenolic hydroxyl groups and pyridine rings. The specific synthetic route is as follows: Figure 1 As shown.
[0047] The XRD pattern of the covalent organic framework (COF) adsorbent in this embodiment is as follows: Figure 2 As shown, the PXRD spectrum shows clear and sharp diffraction peaks at 4.22° and 8.45°, corresponding to the (100) and (200) crystal planes, respectively, confirming that the synthesized HTP-COF-AO has excellent crystallinity and a highly ordered framework structure.
[0048] The infrared spectrum of the covalent organic framework (COF) adsorbent material in this embodiment is obtained from... Figure 3 It can be seen that 3460.6 cm -1 The broad peak shows the OH stretching vibration of the phenolic hydroxyl group; 1697.1 cm⁻¹ -1 The strong peak at 1594.8 cm⁻¹ is due to C=N stretching vibration. -1 The peak at the location is located at the CNC aromatic ring framework vibration, and also includes the coupling of NH bending and CN stretching. It can be seen that the covalent organic framework (COF) adsorbent material of this embodiment contains aromatic molecules with phenolic hydroxyl groups and pyridine rings.
[0049] The method for extracting gallium from an acidic gallium-containing solution using the gallium extraction material of this embodiment comprises the following steps: adding the gallium extraction material synthesized in this embodiment to a coal-based gallium-containing leaching system (the acid leaching solution is a sulfuric acid solution) with a hydrogen ion concentration of 3 mol / L at a solid-liquid ratio of 5 g / L, and adsorbing at a constant temperature of 80℃ for 48 h to achieve efficient and selective separation and extraction of gallium ions by the bifunctional COF material. In this embodiment, the initial mass concentration of gallium ions in the coal-based gallium-containing leaching system is 100 mg / L, and the remaining concentration after adsorption is 0.4 mg / L, that is, the adsorption rate of gallium reaches 99.6%.
[0050] Example 3 The method for preparing a gallium extraction material according to this embodiment includes the following steps: S1. Add 2,4,6-tricarboxymethyl phloroglucinol and 2,5-diaminopyridine to a hard glass tube at a molar ratio of 1:2. Then, add 3 ml of a mixed solution of N,N-dimethylformamide, 1,4-dioxane and glacial acetic acid to the system at a volume ratio of 4:1.5:0.1. After sonication for 10 min, a uniformly dispersed mixture is obtained.
[0051] S2. Place the mixture obtained in step S1 into a sealable hard glass tube and perform two liquid nitrogen freeze-thaw cycles. One liquid nitrogen freeze-thaw cycle involves freezing the mixture in the tube with liquid nitrogen until it is completely solidified for 10 minutes. Then, evacuate the glass tube. At this point, due to the solidification of the solution, the solvent vapor pressure is extremely low, allowing safe extraction of the gas phase. After evacuation, allow it to thaw naturally at room temperature. During thawing, as the solid melts, the gas dissolved in the solution (due to the vacuum treatment) will escape. Finally, evacuate the tube and seal it with a flame.
[0052] S3. The mixture in the sealed state from step S2 is placed in a gradient magnetic field generator for Schiff base polycondensation reaction. Specifically, the sealed mixture is fixed in a gradient magnetic field generator with a magnetic field strength of 0.3 T and simultaneously placed in a constant temperature oven, heated to 100°C and reacted at a constant temperature for 50 h. After the reaction, the mixture is filtered and washed sequentially with anhydrous ethanol and acetone, and then vacuum dried at 80°C for 16 h to obtain the gallium extraction material of this embodiment.
[0053] In this embodiment, the gallium extraction material is a covalent organic framework (COF) adsorbent, prepared by a Schiff base condensation reaction involving the covalent bonding of an aldehyde monomer (2,4,6-tricarboxymethyl phloroglucinol) and an amino monomer (2,5-diaminopyridine). The adsorbent framework contains phenolic hydroxyl groups and pyridine rings. The specific synthetic route is as follows: Figure 1 As shown.
[0054] The method for extracting gallium from an acidic gallium-containing solution using the gallium extraction material of this embodiment comprises the following steps: adding the gallium extraction material synthesized in this embodiment to a coal-based gallium-containing leaching system (the acid leaching solution is nitric acid solution) with a hydrogen ion concentration of 1 g / L at a solid-liquid ratio; and adsorbing the material by constant temperature stirring at 30°C for 8 h to achieve efficient and selective separation and extraction of gallium ions by the bifunctional COF material. In this embodiment, the initial mass concentration of gallium ions in the coal-based gallium-containing leaching system is 100 mg / L, and the remaining concentration after adsorption is 2.8 mg / L, that is, the adsorption rate of gallium reaches 97.2%.
[0055] Example 4 The method for preparing a gallium extraction material according to this embodiment includes the following steps: S1. Add 2,4,6-tricarboxymethyl phloroglucinol and 2,5-diaminopyridine to a hard glass tube at a molar ratio of 1:3. Then, add 4 ml of a mixed solution of N,N-dimethylformamide, 1,4-dioxane and glacial acetic acid to the system at a volume ratio of 7:2.5:0.4. After sonication for 30 min, a uniformly dispersed mixture is obtained.
[0056] S2. Place the mixture obtained in step S1 into a sealable hard glass tube and perform four liquid nitrogen freeze-thaw cycles. One of the liquid nitrogen freeze-thaw cycles involves freezing the mixture in the tube with liquid nitrogen until it is completely solidified for 20 minutes. Then, a vacuum is applied to the glass tube. At this point, due to the solidification of the solution, the solvent vapor pressure is extremely low, allowing for safe extraction of the gas phase. After vacuuming, allow it to thaw naturally at room temperature. During thawing, as the solid melts, the gas dissolved in the solution (due to the vacuum) will escape. Finally, the tube is evacuated and sealed with a flame.
[0057] S3. The mixture in the sealed state from step S2 is placed in a gradient magnetic field generator for Schiff base polycondensation reaction. Specifically, the sealed mixture is fixed in a gradient magnetic field generator with a magnetic field strength of 0.5 T and simultaneously placed in a constant temperature oven, heated to 120°C and reacted at a constant temperature for 60 h. After the reaction, the mixture is filtered and washed sequentially with anhydrous ethanol and acetone, and then vacuum dried at 80°C for 24 h to obtain the gallium extraction material of this embodiment.
[0058] In this embodiment, the gallium extraction material is a covalent organic framework (COF) adsorbent, prepared by a Schiff base condensation reaction involving the covalent bonding of an aldehyde monomer (2,4,6-tricarboxymethyl phloroglucinol) and an amino monomer (2,5-diaminopyridine). The adsorbent framework contains phenolic hydroxyl groups and pyridine rings. The specific synthetic route is as follows: Figure 1 As shown.
[0059] The method for extracting gallium from an acidic gallium-containing solution using the gallium extraction material of this embodiment comprises the following steps: adding the gallium extraction material synthesized in this embodiment to a coal-based gallium-containing leaching system (the acid leaching solution is a perchloric acid solution) with a hydrogen ion concentration of 1 mol / L at a solid-liquid ratio of 2 g / L, and adsorbing at a constant temperature of 50°C for 24 h to achieve efficient and selective separation and extraction of gallium ions by the bifunctional COF material. In this embodiment, the initial mass concentration of gallium ions in the coal-based gallium-containing leaching system is set at 100 mg / L, and the remaining concentration after adsorption is 2.5 mg / L, with an adsorption rate of 97.5% for gallium.
[0060] Example 5 The method for preparing a gallium extraction material according to this embodiment includes the following steps: S1. Add 2,4,6-tricarboxymethyl phloroglucinol and 2,5-diaminopyridine to a hard glass tube at a molar ratio of 1:4. Then, add 5 ml of a mixed solution of N,N-dimethylformamide, 1,4-dioxane and glacial acetic acid to the system at a volume ratio of 5:2:0.2. After sonication for 35 min, a uniformly dispersed mixture is obtained.
[0061] S2. Place the mixture obtained in step S1 into a sealable hard glass tube and perform five liquid nitrogen freeze-thaw cycles. One of the liquid nitrogen freeze-thaw cycles involves freezing the mixture in the tube with liquid nitrogen until it is completely solidified for 25 minutes. Then, a vacuum is applied to the glass tube. At this point, due to the solidification of the solution, the solvent vapor pressure is extremely low, allowing for safe extraction of the gas phase. After vacuuming, allow it to thaw naturally at room temperature. During thawing, as the solid melts, the gas dissolved in the solution (due to the vacuum) will escape. Finally, the tube is evacuated and sealed with a flame.
[0062] S3. The mixture in the sealed state from step S2 is placed in a gradient magnetic field generator for Schiff base polycondensation reaction. Specifically, the sealed mixture is fixed in a gradient magnetic field generator with a magnetic field strength of 0.8 T and simultaneously placed in a constant temperature oven, heated to 120°C and reacted at a constant temperature for 100 h. After the reaction, the mixture is filtered and washed sequentially with anhydrous ethanol and acetone, and then vacuum dried at 100°C for 36 h to obtain the gallium extraction material of this embodiment.
[0063] In this embodiment, the gallium extraction material is a covalent organic framework (COF) adsorbent, prepared by a Schiff base condensation reaction involving the covalent bonding of an aldehyde monomer (2,4,6-tricarboxymethyl phloroglucinol) and an amino monomer (2,5-diaminopyridine). The adsorbent framework contains phenolic hydroxyl groups and pyridine rings. The specific synthetic route is as follows: Figure 1 As shown.
[0064] The method for extracting gallium from an acidic gallium-containing solution using the gallium extraction material of this embodiment comprises the following steps: adding the gallium extraction material synthesized in this embodiment to a coal-based gallium-containing leaching system (the acid leaching solution is hydrochloric acid solution) with a hydrogen ion concentration of 2 mol / L at a solid-liquid ratio of 3 g / L, and adsorbing at a constant temperature of 60℃ for 36 h to achieve efficient and selective separation and extraction of gallium ions by the bifunctional COF material. In this embodiment, the initial mass concentration of gallium ions in the coal-based gallium-containing leaching system is 100 mg / L, and the remaining concentration after adsorption is 1.1 mg / L, with an adsorption rate of 98.9% for gallium.
[0065] The above detailed embodiments provide a specific description of the analytical methods involved in this invention. It should be noted that the above description is only intended to help those skilled in the art better understand the methods and ideas of this invention, and is not intended to limit the scope of the invention. Without departing from the principles of this invention, those skilled in the art can make appropriate adjustments or modifications to this invention, and such adjustments and modifications should also fall within the protection scope of this invention.
Claims
1. A gallium extraction material, characterized in that: The gallium extraction material is a covalent organic framework adsorbent, prepared by a Schiff base condensation reaction of aldehyde monomers and amino monomers. The covalent organic framework adsorbent contains phenolic hydroxyl groups and pyridine rings.
2. The gallium extraction material according to claim 1, characterized in that: The aldehyde monomer is 2,4,6-tricarboxymethyl phloroglucinol, and the amino monomer is 2,5-diaminopyridine. The molar ratio of 2,4,6-tricarboxymethyl phloroglucinol to 2,5-diaminopyridine is 1:(0.5~5).
3. A method for preparing the gallium extraction material according to claim 1 or 2, characterized in that: The steps are as follows: S1. The aldehyde monomer and the amine monomer are uniformly dispersed in an organic solvent to obtain a mixture; S2. The mixture obtained in step S1 is subjected to at least one liquid nitrogen freeze-thaw process, and then sealed under vacuum; S3. The mixture in the sealed state of step S2 is placed in a gradient magnetic field generator to carry out Schiff base polycondensation reaction. After the reaction is completed, the reaction product is filtered, washed and dried to obtain gallium extraction material. The magnetic field strength of the gradient magnetic field generator is 0.01~1.0 T.
4. The method for preparing gallium extraction material according to claim 3, characterized in that: In step S1, the organic solvent is a mixed solution of N,N-dimethylformamide, 1,4-dioxane, and glacial acetic acid, wherein the volume fractions of the three components are: 1-8 parts of N,N-dimethylformamide; 0.5 to 3 parts of 1,4-dioxane; 0.01~0.5 parts of glacial acetic acid.
5. The method for preparing gallium extraction material according to claim 3, characterized in that: In step S2, the liquid nitrogen freezing-thawing process is as follows: the mixture obtained in step S1 is placed in a sealable hard glass tube, and liquid nitrogen is used to freeze the mixture in the tube until it is completely solidified; then the glass tube is evacuated and thawed naturally at room temperature.
6. The method for preparing gallium extraction material according to claim 5, characterized in that: In step S2, liquid nitrogen freezing-thawing treatment is performed 1 to 6 times.
7. The method for preparing gallium extraction material according to any one of claims 3 to 6, characterized in that: In step S3, the reaction conditions for the Schiff base polycondensation reaction are: constant temperature reaction at 80~160℃ for 36~120 h.
8. The method for preparing gallium extraction material according to claim 7, characterized in that: In step S3, the drying process is vacuum drying, with a drying temperature of 60~130℃ and a drying time of 6~48 h.
9. A method for extracting gallium using the gallium extraction material according to claim 1 or 2, characterized in that: Gallium extraction material is added to an acidic gallium-containing solution to undergo an adsorption reaction, adsorbing gallium ions from the acidic gallium-containing solution.
10. The method for extracting gallium according to claim 9, characterized in that: The concentration of hydrogen ions in the acidic gallium-containing solution is 0.01~3 mol / L; the temperature of the adsorption reaction is 25~80℃, and the time of the adsorption reaction is 1~48 h; the solid-liquid ratio of the gallium extraction material to the acidic gallium-containing solution is 0.5~5 g / L.