A method for deep separation of indium
By modifying covalent organic framework materials with functional groups that specifically recognize indium, the problems of poor selectivity and insufficient stability of indium separation in strongly acidic solutions are solved, and efficient recovery of indium is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2025-11-24
- Publication Date
- 2026-05-29
Smart Images
Figure CN122103492A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of non-ferrous metal metallurgy technology, specifically relating to a method for preparing a covalent organic framework material with specific indium recognition sites and its application in the selective adsorption and recovery of indium in complex acidic systems. Background Technology
[0002] Indium, as a key strategic metal, is widely used in the manufacture of liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), touch screens, and solar cells due to its unique physicochemical properties, including low resistivity, high light transmittance, and good processing performance. In addition, indium is also used in the manufacture of compound semiconductors (such as indium antimonide and indium arsenide, used in infrared detection and high-speed electronic devices), low-temperature solders, nuclear reactor control materials, and as an additive element in certain high-performance alloys. With the continuous development of the electronics and information industry, new energy technologies, and the defense industry, global demand for indium is showing a steady growth trend, and its strategic importance is becoming increasingly prominent.
[0003] Against the backdrop of the rapid development of strategic emerging industries, the amount of indium-containing secondary resources (such as waste electronics and industrial waste) generated annually continues to increase. After physical pretreatment and preliminary enrichment, these resources are typically processed using hydrometallurgical processes to obtain complex indium-containing solution systems. These systems are mostly strongly acidic, with low indium concentrations, and simultaneously contain multiple high-concentration competing metal ions (such as Zn). 2+ Fe 3+ Al 3+ and Cu 2+The presence of various ions (such as ions, etc.) leads to severe competitive adsorption between ions, making selective separation difficult. Therefore, developing novel adsorption materials that still possess high adsorption capacity, excellent ion selectivity, and good chemical stability under strongly acidic conditions has become crucial for achieving efficient recovery and sustainable utilization of indium resources. Chinese Patent Application No. 202510543211.8 discloses a method for recovering indium from indium-containing anode bags and waste. This method first pyrolyzes the anode bag, then mixes the resulting precursor with molten salt and indium-containing waste powder and calcines it. Subsequently, the resulting indium-containing slag is purified by acid leaching and resin adsorption to obtain a low-impurity indium-containing solution, achieving separation from impurities. Chinese Patent Application No. 201911296945.1 discloses a hyperbranched polyethyleneimine-modified carbon fiber adsorbent material for adsorbing indium (III) and its preparation method. Using carbon fiber as a matrix, the carbon fiber is treated with a mixed solution of sulfuric acid and nitric acid to obtain oxidized carbon fiber with a large number of carboxyl groups on its surface. The oxidized carbon fiber is then modified with HPEI containing a large number of amine groups to further obtain modified carbon fiber with a large number of amine groups, achieving effective adsorption and separation of indium (III) in acidic solution systems. Chinese Patent Application No. 201911017802.2 discloses the synthesis of P507 composite carbon fiber material and its method for adsorbing and separating indium from liquid crystal panels. The P507 composite carbon fiber material has advantages such as simple preparation, low cost, and strong acid resistance. After adsorbing indium, it can be desorbed in strong acid, thus achieving a recycling effect. Chinese patent application No. 201610421206.0 discloses a method for synthesizing and applying polysulfone microcapsules that adsorb indium. Using polysulfone as raw material, the method combines microcapsule technology with extraction technology, and uses microencapsulation to encapsulate the extractant. By optimizing the stirring speed, dispersant concentration, oil phase composition, and water-oil ratio, the method effectively avoids emulsification and phase separation problems. The prepared polysulfone microcapsules have a smooth and dense surface, making them a good indium adsorbent material.
[0004] However, currently developed adsorption materials generally suffer from poor selectivity, low adsorption capacity, and insufficient stability when separating indium in strongly acidic and complex solution systems. Therefore, further research and development of novel adsorption materials for the efficient adsorption and separation of indium in strongly acidic and highly turbulent environments are needed. Summary of the Invention
[0005] The purpose of this invention is to overcome the technical bottlenecks of existing indium adsorption materials in strongly acidic, multi-ion coexisting systems, such as poor selectivity, limited adsorption capacity, and insufficient chemical stability. To address this, this invention provides a method for deep separation of indium. Through rational molecular design and synthesis strategies, functional groups that specifically recognize indium are modified onto an ordered COF framework with high crystallinity and a large specific surface area, thereby constructing a novel porous material with a well-defined structure and uniformly distributed active sites. This material not only possesses the high porosity, open pore structure, and excellent stability characteristic of COF materials, but also significantly enhances the host-guest binding strength and stability through the specific coordination ability and synergistic effect of functionalized groups on indium, achieving efficient capture and highly selective recognition of indium ions in complex solutions. Its highly ordered porous channels provide ideal pathways for ion migration and mass transfer, while the rigid framework constructed by strong covalent bonds ensures the long-term cycling stability of the material under strongly acidic conditions. This invention provides a robust and reliable solution for the efficient and sustainable recovery of low-concentration indium in strongly acidic environments.
[0006] To solve the above problems, the technical solution adopted by the present invention is as follows: To address the problems of low separation and extraction efficiency of indium ions in strongly acidic systems with multiple coexisting ions, as well as the poor selectivity and insufficient stability of traditional adsorption materials, an indium-selective organic building block was designed and synthesized based on the unique coordination chemistry of indium. This building block, through reversible covalent self-assembly, constructs a highly crystalline covalent organic framework material with a high specific surface area. This material, relying on uniformly distributed functional groups within ordered channels, possesses high-density active sites, excellent chemical stability, and a hierarchical pore structure, enabling specific recognition and strong coordination of indium ions. This allows for efficient and deep separation and recovery of indium under strongly acidic conditions with multiple coexisting ions.
[0007] Furthermore, the specific process operations are as follows: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel in a certain molar ratio. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for a period of time to ensure that the substrate and reagents were fully suspended. The mixture was reacted at a certain temperature for a period of time. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0008] (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a certain molar ratio and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a certain volume ratio. After sonicating the mixture for a period of time, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After several cycles of liquid nitrogen freezing-thawing degassing, the tube was vacuum sealed. The temperature was first programmed to a certain temperature and heated for a period of time in a forced-air drying oven. Then, the temperature was increased and maintained at a certain temperature for a certain period of time. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was extracted with tetrahydrofuran for a period of time under certain temperature conditions. After filtration, the product was vacuum dried at 70℃ for a period of time to obtain the indium selective covalent organic framework adsorbent.
[0009] (3) The synthesized indium selective covalent organic framework adsorbent material is added to an indium-containing leaching system with a certain acidity and reacted at a certain temperature for a period of time to achieve efficient separation and extraction of indium by the indium selective covalent organic framework adsorbent material.
[0010] Furthermore, in step (1), bis(4-nitrophenyl) phosphate, ammonium formate and Fe3O4 nanoparticles are mixed in a molar ratio of (1:5:0.2) to (1:10:0.4), stirred for 1 to 10 h, reacted at a temperature of 60 to 80 °C, and reacted for 4 to 20 h.
[0011] Furthermore, in step (2), the molar ratio of bis(4-aminophenyl)phosphate to the linker 4,4',4''-nitrotribenzaldehyde is (6:5) to (3:2), and the volume ratio of mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution, and triethylamine is (1:1:0.5:0.5) to (1:4:1:1). The ultrasonic treatment time is 5 to 15 min, the number of thawing cycles is 3 to 6, the initial heating temperature is 80 to 90°C, and the heating time is 10 to 15 h. Subsequently, the temperature is maintained at 100 to 130°C for 12 to 24 h. The Soxhlet extraction temperature is 90 to 110°C, the extraction time is 10 to 15 h, and the vacuum drying time is 6 to 12 h.
[0012] Furthermore, in step (3), the acidity of the indium leaching system is 0.01~3 mol / L, the reaction temperature is 25~80℃, and the reaction time is 1~6 h.
[0013] Beneficial effects: (1) The core of the indium deep separation method of the present invention is to combine the strong coordination ability of specific indium recognition groups with the structurally stable covalent organic framework to construct a new type of indium selective covalent organic framework adsorption material. The present invention utilizes the ordered channels of COF as a platform and achieves efficient and selective adsorption and separation of indium ions by means of high-density active sites and the synergistic coordination of multiple functional groups.
[0014] (2) In the indium deep separation method of the present invention, the amination reaction of bis(4-nitrophenyl)phosphate is an important pre-modification step in the preparation of the adsorbent material, aiming to obtain a key intermediate, bis(4-aminophenyl)phosphate, which can be used in the subsequent Schiff base condensation reaction. The present invention proposes to use low-cost Fe3O4 nanoparticles as a catalyst and ammonium formate as a green hydrogen source for catalytic transfer hydrogenation. This system utilizes the abundant Fe on the surface of Fe3O4 nanoparticles... 3+ / Fe 2+ The redox reaction efficiently activates ammonium formate, releasing "active hydrogen" in situ, thus avoiding the risks of directly using high-pressure hydrogen and significantly improving reaction safety. The reaction conditions are mild, with high chemoselectivity, efficiently reducing nitro groups to amino groups, and the byproducts are only harmless CO2, N2, and H2O. Post-processing is simple and environmentally friendly.
[0015] (3) In a method for deep indium separation according to the present invention, triethylamine, a volatile amine compound, is used as a template agent. Acetic acid forms ion pairs with the template agent, and these ion pairs can act as "soft templates" during the reaction. At 80-90°C, a COF framework is generated around the soft template. Upon increasing the temperature, the template agent vaporizes and generates self-pressure within the sealed tube. The escape of gas molecules creates additional mesoporous structures in situ within the COF framework, forming a hierarchical pore structure. The template agent is ultimately converted into gas, and no complex removal steps are required after the reaction. Attached Figure Description
[0016] Figure 1 This is a synthetic route diagram of indium selective covalent organic framework adsorbent material in an indium deep separation method of the present invention. Detailed Implementation
[0017] To address the problems of low separation and extraction efficiency of indium ions in strongly acidic systems with multiple coexisting ions, as well as the poor selectivity and insufficient stability of traditional adsorption materials, this invention designs and synthesizes indium-selective organic building blocks based on the unique coordination chemistry of indium. These blocks are then reversibly self-assembled via covalent bonds to construct highly crystalline, high-specific-surface-area covalent organic framework materials. This material, relying on uniformly distributed functional groups within ordered channels, possesses high-density active sites, excellent chemical stability, and a hierarchical pore structure, enabling specific recognition and strong coordination of indium ions. This allows for efficient and deep separation and recovery of indium ions under strongly acidic conditions with multiple coexisting ions. The processing technology of this invention specifically includes the following steps: The preparation of indium-selective covalent organic framework adsorbents first involved the synthesis of bis(4-aminophenyl) phosphate via a pre-modification strategy, followed by the synthesis of indium-selective covalent organic framework adsorbent (BHPP-TRA-COF) with 4,4',4''-nitrotribenzaldehyde. The specific synthesis scheme is as follows: (1) Synthesis of bis(4-aminophenyl) phosphate (BHHP): Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel in a molar ratio of (1:5:0.2) to (1:10:0.4). The reaction was repeated three times, with the system evacuated and purged with nitrogen to strictly remove oxygen and protect catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature using a constant-pressure dropping funnel. After the addition of anhydrous methanol, the mixture was stirred at room temperature for 1–10 h to ensure complete suspension of the substrate and reagents. The mixture was reacted at 60–80 °C for 4–20 h. After the reaction was complete, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0018] (2) Synthesis of indium selective covalent organic framework adsorbent (BHPP-TRA-COF): The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a molar ratio of (6:5) to (3:2) and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution, and triethylamine were added sequentially to the system at a volume ratio of (1:1:0.5:0.5) to (1:4:1:1). After sonicating the mixture for 5–15 min, the pressure inside the Schlenk tube was maintained at 0.1 Pa using a vacuum pump. The mixture was then degassed by liquid nitrogen freeze-thaw cycles 3–6 times and vacuum-sealed. The mixture was initially heated to 80–90 °C in a forced-air drying oven for 10–15 h, and then the temperature was further increased and maintained at 100–130 °C for 12–24 h. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was then filtered and washed with N,N-dimethylformamide, and the product was subjected to Soxhlet extraction with tetrahydrofuran at 90–110 °C for 10–15 h. After filtration, the product was vacuum dried at 70 °C for 6–12 h to obtain the indium-selective covalent organic framework adsorbent.
[0019] (3) Adsorption experiment of indium by indium selective covalent organic framework adsorbent (BHPP-TRA-COF): The synthesized indium-selective covalent organic framework adsorbent was added to an indium-containing leaching system with an acidity of 0.01–3 mol / L and reacted at 25–80 °C for 1–6 h to achieve efficient separation and extraction of indium by the indium-selective covalent organic framework adsorbent.
[0020] The present invention will be further described below with reference to specific embodiments.
[0021] Example 1 This embodiment of a method for indium depth separation specifically includes the following steps: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel in a molar ratio of 1:5:0.2. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for 1 h to ensure that the substrate and reagents were fully suspended. The mixture was reacted at 60 °C for 4 h. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0022] (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a molar ratio of 6:5 and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a volume ratio of 1:1:0.5:0.5. After sonicating the mixture for 5 min, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After degassing by liquid nitrogen freezing-thawing cycle 3 times, the tube was vacuum sealed. The initial temperature was raised to 80 °C and heated for 10 h in a forced-air drying oven. The temperature was then increased and maintained at 100 °C for 12 h. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was Soxhlet extracted with tetrahydrofuran at 90 °C for 10 h. After filtration, the product was vacuum dried at 70°C for 6 h to obtain an indium-selective covalent organic framework adsorbent.
[0023] (3) The synthesized indium selective covalent organic framework adsorbent was added to an indium-containing leaching system with an acidity of 0.01 mol / L and reacted at 25℃ for 1 h to achieve efficient separation and extraction of indium ions by the indium selective covalent organic framework adsorbent, with an adsorption rate of 99.21% for indium ions.
[0024] Example 2 This embodiment of a method for indium depth separation specifically includes the following steps: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel at a molar ratio of 1:10:0.4. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for 10 h to ensure that the substrate and reagents were fully suspended. The mixture was reacted at 80 °C for 20 h. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0025] (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a molar ratio of 3:2 and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a volume ratio of 1:4:1:1. After sonicating the mixture for 15 min, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After degassing by liquid nitrogen freezing-thawing cycle 6 times, the tube was vacuum sealed. The initial program temperature was raised to 90 °C and heated for 15 h in a forced-air drying oven. The temperature was then increased and maintained at 130 °C for 24 h. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was Soxhlet extracted with tetrahydrofuran at 110 °C for 15 h. After filtration, the product is vacuum dried at 70°C for 12 h to obtain an indium-selective covalent organic framework adsorbent.
[0026] (3) The synthesized indium selective covalent organic framework adsorbent was added to an indium-containing leaching system with an acidity of 3 mol / L and reacted at 80℃ for 6 h to achieve efficient separation and extraction of indium by the indium selective covalent organic framework adsorbent, with an indium adsorption rate of 99.72%.
[0027] Example 3 This embodiment of a method for indium depth separation specifically includes the following steps: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel at a molar ratio of 1:6:0.25. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for 2 h to ensure that the substrate and reagents were fully suspended. The mixture was reacted at 65 °C for 8 h. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0028] (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a molar ratio of 13:10 and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a volume ratio of 1:1.5:0.75:0.75. After sonicating the mixture for 8 min, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After degassing by liquid nitrogen freezing-thawing cycle 4 times, the tube was vacuum sealed. The initial temperature was raised to 85 °C and heated for 12 h in a forced-air drying oven. The temperature was then increased and maintained at 110 °C for 14 h. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was Soxhlet extracted with tetrahydrofuran at 95 °C for 12 h. After filtration, the product is vacuum dried at 70°C for 8 hours to obtain an indium-selective covalent organic framework adsorbent.
[0029] (3) The synthesized indium selective covalent organic framework adsorbent was added to an indium-containing leaching system with an acidity of 0.1 mol / L and reacted at 35℃ for 2 h to achieve efficient separation and extraction of indium by the indium selective covalent organic framework adsorbent, with an indium adsorption rate of 99.38%.
[0030] Example 4 This embodiment of a method for indium depth separation specifically includes the following steps: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel at a molar ratio of 1:8:0.3. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for 5 h to ensure that the substrate and reagents were fully suspended. The mixture was reacted at 70 °C for 15 h. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0031] (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a molar ratio of 7:5 and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a volume ratio of 1:2.5:0.6:0.6. After sonicating the mixture for 8 min, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After degassing by liquid nitrogen freezing-thawing cycle 5 times, the tube was vacuum sealed. The initial temperature was raised to 85 °C and heated for 14 h in a forced-air drying oven. The temperature was then increased and maintained at 120 °C for another 20 h. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was Soxhlet extracted with tetrahydrofuran at 100 °C for 13 h. After filtration, the product is vacuum dried at 70°C for 10 h to obtain an indium-selective covalent organic framework adsorbent.
[0032] (3) The synthesized indium selective covalent organic framework adsorbent was added to an indium-containing leaching system with an acidity of 1 mol / L and reacted at 65℃ for 4 h to achieve efficient separation and extraction of indium by the indium selective covalent organic framework adsorbent, with an indium adsorption rate of 99.42%.
[0033] Example 5 This embodiment of a method for indium depth separation specifically includes the following steps: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel at a molar ratio of 1:9.5:0.38. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for 8 h to ensure that the substrate and reagents were fully suspended. The mixture was reacted at 75 °C for 15 h. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate.
[0034] (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a molar ratio of 5:4 and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a volume ratio of 1:3.5:0.9:0.9. After sonicating the mixture for 13 min, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After degassing by liquid nitrogen freezing-thawing cycle 5 times, the tube was vacuum sealed. The initial temperature was raised to 86 °C and heated for 14 h in a forced-air drying oven. The temperature was then increased and maintained at 125 °C for 22 h. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was Soxhlet extracted with tetrahydrofuran at 105 °C for 14 h. After filtration, the product is vacuum dried at 70°C for 11 h to obtain an indium-selective covalent organic framework adsorbent.
[0035] (3) The synthesized indium selective covalent organic framework adsorbent was added to an indium-containing leaching system with an acidity of 2 mol / L and reacted at 70℃ for 5 h to achieve efficient separation and extraction of indium by the indium selective covalent organic framework adsorbent, with an indium adsorption rate of 99.61%.
Claims
1. The method for deep indium separation according to claim 1, characterized in that: The specific process operation is as follows: (1) Bis(4-nitrophenyl) phosphate, ammonium formate, and Fe3O4 nanoparticles were added to a reaction vessel in a certain molar ratio. The reaction system was evacuated and purged with nitrogen three times to strictly remove oxygen and protect the catalyst activity. Anhydrous methanol was added dropwise to the reaction vessel at room temperature through a constant pressure dropping funnel. After the addition of anhydrous methanol was completed, the mixture was stirred at room temperature for a period of time to ensure that the substrate and reagents were fully suspended. The mixture was reacted at a certain temperature for a period of time. After the reaction was completed, the reaction mixture was cooled to room temperature and washed with anhydrous methanol. The methanol solvent was removed by rotary evaporation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain a light yellow solid bis(4-aminophenyl) phosphate. (2) The ground bis(4-aminophenyl) phosphate and the linker 4,4',4''-nitrotribenzaldehyde were mixed at a certain molar ratio and added to a 25 mL Schlenk tube. Then, mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution and triethylamine were added to the system in a certain volume ratio. After sonicating the mixture for a period of time, the pressure in the Schlenk tube was maintained at 0.1 Pa by a vacuum pump. After several cycles of liquid nitrogen freezing-thawing degassing, the tube was vacuum sealed. The temperature was first programmed to a certain temperature and heated for a period of time in a forced-air drying oven. Then, the temperature was increased and maintained at a certain temperature for a certain period of time. After the reaction was completed, the system was allowed to cool to room temperature. The precipitate was filtered and washed with N,N-dimethylformamide, and the product was extracted with tetrahydrofuran for a period of time under certain temperature conditions. After filtration, the product was vacuum dried at 70℃ for a period of time to obtain the indium selective covalent organic framework adsorbent. (3) The synthesized indium selective covalent organic framework adsorbent material is added to an indium-containing leaching system with a certain acidity and reacted at a certain temperature for a period of time to achieve efficient separation and extraction of indium from an acidic complex solution system.
2. The method for deep indium separation according to claim 2, characterized in that: In step (1), bis(4-nitrophenyl) phosphate, ammonium formate and Fe3O4 nanoparticles are mixed in a molar ratio of (1:5:0.2) to (1:10:0.4), stirred for 1 to 10 h, reacted at a temperature of 60 to 80 °C, and reacted for 4 to 20 h.
3. The method for deep indium separation according to claim 2, characterized in that: In step (2), the molar ratio of bis(4-aminophenyl)phosphate to the linker 4,4',4''-nitrotribenzaldehyde is (6:5) to (3:2), and the volume ratio of mesitylene, 1,4-dioxane, 3M acetic acid aqueous solution, and triethylamine is (1:1:0.5:0.5) to (1:4:1:1). The ultrasonic treatment time is 5 to 15 min, the thawing cycle is 3 to 6 times, the initial heating temperature is 80 to 90 °C, and the heating time is 10 to 15 h. The subsequent temperature is maintained at 100 to 130 °C for 12 to 24 h. The Soxhlet extraction temperature is 90 to 110 °C, the extraction time is 10 to 15 h, and the vacuum drying time is 6 to 12 h.
4. The method for deep indium separation according to claim 2, characterized in that: In step (3), the acidity of the indium-containing leaching system is 0.01~3 mol / L, the reaction temperature is 25~80℃, and the reaction time is 1~6 h.