A method for selectively separating and extracting gallium

Abstract

The present invention discloses a method for selectively separating and extracting gallium, and belongs to the technical field of nonferrous metal metallurgy. The method for selectively separating and extracting gallium of the present invention aims at the problems of low efficiency of separation and extraction of low-concentration gallium in acidic complex systems, insufficient selectivity of traditional gallium adsorption materials, and limited adsorption capacity. Based on the coordination chemical characteristics of gallium ions, amidoxime functionalized calixarene structural units with precise cavity size and multiple coordination sites are designed and synthesized, and three-dimensional covalent organic framework materials with high crystallinity and porosity are constructed through dynamic covalent chemical regulation. Multiple recognition sites for gallium ions are formed, which have the advantages of strong selective coordination ability, high chemical stability and large specific surface area, and can realize the efficient capture and enrichment recovery of low-concentration gallium in acidic multi-metal coexistence environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal metallurgy, and particularly relates to a preparation method of a covalent organic framework material based on amidoxime-functionalized calix[4]arene and its application in selectively adsorbing and recovering gallium in an acidic medium. Background Art

[0002] As a critical metal, gallium plays an irreplaceable role in modern high-tech industries and is one of the core raw materials driving the development of semiconductors, new energy, communications, and national defense technologies. With its excellent semiconductor properties and low melting point, gallium plays a key role in the preparation of third-generation semiconductor materials (such as gallium nitride and gallium arsenide), which are widely used in fields such as 5G communications, high-speed electronic devices, photovoltaic power generation, and laser technology. In particular, gallium nitride (GaN)-based high-power devices have become the core materials for a new generation of power electronics and radio frequency devices due to their high efficiency, high temperature resistance, and high-frequency characteristics. In addition, gallium-based alloys (such as gallium-indium-tin alloys) have shown broad application prospects in flexible electronics, thermal interface materials, and intelligent sensing fields due to their unique liquid metal properties.

[0003] With the rapid development of high-tech industries, a large number of gallium-containing secondary resources (such as semiconductor waste, LED production waste, fly ash, etc.) have been generated. After leaching, these resources usually form an acidic or alkaline complex solution system, in which the gallium concentration is low and often coexists with elements such as aluminum, zinc, and iron. The similar chemical properties make separation difficult. Especially in an acidic environment, traditional extraction and precipitation methods have problems such as poor selectivity, low recovery rate, and high reagent consumption. Therefore, the development of efficient and highly selective gallium adsorption materials to achieve accurate separation and enrichment of gallium in complex systems is of great significance to resource recycling and metal safety. The application of Chinese patent application No. 202510182621.4 discloses the preparation of hydroxamic acid functionalized UiO-66-(COOH)2 fiber membrane adsorbent and its application in adsorbing gallium. It has the characteristics of easy preparation, green and environmentally friendly preparation process, adsorption of gallium ions from trace gallium solutions under acidic conditions, high selective adsorption rate, fast adsorption rate, and easy recycling of powder materials. The application of Chinese patent application No. 202411381795.5 discloses a amidoxime resin having the structural characteristics of diamidoximine and imide dioxime characteristic functional groups, having a large resin particle mass transfer contact area, and improving the resin's adsorption performance for gallium. The application of Chinese patent application No. 202411015949.9 provides a method for preparing a porous chelating resin for gallium adsorption assisted by supercritical CO2 amine oximation, so as to solve the problem that the current process cannot improve the degree of amine oximation on the surface of the porous chelating resin sphere and inside the micropores in a feasible, operable and quantitative manner. The application of Chinese patent application No. 202411058205.5 discloses a gallium adsorbent, which uses nitrogen-containing organic matter to nitrogen-dope molybdenum oxide. The obtained nitrogen-doped molybdenum oxide-based nanowires achieve efficient and selective adsorption of gallium ions in the coexistence system of impurity ions, and the adsorption of gallium ions has excellent cyclic stability, which solves the problems of low adsorption efficiency, selective adsorption and poor reuse performance of low-concentration scattered metal gallium in the prior art. The Chinese patent application No. 202410791402.1 discloses a method for synthesizing a gallium-targeted adsorption material and extracting gallium in depth, which overcomes the problem of poor structural stability of traditional extractants in industrial high-acid environments, effectively increases the solvent affinity of the pyrrole column [5] aromatic functional group in the acidic aqueous solution system, and achieves efficient adsorption. The stable aromatic ring silicon-based skeleton ensures that it still has a good cycle life under highly acidic conditions. The Chinese patent application No. 202410301843.9 provides a method for preparing a hydroxamic acid functionalized gallium ion adsorption resin. The hydroxamic acid functionalized gallium ion adsorption resin prepared by the method can effectively adsorb gallium ions, has a high adsorption rate and adsorption amount, and can efficiently and selectively recover gallium from complex systems.The application case with the Chinese patent application number 202311258889.9 provides a method for preparing a magnetic chitosan-based solid gallium ion adsorbent using ion imprinting technology. At pH = 4, the maximum adsorption capacity for gallium ions reaches 434 mg / g, far exceeding existing gallium ion adsorbents. Through competitive experiments, it is proven to have excellent selective adsorption properties for gallium ions. Summary of the Invention

[0004] The object of the present invention is to overcome the technical problem of low separation and extraction efficiency of low-concentration gallium in current acidic complex systems, and to overcome the defects of traditional gallium adsorption materials such as insufficient selectivity, limited adsorption capacity, and poor acid stability. A method for preparing an amidoxime group-calixarene covalent organic framework adsorption material and its targeted recovery of gallium is provided. Based on the coordination chemistry characteristics of gallium ions, an amidoxime-functionalized calixarene structural unit with precise cavity size and multiple coordination sites is designed and synthesized, and a three-dimensional covalent organic framework material with high crystallinity and porosity is constructed through dynamic covalent chemistry regulation. Through the synergistic effect of the amidoxime group and calixarene, this material forms multiple recognition sites for gallium ions, possessing the advantages of strong selective coordination ability, high chemical stability, and large specific surface area, and can achieve efficient capture and enrichment recovery of low-concentration gallium in an acidic multi-metal coexisting environment.

[0005] To solve the above problems, the technical solutions adopted in the present invention are as follows:

[0006] The present invention provides a method for selectively separating and extracting gallium, and the specific steps are as follows:

[0007] (1) Calix[4]arene and hexamethylenetetramine are heated under reflux in a mixed solvent of methanesulfonic acid and dichloromethane. After cooling to room temperature, powdered NaHCO3 or K2CO3 is added until no more bubbles are generated, and then through extraction, concentration, and recrystallization, tetraformyl calix[4]arene is obtained;

[0008] (2) The ground tetraformyl calix[4]arene is mixed with 4,4-biphenylcarbonitrile in a mixed solvent of o-dichlorobenzene and n-butanol, and ultrasonic treatment is carried out. After degassing, it is vacuum-sealed and reacted under microwave irradiation. After the reaction is completed, it is cooled, washed, and dried to obtain calix[4]arene COF;

[0009] (3) Calix[4]arene COF and hydroxylamine derivatives are refluxed in a solvent, and after washing, amidoxime group-calix[4]arene COF is obtained;

[0010] (4) The amidoxime group-calix[4]arene COF is added to a gallium-containing solution system, and through a constant-temperature reaction, the targeted adsorption separation and extraction of gallium are achieved.

[0011] Preferably, in the above method for selectively separating and extracting gallium, the specific processes of extraction, concentration, and recrystallization in step (1) are as follows: extract with dichloromethane, perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product, and recrystallize with dichloromethane to obtain yellow solid tetraformylcalix[4]arene.

[0012] Preferably, in the above method for selectively separating and extracting gallium, in step (1), the molar ratio of calix[4]arene to hexamethylenetetramine is (1:1.2) - (1:4), the volume ratio of methanesulfonic acid to dichloromethane is (4:1) - (6:1), the reaction time is 12 - 24 h, and the stirring time after adding powdered NaHCO3 or K2CO3 is 0.5 - 2 h.

[0013] Preferably, in the above method for selectively separating and extracting gallium, the specific processes of degassing, vacuum sealing, reacting under microwave radiation, and cooling, washing, and drying in step (2) are as follows: perform several freeze - pump - thaw cycles for degassing, evacuate the pressure in the heat - resistant glass tube to 0.1 Pa and then vacuum seal it, and place it in a microwave reactor; raise the temperature to a specific temperature and then keep it at a constant temperature for heating, perform microwave - assisted radiation for 10 min under the set power condition, and repeat the radiation operation at intervals of 60 min; after the reaction is completed, wait for the system to cool to room temperature, filter and wash the precipitate with DMF, water, and absolute ethanol in sequence, and vacuum dry it at 60 °C for a certain period of time to obtain acetonitrile - calix[4]arene COF.

[0014] Preferably, in the above method for selectively separating and extracting gallium, in step (2), the molar ratio of tetraformylcalix[4]arene to linker 4,4 - biphenylcarbonitrile is (1:1) - (3:2), the volume ratio of o - dichlorobenzene to n - butanol is (3:1) - (1:1), the ultrasonic time of the mixture is 20 - 30 min, the number of freeze - pump - thaw cycles for degassing is 3 - 4 times, raise the temperature to 90 - 120 °C, the reaction time is 24 - 48 h, the microwave - assisted radiation power is 500 - 1000 W, and the vacuum drying time is 6 - 12 h.

[0015] Preferably, in the above method for selectively separating and extracting gallium, in step (3), the molar ratio of calix[4]arene COF, hydroxylamine hydrochloride, and N,N - dimethylformamide is (1:6) - (1:10), and the volume ratio of ethanol to N,N - dimethylformamide is (1:40) - (1:60). The reaction temperature is 80 - 100 °C, and the reaction time is 24 - 36 h.

[0016] Preferably, in the above method for selectively separating and extracting gallium, in step (4), the hydrogen ion concentration of the gallium - containing solution system is 0.05 - 4 mol / L, the reaction temperature is 25 - 90 °C, and the reaction time is 0.5 - 5 h.

[0017] The present invention adopts the above-mentioned method for selectively separating and extracting gallium, and obtains the following beneficial effects:

[0018] (1) In the method for selectively separating and extracting gallium of the present invention, the formylation of calix[4]arene is one of the important methods for functionalizing this type of supramolecular host. The trifluoroacetic acid used in the traditional hexamethylenetetramine formylation reaction (Duff reaction) has strong corrosiveness as a reaction medium, complex post-treatment, and may cause side reactions. Therefore, replacing it with a mixed solution system of methanesulfonic acid (MSA) and dichloromethane with stronger activity and lower corrosiveness can reduce the synthesis time and increase the yield of tetramethanoylcalix[4]arene. Secondly, in the synthesis process of nitrile-calix[4]arene COF, a general synthesis strategy is innovatively proposed, and microwave-assisted radiation is used at intervals during heating. In this method, the ingenious addition of microwave conditions can promote the directional growth of crystals, improve the material properties, and significantly increase the reaction efficiency to prepare nitrile-calix[4]arene COF. In addition, replacing triethylamine with N,N-dimethylformamide with slightly weaker alkalinity can reduce the by-products generated due to the presence of strong bases and improve the purity of the product, and finally obtain amidoxime-calix[4]arene COF.

[0019] (2) In the method for selectively separating and extracting gallium of the present invention, the amidoxime units in the adsorbent material achieve high-selectivity recognition of gallium ions through the synergistic action of coordination and hydrogen bonding. This interaction has both strong binding force and dynamic tunability, which is the key to achieving high-capacity adsorption and desorption under mild conditions; the rigid cavity structure of the calixarene units can precisely match the coordination geometric requirements of gallium ions through the pre-organization effect, significantly enhancing the selectivity. The regular pore structure of the covalent organic framework can optimize the spatial arrangement of pore size and functional units through monomer design and synthesis condition regulation, which not only strengthens the mass transfer kinetics of gallium ions in the pores, but also generates a "molecular recognition enhancement effect" through the synergistic action of amidoxime-calixarene double sites. Description of the Drawings

[0020] Figure 1 It is a process diagram for the formation of amidoxime-calix[4]arene COF. Detailed Embodiments

[0021] Aiming at the problems of low separation and extraction efficiency of low-concentration gallium in acidic complex systems, insufficient selectivity and limited adsorption capacity of traditional gallium adsorbents, based on the coordination chemical properties of gallium ions, an amidoxime-functionalized calixarene structural unit with precise cavity size and multiple coordination sites is designed and synthesized, and a three-dimensional covalent organic framework material with high crystallinity and porosity is constructed through dynamic covalent chemistry regulation. Multiple recognition sites for gallium ions are formed, which have the advantages of strong selective coordination ability, high chemical stability and large specific surface area, and can realize the efficient capture, enrichment and recovery of low-concentration gallium in an acidic multi-metal coexisting environment. AsFigure 1 As shown in the figure, the processing technology of the present invention specifically includes the following steps:

[0022] The preparation of the gallium adsorbent amidoxime-calix[4]arene COF (CX[4]-AO-COF) first requires the synthesis of tetramethoxycalix[4]arene (CX[4]-CHO), and the synthesis of nitrile-calix[4]arene COF (CX[4]-BPCN-COF) with 4,4-biphenylcarbonitrile (BPCN). Finally, the amidoxime-calix[4]arene COF (CX[4]-AO-COF) is prepared through a post-modification strategy. The specific synthesis scheme is as follows:

[0023] (1) Synthesis of tetramethoxycalix[4]arene (CX[4]-CHO):

[0024] Calix[4]arene (CX[4]) and hexamethylenetetramine are dissolved in a mixed solvent of methanesulfonic acid (MSA) / dichloromethane (V:V=(4:1)~(6:1)) according to a molar ratio of (1:1.2)~(1:4) and heated under reflux for 12~24 h. After the reaction is completed, wait for the system to cool to room temperature, add powdered NaHCO3 or K2CO3 to the system until no more bubbles are generated. After stirring for 0.5~2 h, extract with dichloromethane, and perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product. Recrystallize from dichloromethane to obtain the yellow solid tetramethoxycalix[4]arene.

[0025] (2) Synthesis of nitrile-calix[4]arene COF (CX[4]-BPCN-COF):

[0026] The ground tetramethoxycalix[4]arene and the linker 4,4-biphenylcarbonitrile are added to a 20 mL Pyrex tube according to a molar ratio of (1:1)~(3:2). Subsequently, add a mixed solvent of o-dichlorobenzene and n-butanol (6 ml, V:V=(3:1)~(1:1)) to the tube. Ultrasonic the mixture for 20~30 min, degas through 3~4 freeze-pump-thaw cycles, and evacuate the pressure in the Pyrex tube to 0.1 Pa and then seal it under vacuum. Place it in a microwave reactor. Heat at a programmed temperature of 90~120 °C for 24~48 h, and perform microwave-assisted radiation for 10 min under the condition of 500~1000 W, and repeat the radiation operation every 60 min. After the reaction is completed, wait for the system to cool to room temperature, and filter and wash the precipitate with DMF, water, and absolute ethanol in sequence. Dry under vacuum at 60 °C for 6~12 h to obtain acetonitrile-calix[4]arene COF.

[0027] (3) Synthesis of amidoxime-calix[4]arene COF (CX[4]-AO-COF):

[0028] Dissolve calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide in an ethanol solution (the molar ratio of acetonitrile-calix[4]arene COF to hydroxylamine hydrochloride is 1:6 to 1:10, and the volume ratio of ethanol to N,N-dimethylformamide is 1:40 to 1:60). Stir the mixture for 24 to 36 h under reflux conditions at 80 to 100 °C. Wash the precipitate successively with H2O and absolute ethanol to finally obtain amidoxime-based calix[4]arene COF.

[0029] (4)Adsorption experiment of amidoxime-calix[4]arene COF (CX[4]-AO-COF) on gallium:

[0030] Add the synthesized amidoxime-based calix[4]arene covalent organic framework adsorbent material to a gallium-containing solution system with a hydrogen ion concentration of 0.05 to 4 mol / L, and react at a temperature of 25 to 90 °C for 0.5 to 5 h to achieve targeted adsorption separation and extraction of gallium.

[0031] The present invention will be further described below in conjunction with specific embodiments.

[0032] Example 1

[0033] A method for selectively separating and extracting gallium in this example specifically includes the following steps:

[0034] (1)Dissolve calix[4]arene (CX[4]) and hexamethylenetetramine in a mixed solvent of methanesulfonic acid (MSA) / dichloromethane (V:V = 4:1) at a molar ratio of 1:1.2 and heat under reflux for 12 h. After the reaction is completed, wait for the system to cool to room temperature, add powdered NaHCO3 or K2CO3 to the system until no more bubbles are generated. Stir for 0.5 h, extract with dichloromethane, and perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product. Recrystallize from dichloromethane to obtain yellow solid tetraformyl calix[4]arene.

[0035] (2)Add the ground tetraformyl calix[4]arene and linker 4,4-biphenylcarbonitrile to a 20 mL Pyrex tube at a molar ratio of 1:1. Subsequently, add a mixed solvent of o-dichlorobenzene and n-butanol (6 ml, V:V = 3:1) to the tube. Ultrasonic the mixture for 20 min, degas through 3 freeze-pump-thaw cycles, and evacuate the pressure in the Pyrex tube to 0.1 Pa and then seal it under vacuum. Place it in a microwave reactor. Heat at a programmed temperature of 90 °C for 24 h, irradiate with microwave assistance at 500 W for 10 min, and repeat the irradiation operation at intervals of 60 min. After the reaction is completed, wait for the system to cool to room temperature, and filter and wash the precipitate successively with DMF, water, and absolute ethanol. Dry under vacuum at 60 °C for 60 h to obtain acetonitrile-calix[4]arene COF.

[0036] (3) Dissolve calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide in an ethanol solution (the molar ratio of acetonitrile-calix[4]arene COF to hydroxylamine hydrochloride is 1:6, and the volume ratio of ethanol to N,N-dimethylformamide is 1:40). Stir the mixture under reflux at 80 °C for 24 h. Wash the precipitate successively with H2O and absolute ethanol to finally obtain amidoxime-calix[4]arene COF.

[0037] (4) Add the synthesized amidoxime-calix[4]arene covalent organic framework adsorbent to a gallium-containing solution system with a hydrogen ion concentration of 0.05 mol / L, and react at 25 °C for 0.5 h to achieve the targeted adsorption separation and extraction of gallium. The adsorption rate of gallium is 99.24%.

[0038] Example 2

[0039] A method for selectively separating and extracting gallium in this example specifically includes the following steps:

[0040] (1) Dissolve calix[4]arene (CX[4]) and hexamethylenetetramine in a mixed solvent of methanesulfonic acid (MSA) / dichloromethane (V:V = 6:1) according to a molar ratio of 1:4 and heat under reflux for 24 h. After the reaction is completed, wait for the system to cool to room temperature, and add powdered NaHCO3 or K2CO3 to the system until no more bubbles are generated. After stirring for 2 h, extract with dichloromethane, and perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product. Recrystallize from dichloromethane to obtain yellow solid tetraformyl calix[4]arene.

[0041] (2) Add the ground tetraformyl calix[4]arene and linker 4,4-biphenylcarbonitrile to a 20 mL Pyrex tube according to a molar ratio of 3:2. Subsequently, add a mixed solvent of o-dichlorobenzene and n-butanol (6 ml, V:V = 1:1) to the tube. Ultrasonic the mixture for 30 min, degas it three times through 4 freeze-pump-thaw cycles, and evacuate the pressure in the Pyrex tube to 0.1 Pa and then seal it under vacuum. Place it in a microwave reactor. Heat it at a programmed temperature of 120 °C for 48 h, perform microwave-assisted radiation at 1000 W for 10 min, and repeat the radiation operation at intervals of 60 min. After the reaction is completed, wait for the system to cool to room temperature, and filter and wash the precipitate successively with DMF, water, and absolute ethanol. Dry it under vacuum at 60 °C for 12 h to obtain acetonitrile-calix[4]arene COF.

[0042] (3) Dissolve calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide in an ethanol solution (the molar ratio of acetonitrile-calix[4]arene COF to hydroxylamine hydrochloride is 1:10, and the volume ratio of ethanol to N,N-dimethylformamide is 1:60). Stir the mixture at reflux for 36 h at 100 °C. Wash the precipitate successively with H2O and absolute ethanol to finally obtain amidoxime-calix[4]arene COF.

[0043] (4) Add the synthesized amidoxime-calix[4]arene covalent organic framework adsorbent material to a gallium-containing solution system with a hydrogen ion concentration of 4 mol / L, and react at 90 °C for 5 h to achieve the targeted adsorption separation and extraction of gallium. The adsorption rate of gallium is 99.69%.

[0044] Example 3

[0045] A method for selectively separating and extracting gallium in this example specifically includes the following steps:

[0046] (1) Dissolve calix[4]arene (CX[4]) and hexamethylenetetramine in methanesulfonic acid (MSA) / dichloromethane (V:V = 4.5:1) at a molar ratio of 1:2 and heat under reflux for 16 h. After the reaction is completed, wait for the system to cool to room temperature, add powdered NaHCO3 or K2CO3 to the system until no more bubbles are generated. Stir for 1 h and then extract with dichloromethane. Perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product, and recrystallize from dichloromethane to obtain yellow solid tetraformyl calix[4]arene.

[0047] (2) Add the ground tetraformyl calix[4]arene and linker 4,4-biphenylcarbonitrile to a 20 mL Pyrex tube at a molar ratio of 6:5. Subsequently, add a mixed solvent of o-dichlorobenzene and n-butanol (6 mL, volume ratio = 2:1) to the tube. Ultrasonic the mixture for 25 min, degas it through 3 freeze-pump-thaw cycles, and evacuate the pressure in the Pyrex tube to 0.1 Pa and then seal it under vacuum. Place it in a microwave reactor. Heat it under a programmed temperature rise to 100 °C for 28 h, perform microwave-assisted radiation at 600 W for 10 min, and repeat the radiation operation at intervals of 60 min. After the reaction is completed, wait for the system to cool to room temperature, and filter and wash the precipitate successively with DMF, water, and absolute ethanol. Dry it under vacuum at 60 °C for 8 h to obtain acetonitrile-calix[4]arene COF.

[0048] (3) Dissolve calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide in an ethanol solution (the molar ratio of acetonitrile-calix[4]arene COF to hydroxylamine hydrochloride is 1:7, and the volume ratio of ethanol to N,N-dimethylformamide is 1:45). Stir the mixture under reflux at 85 °C for 28 h. Wash the precipitate successively with H2O and absolute ethanol to finally obtain amidoxime-calix[4]arene COF.

[0049] (4) Add the synthesized amidoxime-calix[4]arene covalent organic framework adsorbent material to a gallium-containing solution system with a hydrogen ion concentration of 1 mol / L and react at 45 °C for 1 h to achieve the targeted adsorption separation and extraction of gallium. The adsorption rate of gallium is 99.38%.

[0050] Example 4

[0051] A method for selectively separating and extracting gallium in this example specifically includes the following steps:

[0052] (1) Dissolve calix[4]arene (CX[4]) and hexamethylenetetramine in a mixed solvent of methanesulfonic acid (MSA) / dichloromethane (V:V = 5:1) according to a molar ratio of 1:3 and heat under reflux for 18 h. After the reaction is completed, wait for the system to cool to room temperature, add powdered NaHCO3 or K2CO3 to the system until no more bubbles are generated. After stirring for 1.5 h, extract with dichloromethane, and perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product. Recrystallize from dichloromethane to obtain yellow solid tetraformylcalix[4]arene.

[0053] (2) Add the ground tetraformylcalix[4]arene and linker 4,4-biphenylcarbonitrile to a 20 mL Pyrex tube according to a molar ratio of 7:5. Subsequently, add a mixed solvent of o-dichlorobenzene and n-butanol (6 ml, V:V = 1.5:1) to the tube. Ultrasonic the mixture for 25 min, degas it three times through 4 freeze-pump-thaw cycles, and evacuate the pressure in the Pyrex tube to 0.1 Pa and then seal it under vacuum. Place it in a microwave reactor. Heat it under a programmed temperature rise to 110 °C for 32 h, perform microwave-assisted radiation at 700 W for 10 min, and repeat the radiation operation at intervals of 60 min. After the reaction is completed, wait for the system to cool to room temperature, and filter and wash the precipitate successively with DMF, water, and absolute ethanol. Dry it under vacuum at 60 °C for 10 h to obtain acetonitrile-calix[4]arene COF.

[0054] (3) Dissolve calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide in an ethanol solution (the molar ratio of acetonitrile-calix[4]arene COF to hydroxylamine hydrochloride is 1:8, and the volume ratio of ethanol to N,N-dimethylformamide is 1:50). Stir the mixture under reflux at 90 °C for 30 h. Wash the precipitate successively with H2O and absolute ethanol to finally obtain amidoxime-calix[4]arene COF.

[0055] (4) Add the synthesized amidoxime-calix[4]arene covalent organic framework adsorbent to a gallium-containing solution system with a hydrogen ion concentration of 2 mol / L, and react at 60 °C for 2 h to achieve targeted adsorption separation and extraction of gallium. The adsorption rate of gallium is 99.49%.

[0056] Example 5

[0057] A method for selectively separating and extracting gallium in this example specifically includes the following steps:

[0058] (1) Dissolve calix[4]arene (CX[4]) and hexamethylenetetramine in a mixed solvent of methanesulfonic acid (MSA) / dichloromethane (V:V = 5.5:1) according to a molar ratio of 1:3.5 and heat under reflux for 20 h. After the reaction ends, wait for the system to cool to room temperature, add powdered NaHCO3 or K2CO3 to the system until no more bubbles are generated. After stirring for 1.8 h, extract with dichloromethane, and perform rotary evaporation under reduced pressure on the organic phase to obtain a crude product. Recrystallize from dichloromethane to obtain yellow solid tetramethoxycarbonyl calix[4]arene.

[0059] (2) Add the ground tetramethoxycarbonyl calix[4]arene and linker 4,4-biphenylcarbonitrile to a 20 mL Pyrex tube according to a molar ratio of (4:3). Subsequently, add a mixed solvent of o-dichlorobenzene and n-butanol (6 ml, volume ratio = 2:1) to the tube. Ultrasonicate the mixture for 25 min, degas it three times through 4 freeze-pump-thaw cycles, and evacuate the pressure in the Pyrex tube to 0.1 Pa and then seal it under vacuum. Place it in a microwave reactor. Heat it at a programmed temperature of 115 °C for 40 h, and perform microwave-assisted radiation at 800 W for 10 min. Repeat the radiation operation every 60 min. After the reaction ends, wait for the system to cool to room temperature, and filter and wash the precipitate successively with DMF, water, and absolute ethanol. Dry it under vacuum at 60 °C for 11 h to obtain acetonitrile-calix[4]arene COF.

[0060] (3) Dissolve calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide in an ethanol solution (the molar ratio of acetonitrile-calix[4]arene COF to hydroxylamine hydrochloride is 1:9, and the volume ratio of ethanol to N,N-dimethylformamide is 1:55). Stir the mixture under reflux at 95 °C for 32 h, and wash the precipitate successively with H2O and absolute ethanol to finally obtain amidoxime-calix[4]arene COF.

[0061] (4) Add the synthesized amidoxime-calix[4]arene covalent organic framework adsorbent to a gallium-containing solution system with a hydrogen ion concentration of 3 mol / L, and react at 70 °C for 3 h to achieve targeted adsorption separation and extraction of gallium, with a gallium adsorption rate of 99.51%.

Claims

1. A method for selectively separating and extracting gallium, characterized in that, The specific steps are as follows: (1) Calix[4]arene and hexamethylenetetramine are heated under reflux in a mixed solvent of methanesulfonic acid and dichloromethane. After cooling to room temperature, powdered NaHCO3 or K2CO3 is added until no more bubbles are generated. After extraction, concentration, and recrystallization, tetraformyl calix[4]arene is obtained. (2) The ground tetraformyl calix[4]arene is mixed with 4,4-biphenylcarbonitrile in a mixed solvent of o-dichlorobenzene and n-butanol and subjected to ultrasonic treatment. After degassing, it is vacuum-sealed and reacted under microwave irradiation. After the reaction is completed, it is cooled, washed, and dried to obtain calix[4]arene COF. (3) Calix[4]arene COF and hydroxylamine derivative are refluxed in a solvent and washed to obtain amidoxime-based calix[4]arene COF. (4) The amidoxime-based calix[4]arene COF is added to a gallium-containing solution system, and the targeted adsorption separation and extraction of gallium are achieved through a constant-temperature reaction.

2. The method for selectively separating and extracting gallium according to claim 1, characterized in that: The specific processes of extraction, concentration, and recrystallization in step (1) are as follows: Extraction is carried out with dichloromethane, and the organic phase is rotary-evaporated under reduced pressure to obtain a crude product. The yellow solid tetraformyl calix[4]arene is obtained by recrystallization from dichloromethane.

3. The method for selectively separating and extracting gallium according to claim 2, wherein: In step (1), the molar ratio of calix[4]arene to hexamethylenetetramine is (1:1.2) - (1:4), the volume ratio of methanesulfonic acid to dichloromethane is (4:1) - (6:1), the reaction time is 12 - 24 h, and the stirring time after adding powdered NaHCO3 or K2CO3 is 0.5 - 2 h.

4. A method for selectively separating and extracting gallium according to claim 1, characterized in that: The specific processes of degassing, vacuum-sealing, reacting under microwave irradiation, cooling, washing, and drying in step (2) are as follows: After several freeze-pump-thaw cycles for degassing, the pressure in the heat-resistant glass tube is pumped to 0.1 Pa and then vacuum-sealed, and it is placed in a microwave reactor; The temperature is programmed to 90 - 120 °C and then heated at a constant temperature, and microwave-assisted irradiation is carried out for 10 min under the set power condition, and the irradiation operation is repeated at intervals of 60 min; After the reaction is completed, wait for the system to cool to room temperature, and the precipitate is filtered and washed successively with DMF, water, and absolute ethanol, and vacuum-dried at 60 °C to obtain acetonitrile-calix[4]arene COF.

5. A method for selectively separating and extracting gallium according to claim 4, characterized in that: In step (2), the molar ratio of tetraformyl calix[4]arene to the linker 4,4-biphenylcarbonitrile is (1:1) - (3:2), the volume ratio of o-dichlorobenzene to n-butanol is (3:1) - (1:1), the ultrasonic time of the mixture is 20 - 30 min, the number of freeze-pump-thaw cycles for degassing is 3 - 4 times, the reaction time is 24 - 48 h, the microwave-assisted irradiation power is 500 - 1000 W, and the vacuum-drying time is 6 - 12 h.

6. A method for selectively separating and extracting gallium according to claim 1, characterized in that: In step (3), the molar ratio of calix[4]arene COF, hydroxylamine hydrochloride, and N,N-dimethylformamide is (1:6) - (1:10), the volume ratio of ethanol to N,N-dimethylformamide is (1:40) - (1:60), the reaction temperature is 80 - 100 °C, and the reaction time is 24 - 36 h.

7. A method for selectively separating and extracting gallium according to claim 1, characterized in that: In the step (4), the hydrogen ion concentration of the gallium-containing solution system is 0.05 to 4 mol / L, the reaction temperature is 25 to 90 °C, and the reaction time is 0.5 to 5 h.

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