Aminophosphonate-functionalized carbon materials, their preparation methods and applications

Abstract

This invention relates to an aminophosphonate-functionalized carbon material, its preparation method, and its uses. The aminophosphonate-functionalized carbon material comprises a carbon matrix and a structure of Formula I covalently linked to the carbon matrix. It can be applied to capacitive deionization technology to selectively adsorb thorium from a mixed solution containing thorium and rare earth elements, exhibiting a high adsorption capacity for thorium.

Description

Technical Field

[0001] This invention belongs to the field of thorium separation technology, specifically relating to an aminophosphonate-functionalized carbon material, its preparation method, and its uses. Background Technology

[0002] High-purity rare earth elements are widely used in advanced optoelectronic materials, but the residual trace amounts of the radioactive element thorium significantly affect the performance of rare earth functional materials. Therefore, deep separation and removal of trace radioactive thorium from rare earth elements is a prerequisite for developing high-performance rare earth functional materials.

[0003] Solvent extraction is a classic method for enriching and separating thorium. However, for the separation and removal of trace amounts of thorium, it usually requires a high water-to-oil ratio to improve enrichment and separation efficiency. However, this method suffers from problems such as phase imbalance and extractant loss due to organic phase entrainment. Therefore, this method has significant shortcomings in terms of efficiency and economy. In contrast, adsorption effectively solves the problems of phase imbalance, extractant entrainment loss, and the occurrence of three phases.

[0004] CN112387249B discloses a method for adsorbing thorium using a magnetic porous biochar / zinc ferrite composite material. When the initial concentration of thorium is 20 mg / L, the adsorption capacity of the composite material for thorium is 20.81 mg / g.

[0005] CN110449131B discloses an adsorbent and a method for removing radioactive thorium and uranium impurities from high-purity rare earth products, achieving a thorium removal rate of 98.1% in high-purity lutetium solution.

[0006] CN109651240A discloses an organic ligand H2dtp and a metal-organic framework material, as well as their preparation methods and applications, and a method for separating thorium and rare earth elements. In a mixed solution containing thorium and rare earth elements, the adsorption capacity for thorium is 360 mg / g, and the separation coefficients for thorium and rare earth elements are both greater than 6.

[0007] CN105664873A discloses a method for adsorbing thorium using a bridged β-cyclodextrin derivative. This type of adsorbent has a maximum adsorption capacity of 52.2 mg / g for thorium ions and Mg. 2+ Pb 2+ Zn 2+ Fe 3+ Cd 2+ Interfering ions on Th 4+ The adsorption capacity is almost unaffected.

[0008] However, traditional adsorption methods cannot simultaneously achieve both high adsorption capacity and high selectivity for target metal ions. Furthermore, their shortcomings in stability, adsorption equilibrium time, recyclability, and large-scale preparation further limit their widespread application.

[0009] Therefore, there is a need to develop new and efficient thorium separation methods. Summary of the Invention

[0010] To address the shortcomings of the solvent extraction and adsorption methods described above, the inventors designed and prepared an aminophosphonate-functionalized carbon electrode material and applied it to capacitive deionization technology for thorium separation. Experiments have confirmed that this material has a high adsorption capacity for thorium and can be used to selectively adsorb thorium from mixed solutions containing thorium and rare earth elements, thus completing this invention.

[0011] On one hand, the present invention provides an aminophosphonate-functionalized carbon material, comprising:

[0012] (1) Carbon material matrix;

[0013] (2) The structure shown in Formula I, covalently bonded to a carbon material matrix:

[0014]

[0015] in,

[0016] R1 is selected from C1 to C1. 16 Alkylene;

[0017] R2 is selected from hydrogen, C1 to C2. 16 alkyl;

[0018] R3 and R4 are each independently selected from hydrogen, C1-C8 alkyl, C3-C4 alkyl, C4-C5 alkyl, C6-C6 alkyl, C7-C8 alkyl, C8-C9 ... 10 cycloalkyl and C6-C 10 Aryl;

[0019] R5 and R6 are each independently selected from C1 to C6. 16 Alkyl groups and C6-C 10 Aryl,

[0020] The asterisk (*) indicates that the material is connected to the carbon matrix at that location.

[0021] The carbon material matrix can be selected from any carbon material suitable for use as a conductive substrate, such as artificial graphite, carbon black, linear carbon, activated carbon fiber, carbon / carbon composite material, fullerene, carbon nanotube, graphene, carbon-coated nano-metal particles, more preferably activated carbon fiber, carbon nanotube, and most preferably carbon nanotube.

[0022] In some implementations, R1 is selected from C1 to C2. 12 Alkylene, for example, C1-C 10 Alkylene, C1-C8 alkylene or C1-C6 alkylene.

[0023] In some embodiments, R2 is selected from hydrogen and C1-C8 alkyl groups.

[0024] In some embodiments, R3 and R4 may be the same or different. In some embodiments, R3 and R4 are each independently selected from hydrogen, C1-C6 alkyl, C5-C8 cycloalkyl, and C6-C8 aryl.

[0025] In some embodiments, R5 and R6 may be the same or different. In some embodiments, R5 and R6 are each independently selected from C2 to C6. 14 Alkyl and C6-C8 aryl, more preferably C3-C 12 Alkyl and C6-C8 aryl.

[0026] In some embodiments, Formula I may be one or more selected from the following structures:

[0027]

[0028]

[0029] Based on the structure disclosed herein, the aminophosphonate functionalized carbon material of the present invention can be synthesized by combining known or similar methods in the prior art (such as J. Hazard. Mater, 2009, 176(1):119-124; CN201410765062.1; CN201611012369.X), or by methods similar to those disclosed in the examples.

[0030] In some embodiments, the aminophosphonate-functionalized carbon material can be prepared by a method comprising the following steps:

[0031] (1) The carbon material matrix is ​​activated with nitric acid solution to obtain hydroxylated carbon material;

[0032] (2) Hydroxylated carbon material is substituted with a halogenated organic amine X-R1-NH-R2 to obtain an organic amine *-O-R1-NH-R2 grafted carbon material, which is then subjected to an aminomethylation reaction with a phosphite PH(=O)(R5O)(R6O) and a carbonyl compound C(=O)R3R4 to obtain an aminophosphonate functionalized carbon material; or

[0033] Hydroxylated carbon materials with halogenated aminophosphonates Aminophosphonate-functionalized carbon materials were prepared via a substitution reaction.

[0034] Where X represents chlorine, bromine or iodine, and R1, R2, R3, R4, R5, R6 and * have the same meaning as described above.

[0035] To illustrate the above reaction more clearly, carbon materials were used... The hydroxylated carbon material is represented by Formula II, the halogenated organic amine by Formula III, the organic amine-grafted carbon material by Formula IV, the phosphite by Formula V, the carbonyl compound by Formula VI, the aminophosphonate-functionalized carbon material by Formula I-1, and the halogenated aminophosphonate by Formula VII. The reaction in step (2) above can be shown using the following reaction formula 1 or 2, but the invention is not limited thereto. In particular, the hydroxyl groups on the carbon material can be one or more:

[0036]

[0037]

[0038]

[0039] Furthermore, the method may include a pretreatment step of the carbon material matrix before step (1). For example, the carbon material matrix may be heated under an inert atmosphere and then soaked in hydrochloric acid solution to remove impurities from the carbon material carrier. However, the present invention is not limited to this. In some embodiments, the inert atmosphere includes, but is not limited to, gases that do not react with carbon materials, such as nitrogen and argon; the heating temperature may be 200-500°C, and the heating time may be 2-24 hours; the concentration of the hydrochloric acid solution may be 1-20% by volume; and the soaking time may be 4-36 hours. However, the present invention is not limited to this.

[0040] In some embodiments, in step (1), the concentration of the nitric acid solution can be 1.0-12 mol / L; the heating temperature can be 80-120℃; and the reaction time can be 2-24 hours, but the present invention is not limited thereto.

[0041] In some embodiments, the substitution reaction in step (2) is carried out in an organic solvent, including but not limited to methanol, ethanol, acetonitrile, tetrahydrofuran, and dioxane, at a reaction temperature of 25-120°C and a reaction time of 12-36 hours, but the present invention is not limited thereto.

[0042] Furthermore, the haloaminophosphonate in step (2) can be obtained by amine methylation of compounds III, V and VI, as shown in reaction formula 3, but the present invention is not limited thereto:

[0043]

[0044] The meanings of X, R1, R2, R3, R4, R5, and R6 are the same as those described above.

[0045] In some embodiments, the above-mentioned aminomethylation reaction can be carried out with or without a catalyst and with or without a solvent. The solvent may be, for example, benzene, toluene, xylene, tetrahydrofuran, dichloromethane, or chloroform. The catalyst may be, for example, hydrochloric acid, p-toluenesulfonic acid, InCl3, SnCl2, SnCl4, ZnCl2, MgBr2, BF3·Et2O, or other Lewis acids. The reaction time is 25 min to 72 h, and the reaction temperature is room temperature to 150 °C. However, the present invention is not limited thereto.

[0046] The terms C1 to C used in this invention 16 Alkyl refers to a straight-chain or branched alkyl group containing 1 to 16 carbon atoms, such as straight-chain or branched alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 carbon atoms. It includes, without limitation, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, neopentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, etc. (C1-C2) 12 Alkyl, C1-C 10 Alkyl, C1-C8 alkyl, C1-C6 alkyl, C2-C 14 Alkyl groups and C3-C 12 The meaning of alkyl is similar.

[0047] The terms C1 to C used in this invention 16 Alkylene refers to the group consisting of C1 to C2 atoms. 16 An alkyl group is formed by losing another hydrogen atom to obtain a divalent group.

[0048] The terms C3 to C used in this invention 10 Cycloalkyl refers to a saturated cyclic alkyl group containing 3 to 10 carbon atoms, including the number of carbon atoms in the substituents. The saturated cyclic alkyl group can be a monocyclic or bicyclic group, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc. The substituents can be one or more substituents selected from C1 to C4 alkyl groups. The meanings of C5 to C8 cycloalkyl groups are similar.

[0049] The terms C6 to C used in this invention 10 Aryl refers to an aryl group containing 6 to 10 carbon atoms, including the number of carbon atoms in the substituents. Examples include phenyl and phenyl groups substituted with one or more substituents selected from C1 to C4 alkyl groups, such as tolyl, dimethylphenyl, trimethylphenyl, ethylphenyl, etc. The meanings of C6 to C8 aryl groups are deduced similarly.

[0050] Experiments have confirmed that the aminophosphonate-functionalized carbon material of the present invention can selectively adsorb thorium, especially when used as an electrode material after being prepared into an electrode, it can selectively adsorb thorium, thereby separating thorium from rare earth elements.

[0051] Therefore, another aspect of the present invention provides the use of the aminophosphonate-functionalized carbon material of the present invention in the preparation of materials or devices for adsorbing thorium.

[0052] Another aspect of the present invention provides an electrode plate comprising: an electrode substrate, an electrode material layer on the electrode substrate, wherein the electrode material layer comprises the aminophosphonate functionalized carbon material of the present invention.

[0053] In addition to the aminophosphonate-functionalized carbon material of the present invention, the electrode material layer may also contain other materials used in the art for preparing the electrode material layer, such as conductive agents, binders, dispersants, etc., but are not limited thereto. The conductive agents include, but are not limited to, traditional conductive agents such as carbon black, conductive graphite, and carbon fibers, and novel conductive agents including carbon nanotubes, graphene, and their mixed conductive slurries. The binders include, but are not limited to, oil-based binders such as polyvinylidene fluoride (PVDF), water-based binders such as styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylonitrile (PAN), and polyvinyl alcohol (PVA). The dispersants include, but are not limited to, anionic wetting and dispersing agents such as carboxylates and sulfates, polymeric hyperdispersants such as acrylate polymeric dispersants, polyurethane or polyester polymeric dispersants including N-methylpyrrolidone, and cationic wetting and dispersing agents including amine salts, quaternary ammonium salts, and pyridinium salts.

[0054] In the electrode material layer, there is no particular limitation on the size of the aminophosphonate functionalized carbon material of the present invention, as long as it is suitable for preparing the electrode plate. For example, the mesh size of the aminophosphonate functionalized carbon material after grinding and sieving can be 50-400 mesh, but it is not limited to this.

[0055] There are no particular restrictions on the proportions of the components in the electrode material layer, as long as the required performance is met. For example, the mass ratio of aminophosphonate functionalized carbon material to conductive agent and binder can be 1:0.01 to 10:0.01 to 100, but it is not limited to this.

[0056] The electrode plate can be prepared by any suitable method; therefore, the present invention does not impose any particular limitation on the preparation method. For example, the aminophosphonate-functionalized carbon material can be ground and sieved, mixed with a conductive agent, binder, dispersant and optional other materials in a certain proportion, stirred until liquid, and finally uniformly coated onto the surface of a titanium plate. After drying, the aminophosphonate-functionalized carbon electrode plate is obtained.

[0057] There are no particular limitations on the thickness of the electrode material layer, as long as the required adsorption amount is met. Therefore, this invention does not impose any particular limitations on the thickness of the electrode material layer. The thickness of the electrode material layer can be conveniently controlled by controlling the wet coating thickness, for example, the wet coating thickness can be controlled to be 0.001-0.30 mm, but is not limited to this.

[0058] Another aspect of the present invention provides a capacitive deionization device, which includes the electrode plate of the present invention.

[0059] Apart from the electrode plate of the present invention, the capacitive deionization device can have any suitable capacitive deionization device structure without particular limitation.

[0060] Another aspect of the present invention provides a method for adsorbing thorium, the method comprising the step of passing a thorium-containing solution into the capacitive deionization device of the present invention to adsorb thorium from the solution. After thorium adsorption, the aminophosphonate-functionalized carbon electrode material adsorbs thorium and is sometimes referred to as a thorium-containing electrode material.

[0061] In some embodiments, the method for adsorbing thorium according to the present invention includes:

[0062] A thorium-containing solution is passed into the capacitor deionization device of the present invention to adsorb thorium from the solution to obtain a thorium-containing electrode material; the thorium-containing electrode material is optionally washed with a detergent, and

[0063] Thorium in the electrode material is desorbed using a desorbent.

[0064] The washing process can remove impurity elements adsorbed on the electrode material, improving the purity of thorium adsorbed on the electrode material, thereby helping to improve the purity of the final thorium product. The washing agent can be a solution of nitric acid, sulfuric acid, hydrochloric acid, or a mixture of these acids in any proportion. The acidity of the washing agent, calculated as the molar concentration of hydrogen ions, is approximately 0.01–1 mol / L.

[0065] The desorption process is used to elute thorium from electrode materials to obtain thorium-containing desorption products, which are then used to produce thorium products. The desorbent is a solution of nitric acid, hydrochloric acid, sulfuric acid, or a mixture of the above acids, with an acidity of approximately 0.1–8 mol / L, calculated by the hydrogen ion molar concentration. Other desorbents that can be used include EDTA, sodium carbonate, and sodium sulfate.

[0066] The desorbed electrode material can be recycled and reused to adsorb and separate thorium from thorium-containing liquid.

[0067] The thorium-containing solution comprises thorium, mineral acids, and other non-thorium elements. The thorium concentration can be approximately 0.0001–2.0 mol / L, preferably approximately 0.0003–1 mol / L. Furthermore, the solution may also contain other elements such as rare earth elements, alkali metals, alkaline earth metals, transition metals, and non-metallic elements. There are no restrictions on the raw materials used to prepare the thorium-containing solution, as long as they contain thorium. In this case, the method of the present invention can selectively adsorb and separate thorium, thereby separating it from non-thorium impurity elements.

[0068] Preferably, the pH of the thorium-containing solution can be from 0 to 4, preferably 1-4, such as 1.5, 2, 2.5, 3, 3.5, etc., but is not limited thereto. Within the above pH range, the electrode material of the present invention maintains a high adsorption capacity, thereby efficiently adsorbing thorium. Outside the above pH range, the adsorption capacity of the electrode material of the present invention decreases, leading to a reduction in adsorption efficiency. Therefore, when the pH of the original thorium-containing solution is not within the above range, it is preferable to adjust the pH of the original thorium-containing solution to the above range to improve the thorium extraction efficiency. The thorium-containing solution is generally a nitric acid, sulfuric acid, or hydrochloric acid solution, but is not limited thereto.

[0069] Unless otherwise stated, the numerical ranges listed in this invention include the endpoint values ​​and all point values ​​between the endpoint values ​​that increase or decrease in the smallest unit of the endpoint value, as well as all subranges composed of these point values.

[0070] Beneficial effects

[0071] The carbon electrode material of this invention has a simple preparation method, a large adsorption capacity for thorium, and good selectivity, making it suitable for the efficient enrichment and separation of low-concentration thorium. The thorium-loaded electrode material can be desorbed and recycled after power-off and inorganic acid washing. Attached Figure Description

[0072] Figure 1 The thermogravimetric curve of the carbon electrode material prepared in Example 1 of this invention is shown.

[0073] Figure 2 The XPS high-resolution P2P spectrum of the carbon electrode material prepared in Preparation Example 1 of the present invention is shown.

[0074] Figure 3 The XPS high-resolution N1s spectrum of the carbon electrode material prepared in Example 1 of this invention is shown.

[0075] Figure 4 This diagram shows the capacitor deionization module.

[0076] Figure 5 This shows a SEM image of the carbon electrode surface prepared in Comparative Example 1. Detailed Implementation

[0077] To further illustrate the present invention, specific embodiments are provided to help those skilled in the art understand and implement the invention; however, the invention is not limited to these embodiments.

[0078] Furthermore, it should be noted that the structure of the carbon electrode material given in the preparation examples of this invention is illustrative and does not constitute a limitation on this invention.

[0079] Reagents and Instruments

[0080] Carbon nanotubes (CNTs) were purchased from Shanghai Titan Technology Co., Ltd., product number 041045707.

[0081] Porous activated carbon (AC) was purchased from Shanghai Titan Technology Co., Ltd., product number 013550462.

[0082] The carbon fiber (CF) was purchased from Shanghai Titan Technology Co., Ltd., product number 041122102.

[0083] The graphene was purchased from Shanghai Titan Technology Co., Ltd., product number 041122039.

[0084] Graphene oxide (GO) was purchased from Shanghai Titan Technology Co., Ltd., product number 041402566.

[0085] Fullerene (C 60 Purchased from Shanghai Titan Technology Co., Ltd., product number 013220131.

[0086] Activated carbon fiber (ACF) was prepared in-house using a gas activation method. First, the carbon fiber (CF) was soaked in a hydrogen phosphate solution for 1 hour, filtered, and dried. Then, it was placed in a tube furnace and heated to 1500°C under a nitrogen atmosphere for carbonization treatment at a heating rate of 8°C / min for 4 hours. Afterward, the temperature was slowly lowered to 850°C at a cooling rate of 5°C / min. At 850°C, air was introduced to oxidize the carbon fiber for 4 hours. Finally, it was cooled to room temperature to obtain ACF.

[0087] The PVDF was purchased from Shanghai Titan Technology Co., Ltd., product number 013658853, MW is 180000.

[0088] The conductive carbon black was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., product number #101095.

[0089] Organic amines, aldehydes, ketones, dialkyl phosphites, and other reagents were purchased from Aladdin Reagent Company and were all of analytical grade.

[0090] The solution was prepared in the laboratory.

[0091] Other reagents (such as acids, organic solvents, etc.) are all commercially available analytical grade reagents.

[0092] The thorium concentration in the feed solution was determined using ICP-OES (instrument model: PQ9000, manufacturer: Jena) and ICP-MS (instrument model: Agilent 8900, manufacturer: Agilent).

[0093] Preparation Example 1: Preparation of aminophosphonate-functionalized carbon nanotubes (1)

[0094]

[0095] (1) Weigh 3.6g of carbon nanotubes (CNTs) and place them in a crucible. Heat them in a muffle furnace at 500°C for 4 hours under a nitrogen atmosphere. Then cool them to room temperature, transfer the sample to a beaker, soak the heat-treated carbon nanotube sample in 10% hydrochloric acid solution for 24 hours, filter, wash with pure water and ethanol alternately until neutral, and dry to obtain the purified sample.

[0096] (2) The sample in (1) was immersed in 200 mL of 3.2 mol / L nitric acid solution, heated to 100 °C for 6 hours to activate the reaction, cooled to room temperature after the reaction was completed, washed with pure water until neutral, and dried to obtain hydroxylated carbon nanotubes.

[0097] (3) Weigh 2.0g of hydroxylated carbon nanotubes, 100mL of tetrahydrofuran, and 1.3g of 3-chloropropylamine. Mix them and heat under reflux at 80°C for 24 hours. After the reaction is complete, cool to room temperature, filter, wash with water until neutral, and vacuum dry to obtain organic amine-grafted carbon nanotubes.

[0098] (4) Weigh 50 mmol of organic amine-grafted carbon nanotubes and mix them with 50 mmol of di(2-ethylhexyl) phosphite, 52.5 mmol of paraformaldehyde, 100 mg of p-toluenesulfonic acid, and 100 mL of toluene. Heat the mixture at 120 °C for 12 hours. After the reaction is complete, cool to room temperature, filter, and wash the product alternately with water and ethanol to obtain aminophosphonate-functionalized carbon nanotubes. Thermogravimetric analysis, high-resolution P2P XPS, and high-resolution N1s XPS analyses were performed. The results are shown in the figure. Figure 1-3 .

[0099] 31 P NMRδ P ppm: 19.39

[0100] Thermogravimetric results ( Figure 1The results show that under a nitrogen atmosphere, when heated to 800℃, the mass of carbon nanotubes remains unchanged, while the mass of functionalized carbon nanotubes decreases to some extent. Calculations show a grafting rate of approximately 7.33%, proving successful grafting of organic matter. High-resolution P2P XPS spectra of functionalized carbon nanotubes are shown. Figure 2 This indicates that the peaks appearing at 133.48 eV and 134.08 eV can be attributed to phosphorus atoms in P=O and PO bonds, respectively, with the peak area ratio of PO to P=O being 2:1, consistent with the proportion of chemical bonds in the target molecule; the high-resolution N1s XPS spectrum shows that... Figure 3 The binding energy of the amino nitrogen atom is 399.58 eV. The above characterization results indicate that aminophosphonate was successfully grafted onto the surface of carbon nanotubes.

[0101] Preparation Example 2: Preparation of aminophosphonate-functionalized porous activated carbon (2)

[0102]

[0103] Except for using porous activated carbon (AC) instead of carbon nanotubes and diethylphosphonite instead of di(2-ethylhexyl)phosphite, the other steps are exactly the same as in Preparation Example 1.

[0104] 31 P NMRδ P ppm: 19.60

[0105] Preparation Example 3: Preparation of aminophosphonate functionalized carbon fiber (3)

[0106]

[0107] Except for using acetaldehyde instead of paraformaldehyde, N-(3-chloropropyl)hexadecyl-1-amine instead of 3-chloropropylamine, di(hexadecyl)phosphite instead of di(2-ethylhexyl)phosphite, and carbon fiber (CF) instead of carbon nanotubes, the other steps are exactly the same as in Preparation Example 1.

[0108] 31 P NMRδ P ppm: 19.45

[0109] Preparation Example 4: Preparation of aminophosphonate-functionalized graphene (4)

[0110]

[0111] Except for using acetone instead of paraformaldehyde, graphene instead of carbon nanotubes, and 2-ethylhexylphenyl phosphite instead of di(2-ethylhexyl) phosphite, the other steps are exactly the same as in Preparation Example 1.

[0112] 31 P NMRδ P ppm: 19.59

[0113] Preparation Example 5: Preparation of aminophosphonate-functionalized graphene oxide (5)

[0114]

[0115] Except for using acetone instead of paraformaldehyde and graphene oxide (GO) instead of carbon nanotubes, the other steps are exactly the same as in Preparation Example 1.

[0116] 31 P NMRδ P ppm: 19.74

[0117] Preparation Example 6: Preparation of aminophosphonate-functionalized fullerene (6)

[0118]

[0119] In addition to using fullerene (C 60 Except for replacing carbon nanotubes, diphenyl phosphite instead of di(2-ethylhexyl) phosphite, and N-(4-chloro-2-ethylbutyl)ethyl-1-amine instead of 3-chloropropylamine, the other steps are exactly the same as in Preparation Example 1.

[0120] 31 P NMRδ P ppm: 19.68

[0121] Preparation Example 7: Preparation of aminophosphonate-functionalized carbon nanotubes (7)

[0122]

[0123] Except for the use of diphenyl phosphite instead of di(2-ethylhexyl) phosphite and N-(4-chloro-2-ethylbutyl)ethyl-1-amine instead of 3-chloropropylamine, the other steps are exactly the same as in Preparation Example 1.

[0124] 31 P NMRδ P ppm: 19.80

[0125] Preparation Example 8: Preparation of aminophosphonate-functionalized activated carbon fiber (8)

[0126]

[0127] Except for the use of heptadecano-9-one instead of paraformaldehyde, 4-chloro-2-ethylbutamine instead of 3-chloropropaneamine, activated carbon fiber (ACF) instead of carbon nanotubes, and diphenyl phosphite instead of di(2-ethylhexyl) phosphite, the other steps are exactly the same as in Preparation Example 1.

[0128] 31 P NMRδ P ppm: 19.24

[0129] Example

[0130] To prepare a single thorium chloride solution: Take a 0.2 mol / L thorium chloride solution, dilute it with distilled water to the required concentration, and adjust the pH of the solution with hydrochloric acid and sodium hydroxide.

[0131] Prepare a mixed metal ion solution: Take separate solutions of thorium chloride and rare earth chloride, mix them, and dilute with distilled water to the required concentration. Adjust the pH of the solution with hydrochloric acid and sodium hydroxide.

[0132] Electrode plate preparation: PVDF was dissolved in dispersant NMP (N-methylpyrrolidone) with a mass fraction of 5% PVDF in the solution. The aminophosphonate functionalized carbon material from Preparation Examples 1-8 was used as the electrode material and mixed with conductive carbon black and PVDF in a mass ratio of 8:1:1. The mixture was then uniformly coated on the surface of the titanium plate with a wet coating thickness of 0.15 mm and then vacuum dried.

[0133] Electroadsorption experimental procedure: The prepared electrode plate is placed in the capacitive deionization (CDI) module, the feed solution is injected into the CDI device using a peristaltic pump, the conductivity value of the effluent is monitored using a conductivity meter, and after adsorption is completed, the concentration of adsorbed metal ions is determined by inductively coupled plasma atomic emission spectrometry (ICP). Figure 4 The diagram shows a capacitive deionization (CDI) module. The outermost two acrylic plates are used to fix the CDI module. The solution enters the device from the lower inlet and exits from the upper outlet. The next outermost layer consists of two titanium plates coated with electrode material, i.e., electrode plates, with a reaction area of ​​50mm*50mm. Inside the two electrode plates are two layers of perforated plastic partitions to separate the two electrodes. A perforated acrylic plate is placed between the two plastic partitions to fix the plastic partitions. The electro-adsorption and separation of metal ions in the solution takes place in the space formed by the two electrodes.

[0134] Adsorption capacity Q, distribution ratio K d Separation coefficient β of thorium and rare earth ions Th / RE The cycle performance R is calculated using the following formula.

[0135]

[0136]

[0137]

[0138]

[0139] Where Q is the adsorption capacity (mg / g), Q1 and Q i The adsorption capacities (mg / g) for the first electroadsorption cycle and for the i-th cycle are respectively, C. i With C t The values ​​are the rare earth ion concentrations (mg / L) before and after electroadsorption, V is the volume of the liquid (L), and m is the mass (g) of the electrode material coated on the electrode plate surface.

[0140] Examples 1-8

[0141] Electroadsorption experiments were conducted using the following conditions and the carbon electrode materials listed in Table 1, and the adsorption capacity was calculated.

[0142] Thorium chloride solution: thorium ion concentration of 200 ppm, initial pH of 3.0;

[0143] Adsorption time: 180 minutes;

[0144] Voltage: U = 4.0V.

[0145] The adsorption capacities of different carbon electrode materials are shown in Table 1.

[0146] Comparative Example 1

[0147] Electrode plates were prepared according to a method similar to that reported in Nuclear Engineering and Technology, 2021, 53(9), 2926-2936 for the preparation of activated carbon electrodes.

[0148] The preparation process is as follows: PVDF is dissolved in dispersant NMP (N-methylpyrrolidone), and the mass fraction of PVDF in the solution is 5%. Porous activated carbon (AC), PVDF and conductive carbon black are mixed in a mass ratio of 8:1:1 and stirred evenly. Then, it is uniformly coated on the surface of a titanium plate with a wet coating thickness of 0.15 mm, and then vacuum dried.

[0149] SEM image of the prepared carbon electrode surface ( Figure 5 The results show that a large number of pores appear on the electrode surface, and the surface exhibits an uneven, layered structure. This structural feature increases the specific surface area of ​​the material, which is beneficial for the adsorption of metal ions.

[0150] Except for the different electrode plates, the electroadsorption experiment was conducted according to the method and conditions of Example 2, and the adsorption capacity was calculated. The adsorption capacity for thorium ions is shown in Table 1.

[0151] Table 1

[0152]

[0153]

[0154] The results above demonstrate that the aminophosphonate-functionalized carbon material of the present invention exhibits a high adsorption capacity for thorium. In particular, the results of Comparative Example 2 and Comparative Example 1 show that the adsorption capacity of the aminophosphonate-functionalized carbon material of the present invention for thorium is significantly higher than that of the unfunctionalized carbon material.

[0155] Experimental Example 9

[0156] Electroadsorption experiments were conducted under the following conditions and with the voltages in Table 2, and the separation coefficients of thorium and rare earth ions were calculated.

[0157] Mixed solution: The concentrations of Th, La, Gd, and Lu are all 200 ppm, and the initial pH is 3.0;

[0158] Electrode materials: Preparation example 1;

[0159] Adsorption time: 180 minutes.

[0160] The separation coefficients of thorium and rare earth ions under different voltage conditions are shown in Table 2.

[0161] Table 2

[0162] Voltage (V) <![CDATA[β Th / La ]]> <![CDATA[β Th / Gd ]]> <![CDATA[β Th / Lu ]]> 0.3 3.27 1.62 1.29 1.5 3.43 1.69 1.57 2.0 5.96 3.43 2.29 2.5 9.56 4.13 3.67 3.5 12.07 15.31 17.86 4.0 9.77 15.67 7.38

[0163] The results show that this type of electroadsorption material has high selectivity for thorium and can be used to separate thorium from rare earth elements.

[0164] Example 10

[0165] Electroadsorption experiments were conducted using the following conditions and the carbon electrode materials listed in Table 3, and the adsorption capacity was calculated.

[0166] Thorium chloride solution: thorium ion concentration of 200 ppm, initial pH of 3.0;

[0167] Adsorption time: 180 minutes;

[0168] Voltage: U = 4.0V.

[0169] After the electrode material finishes adsorption, hydrochloric acid solution is introduced for desorption and regeneration. Then, water is introduced to wash the electrode material until it is neutral. The feed solution is introduced again, and the adsorption capacity of thorium is measured. This cycle is repeated 5 times.

[0170] The adsorption capacities of different carbon electrode materials under each cycle are shown in Table 3.

[0171] Table 3

[0172]

[0173]

[0174] In summary, the functionalized carbon electrode material prepared by this invention has the advantages of simple preparation method, large thorium adsorption capacity, good selectivity and stable cycling performance. It can be used to adsorb and remove thorium ions and has good application prospects.

Claims

1. An aminophosphonate-functionalized carbon material, comprising: (1) Carbon material matrix, selected from artificial graphite, carbon black, linear carbon, activated carbon fiber, carbon / carbon composite material, fullerene, carbon nanotube, graphene, carbon-coated nano-metal particles; (2) The structure shown in Formula I, covalently bonded to a carbon material matrix: （Ⅰ） in, R1 is selected from C1~C 16 Alkylene; R2 is selected from hydrogen, C1~C2. 16 alkyl; R3 and R4 are each independently selected from hydrogen, C1~C8 alkyl, C3~C 10 cycloalkyl and C6~C 10 Aryl; R5 and R6 are each independently selected from C1 to C2. 16 Alkyl and C6~C 10 Aryl; " This indicates that it is connected to a carbon material matrix at this location. The aminophosphonate-functionalized carbon material is prepared according to the following method: (1) The carbon material matrix is ​​activated with nitric acid solution to obtain hydroxylated carbon material; (2) Organic amines are prepared by substitution reaction of hydroxylated carbon materials with halogenated organic amines X-R1-NH-R2. -O-R1-NH-R2 grafted carbon materials are then subjected to aminomethylation reactions with phosphites PH(=O)(R5O)(R6O) and carbonyl compounds C(=O)R3R4 to obtain aminophosphonate functionalized carbon materials; or Hydroxylated carbon materials with halogenated aminophosphonates Aminophosphonate-functionalized carbon materials were prepared via a substitution reaction. Where X represents chlorine, bromine, or iodine.

2. The aminophosphonate-functionalized carbon material according to claim 1, wherein, R1 is selected from C1~C 12 Alkylene; and / or R2 is selected from hydrogen, C1-C8 alkyl; and / or R3 and R4 are each independently selected from hydrogen, C1-C6 alkyl, C5-C8 cycloalkyl, and C6-C8 aryl; and / or R5 and R6 are each independently selected from C2~C 14 Alkyl and C6~C8 aryl.

3. The aminophosphonate-functionalized carbon material according to claim 2, wherein, R1 is selected from C1~C 10 Alkylene; and / or R5 and R6 are each independently selected from C3~C 12 Alkyl and C6~C8 aryl.

4. The aminophosphonate-functionalized carbon material according to claim 3, wherein, R1 is selected from C1~C8 alkylene groups.

5. The aminophosphonate-functionalized carbon material according to claim 3, wherein, R1 is selected from C1~C6 alkylene groups.

6. The aminophosphonate-functionalized carbon material according to claim 1, wherein, Formula I is selected from one or more of the following structures: 。 7. A method for preparing aminophosphonate-functionalized carbon materials according to any one of claims 1-6, comprising the following steps: (1) The carbon material matrix is ​​activated with nitric acid solution to obtain hydroxylated carbon material; (2) Organic amines are prepared by substitution reaction of hydroxylated carbon materials with halogenated organic amines X-R1-NH-R2. -O-R1-NH-R2 grafted carbon materials are then subjected to aminomethylation reactions with phosphites PH(=O)(R5O)(R6O) and carbonyl compounds C(=O)R3R4 to obtain aminophosphonate functionalized carbon materials; or Hydroxylated carbon materials with halogenated aminophosphonates Aminophosphonate-functionalized carbon materials were prepared via a substitution reaction. Where X represents chlorine, bromine, or iodine, and R1, R2, R3, R4, R5, R6, and The meaning is the same as that of the cited claims.

8. Use of the aminophosphonate-functionalized carbon material according to any one of claims 1-6 in the preparation of materials or devices for adsorbing thorium.

9. An electrode plate comprising: An electrode substrate, an electrode material layer on the electrode substrate, wherein the electrode material layer comprises the aminophosphonate functionalized carbon material according to any one of claims 1-6.

10. A capacitive deionization device comprising the electrode plate of claim 9.

11. A method for adsorbing thorium, the method comprising the step of passing a thorium-containing liquid into the capacitive deionization apparatus of claim 10 to adsorb thorium from the liquid.

12. The method of claim 11, further comprising: The thorium-containing liquid is passed into the capacitor deionization device of claim 10 to adsorb thorium from the liquid to obtain a thorium-containing electrode material. Thorium-containing electrode materials should not be washed with detergent unless absolutely necessary. and Thorium in the electrode material is desorbed using a desorbent.

13. The method of claim 12, wherein, The detergent is a mixed solution of nitric acid, sulfuric acid, hydrochloric acid, or any proportion of the above acids; the acidity of the detergent, calculated as the molar concentration of hydrogen ions, is 0.01~1 mol / L; and / or The desorbent is a solution of nitric acid, hydrochloric acid, sulfuric acid, or a mixture of the above acids, with an acidity of 0.1 to 8 mol / L, calculated by the molar concentration of hydrogen ions.

14. The method according to claim 11 or 12, wherein, The thorium concentration in the thorium-containing solution is 0.0001~2.0 mol / L; and / or The pH of the thorium-containing solution is between 0 and 4.

15. The method of claim 14, wherein, The thorium concentration in the thorium-containing solution is 0.0003~1 mol / L; and / or The pH of the thorium-containing solution is 1-4.

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