Silicon-based adsorbent material, method for its production and use thereof

Abstract

This invention relates to silicon-based adsorbent materials for thorium extraction, their preparation methods, and applications. The silicon-based adsorbent material comprises: silicon spheres; and a compound of formula I coupled to the silicon spheres, wherein R1 is selected from C1-C1. 10 Alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl, C3-C 10 cycloalkyl, C3-C 10 Cycloalkyl C1-C2 alkyl; R2 and R3 are each independently selected from hydrogen, C1-C4 alkyl, C3-C 10 cycloalkyl, C3-C 10 Cycloalkyl C1-C2 alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl; R4 is selected from C1-C 10 Alkyl, C3-C6 cycloalkyl, C3-C6 cycloalkyl, C1-C2 alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl. The silicon-based adsorbent material of the present invention has the advantages of simple preparation method, wide availability and low cost of raw materials, strong selectivity for thorium, large adsorption capacity, small influence of pH value on adsorption capacity, no use of saponifying agent in the removal process, and environmental friendliness. It can be widely used for the removal of thorium ions in high-purity rare earth solutions.

Description

Technical Field

[0001] This invention relates to the field of thorium extraction technology, and more particularly to a silicon-based adsorbent material for thorium extraction, its preparation method, and its uses. Background Technology

[0002] Radioactive thorium has similar chemical properties to rare earth elements and is often found as a byproduct of rare earth minerals. Compared to trivalent rare earth elements, thorium is more readily extracted. Therefore, the presence of thorium reduces the extraction efficiency of the extractant for trivalent rare earth elements during the rare earth extraction process and affects the rare earth separation effect.

[0003] In single high-purity rare earth products, the presence of trace amounts of thorium can severely affect product quality. For example, the particle radiation generated by trace amounts of thorium remaining in rare earth oxides can damage rare earth-doped barium titanate ceramics, leading to a decrease in photocurrent and an increase in dark current. The radioactive impurity content requirement for high-purity tungsten oxide used in positron emission tomography (PET) systems is: the content of the radioactive element thorium must be less than 0.5 ppm. If domestically produced high-purity lutetium oxide products contain 0.54–18 ppm of thorium, the resulting radioactive background will directly affect the light output performance of scintillator crystal devices made of lutetium oxide.

[0004] Furthermore, a small amount of thorium remains in the wastewater generated from the rare earth separation industry and cannot be easily removed. Therefore, it is necessary to perform deep thorium removal on the wastewater to meet the emission standards of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011) (total radioactive elements thorium and uranium not exceeding 0.1 mg / L). Therefore, based on environmental and economic factors, the development of deep thorium removal technology is urgently needed.

[0005] Solvent extraction is currently widely used to separate and enrich thorium from rare earth solutions. CN201610533648.4 discloses a method for removing radioactive thorium from lanthanum chloride solution, wherein lanthanum chloride is extracted with saponified P507 extractant in 5-15 stages, washed with 0.5-3 mol / L hydrochloric acid in 10-40 stages, and back-extracted with 4-5 mol / L hydrochloric acid. In the examples, the total number of extraction, washing, and back-extraction stages is 35-54. CN201510148009.1 discloses a method for extracting high-purity thorium from high-purity solvent residue, wherein dimethylheptyl methylphosphonate (P350) is used as the extractant, kerosene as the diluent, and the number of extraction, washing, and back-extraction stages is 4-20. In the examples, the total number of extraction, washing, and back-extraction stages is 21-35. Therefore, it is difficult to achieve effective separation of thorium and rare earth elements using a limited number of extraction stages.

[0006] Therefore, there is a need to further develop new and effective methods for separating thorium and rare earth elements. Summary of the Invention

[0007] Adsorption methods are particularly suitable for the enrichment and separation of low-concentration ions, offering advantages such as high selectivity, low secondary waste volume, and easy desorption. Therefore, the invention of a highly selective adsorbent for the radioactive element thorium, employing a solid-liquid adsorption method to separate and remove trace amounts of thorium from various liquid solutions, not only eliminates the radioactive pollution of thorium to the environment and high-purity rare earth products, but also provides a reference for the extraction and separation of thorium from leachates of other rare earth minerals, which is of great significance to the green and sustainable development of the rare earth industry.

[0008] Based on this, the inventors designed and prepared a silicon-based adsorbent material, and experimentally verified that it can be used to selectively extract thorium from a mixture of thorium and rare earth elements, and then to remove thorium from rare earth leachate or rare earth industrial wastewater, thus completing the present invention.

[0009] On one hand, the present invention provides a silicon-based adsorbent material, comprising:

[0010] (1) Silicon spheres;

[0011] (2) Compound of Formula I coupled with silicon spheres:

[0012]

[0013] Among them, R1 is selected from C1-C 10 Alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl, C3-C 10 cycloalkyl, C3-C 10 Cycloalkyl C1-C2 alkyl;

[0014] R2 and R3 are each independently selected from hydrogen, C1-C4 alkyl, C3-C 10 cycloalkyl, C3-C 10 Cycloalkyl C1-C2 alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl;

[0015] R4 is selected from C1-C 10 Alkyl, C3-C6 cycloalkyl, C3-C6 cycloalkyl, C1-C2 alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl.

[0016] In some embodiments, R1 is selected from C1-C8 alkyl, phenyl, C1-C4 alkylphenyl, phenylC1-C2 alkyl, and in particular, R1 is selected from C2-C8 alkyl, phenyl, tolyl, xylyl, ethylphenyl, benzyl, phenethyl.

[0017] In some embodiments, R2 and R3 are each independently selected from hydrogen and C1-C4 alkyl groups. In particular, R2 and R3 are each independently selected from hydrogen, methyl, and ethyl groups. More particularly, R2 and R3 are each independently selected from hydrogen and methyl groups.

[0018] In some embodiments, R4 is selected from C1-C8 alkyl, phenyl, C1-C4 alkylphenyl, phenylC1-C2 alkyl, and in particular, R4 is selected from C2-C8 alkyl, phenyl, tolyl, xylyl, ethylphenyl, benzyl, phenethyl.

[0019] In some embodiments, the compound of formula I is selected from one or more of the following compounds:

[0020]

[0021]

[0022] In this invention, silica spheres, sometimes also referred to as silica gel, refer to silica microspheres. There are no particular limitations on the silica spheres, as long as they are suitable for use as a chromatographic column substrate. For example, the silica spheres may have a particle size of 100-200 mesh, and / or 300-500 μm. 2 Specific surface area per g, but not limited to this.

[0023] Compound of Formula I can be coupled to silicon spheres in any suitable manner, as long as the manner does not affect the intended purpose of the final application. For example, compound of Formula I can be modified to have groups that can react with the surface of silicon spheres, and then coupled to the surface of silicon spheres by reacting with them; or the surface of silicon spheres can be modified to have groups that can react with compound of Formula I, and then coupled to the surface of silicon spheres by reacting with compound of Formula I.

[0024] In some embodiments, in the silicon-based adsorbent material, the compound of formula I is coupled to the surface of the silicon spheres via nitrogen coupling thereon. For example, the silicon-based adsorbent material may include the structure of formula III:

[0025]

[0026] In this context, R1 to R4 are defined as described above, and X represents a linking group. However, the structure of Formula III is merely illustrative, and the structure of the silicon-based adsorbent material of the present invention is not limited to Formula III. For example, multiple compounds of Formula I may be coupled to a silicon sphere, and the connection between the linking group X and the silicon sphere may not be a single bond, but rather a combination of multiple bonds.

[0027] In some embodiments, in the silicon-based adsorbent material, the compound of formula I is coupled to the silicon spheres via a silane coupling agent, that is, the silicon-based adsorbent material has the following structure: silicon spheres - silane coupling agent - compound of formula I.

[0028] Here, the silane coupling agent acts as a linker. On the one hand, it connects to the silicon spheres through the interaction between the inorganic-loving groups (i.e., the silanoxy groups of the silane coupling agent) and the surface groups of the silicon spheres. On the other hand, it covalently connects to the compound of formula I through the organic-loving groups (i.e., the organic functional groups of the silane coupling agent), thereby coupling the compound of formula I to the silicon spheres to obtain the silicon-based adsorbent material.

[0029] Any silane coupling agent that can achieve the above objectives can be selected.

[0030] In some embodiments, the silane coupling agent has a functional group capable of directly reacting with the amine group in the structure of the compound of formula I. In this case, the silane coupling agent can be directly reacted with the compound of formula I by reacting the organic functional group of the silane coupling agent with the amine group in the structure of the compound of formula I, thereby covalently attaching one end of the silane coupling agent to the amine group in the structure of the compound of formula I. In this case, X in formula III is a group derived from the silane coupling agent.

[0031] In some embodiments, the silane coupling agent is shown in Formula II as follows:

[0032]

[0033] R5, R6 and R7 are each independently selected from C1-C4 alkyl and C1-C4 alkoxy, and at least one is an alkoxy; preferably, each is independently selected from C1-C2 alkyl (methyl, ethyl) and C1-C2 alkoxy (methoxy, ethoxy), and at least one is an alkoxy.

[0034] R8 is selected from halogens (especially Cl, bromine and iodine), epoxy groups (i.e. oxacyclopropane), epoxy methoxy groups (i.e. glycidyl ether oxy groups), and isocyanate groups;

[0035] n is an integer from 1 to 8.

[0036] In some embodiments, the silane coupling agent is selected from epoxy silanes, halogen silanes, and isocyanate silanes, each having an epoxy group, a halogen group, and an isocyanate group that can react with an amine group. These silanes can be trialkoxysilanes, dialkoxysilanes, or monoalkoxysilanes.

[0037] Epoxysilanes refer to silane coupling agents that contain at least one epoxy group in their molecule. For example, epoxysilanes can be 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), 5,6-epoxyhexyltriethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-[(2,3)-epoxypropoxy]propylmethyldiethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, (3-epoxypropoxypropyl)dimethylethoxysilane, etc., but are not limited to these.

[0038] When using epoxy silane as a silane coupling agent, the epoxy group in the epoxy silane can undergo an addition reaction with the amine group in the structure of compound I, thereby opening the ring and covalently attaching one end of the epoxy silane to the amine group in the structure of compound I. In this case, X in formula III can be represented, for example, as... And so on, where R6, R7 and n are as defined above.

[0039] Halogenated silanes are silane coupling agents that contain at least one halogen group in their molecule. Halogens include fluorine, chlorine, bromine, and iodine. Chlorine and bromine are particularly common halogen groups in silane coupling agents. Examples of halogenated silanes include, but are not limited to, 3-bromopropyltrimethoxysilane, 4-bromobutyltrimethoxysilane, 5-bromopentyltrimethoxysilane, 7-bromoheptyltrimethoxysilane, 3-chloroisopropyltrimethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-iodopropyltrimethoxysilane, chloromethylmethyldiethoxysilane, 3-chloropropylmethyldiethoxysilane, 3-chloropropylmethyltrimethoxysilane, chloromethyldimethylethoxysilane, chloromethyldimethylmethoxysilane, etc.

[0040] When a halogenated silane is used as a silane coupling agent, the halogenated silane can undergo an amination reaction with the amino group in the structure of compound I, thereby removing the halogen group and covalently attaching one end of the halogenated silane to the amino group in the structure of compound I. In some embodiments, the amination reaction can be carried out in the presence of an acid-binding agent to promote the reaction. Common acid-binding agents include, for example, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), but are not limited thereto. In this case, X in formula III can be represented, for example, as... R6, R7, and n are defined as above.

[0041] Isocyanate silanes refer to silane coupling agents whose molecules contain at least one isocyanate. For example, isocyanate silanes can be 3-isocyanate propyltriethoxysilane, 3-isocyanate propyltrimethoxysilane, 3-isocyanate propylmethyldiethoxysilane, 3-isocyanate propylmethyldimethoxysilane, etc., but are not limited to these.

[0042] When isocyanate silanes are used as silane coupling agents, the isocyanate groups in the isocyanate silane can undergo a nucleophilic addition reaction with the amine group in the compound of formula I to generate a urea group, thereby covalently attaching one end of the isocyanate silane to the amine group in the compound of formula I. In this case, X in formula III can be represented, for example, as... R6, R7, and n are defined as above.

[0043] Silane coupling agents can also be hydroxysilanes, aldehyde silanes, carboxyl silanes, etc. Through the reaction of hydroxyl, aldehyde, carboxyl, and other groups with amine groups, one end of the silane coupling agent is covalently attached to the amine group in the structure of compound I.

[0044] In other embodiments, the silane coupling agent does not have a functional group that can directly react with the amine group in the structure of the compound of formula I. In this case, another compound that acts as a linker can be added as a linking agent to covalently link one end of the silane coupling agent to the amine group in the structure of the compound of formula I through a linking group. Alternatively, the silane coupling agent can be modified to have a functional group that can directly react with the amine group in the structure of the compound of formula I.

[0045] There are no particular limitations on the source of the compound of formula I. The compound of formula I can be commercially available, or it can be synthesized by a person skilled in the art by designing a synthetic route based on its structure and in combination with synthetic methods in organic chemistry, or it can be synthesized similarly with reference to the methods described below and the methods described in the examples.

[0046] For example, compounds of formula I can be synthesized as follows:

[0047]

[0048] As shown in the reaction equation, hydrolysis of compound IA yields compound I.

[0049] The definitions of R1 to R4 are as described above, and the definition of R1' is the same as that of R1.

[0050] There are no particular limitations on the source of compounds of formula IA. Compounds of formula IA can be commercially available or can be synthesized by a person skilled in the art by designing a synthetic route based on their structure and synthetic methods in organic chemistry. For example, compounds of formula IA can be synthesized according to known methods in the prior art (such as patent 201610227923X).

[0051] Based on the known structure of the silicon-based adsorbent material according to the present invention, those skilled in the art can design synthetic routes and synthesize it by combining its structure with synthetic methods in organic chemistry. For example, it can be synthesized similarly with reference to the methods in existing literature (Functionalisation of mesoporous silica gel with 2-[(phosphonomethyl)-amino]acetic acid functional groups. Characterisation and application, Applied Surface Science, Volume 288, January 2014, Pages 373-380). Alternatively, the silicon-based adsorbent material according to the present invention can be synthesized using the methods described below or with reference to the methods disclosed in the embodiments of this application.

[0052] In some embodiments, a method for preparing the above-mentioned silicon-based adsorbent material is provided, comprising:

[0053] (1) The compound of formula I is coupled with the silane coupling agent of formula II to obtain the coupling compound of formula IV.

[0054]

[0055] (2) The coupling compound of formula IV is coupled with silicon spheres to obtain silicon-based adsorbent material.

[0056] Among them, R1 to R8 and n are defined as described above, and L is selected from direct bonds,

[0057] In step (1), there is no particular limitation on the molar ratio of the compound of formula I to the silane coupling agent of formula II, as long as the target compound can be obtained. For example, it can be 1:0.5 to 1.5, 1:0.8 to 1.2, 1:1.0, 1:1.1, etc.

[0058] Step (1) can be carried out in an organic solvent. There are no particular restrictions on the type of organic solvent, as long as it does not adversely affect the reaction. For example, the organic solvent includes, but is not limited to, methanol, ethanol, acetonitrile, tetrahydrofuran, and dioxane, and can be any one or more of these.

[0059] There is no particular limitation on the reaction temperature in step (1), as long as the coupling reaction can be carried out. For example, the reaction temperature can be 50-100℃, such as 65-80℃, such as 65℃, 70℃, 75℃ or 80℃, but it is not limited to these.

[0060] There is no particular limitation on the reaction time in step (1), as long as the desired target compound can be obtained. For example, the reaction time can be more than 2 hours, more than 5 hours, more than 10 hours, more than 12 hours, such as 12-72 hours, 24-40 hours, such as 24 hours, 28 hours, 32 hours, 36 hours or 40 hours, but it is not limited to these.

[0061] In step (2), the mass ratio of the coupling compound of formula IV to the silicon sphere is not particularly limited. For example, it can be 1:0.5 to 5, 1:0.8 to 4, 1:1.0, 1:1.5, 1:2.0, 1:3.0, etc., but is not limited to this.

[0062] Step (2) can be carried out in an organic solvent. There are no particular restrictions on the type of organic solvent, as long as it does not adversely affect the reaction. For example, the organic solvent includes, but is not limited to, toluene, xylene, trimethylbenzene, cyclohexane, n-heptane, and isooctane, and can be any one or more of these.

[0063] There is no particular limitation on the reaction temperature in step (2), as long as the coupling reaction can be carried out. For example, the reaction temperature can be 60-150℃, such as 80-120℃, such as 90℃, 100℃, 110℃ or 120℃, but it is not limited to these.

[0064] There is no particular limitation on the reaction time in step (2), as long as the desired target product can be obtained. For example, the reaction time can be more than 2 hours, more than 5 hours, more than 10 hours, more than 12 hours, such as 12-96 hours, 48-72 hours, such as 48 hours, 54 hours, 60 hours, 66 hours or 72 hours, but it is not limited to these.

[0065] Another aspect of the present invention provides a coupling compound of formula IV:

[0066]

[0067] Among them, R1 to R7 and n are defined as described above, and L is selected from direct bonds,

[0068] Experiments have confirmed that the silicon-based adsorbent material of this invention can selectively extract thorium as an extractant, thereby separating thorium from rare earth elements.

[0069] Therefore, another aspect of the present invention provides the use of the obtained silicon-based adsorbent in the preparation of an extractant for the extraction of thorium. Here, the extractant is sometimes also referred to as an adsorbent.

[0070] In another aspect, the present invention provides a method for extracting thorium, the method comprising contacting a thorium-containing solution with a silicon-based adsorbent of the present invention to extract thorium from the solution. After thorium extraction, the silicon-based adsorbent adsorbs thorium and is sometimes referred to as a thorium-containing silicon-based adsorbent.

[0071] In one embodiment, the method for extracting thorium according to the present invention further includes: washing the thorium-containing silicon-based adsorbent material with a washing solution, and back-extracting the thorium from the silicon-based adsorbent material with a back-extraction solution.

[0072] The washing process can remove impurity elements adsorbed by the silicon-based adsorbent material, improving the purity of thorium adsorbed on the silicon-based adsorbent material, thereby helping to improve the purity of the final thorium product. The washing solution can be a mixture of nitric acid, sulfuric acid, hydrochloric acid, or any proportion of the above acids. The acidity of the washing solution, calculated as the molar concentration of hydrogen ions, is approximately 0.2–8 mol / L.

[0073] The back-extraction process is used to elute thorium from a silicon-based adsorbent to obtain a thorium-containing back-extraction product, which is then used to produce thorium products. The back-extraction solution, also called a back-extraction liquid, back-extraction agent, or back-extraction solution, is a solution of nitric acid, hydrochloric acid, sulfuric acid, or a mixture of these acids, or an aqueous solution of a carbonate. The carbonate can be an alkali metal salt, an alkaline earth metal salt, or an ammonium salt, such as a sodium salt or a potassium salt. Preferably, when an acid solution is used as the back-extraction solution, the acidity, calculated by the molar concentration of hydrogen ions, is about 0.05–2 mol / L; when an aqueous solution of sodium carbonate is used, its concentration can be about 0.5–5 wt%. Preferably, the back-extraction solution is a dilute nitric acid with a concentration of about 0.1–0.5 mol / L or an aqueous solution of sodium carbonate with a concentration of about 0.5–3 wt%.

[0074] The back-extracted silicon-based adsorbent material can be recycled and reused to extract and separate thorium from thorium-containing liquids.

[0075] 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. Suitable raw materials for preparing the solution include various thorium-containing materials, such as monazite, bastnaesite, mixtures of bastnaesite and monazite, and thorium concentrates. The aforementioned thorium-containing raw materials are pretreated and dissolved in nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, or a mixture thereof to obtain a solution suitable for the method of this invention. In practical applications, the solution may also contain other elements such as rare earth elements, alkali metals, alkaline earth metals, transition metals, and non-metallic elements (the type and content of which depend on the composition of the thorium raw material mineral). In this case, the method of the present invention can selectively extract and separate thorium, thereby separating it from non-thorium impurity elements.

[0076] In some embodiments, the thorium-containing liquid may also be a high-purity rare earth liquid, a rare earth leachate, or a rare earth industrial wastewater liquid, but is not limited thereto.

[0077] 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 silicon-based adsorbent material of the present invention maintains a high adsorption capacity, thereby extracting thorium efficiently. Outside the above pH range, the adsorption capacity of the silicon-based adsorbent material of the present invention decreases, leading to a reduction in extraction efficiency. Therefore, when the pH of the original thorium-containing solution (e.g., high-purity rare earth solution, rare earth leachate, rare earth industrial wastewater 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. Therefore, the present invention also provides a method for separating thorium from a thorium-containing high-purity rare earth solution, the method comprising the step of contacting the thorium-containing high-purity rare earth solution with the silicon-based adsorbent material of the present invention to extract thorium from the solution. The thorium concentration in high-purity rare earth feed solutions containing thorium can be above 0.1 ppm, above 0.5 ppm, or above 1 ppm. There is no specific upper limit on the concentration; for example, it can be below 1000 ppm or below 500 ppm. The "high-purity rare earth feed solution" here can be a feed solution containing a single rare earth element. It can be a feed solution obtained during the production of high-purity rare earth products, or a feed solution obtained after treating rare earth products with a single rare earth element purity of 99.9% or higher. After treatment, the thorium removal rate in high-purity rare earth feed solutions containing thorium can reach over 90%, especially over 95%, or even over 97%.

[0078] This invention also provides a method for separating thorium from a thorium-containing rare earth leachate, the method comprising contacting the thorium-containing rare earth leachate with the silicon-based adsorbent material of this invention to extract thorium from the rare earth leachate. The rare earth leachate contains rare earth elements, thorium, mineral acids, and other non-thorium elements, the specific types and contents depending on the composition of the rare earth raw material minerals. Furthermore, the rare earth leachate may also contain other elements such as alkali metals, alkaline earth metals, transition metals, and non-metallic elements. Suitable raw materials for preparing the rare earth leachate include various rare earth raw materials, such as rare earth minerals and rare earth concentrates. The above-mentioned rare earth-containing raw materials are pretreated and dissolved with nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, or a mixture thereof to obtain a rare earth leachate suitable for the method of this invention. After treatment, the removal rate of thorium in the rare earth leachate can reach over 90%, particularly over 95%, or even over 97%.

[0079] This invention also provides a method for separating thorium from thorium-containing rare earth industrial wastewater. The method includes contacting the thorium-containing rare earth industrial wastewater with the silicon-based adsorbent material of this invention to extract thorium from the wastewater. "Rare earth industrial wastewater" refers to waste liquid generated from rare earth separation industries, containing small amounts of rare earth elements (e.g., concentrations of each rare earth element above 1 mmol / L, above 10 mmol / L, and below 200 mmol / L and below 100 mmol / L) and trace amounts of thorium (e.g., concentrations of 0.1 ppm, above 0.5 ppm, above 1 ppm, and below 1000 ppm and below 500 ppm). After treatment, the removal rate of thorium from the rare earth industrial wastewater can reach over 90%, particularly over 95%, and even over 97%.

[0080] In some embodiments, the method for extracting thorium according to the present invention further includes the step of regenerating the silicon-based adsorbent material of the present invention. The regeneration can be carried out by treating the silicon-based adsorbent material of the present invention with an inorganic acid. The inorganic acid can be selected from hydrochloric acid, sulfuric acid, and nitric acid. Regeneration can elute the thorium adsorbed on the silicon-based adsorbent material. The eluted thorium, after enrichment, can be used to prepare thorium products.

[0081] the term

[0082] In this invention, "separation of thorium" refers to the extraction of thorium (i.e., tetravalent thorium(IV) or tetravalent thorium ions Th) through an extraction method. 4 + ) and rare earth elements (i.e., lanthanides or trivalent lanthanide ions Ln) 3+ Separate.

[0083] In this invention, rare earth elements refer to lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), yttrium (Y), and scandium (Sc).

[0084] In this invention, C1-C 10 Alkyl refers to a straight-chain or branched alkyl group containing 1 to 10 carbon atoms, such as straight-chain or branched alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 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, etc. The meanings of C1-C8 alkyl, C2-C8 alkyl, C1-C4 alkyl, C1-C2 alkyl, etc., follow the same logic.

[0085] In this invention, C3-C 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 monocyclic or bicyclic, such as cyclopropyl, cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, cycloheptyl, cyclooctyl, etc. The substituents can be one or more substituents selected from C1-C4 alkyl groups. The meanings of C5-C6 cycloalkyl groups are similar.

[0086] In this invention, C6-C 10 Aryl refers to an aryl group containing 6 to 10 carbon atoms, including the number of carbon atoms of the substituents, such as phenyl and phenyl groups substituted with one or more substituents selected from C1-C4 alkyl groups, such as tolyl, dimethylphenyl, trimethylphenyl, ethylphenyl, etc.

[0087] 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.

[0088] Unless otherwise stated, numerical values ​​in this invention represent approximate measures or limitations on the range of embodiments including minute deviations from a given value and having approximately the mentioned value as well as having the mentioned precise value. Except in the detailed description of the final embodiments, all numerical values ​​of parameters (e.g., quantities or conditions) in this application (including the appended claims) should in all cases be understood to be modified by the term "approximately," regardless of whether "approximately" actually appears before the numerical value. "Approximately" indicates that the stated numerical value allows for slight inaccuracies (some close to precision at that value; approximately or reasonably close to the value; approximate). If the inaccuracy provided by "approximately" is not understood in this general sense in the art, then "approximately" as used herein at least indicates a variation that can be produced by common methods of measuring and using these parameters. For example, "approximately" can include variations less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, less than or equal to 0.5%, less than or equal to 0.1%, and in some respects, less than or equal to 0.01%.

[0089] The present invention has been described in detail above, but the present invention is not limited to the above content.

[0090] Beneficial effects

[0091] The silicon-based adsorbent of this invention has the advantages of simple preparation method, wide availability and low cost of raw materials, strong selectivity for thorium, large adsorption capacity, small influence of pH value on adsorption capacity, no use of saponifying agent in the removal process, and environmental friendliness. It can be widely used for the removal of thorium ions in high-purity rare earth solutions. After use, the adsorbent can be regenerated by inorganic acid to complete the recycling of the adsorbent. Attached Figure Description

[0092] Figure 1 This shows a scanning electron microscope image of the silicon-based adsorbent material prepared in Example 1 of the present invention.

[0093] Figure 2 The infrared spectra of the silicon spheres and the prepared silicon-based adsorbent material used in Example 1 of this invention are shown. Detailed Implementation

[0094] To further illustrate the present invention, specific embodiments are provided to help those skilled in the art understand and implement the present invention; however, the present invention is not limited to these embodiments.

[0095] Furthermore, it should be noted that the structure of the silicon-based adsorbent material given herein is illustrative and does not constitute a limitation of the present invention.

[0096] Example

[0097] Reagents and sources

[0098] Di(2-ethylhexyl) phosphite, diphenyl phosphite, diethyl phosphite, and dibenzyl phosphite were purchased from Shanghai Laiyashi Chemical Co., Ltd. Paraformaldehyde, 2-ethylhexylamine, isobutylamine, cyclopropylmethylamine, cyclohexylmethylamine, 3-chloropropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane were purchased from Aladdin Reagent Co., Ltd.

[0099] The silica spheres were purchased from Qingdao Jiyida Silica Globule Reagent Factory. Their particle size is 100-200 mesh, and their specific surface area is 400-500 m². 2 / g. The silicon spheres undergo activation treatment before use.

[0100] Other reagents (such as acids, organic solvents, etc.) are all commercially available analytical grade reagents.

[0101] Product purity was determined using ICP-OES (instrument model: PQ9000, manufacturer: Jena) and ICP-MS (instrument model: Agilent 8900, manufacturer: Agilent).

[0102] The MRI scanner was a Varian Mercury 300.

[0103] The high-resolution field emission scanning electron microscope used is JSM-IT800.

[0104] The Fourier transform infrared spectrometer is an iS5.

[0105] Example 1: Preparation of 2-ethylhexylaminomethylphosphonic acid monophenyl ester silicon-based adsorbent material

[0106] (1) Preparation of 2-ethylhexylaminomethylphosphonic acid diphenyl ester

[0107]

[0108] To a single-necked flask equipped with a mechanical stirrer and reflux condenser, add 1 mol of diphenyl phosphite, 1.1 mol of paraformaldehyde, 1.1 mol of 2-ethylhexylamine, 800 ml of acetonitrile, and 0.8 g of p-toluenesulfonic acid. Stir and reflux, react at 80–90 °C for 8 h. Remove acetonitrile by rotary evaporation. Wash the residue sequentially with an equivalence of sodium carbonate aqueous solution and an equivalence of hydrochloric acid to remove unreacted products, yielding diphenyl 2-ethylhexylaminomethylphosphonate, which is used directly in the next step.

[0109] (2) Preparation of 2-ethylhexylaminomethylphosphonic acid monophenyl ester

[0110]

[0111] The 2-ethylhexylaminomethylphosphonic acid diphenyl ester obtained in step (1) was added to a single-necked flask, followed by 1.5 mol (600 ml) of potassium hydroxide aqueous solution and 800 ml of ethanol. The mixture was stirred and refluxed at 80–90 °C for 36 h. After removing the ethanol by rotary evaporation, the residue was washed with a slight excess of hydrochloric acid relative to the potassium hydroxide to remove the potassium hydroxide. After drying with excess anhydrous Na₂SO₄, 2-ethylhexylaminomethylphosphonic acid monophenyl ester was obtained, which was used directly in the next step.

[0112] (3) Preparation of coupling compounds

[0113]

[0114] Add 1 mol of 2-ethylhexylaminomethylphosphonic acid monophenyl ester prepared in step (2) to a single-necked flask, then add 1.2 mol of γ-glycidyl etheroxypropyltrimethoxysilane and 800 ml of acetonitrile, stir and reflux, react at 65-85 °C for 24 h, remove acetonitrile by rotary evaporation to obtain the coupling compound, which can be used directly in the next step.

[0115] (4) Preparation of silicon-based adsorbent materials

[0116]

[0117] Add the coupling compound (1 mol) prepared in step (3) to a single-necked flask, then add silicon balls (150 g) and toluene (800 ml), stir and reflux, react at 105-115 °C for 48 h, remove toluene by rotary evaporation, wash with deionized water and ethanol in sequence, and dry under vacuum to obtain silicon-based adsorbent material.

[0118] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ7.01-6.93 (m, Ph-H), 4.63-3.47 (m, Si-H, Si-OH), 1.72-0.62 (m, CH, CH2, CH3)

[0119] Figure 1 This image shows a scanning electron microscope (SEM) image of the silicon-based adsorbent material prepared above. The image shows that the silicon-based adsorbent material largely retains the original morphology of the silicon spheres.

[0120] Figure 2 The infrared spectra of the silicon spheres (SG) and the silicon-based adsorbent material (SG-PHO) prepared above are shown.

[0121] For silicon spheres (SG), 1079.00 cm -1 The strong peak appearing at 808.27 cm⁻¹ is an antisymmetric absorption peak of the silicon-based framework Si-O-Si. -1 and 464.21cm -1The two peaks appearing at [location missing] represent the stretching and bending vibrations of Si-O-Si, respectively; these three peaks are characteristic peaks of silicon-based supports. For the adsorbent (SG-PHO), the three peaks are located at [location missing] 1092.18 cm⁻¹. -1 803.21cm -1 461.18cm -1 The modification did not result in significant changes, indicating that crosslinking the coupling compound onto the silicon spheres essentially does not affect the chemical structure of the silicon spheres. Furthermore, the silicon spheres (SG) and the silicon-based adsorbent material (SG-PHO) were compared at 3450 cm⁻¹. -1 The large absorption peak around the left and right can be considered as the stretching vibration peak of the silanol OH group on the silica gel surface and the OH group of the physically adsorbed water on the surface.

[0122] It is worth noting that the silicon sphere (SG) is at 970cm -1 A peak exists at this location, which is generated by the stretching vibration of silanol groups. In contrast, the peak disappears at this location in the silicon-based adsorbent material (SG-PHO), indicating that most of the active sites on the silicon sphere surface have been successfully grafted.

[0123] Furthermore, for silicon-based adsorbent materials (SG-PHO), 2927.44 cm -1 The peak at 1641.17 cm⁻¹ represents the CH stretching vibration. -1 The peak at 1400 cm⁻¹ represents the bending vibration peak of silanol OH and surface physically adsorbed water OH. -1 Up to 1450cm -1 The series of peaks are CH bending vibration peaks on saturated hydrocarbons or benzene rings. At 1200 cm⁻¹... -1 The small peak at this point can be considered as the stretching vibration peak of P=O. Meanwhile, PO and CN bonds generally exist at 1000 cm⁻¹. -1 Up to 1100cm -1 At this point, the antisymmetric absorption peaks of Si-O-Si are masked, forming a single giant peak. 889.32 cm⁻¹ -1 The peak at this location represents the out-of-plane bending vibration of 1-substituted benzene.

[0124] The above infrared results indicate that the coupling compound was successfully grafted onto the surface of the silicon sphere in the silicon-based adsorbent material.

[0125] Example 2: Preparation of 2-ethylhexylaminomethylphosphonic acid monobenzyl ester silicon-based adsorbent material

[0126] Except that dibenzyl phosphite was used instead of diphenyl phosphite, the target silicon-based adsorbent material was prepared using the same process as in Example 1.

[0127] (1) Dibenzyl 2-ethylhexylaminomethylphosphonate

[0128]

[0129] (2) 2-Ethylhexylaminomethylphosphonic acid monobenzyl ester

[0130]

[0131] (3) Coupling compounds

[0132]

[0133] (4) Silicon-based adsorbent materials

[0134]

[0135] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ7.06-6.97 (m, Ph-H), 4.47-3.59 (m, Si-H, Si-OH), 1.04-0.61 (m, CH, CH2, CH3)

[0136] Example 3: Preparation of 2-ethylhexylaminomethylphosphonic acid monoethyl ester silicon-based adsorbent material

[0137] Except for replacing diphenyl phosphite with diethyl phosphite, the target silicon-based adsorbent material was prepared using the same process as in Example 1.

[0138] (1) Diethyl 2-ethylhexylaminomethylphosphonate

[0139]

[0140] (2) Monoethyl 2-ethylhexylaminomethylphosphonic acid

[0141]

[0142] (3) Coupling compounds

[0143]

[0144] (4) Silicon-based adsorbent materials

[0145]

[0146] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ4.25-3.40 (m, Si-H, Si-OH), 1.09-0.66 (m, CH, CH2, CH)

[0147] Example 4: Preparation of 2-ethylhexylaminomethylphosphonic acid mono(2-ethylhexyl) ester silicon-based adsorbent material

[0148] The target silicon-based adsorbent material was prepared using the same process as in Example 1, except that bis(2-ethylhexyl) phosphite was used instead of diphenyl phosphite.

[0149] (1) Di(2-ethylhexyl)aminomethylphosphonic acid ester

[0150]

[0151] (2) 2-Ethylhexylaminomethylphosphonic acid mono(2-ethylhexyl) ester

[0152]

[0153] (3) Coupling compounds

[0154]

[0155] (4) Silicon-based adsorbent materials

[0156]

[0157] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ4.39-3.28 (m, Si-H, Si-OH), 1.15-0.59 (m, CH, CH2, CH3)

[0158] Example 5: Preparation of 2-methylpropylaminomethylphosphonic acid monophenyl ester silicon-based adsorbent material

[0159] The target silicon-based adsorbent material was prepared using the same process as in Example 1, except that isobutylamine was used instead of 2-ethylhexylamine.

[0160] (1) 2-Methylpropylaminomethylphosphonic acid diphenyl ester

[0161]

[0162] (2) 2-Methylpropylaminomethylphosphonic acid monophenyl ester

[0163]

[0164] (3) Coupling compounds

[0165]

[0166] (4) Silicon-based adsorbent materials

[0167]

[0168] Silicon-based adsorbent materials: 1H NMR (500MHz, CDCl3) δ7.09-6.99 (m, Ph-H), 4.96-3.28 (m, Si-H, Si-OH), 1.45-0.63 (m, CH, CH2, CH3)

[0169] Example 6: Preparation of cyclopropylmethylaminomethylphosphonic acid monophenyl ester silicon-based adsorbent material

[0170] The target silicon-based adsorbent material was prepared using the same process as in Example 1, except that cyclopropylmethylamine was used instead of 2-ethylhexylamine.

[0171] (1) Cyclopropylmethylaminomethylphosphonic acid diphenyl ester

[0172]

[0173] (2) Cyclopropylmethylaminomethylphosphonic acid monophenyl ester

[0174]

[0175] (3) Coupling compounds

[0176]

[0177] (4) Silicon-based adsorbent materials

[0178]

[0179] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ7.04-6.85 (m, Ph-H), 4.83-3.31 (m, Si-H, Si-OH), 1.38-0.59 (m, CH, CH2, CH3)

[0180] Example 7: Preparation of cyclohexylmethylaminomethylphosphonic acid monophenyl ester silicon-based adsorbent material

[0181] Except for replacing 2-ethylhexylamine with cyclohexylamine, the target silicon-based adsorbent material was prepared using the same process as in Example 1.

[0182] (1) Cyclohexylaminomethylphosphonic acid diphenyl ester

[0183]

[0184] (2) Cyclohexylaminomethylphosphonic acid monophenyl ester

[0185]

[0186] (3) Coupling compounds

[0187]

[0188] (4) Silicon-based adsorbent materials

[0189]

[0190] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ7.12-6.96 (m, Ph-H), 4.79-3.42 (m, Si-H, Si-OH), 1.58-0.57 (m, CH, CH2, CH3)

[0191] Example 8: Preparation of 2-ethylhexylaminomethylphosphonic acid monophenyl ester silicon-based adsorbent material

[0192] The target silicon-based adsorbent material was prepared using the same process as in Example 1, except that 3-chloropropyltrimethoxysilane was used instead of γ-glycidoxypropyltrimethoxysilane.

[0193] (3) Coupling compounds

[0194]

[0195] (4) Silicon-based adsorbent materials

[0196]

[0197] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ6.93-6.65(m,Ph-H), 5.51-3.32(m,Si-H,Si-OH), 3.32(m,Cl-CH2-R), 1.08-0.64(m,CH,CH2,CH3)

[0198] Comparative Example 1: Preparation of 2-ethylhexylaminomethylphosphonic acid diphenyl ester silicon-based adsorbent material

[0199] Except for using the 2-ethylhexylaminomethylphosphonic acid diphenyl ester obtained in step (1) directly in step (3) instead of 2-ethylhexylaminomethylphosphonic acid monophenyl ester, without performing step (2) of hydrolysis with potassium hydroxide, the 2-ethylhexylaminomethylphosphonic acid diphenyl ester silicon-based adsorbent material was prepared according to the method of Example 1.

[0200]

[0201] Silicon-based adsorbent materials: 1H NMR (500MHz, CDCl3) δ6.98-6.84(m,Ph-H), 4.85-3.59(m,Si-H,Si-OH), 1.84-0.57(m,CH,CH2,CH3)

[0202] Comparative Example 2: Preparation of 2-ethylhexylaminomethylphosphonic acid di(2-ethylhexyl) ester silicon-based adsorbent material

[0203] Except for using the 2-ethylhexylaminomethylphosphonic acid di(2-ethylhexyl) ester obtained in step (1) directly in step (3) instead of the 2-ethylhexylaminomethylphosphonic acid mono(2-ethylhexyl) ester, without performing step (2) of hydrolysis with potassium hydroxide, the 2-ethylhexylaminomethylphosphonic acid di(2-ethylhexyl) ester silicon-based adsorbent material was prepared according to the method of Example 4.

[0204]

[0205] Silicon-based adsorbent materials: 1 H NMR (500MHz, CDCl3) δ4.49-3.38 (m, Si-H, Si-OH), 1.48-0.52 (m, CH, CH2, CH3)

[0206] Experimental Example 1: Adsorption Capacity Determination

[0207] Preparation of the solution: Take a single thorium chloride solution, precipitate it with an equal amount of sodium carbonate, centrifuge, add excess sulfuric acid to dissolve the precipitate to obtain a thorium sulfate solution, and titrate to obtain the concentration of the thorium sulfate solution. Then dilute the thorium sulfate solution with distilled water to the required concentration. Thus, a 2 mmol / L Th(Ⅳ) solution is prepared.

[0208] Weigh 40 mg of the silicon-based adsorbent obtained in Examples 1-8 and Comparative Examples 1-2, add 8 mL of the prepared solution, adjust the pH to 3.5 with sulfuric acid solution, and shake on a gas bath constant temperature shaker at 30°C for 60 h at a shaking rate of 300 rpm to conduct a static adsorption experiment. After adsorption is complete, filter out the silicon-based adsorbent, and use ICP-MS to determine the thorium ion concentration (Th). 4+ )concentration.

[0209] Then, the adsorption capacity of the silicon-based adsorbent material for ions is calculated using formula (1):

[0210]

[0211] Where Q represents the adsorption capacity (mg / g), C i With C tV represents the concentration of ions before and after adsorption (mg / L), V represents the volume of the liquid (L), and m represents the amount of silicon-based adsorbent used (g).

[0212] Given that thorium ions (Th) still exist in the filtrate after adsorption 4+ Therefore, the adsorption amount measured above can be regarded as the adsorption capacity of the silicon-based adsorbent material. The adsorption capacity of the silicon-based adsorbent materials of Examples 1-8 and Comparative Examples 1-2 for thorium is shown in Table 1.

[0213] Table 1. Adsorption capacity (mg / g) of silicon-based adsorbents for thorium in each embodiment and comparative example.

[0214]

[0215] Comparing the results of Examples 1-8 with those of Comparative Examples 1 and 2, it can be seen that the silicon-based adsorbent material of the present invention has a better adsorption effect on thorium.

[0216] Furthermore, compared with the 6-p-toluenesulfonyl ester-β-cyclodextrin-bridged diphenylethylene glycol (BBβ-CD) adsorbent disclosed in CN105664873A and the hydrogel adsorbent disclosed in CN111841512A, the silicon-based adsorbent of the present invention has a significantly higher adsorption capacity.

[0217] Separation Example 1

[0218] Preparation of simulated mixed rare earth leaching solution: Take lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, dysprosium sulfate, holmium sulfate, erbium sulfate, thulium sulfate, ytterbium sulfate, lutetium sulfate, yttrium sulfate, thorium sulfate solution prepared in Experiment 1, calcium sulfate, ferric sulfate, magnesium sulfate and aluminum sulfate solution, calculate the required volume of each solution, and add distilled water to make up to the volume. Thus, a mixed rare earth leaching solution containing 2 mmol / L of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III), Y(III), Ca(II), Fe(III), Mg(II), Al(III) and Th(IV) in the sulfuric acid system is prepared.

[0219] 40 mg (±0.02 mg) of the silicon-based adsorbent prepared in Example 1 was weighed and placed in a threaded sample bottle. The mixed rare earth leaching solution prepared above was added, and the pH was adjusted to 1, 1.5, 2, 2.5, 3, and 3.5, respectively. The samples were shaken at 30°C for 60 h on an air bath constant temperature shaker with a shaking rate of 300 rpm for static adsorption experiments. After adsorption, the silicon-based adsorbent was filtered off, the filtrate was collected, and the equilibrium pH was tested. The pH changes before and after the adsorption experiment are shown in Table 2. In addition, the concentrations of each ion in the solution before and after adsorption were determined by ICP-OES. Then, the adsorption amount and adsorption rate of each element were calculated using the above formula (1) and the following formula (2). The results are shown in Table 2.

[0220] The adsorption rate of the silicon-based adsorbent material for the ions to be tested is calculated using formula (2).

[0221]

[0222] Where A represents the adsorption rate (%), C i With C t The values ​​represent the concentrations (mg / L) of the analyte ions before and after adsorption, respectively.

[0223] Table 2. Adsorption capacity Q (mg / g) and adsorption rate A (%) of various elements by silicon-based adsorbent materials at different pH values.

[0224]

[0225]

[0226] Among them, pH i Represents the initial pH, pH e This represents the equilibrium pH.

[0227] Table 2 shows that, in the presence of thorium and rare earth element ions, the silicon-based adsorbent material according to the present invention can selectively adsorb thorium, and essentially does not adsorb other elements until thorium is completely adsorbed. Furthermore, the adsorption of thorium by the silicon-based adsorbent material according to the present invention is minimally affected by pH.

[0228] Thorium removal from high-purity rare earth products

[0229] Separation Example 2

[0230] Preparation of simulated high-purity rare earth product feed solution: Take single lanthanum sulfate and single thorium sulfate solutions, mix them according to the concentration ratio, add distilled water and adjust the pH with sulfuric acid solution, and finally make up the volume to prepare a feed solution with pH=3 containing 20 mmol / L La(III) and 100 ppm Th(IV).

[0231] 25g of the silica-based adsorbent obtained in Example 1 was weighed and packed onto a chromatography column with a diameter of 1cm and a total length of 0.5m. The adsorbent was washed with water and compacted, then air was introduced to remove water from the column. The prepared feed solution was then introduced, and the fraction was collected. The concentrations of La(III) and Th(IV) were determined using ICP-OES. After column purification, the residual concentration of thorium was 0.02ppm, and the thorium removal rate reached 99.98%.

[0232] Separation Example 3

[0233] Preparation of simulated high-purity rare earth product solution: Take a single lutetium sulfate solution and a single thorium sulfate solution, mix them according to the concentration ratio, add distilled water and adjust the pH with sulfuric acid solution, and finally make up the volume to prepare a solution containing 20 mmol / L Lu(III) and 200 ppm Th(IV).

[0234] 50g of the silica-based adsorbent obtained in Example 8 was weighed and packed onto a chromatography column with a diameter of 1cm and a total length of 1m. The adsorbent was washed with water and compacted, then air was introduced to remove water from the column. The prepared feed solution was then introduced, and the fraction was collected. The concentrations of Lu(III) and Th(IV) were determined using ICP-OES. After column purification, the residual thorium concentration was 4.1ppm, and the thorium removal rate reached 97.95%.

[0235] Thorium removal from rare earth leachate

[0236] Separation Example 4

[0237] Preparation of simulated rare earth leaching solution: Take lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, dysprosium sulfate, holmium sulfate, erbium sulfate, thulium sulfate, ytterbium sulfate, lutetium sulfate, yttrium sulfate, and the thorium sulfate solution prepared above, mix them according to the concentration ratio, add distilled water and adjust the pH with sulfuric acid solution, and finally make up to volume. Thus, prepare a solution with pH=3 containing La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III), Y(III) at a concentration of 50 mmol / L and Th(IV) at a concentration of 10 mmol / L.

[0238] 75g of the silicon-based adsorbent obtained in Example 5 was weighed and packed onto a chromatography column with a diameter of 1cm and a total length of 1.5m. The adsorbent was washed with water and compacted, then air was introduced to remove water from the column. The prepared rare earth leachate was then introduced, and the fractions were collected. The concentrations of 16 rare earth elements were determined using ICP-OES. After column purification, the thorium removal rate reached 98.56%.

[0239] Separation Example 5

[0240] 100g of the silicon-based adsorbent obtained in Example 3 was weighed and packed onto a chromatography column with a diameter of 1cm and a total length of 2m. The adsorbent was washed with water and compacted, then air was introduced to remove water from the column. The rare earth leachate prepared in Example 4 was then introduced, and the fraction was collected. The concentrations of 16 rare earth elements were determined using ICP-OES. After column purification, the thorium removal rate reached 99.49%.

[0241] Thorium removal from rare earth industrial wastewater

[0242] Separation Example 6

[0243] Preparation of simulated rare earth industrial wastewater: Take lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, dysprosium sulfate, holmium sulfate, erbium sulfate, thulium sulfate, ytterbium sulfate, lutetium sulfate, yttrium sulfate, and the thorium sulfate solution prepared above, as well as calcium sulfate, ferric sulfate, magnesium sulfate, and aluminum sulfate solutions. Calculate the required volume of each solution, add distilled water, adjust the pH with sulfuric acid solution, and finally make up to the final volume. Therefore, a rare earth industrial wastewater with pH=3 was prepared, containing La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Tb(Ⅲ), Dy(Ⅲ), Ho(Ⅲ), Er(Ⅲ), Tm(Ⅲ), Yb(Ⅲ), Lu(Ⅲ), Y(Ⅲ), Ca(Ⅱ), Fe(Ⅲ), Mg(Ⅱ), Al(Ⅲ) at a concentration of 20 mmol / L and Th(Ⅳ) at a concentration of 200 ppm.

[0244] 100g of the silicon-based adsorbent obtained in Example 6 was weighed and packed onto a chromatography column with a diameter of 1cm and a total length of 2m. The adsorbent was washed with water and compacted, then air was introduced to remove water from the column. The rare earth industrial wastewater prepared above was then introduced, and the fraction was collected. The concentrations of 19 ions were determined using ICP-OES, and the thorium ion concentration was determined using ICP-MS. After column purification, the thorium removal rate reached 99.7%.

[0245] Separation Example 7

[0246] Preparation of simulated rare earth industrial wastewater: Lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, dysprosium sulfate, holmium sulfate, erbium sulfate, thulium sulfate, ytterbium sulfate, lutetium sulfate, yttrium sulfate, and the thorium sulfate solution prepared above, calcium sulfate, ferric sulfate, magnesium sulfate, and aluminum sulfate solutions. After calculating the required volume of each solution, distilled water is added, and the pH is adjusted using sulfuric acid solution. Finally, the volume is brought to a final consistency. Therefore, a rare earth industrial wastewater with pH=3 was prepared, containing La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Tb(Ⅲ), Dy(Ⅲ), Ho(Ⅲ), Er(Ⅲ), Tm(Ⅲ), Yb(Ⅲ), Lu(Ⅲ), Y(Ⅲ), Ca(Ⅱ), Fe(Ⅲ), Mg(Ⅱ), Al(Ⅲ) at a concentration of 10 mmol / L and Th(Ⅳ) at a concentration of 125 ppm.

[0247] 75g of the silicon-based adsorbent obtained in Example 4 was weighed and packed onto a chromatography column with a diameter of 1cm and a total length of 1.5m. The adsorbent was washed with water and compacted, then air was introduced to remove water from the column. The prepared rare earth industrial wastewater was then introduced, and the fraction was collected. The concentrations of 19 ions were determined using ICP-OES, and the thorium ion concentration was determined using ICP-MS. After column purification, the thorium removal rate reached 98.79%.

[0248] In summary, the silicon-based adsorbent material of the present invention has the advantages of simple preparation method, strong selectivity for thorium, large adsorption capacity, small influence of pH value on adsorption capacity, good circulation performance, and no use of saponifying agent in the removal process, and is environmentally friendly. It can be widely used for the extraction and separation of thorium, and can also be used for the adsorption and removal of thorium, and has good application prospects.

[0249] The objectives, technical solutions, and beneficial effects of the present invention have been described in detail above with reference to specific embodiments. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. Various modifications, substitutions, or improvements can be made within the spirit and principles of the present invention, and all such modifications, substitutions, and improvements should be included within the scope of protection of the present invention.

Claims

1. A silicon-based adsorbent material, comprising: (1) Silicon spheres; (2) Compound of formula I coupled with silicon spheres: （I） Among them, R1 is selected from C1-C 10 Alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl, C3-C 10 cycloalkyl, C3-C 10 Cycloalkyl C1-C2 alkyl; R2 and R3 are each independently selected from hydrogen, C1-C4 alkyl, C3-C 10 cycloalkyl, C3-C 10 Cycloalkyl C1-C2 alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl; R4 is selected from C1-C 10 Alkyl, C3-C6 cycloalkyl, C3-C6 cycloalkyl, C1-C2 alkyl, C6-C 10 Aryl, C6-C 10 Aryl C1-C2 alkyl Wherein, the compound of formula I is coupled to the silicon spheres via a nitrogen and silane coupling agent thereon; the silicon-based adsorbent material comprises the structure of formula III: (III) Where X represents a group derived from a silane coupling agent, The silane coupling agent has a functional group that can directly react with the amine group in the structure of compound I. The direct reaction between the silane coupling agent and compound I is achieved by the organic functional group of the silane coupling agent reacting with the amine group in the structure of compound I, thereby covalently attaching one end of the silane coupling agent to the amine group in the structure of compound I.

2. The silicon-based adsorbent material according to claim 1, wherein, R1 is selected from C1-C8 alkyl, phenyl, C1-C4 alkylphenyl, phenylC1-C2 alkyl; and / or R2 and R3 are each independently selected from hydrogen, C1-C4 alkyl; and / or R4 is selected from C1-C8 alkyl, phenyl, C1-C4 alkylphenyl, and phenylC1-C2 alkyl.

3. The silicon-based adsorbent material according to claim 2, wherein, R1 is selected from C2-C8 alkyl, phenyl, tolyl, xylyl, ethylphenyl, benzyl, phenethyl; and / or R2 and R3 are each independently selected from hydrogen, methyl, ethyl; and / or R4 is selected from C2-C8 alkyl, phenyl, tolyl, xylyl, ethylphenyl, benzyl, and phenethyl.

4. The silicon-based adsorbent material according to claim 3, wherein, R2 and R3 are each independently selected from hydrogen and methyl.

5. The silicon-based adsorbent material according to claim 1, wherein, The compound of formula I is selected from the following compounds: 。 6. The silicon-based adsorbent material according to any one of claims 1-5, wherein, Silane coupling agents are shown in Formula II below: (II) R5, R6 and R7 are each independently selected from C1-C4 alkyl and C1-C4 alkoxy groups, and at least one of them is an alkoxy group; R8 is selected from halogen, epoxy group, epoxy methoxy group and isocyanate group; n is an integer from 1 to 8.

7. The silicon-based adsorbent material according to claim 6, wherein, R5, R6 and R7 are each independently selected from C1-C2 alkyl and C1-C2 alkoxy groups, and at least one of them is an alkoxy group.

8. The silicon-based adsorbent material according to claim 6, wherein, The silane coupling agent is selected from epoxy silane, halosilane, and isocyanate silane; The epoxy silane is selected from 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 5,6-epoxyhexyltriethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-[(2,3)-epoxypropoxy]propylmethyldiethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and (3-epoxypropoxypropyl)dimethylethoxysilane; The halogenated silane is selected from 3-bromopropyltrimethoxysilane, 4-bromobutyltrimethoxysilane, 5-bromopentyltrimethoxysilane, 7-bromoheptyltrimethoxysilane, 3-chloroisopropyltrimethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-iodopropyltrimethoxysilane, chloromethylmethyldiethoxysilane, 3-chloropropylmethyldiethoxysilane, 3-chloropropylmethyltrimethoxysilane, chloromethyldimethylethoxysilane, and chloromethyldimethylmethoxysilane. The isocyanate silane is selected from 3-isocyanate propyltriethoxysilane, 3-isocyanate propyltrimethoxysilane, 3-isocyanate propylmethyldiethoxysilane, and 3-isocyanate propylmethyldimethoxysilane.

9. The silicon-based adsorbent material according to claim 1, wherein, X is selected from , , , ; wherein R6, R7 and n are as defined in Formula II of claim 6.

10. A method for preparing a silicon-based adsorbent material, comprising: (1) The compound of formula I is coupled with the silane coupling agent of formula II to obtain the coupling compound of formula IV. (2) The coupling compound of formula IV is coupled with silicon spheres to obtain silicon-based adsorbent material; Wherein, the definitions of R1 to R4 are the same as in any one of claims 1-5, and the definitions of R5 to R8 and n are the same as in claim 6. L is selected from direct bond, , , .

11. The method of claim 10, wherein, In step (1), the molar ratio of the compound of formula I to the silane coupling agent of formula II is 1:0.5~1.5; and / or Step (1) is carried out in an organic solvent; and / or The reaction temperature in step (1) is 50-100℃; and / or The reaction time for step (1) is more than 2 hours; and / or In step (2), the mass ratio of the coupling compound of formula IV to the silicon spheres is 1:0.5~5; and / or Step (2) is carried out in an organic solvent; and / or The reaction temperature in step (2) is 60-150℃; and / or The reaction time for step (2) is more than 2 hours.

12. The method of claim 11, wherein, In step (1), the molar ratio of the compound of formula I to the silane coupling agent of formula II is 1:0.8~1.2; and / or Step (1) is carried out in an organic solvent selected from any one or more of methanol, ethanol, acetonitrile, tetrahydrofuran, and dioxane; and / or The reaction temperature in step (1) is 65-80℃; and / or The reaction time for step (1) is more than 5 hours; and / or In step (2), the mass ratio of the coupling compound of formula IV to the silicon spheres is 1:0.8~4; and / or Step (2) is carried out in an organic solvent selected from any one or more of toluene, xylene, trimethylbenzene, cyclohexane, n-heptane, and isooctane; and / or The reaction temperature in step (2) is 80-120℃; and / or The reaction time for step (2) is more than 5 hours.

13. Use of the silicon-based adsorbent material according to any one of claims 1-9 or the silicon-based adsorbent material prepared by the method according to any one of claims 10-12 in the preparation of an extractant for extracting thorium.

14. A method for extracting thorium, the method comprising the step of contacting a thorium-containing solution with a silicon-based adsorbent according to any one of claims 1-9 or a silicon-based adsorbent prepared by the method according to any one of claims 10-12 to extract thorium from the solution.

15. The method of claim 14, wherein, The thorium-containing solution is selected from high-purity rare earth solutions, rare earth leachates, and rare earth industrial wastewater solutions; and / or The pH of the thorium-containing solution is 0 to 4; and / or The thorium-containing solution is a nitric acid, sulfuric acid, or hydrochloric acid solution.

16. The method according to claim 15, wherein, The pH of the thorium-containing solution is 1-4.

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