Benzene sulfonic acid group functionalized silica gel and preparation method and application thereof

Abstract

The invention relates to benzenesulfonic functionalized silica gel as well as a preparation method and application thereof, and the preparation method comprises the step of reacting silica gel with 2-(4-chlorosulfonylphenyl) ethyl trichlorosilane in a solvent to obtain the benzenesulfonic functionalized silica gel. The benzenesulfonic acid group functionalized silica gel provided by the invention has high surface coverage rate and sulfonic acid group modification degree, shows excellent separation selectivity for at least 15 rare earth elements, and can be used in macro preparation of high-purity rare earth.

Description

Technical Field

[0001] The present invention relates to the technical field of ion exchange chromatography, and particularly relates to a benzenesulfonic acid group-functionalized silica gel, a preparation method thereof, and an application thereof. Background Art

[0002] Ion exchange chromatography is a separation technique based on the principle of ion exchange. In this method, sample ions are exchanged with exchangeable ions (usually resins or silica gels with ion exchange groups) on the stationary phase in the chromatographic column, and separation is achieved through exchange equilibrium. Different ions in the sample have different abilities to bind to the stationary phase due to differences in charge magnitude and affinity, so they migrate at different speeds in the chromatographic column and finally achieve the separation effect.

[0003] Ion exchange chromatography is widely used in the analysis and separation of charged samples, and is particularly suitable for the separation and purification of metal ions, proteins, nucleic acids, etc. Its separation mechanism depends on the charge interaction between sample ions and exchangeable ions on the stationary phase.

[0004] Rare earth elements and their compounds have unique optical, magnetic, and electrochemical properties and are currently widely used. Rare earth elements include 15 lanthanide elements, as well as scandium and yttrium. Due to their extremely similar physical and chemical properties, their separation and purification are extremely difficult. Traditional separation methods often have difficulty in effectively separating and have problems such as long steps, low efficiency, and large pollution. Previous studies have shown that ion exchange chromatography is a technique that can be used for rare earth separation, which can achieve the separation of rare earth elements from trace amounts to large amounts, and generally does not use organic solvents, making it a truly green chromatographic analysis technique. However, limited by ion exchange chromatography packing materials, currently only single rare earth element separation can be achieved (such as CN201810998747.9, CN202311129333.X), and the simultaneous separation of multiple rare earth elements cannot be achieved.

[0005] Therefore, it is very necessary to provide a silica gel ion chromatography packing material that can be applied to the separation of multiple rare earth elements. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a benzenesulfonic acid group-functionalized silica gel, a preparation method thereof, and an application thereof. The benzenesulfonic acid group-functionalized silica gel provided by the present invention has a high surface coverage rate and sulfonic acid group modification degree, and shows excellent separation selectivity for at least 15 rare earth elements, and can be used in the macroscale preparation of high-purity rare earths.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a benzenesulfonic acid-functionalized silica gel, the preparation method comprising: reacting silica gel with 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane in a solvent to obtain benzenesulfonic acid-functionalized silica gel.

[0009] The present invention uses 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane as a specific aromatic sulfonic acid functionalizing reagent to prepare benzenesulfonic acid-functionalized silica gel. The obtained product has a high surface coverage rate and sulfonic acid group modification degree, and shows excellent separation selectivity for at least 15 rare earth elements, and can be used in the macroscale preparation of high-purity rare earths.

[0010] Preferably, the dosage ratio of the silica gel to 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane is 1 g:(0.2-0.6) mL (for example, it can be 1 g:0.2 mL, 1 g:0.3 mL, 1 g:0.4 mL, 1 g:0.5 mL, 1 g:0.6 mL, etc.).

[0011] Preferably, the silica gel is pre-activated with an acid.

[0012] Preferably, the acid includes concentrated hydrochloric acid.

[0013] Preferably, the particle size of the silica gel is 1-10 μm (for example, it can be 1.5 μm, 3 μm, 5 μm, 10 μm, etc.).

[0014] Preferably, the solvent includes anhydrous toluene, or the solvent includes a mixture of choline chloride and ethylene glycol.

[0015] Preferably, the molar ratio of choline chloride to ethylene glycol is 1:(1.5-2.5) (for example, it can be 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, etc.).

[0016] Preferably, when the solvent is anhydrous toluene, the temperature of the reaction is 80-130 °C (for example, it can be 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, etc.), and the reaction time is 12-48 h (for example, it can be 12 h, 24 h, 36 h, 48 h, etc.).

[0017] In the present invention, when anhydrous toluene is used as the solvent, the obtained benzenesulfonic acid-functionalized silica gel contains more benzenesulfonic acid functional groups, which can provide abundant interaction sites for the efficient separation of rare earth samples. As an ion exchange chromatography packing, the separation of 16 rare earth elements can be achieved, and the complete separation of Dy and Y, which is difficult to separate on conventional chromatography packings, can be realized.

[0018] Preferably, when the solvent is a mixture of choline chloride and ethylene glycol, the reaction temperature is 45 - 80 °C (for example, it can be 45 °C, 55 °C, 65 °C, 75 °C, 80 °C, etc.), and the reaction time is 12 - 48 h (for example, it can be 12 h, 24 h, 36 h, 48 h, etc.).

[0019] In the present invention, when using a deep eutectic solvent (DES), the obtained benzenesulfonic acid-functionalized silica gel can be used as an ion exchange chromatography packing material to achieve the separation of 15 rare earth elements.

[0020] Preferably, the reaction is carried out under nitrogen protection.

[0021] Preferably, after the reaction, it also includes washing and drying steps.

[0022] Preferably, the solvents used for washing include at least two combinations of toluene, ethanol, or methanol, and also include water and hydrochloric acid.

[0023] In the second aspect, the present invention provides a benzenesulfonic acid-functionalized silica gel prepared by the preparation method of the benzenesulfonic acid-functionalized silica gel according to the first aspect.

[0024] In the third aspect, the present invention provides an application of the benzenesulfonic acid-functionalized silica gel according to the second aspect in the separation of rare earth elements or the preparation of high-purity rare earths.

[0025] In the fourth aspect, the present invention provides a method for separating rare earth elements, the method comprising: separating rare earth elements by ion exchange chromatography, and the stationary phase of the ion exchange chromatography is the benzenesulfonic acid-functionalized silica gel according to the second aspect.

[0026] Preferably, the column temperature of the ion exchange chromatography is 15 - 45 °C (for example, it can be 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, etc.).

[0027] Preferably, the detection wavelength of the ion exchange chromatography is 655 - 660 nm (for example, it can be 655 nm, 656 nm, 657 nm, 658 nm, 659 nm, 660 nm, etc.), and preferably 658 nm.

[0028] Preferably, the flow rate of the ion exchange chromatography is 0.8 - 1.2 mL / min (for example, it can be 0.8 mL / min, 0.9 mL / min, 1 mL / min, 1.1 mL / min, 1.2 mL / min, etc.).

[0029] Preferably, the flow rate of the post-column derivatization pump for the ion exchange chromatography is 0.4 - 1.0 mL / min (e.g., it can be 0.4 mL / min, 0.5 mL / min, 0.6 mL / min, 0.7 mL / min, 0.8 mL / min, 1.0 mL / min, etc.).

[0030] Preferably, the mobile phase for the ion exchange chromatography includes phase A and phase B; phase A is an aqueous solution of α-hydroxyisobutyric acid (α-HIBA) with a pH of 2.5 - 4.0 (e.g., it can be 2.5, 3, 3.5, 4, etc.) and a concentration of 100 - 600 mM (e.g., it can be 100 mM, 200 mM, 300 mM, 400 mM, 500 mM, 600 mM, etc.); phase B is water.

[0031] Preferably, the ion exchange chromatography adopts gradient elution, and the gradient elution program is as follows: from 0 - 25 min, the volume percentage of phase A is 30 - 40% (e.g., it can be 30%, 32%, 35%, 38%, 40%, etc.), and the volume percentage of phase B is 60 - 70% (e.g., it can be 60%, 62%, 65%, 68%, 70%, etc.); then it changes uniformly to 30 min, the volume percentage of phase A is 55 - 65% (e.g., it can be 55%, 58%, 60%, 62%, 65%, etc.), and the volume percentage of phase B is 35 - 45% (e.g., it can be 35%, 38%, 40%, 42%, 45%, etc.); then it changes uniformly to 40 min, the volume percentage of phase A is 95 - 100% (e.g., it can be 95%, 96%, 97%, 98%, 99%, 100%, etc.), and the volume percentage of phase B is 0 - 5% (e.g., it can be 0%, 1%, 2%, 3%, 4%, 5%, etc.); the volume percentage is kept constant until 50 - 80 min (e.g., it can be 50 min, 60 min, 70 min, 80 min, etc.).

[0032] Preferably, the ion exchange chromatography adopts gradient elution, and the gradient elution program is as follows: from 0 - 20 min, the volume percentage of phase A is 20 - 30% (e.g., it can be 20%, 22%, 25%, 28%, 30%, etc.), and the volume percentage of phase B is 70 - 80% (e.g., it can be 70%, 72%, 75%, 78%, 80%, etc.); then it changes uniformly to 50 min, the volume percentage of phase A is 95 - 100% (e.g., it can be 95%, 96%, 97%, 98%, 99%, 100%, etc.), and the volume percentage of phase B is 0 - 5% (e.g., it can be 0%, 1%, 2%, 3%, 4%, 5%, etc.); the volume percentage is kept constant until 50 - 80 min (e.g., it can be 50 min, 60 min, 70 min, 80 min, etc.).

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] The present invention uses 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane as a specific arene sulfonic acid functionalizing reagent to prepare benzenesulfonic acid group-functionalized silica gel. The obtained product has a high surface coverage rate and sulfonic acid group modification degree, and shows excellent separation selectivity for at least 15 rare earth elements, and can be used in the macroscale preparation of high-purity rare earths. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a reaction formula diagram of the examples.

[0036] Figure 2 It is an XPS full spectrum diagram of the products prepared in Example 1 and Example 2.

[0037] Figure 3 It is an XPS high-resolution C1s spectrum diagram of the products prepared in Example 1 and Example 2.

[0038] Figure 4 It is an XPS high-resolution S2p spectrum diagram of the products prepared in Example 1 and Example 2.

[0039] Figure 5 It is a chromatographic separation diagram of 16 rare earth elements of the product prepared in Example 1.

[0040] Figure 6 It is a chromatographic separation diagram of 16 rare earth elements of the product prepared in Example 2.

[0041] Figure 7 It is a chromatographic separation diagram of 16 rare earth elements of the product prepared in Example 3.

[0042] Figure 8 It is a chromatographic separation diagram of 16 rare earth elements of the product prepared in Example 4.

[0043] Figure 9 It is a chromatographic separation diagram of 16 rare earth elements of the product prepared in Example 5.

[0044] Figure 10 It is a chromatographic separation diagram of 16 rare earth elements of the product prepared in Example 6.

[0045] Figure 11 It is a chromatographic separation diagram of 15 rare earth elements of the product prepared in Comparative Example 1.

[0046] Figure 12 It is a chromatographic separation diagram of 15 rare earth elements of the product prepared in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0047] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0048] The reaction formulas of the following examples are as Figure 1 shown.

[0049] Example 1

[0050] This example provides a preparation method of phenylsulfonic acid-functionalized silica gel:

[0051] 5 g of silica gel (3 μm) activated with concentrated hydrochloric acid and 40 mL of anhydrous toluene (previously dried with molecular sieve) were added to a three-necked flask. After mechanical stirring and dispersion, 2 mL of 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane was slowly added under nitrogen protection. The mixture was heated to 110 °C and mechanically stirred for 24 h. The product was washed successively with toluene, ethanol, water, 0.5 M hydrochloric acid, and water, and then dried under vacuum at 70 °C to obtain phenylsulfonic acid-functionalized silica gel, named SCX-Tol.

[0052] Example 2

[0053] This example provides a preparation method of phenylsulfonic acid-functionalized silica gel:

[0054] 5 g of silica gel (3 μm) activated with concentrated hydrochloric acid and 40 mL of deep eutectic solvent (DES, choline chloride and ethylene glycol with a molar ratio of 1:2) were added to a three-necked flask. After mechanical stirring and dispersion, 2 mL of 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane was slowly added under nitrogen protection. The mixture was heated to 65 °C and mechanically stirred for 24 h. The product was washed successively with methanol, water, 0.5 M hydrochloric acid, and water, and then dried under vacuum at 70 °C to obtain phenylsulfonic acid-functionalized silica gel, named SCX-DES.

[0055] Example 3

[0056] This example provides a preparation method of phenylsulfonic acid-functionalized silica gel, which is only different from Example 1 in that 1 mL of 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane is added, and the obtained phenylsulfonic acid-functionalized silica gel is named SCX-Tol-1mL.

[0057] Example 4

[0058] This example provides a preparation method of phenylsulfonic acid-functionalized silica gel, which is only different from Example 1 in that 1.5 mL of 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane is added, and the obtained phenylsulfonic acid-functionalized silica gel is named SCX-Tol-1.5mL.

[0059] Example 5

[0060] This example provides a method for preparing phenylsulfonic acid-functionalized silica gel. The difference from Example 1 is only that the amount of 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane added is 2.5 mL, and the obtained phenylsulfonic acid-functionalized silica gel is named SCX-Tol-2.5 mL.

[0061] Example 6

[0062] This example provides a method for preparing phenylsulfonic acid-functionalized silica gel. The difference from Example 1 is only that the particle size of the silica gel used is 10 μm, and the obtained phenylsulfonic acid-functionalized silica gel is named SCX-Tol-10 μm.

[0063] Comparative Example 1

[0064] This comparative example provides a method for preparing sulfonic acid-functionalized silica gel, in which the sulfonating agent used is 1,3-propane sultone. Specifically, it is prepared with reference to Example 2 in the specific implementation manner of CN118454662A (a sulfonic acid-functionalized ion exchange chromatography packing and its application in rare earth element separation) to obtain sulfonic acid-functionalized silica gel Sil-SCX.

[0065] Comparative Example 2

[0066] This comparative example provides a method for preparing sulfonic acid-functionalized silica gel, in which the sulfonating agent used is 1,4-butane sultone. Specifically, it is prepared with reference to Example 3 in the specific implementation manner of CN118454662A (a sulfonic acid-functionalized ion exchange chromatography packing and its application in rare earth element separation) to obtain sulfonic acid-functionalized silica gel Sil-SCX.

[0067] Test Example 1

[0068] Carbon and sulfur element analysis

[0069] The samples were analyzed for carbon and sulfur elements, and the surface coverage α was calculated. The calculation formula is:

[0070]

[0071] where S% is the percentage of sulfur mass content, M S is the molar mass of the bonded phase, N S is the number of sulfur in the bonded phase, S BET is the specific surface area of the bare silica gel.

[0072] The test results are shown in Table 1.

[0073] Table 1

[0074]

[0075] The experimental results show that, compared with Comparative Example 1, the phenylsulfonic acid-functionalized silica gels provided in Examples 1-2 have higher C and S contents and a higher surface coverage. At the same time, SCX-Tol has higher C and S contents and a higher surface coverage rate compared with SCX-DES.

[0076] Test Example 2

[0077] X-ray photoelectron spectroscopy analysis

[0078] X-ray photoelectron spectroscopy analysis was performed on the samples provided in Example 1 and Example 2. The full spectrum ( Figure 2 ) shows that the characteristic peaks at 103, 169, 285, and 532 eV correspond to Si 2p, S2p, C 1s, and O 1s, respectively.

[0079] The high-resolution C 1s spectrum ( Figure 3 ) and S2p spectrum ( Figure 4 ) show that the peaks at 284.8 eV, 286.3 eV, and 288.7 eV are attributed to C-C, C-Si, and C-S bonds, respectively, which confirms the successful introduction of sulfonic acid groups into the silica stationary phase. By comparing the C 1s and S2p fine spectra of SCX-Tol and SCX-DES, it can be concluded that SCX-Tol contains more sulfonic acid groups.

[0080] Test Example 3

[0081] Chromatographic performance test

[0082] The products prepared in Examples 1-5 were respectively filled into a 4.6×150 mm stainless steel chromatographic column tube as the packing of the ion exchange chromatographic column, and the product prepared in Example 6 was filled into a 4.6×250 mm stainless steel chromatographic column tube as the packing of the ion exchange chromatographic column to prepare chromatographic columns, and 16 rare earth elements (except Pm) were separated.

[0083] Chromatographic conditions: column temperature 25 °C, wavelength of ultraviolet-visible detector 658 nm, flow rate 1.0 mL / min, and flow rate of post-column derivatization pump 0.6 mL / min.

[0084] The gradient elution program of the chromatographic mobile phase for Examples 1 and 5 is as follows:

[0085] Time (min) A% (α-HIBA, 350 mM, pH = 3.6) B% (Water) 0 35 65 25 35 65 30 60 40 40 100 0 80 100 0

[0086] The gradient elution program of the chromatographic mobile phase for Example 2 is as follows:

[0087]

[0088]

[0089] The chromatographic mobile phase gradient elution procedures for Examples 3 and 4 are as follows:

[0090] Time (min) A% (α-HIBA, 350 mM, pH = 3.6) B% (Water) 0 35 65 25 35 65 30 60 40 40 100 0 60 100 0

[0091] The chromatographic mobile phase gradient elution procedure for Example 6 is as follows:

[0092] Time (min) A% (α-HIBA, 500 mM, pH = 3.6) B% (Water) 0 25 75 20 40 60 50 100 0 70 100 0

[0093] The products prepared in Comparative Examples 1-2 were separated for rare earth elements according to the chromatographic conditions in Examples 2-3 of the specific implementation manner of CN118454662A (a sulfonic acid-functionalized ion exchange chromatographic packing and its application in rare earth element separation).

[0094] As Figure 5 shown, the elution order of 16 rare earth elements by the SCX-Tol benzenesulfonic acid-based functionalized ion exchange chromatographic packing provided in Example 1 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium (Dy), yttrium (Y), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La); Dy and Y can be separated. Almost no tailing phenomenon occurs for all chromatographic peaks.

[0095] As Figure 6 shown, the elution order of 16 rare earth elements by the SCX-DES benzenesulfonic acid-based functionalized ion exchange chromatographic packing provided in Example 2 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium + yttrium (Dy+Y), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La); Dy and Y cannot be separated. Almost no tailing phenomenon occurs for all chromatographic peaks.

[0096] As Figure 7 shown, the elution order of 16 rare earth elements by the SCX-Tol-1mL benzenesulfonic acid-based functionalized ion exchange chromatographic packing provided in Example 3 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium + yttrium (Dy+Y), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La); Dy and Y cannot be separated. Obvious tailing phenomenon occurs for all chromatographic peaks.

[0097] As Figure 8As shown, the elution order of 16 rare earth elements by the SCX-Tol-1.5 mL benzenesulfonic acid-functionalized ion exchange chromatography packing provided in Example 4 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium + yttrium (Dy+Y), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La); Dy and Y cannot be separated. There is a slight tailing phenomenon for all chromatographic peaks.

[0098] As Figure 9 shown, the elution order of 16 rare earth elements by the SCX-Tol-2.5 mL benzenesulfonic acid-functionalized ion exchange chromatography packing provided in Example 5 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium (Dy), yttrium (Y), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La); Dy and Y can be separated. There is almost no tailing phenomenon for all chromatographic peaks.

[0099] As Figure 10 shown, the elution order of 16 rare earth elements by the SCX-Tol-10 μm benzenesulfonic acid-functionalized ion exchange chromatography packing provided in Example 6 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium + yttrium (Dy+Y), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La); Dy and Y cannot be separated. There is almost no tailing phenomenon for all chromatographic peaks.

[0100] As Figure 11 shown, the elution order of 15 rare earth elements by the sulfonic acid-functionalized chromatography packing (Sil-SCX) provided in Comparative Example 1 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium (Dy), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La). The separation effect of Dy and Y was not investigated, and there is an obvious tailing phenomenon for all chromatographic peaks.

[0101] As Figure 12 shown, the elution order of 15 rare earth elements by the sulfonic acid-functionalized chromatography packing (Sil-SCX) provided in Comparative Example 2 is: scandium (Sc), lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium (Dy), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), neodymium (Nd), praseodymium (Pr), cerium (Ce), lanthanum (La). The separation effect of Dy and Y was not investigated, and there is an obvious tailing phenomenon for all chromatographic peaks.

[0102] In summary, the SCX-Tol and SCX-DES stationary phases provided by the embodiments of the present invention have more benzenesulfonic acid functional groups on the surface, which can provide rich interaction sites for the efficient separation of rare earth samples, and there are more benzenesulfonic acid functional groups on the surface of SCX-Tol. The results of chromatographic separation experiments show that the benzenesulfonic acid-functionalized silica gel SCX-DES prepared by the present invention exhibits excellent separation selectivity for 15 rare earth elements; SCX-Tol exhibits excellent separation selectivity for 16 rare earth elements, and can achieve the complete separation of Dy and Y, which are difficult to separate on conventional chromatographic packings; both stationary phases provided by the embodiments are superior to the comparative examples and can be used for the macroscale preparation of high-purity rare earths.

[0103] The applicant declares that the above description is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a benzenesulfonic acid group-functionalized silica gel, characterized in that, The preparation method includes: reacting silica gel with 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane in a solvent to obtain benzenesulfonic acid group-functionalized silica gel.

2. The preparation method according to claim 1, wherein The dosage ratio of the silica gel to 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane is 1 g:(0.2 - 0.6) mL.

3. The preparation method according to claim 1 or 2, characterized in that, The solvent includes anhydrous toluene, or the solvent includes a mixture of choline chloride and ethylene glycol; Preferably, the molar ratio of choline chloride to ethylene glycol is 1:(1.5 - 2.5).

4. The preparation method according to claim 3, characterized in that, When the solvent is anhydrous toluene, the reaction temperature is 80 - 130 °C and the reaction time is 12 - 48 h; Preferably, when the solvent is a mixture of choline chloride and ethylene glycol, the reaction temperature is 45 - 80 °C and the reaction time is 12 - 48 h.

5. The preparation method according to any one of claims 1-4, characterized in that, The reaction is carried out under nitrogen protection; Preferably, after the reaction, washing and drying steps are further included; Preferably, the solvents used for washing include at least two combinations of toluene, ethanol, or methanol, and also include water and hydrochloric acid.

6. Benzenesulfonic acid group-functionalized silica gel prepared by the preparation method of the benzenesulfonic acid group-functionalized silica gel according to any one of claims 1 - 5.

7. Application of the benzenesulfonic acid group-functionalized silica gel according to claim 6 in rare earth element separation or high-purity rare earth preparation.

8. A method for separating rare earth elements, characterized in that, The method includes: separating rare earth elements by ion exchange chromatography, and the stationary phase of the ion exchange chromatography is the benzenesulfonic acid group-functionalized silica gel according to claim 6.

9. The method according to claim 8, wherein The column temperature of the ion exchange chromatography is 15 - 45 °C; Preferably, the detection wavelength of the ion exchange chromatography is 655 - 660 nm; Preferably, the flow rate of the ion exchange chromatography is 0.8 - 1.2 mL / min; Preferably, the flow rate of the post-column derivatization pump of the ion exchange chromatography is 0.4 - 1.0 mL / min.

10. The method according to claim 8 or 9, characterized in that, The mobile phase of the ion exchange chromatography includes phase A and phase B; phase A is an aqueous solution of α-hydroxyisobutyric acid with a pH of 2.5 - 4.0 and a concentration of 100 - 600 mM; phase B is water; Preferably, the ion exchange chromatography adopts gradient elution, and the gradient elution program is: from 0 - 25 min, the volume ratio of phase A is 30 - 40%, and the volume ratio of phase B is 60 - 70%; then it changes uniformly to 30 min, the volume ratio of phase A is 55 - 65%, and the volume ratio of phase B is 35 - 45%; then it changes uniformly to 40 min, the volume ratio of phase A is 95 - 100%, and the volume ratio of phase B is 0 - 5%; keep the volume ratio constant until 50 - 80 min; Preferably, the ion exchange chromatography adopts gradient elution, and the gradient elution program is: from 0 - 20 min, the volume ratio of phase A is 20 - 30%, and the volume ratio of phase B is 70 - 80%; then it changes uniformly to 50 min, the volume ratio of phase A is 95 - 100%, and the volume ratio of phase B is 0 - 5%; keep the volume ratio constant until 50 - 80 min.

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