A tributyl phosphonium acid modified ZIF-8 adsorbent and a preparation method and application thereof

Abstract

The application belongs to the field of chemical materials, and particularly relates to a tributyl phosphonium modified ZIF-8 adsorbent and a preparation method and application thereof. The preparation method provided by the application comprises the following steps: synthesizing ZIF-8 metal organic framework particles, mixing the ZIF-8 metal organic framework particles with an organic solution of tributyl phosphonium and then heating, filtering, washing, drying and crushing to obtain the tributyl phosphonium modified ZIF-8 adsorbent. The preparation method provided by the application has few processes, low cost and mild conditions, can effectively realize the modification of tributyl phosphonium on ZIF-8, and the prepared adsorbent material can perform high-selectivity enrichment and recovery on high-value rare earth ions Dy 3+ in rare earth mine wastewater.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials, and particularly relates to a ZIF-8 adsorbent modified with tributyl phosphonate, its preparation method and application. Background Technology

[0002] The overexploitation and use of traditional fossil fuels has led to energy crises and environmental problems. In recent years, the increasing frequency of geopolitical conflicts has seriously impacted global energy security. Therefore, given the necessity of ensuring energy security and addressing environmental issues, the gradual replacement of traditional fossil fuels with new, clean energy sources is urgently needed.

[0003] Currently, safe, reliable, technologically mature, and cost-controllable clean energy sources mainly include wind and solar power. Furthermore, the rapid advancement of electric vehicle technology has facilitated humanity's gradual reduction of dependence on traditional fossil fuels. The acquisition, storage, and downstream application of clean energy in electric vehicles and other new energy equipment require large quantities of rare earth elements as raw materials. However, rare earth elements, primarily lanthanides, are characterized by uneven spatial and temporal distribution, low total reserves, and high mining difficulty. Therefore, in recent years, the prices of rare earth elements such as dysprosium, neodymium, and cerium, used in the production of new energy equipment, have risen sharply, limiting the development of the new energy industry. In the mining of ion-adsorption rare earth deposits in southern China, ammonium sulfate is first used as a leaching agent to dissolve the ore, followed by unified collection and extraction enrichment. This process generates a large amount of mine wastewater, in which the concentration of rare earth ions is far higher than in ordinary water bodies. Finding economical and reliable methods to selectively enrich and recover high-value rare earth ions from mine wastewater can not only bring considerable economic value but also reduce the environmental impact of acidic mine wastewater.

[0004] Currently, the main method for selectively enriching and separating rare earth ions from solution is extraction using organic extractants. However, this method is not suitable for the large volume and low concentration of rare earth ions in rare earth mine wastewater. Precipitation of target ions by adding reagents also faces problems such as high recovery costs, difficult treatment, and secondary pollution. Selective recovery of heavy metal ions from water using adsorption separation is widely used. However, the recovery of rare earth ions from rare earth mine wastewater using existing adsorbents has certain limitations. These limitations primarily include poor selectivity, making it impossible to selectively adsorb and separate high-value lanthanides; high cost, limiting practical application potential; and low adsorption capacity, restricting the total amount of target ions that can be recovered. Therefore, developing adsorbents with high selectivity, controllable cost, strong stability, and large adsorption capacity is of significant application value. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a ZIF-8 adsorbent modified with tributyl phosphonate, its preparation method, and its application. The preparation method provided by this invention has fewer steps, lower cost, and milder conditions, and can effectively modify ZIF-8 with tributyl phosphonate. Furthermore, the resulting adsorbent material can effectively adsorb high-value rare earth ions (Dy) from rare earth mine wastewater. 3+ To perform highly selective enrichment and recovery.

[0006] This invention provides a method for preparing a ZIF-8 adsorbent modified with tributyl phosphonate, comprising the following steps:

[0007] ZIF-8 metal-organic framework particles were synthesized by heating and mixing the ZIF-8 metal-organic framework particles with an organic solution of tributyl phosphonate, followed by filtration, washing, drying, and crushing to obtain a tributyl phosphonate-modified ZIF-8 adsorbent.

[0008] Preferably, the synthesis steps of the ZIF-8 metal-organic framework particles specifically include:

[0009] i) The organic ligand and zinc salt are mixed in an organic solvent to obtain a milky white mixed solution;

[0010] ii) The milky white mixed solution was heated in a sealed environment, then filtered, washed, dried and crushed to obtain ZIF-8 metal-organic framework particles.

[0011] Preferably, step i) specifically includes:

[0012] i-1) Mix the organic ligand with an organic solvent to obtain a solution of the organic ligand; mix the zinc salt with an organic solvent to obtain a solution of the zinc salt;

[0013] i-2) The solution of the organic ligand is mixed with the solution of the zinc salt. During the mixing process, the solution changes from transparent to milky white, resulting in a milky white mixed solution.

[0014] Preferably, in step ii), the heating temperature is 100~150℃; the heating time is 2~8h.

[0015] Preferably, the ZIF-8 metal-organic framework particles are heated and dried before being involved in the heating and mixing process.

[0016] Preferably, the heating and mixing temperature is 60~100℃; the heating and mixing time is 8~16h.

[0017] This invention provides a ZIF-8 adsorbent modified with tributyl phosphonate, which is prepared according to the preparation method described in the above technical solution.

[0018] This invention provides a method for treating Dy in rare earth mine wastewater.3+ The recycling method includes the following steps:

[0019] Using adsorbents to remove Dy from rare earth mine wastewater 3+ Adsorption and recovery are carried out;

[0020] The adsorbent includes the ZIF-8 adsorbent modified with tributyl phosphonate as described in the above technical solution.

[0021] Preferably, the rare earth mine wastewater undergoes Dy 3+ Before recycling, adjust its pH value to 5-6.

[0022] Preferably, the rare earth mine wastewater undergoes Dy 3+ Before recycling, it is filtered to remove impurities.

[0023] Compared with existing technologies, this invention provides a ZIF-8 adsorbent modified with tributyl phosphonate, its preparation method, and its application. The preparation method provided by this invention includes the following steps: synthesizing ZIF-8 metal-organic framework particles; heating and mixing the ZIF-8 metal-organic framework particles with an organic solution of tributyl phosphonate; then filtering, washing, drying, and crushing to obtain the ZIF-8 adsorbent modified with tributyl phosphonate. The preparation method provided by this invention first synthesizes ZIF-8, and then modifies tributyl phosphonate (TBP) using a solvothermal method, ensuring high selectivity and structural stability of the material. The synthesis steps are simple, do not use toxic or harmful reagents, and the synthesis conditions are mild, not involving high-temperature or high-pressure reaction conditions, making it energy-saving and environmentally friendly. The preparation method provided by this invention effectively modifies the surface of ZIF-8 with TBP groups while maintaining the structural stability of ZIF-8, ensuring sufficient adsorption sites for the adsorbent. Simultaneously, it utilizes the phosphono-oxygen functional groups in the TBP groups for Dy 3+ It has a strong affinity and can bind to it through coordination, making the prepared adsorbent effective against Dy. 3+ It exhibits specific selectivity. The adsorbent prepared in this invention is effective for Dy 3+ The selectivity is significantly improved, and it can effectively separate Dy when multiple monovalent and divalent interfering ions coexist. 3+ Therefore, it is possible to selectively and efficiently recover high-value lanthanide ions (Dy) from rare earth mine wastewater. 3+ More specifically, the technical solution of the present invention has the following advantages: (1) ZIF-8 as the substrate has a large specific surface area and good stability, providing excellent adsorption capacity; (2) The synthesis method of ZIF-8 substrate is simple, safe and easy to operate, and does not require a high temperature, strong acid and strong alkali synthesis environment. The synthesis technology is mature and the cost is easy to control, and it has the potential for large-scale commercial use; (3) The synthesized ZIF-8-TBP is effective for high-value heavy rare earth ions Dy 3+It exhibits significant selectivity, enabling rapid and highly selective recovery of target ions from rare earth mine wastewater. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This invention provides a preparation route for ZIF-8-TBP and a method for selectively adsorbing Dy. 3+ A schematic diagram;

[0026] Figure 2 This is a SEM image of ZIF-8 provided in Embodiment 1 of the present invention;

[0027] Figure 3 This is a SEM image of ZIF-8-TBP provided in Embodiment 1 of the present invention;

[0028] Figure 4 These are the X-ray diffraction patterns of ZIF-8 and ZIF-8-TBP provided in Embodiment 1 of the present invention;

[0029] Figure 5 These are the infrared spectra of ZIF-8 and ZIF-8-TBP provided in Embodiment 1 of the present invention;

[0030] Figure 6 The ZIF-8-TBP provided in Example 2 of this invention is effective for Dy at different pH values. 3+ Adsorption capacity diagram;

[0031] Figure 7 This is a distribution coefficient diagram of ZIF-8-TBP for different cations in simulated wastewater provided in Embodiment 3 of the present invention;

[0032] Figure 8 The ZIF-8-TBP provided in Embodiment 4 of this invention is for Nd 3+ Dy 3+ Distribution coefficient diagram;

[0033] Figure 9 This is a distribution coefficient diagram of ZIF-8-TBP for different cations in rare earth mine wastewater provided in Embodiment 5 of the present invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] This invention provides a method for preparing a ZIF-8 adsorbent modified with tributyl phosphonate, comprising the following steps:

[0036] ZIF-8 metal-organic framework particles were synthesized by heating and mixing the ZIF-8 metal-organic framework particles with an organic solution of tributyl phosphonate (TBP), followed by filtration, washing, drying, and crushing to obtain a tributyl phosphonate-modified ZIF-8 adsorbent (ZIF-8-TBP).

[0037] In the preparation method provided by this invention, the synthesis steps of the ZIF-8 metal-organic framework particles specifically include:

[0038] i) The organic ligand and zinc salt are mixed in an organic solvent to obtain a milky white mixed solution;

[0039] ii) The milky white mixed solution was heated in a sealed environment, then filtered, washed, dried and crushed to obtain ZIF-8 metal-organic framework particles.

[0040] In the above-mentioned synthesis steps of ZIF-8 metal-organic framework particles provided by the present invention, in step i), the organic ligand is preferably 2-methylimidazole; the zinc salt is preferably zinc nitrate, more specifically zinc nitrate hexahydrate; the organic solvent is preferably methanol; the molar ratio of the organic ligand to the zinc salt is preferably (1.5~3):1, specifically 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3:1.

[0041] In the ZIF-8 metal-organic framework particle synthesis steps provided by this invention, step i) specifically includes:

[0042] i-1) Mix the organic ligand with an organic solvent to obtain a solution of the organic ligand; mix the zinc salt with an organic solvent to obtain a solution of the zinc salt;

[0043] i-2) The solution of the organic ligand is mixed with the solution of the zinc salt. During the mixing process, the solution changes from transparent to milky white, resulting in a milky white mixed solution.

[0044] In the above-mentioned synthesis steps of ZIF-8 metal-organic framework particles provided by the present invention, in step i-1), the preferred ratio of the organic ligand to the organic solvent is (1~1.5) g:30 mL, more preferably 1.23 g:30 mL; the preferred ratio of the zinc salt to the organic solvent is (1.5~2) g:60 mL, more preferably 1.91 g:60 mL.

[0045] In the above-mentioned ZIF-8 metal-organic framework particle synthesis steps provided by the present invention, in step i-2), the mixing method is preferably vigorous stirring; the mixing temperature is preferably 10~40℃, more preferably 25℃ (room temperature); and the mixing time is preferably ≥30min.

[0046] In the ZIF-8 metal-organic framework particle synthesis steps provided by the present invention, in step ii), the heating temperature is preferably 100~150℃, specifically 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃ or 150℃, most preferably 120℃; the heating time is preferably 2~8h, specifically 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h.

[0047] In the ZIF-8 metal-organic framework particle synthesis steps provided by the present invention, in step ii), the washing is preferably performed 2 to 5 times, more preferably 3 times; the washing agent is preferably methanol.

[0048] In the ZIF-8 metal-organic framework particle synthesis steps provided by the present invention, in step ii), the drying method is preferably vacuum drying; the drying temperature is preferably 50~80℃, specifically 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃; the drying time is preferably 8~16h, specifically 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h.

[0049] In the preparation method provided by the present invention, the ZIF-8 metal-organic framework particles are preferably heated and dried before participating in the heating and mixing; wherein, the heating and drying method is preferably vacuum drying; the heating and drying temperature is preferably 50~80℃, specifically 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃; the heating and drying time is preferably 2~8h, specifically 2h, 3h, 4h, 5h, 6h, 7h or 8h.

[0050] In the preparation method provided by the present invention, the organic solution of tributyl phosphonate is prepared by mixing tributyl phosphonate with an organic solvent; wherein, the organic solvent is preferably N,N-dimethylformamide (DMF); the mixing temperature is preferably 30~50℃, specifically 30℃, 35℃, 40℃, 45℃ or 50℃; the mixing time is preferably 20~60min, specifically 20min, 30min, 40min, 50min or 60min.

[0051] In the preparation method provided by the present invention, the preferred ratio of ZIF-8 metal-organic framework particles to tributyl phosphonate is 40 mg: (2~8) mL, specifically 40 mg: 2 mL, 40 mg: 2.5 mL, 40 mg: 3 mL, 40 mg: 3.5 mL, 40 mg: 4 mL, 40 mg: 4.5 mL, 40 mg: 5 mL, 40 mg: 5.5 mL, 40 mg: 6 mL, 40 mg: 6.5 mL, 40 mg: 7 mL, 40 mg: 7.5 mL or 40 mg: 8 mL.

[0052] In the preparation method provided by the present invention, the preferred temperature for heating and mixing the ZIF-8 metal-organic framework particles with the organic solution of tributyl phosphonate is 60~100℃, specifically 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃; the preferred heating and mixing time is 8~16h, specifically 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h.

[0053] In the preparation method provided by the present invention, after the ZIF-8 metal-organic framework particles and the organic solution of tributyl phosphonate are heated, mixed and filtered, the washing is preferably performed 2 to 5 times, more preferably 3 times; the washing agent is preferably N,N-dimethylformamide.

[0054] In the preparation method provided by this invention, after the ZIF-8 metal-organic framework particles and the organic solution of tributyl phosphonate are heated, mixed, filtered, and washed, the drying method is preferably vacuum drying; the drying temperature is preferably 50~80℃, specifically 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃; the drying time is preferably 8~16h, specifically 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h.

[0055] The present invention also provides a ZIF-8 adsorbent modified with tributyl phosphonate, wherein the adsorbent is prepared according to the preparation method described in the above technical solution.

[0056] This invention also provides a method for treating Dy in rare earth mine wastewater.3+ The recycling method is characterized by comprising the following steps:

[0057] Using adsorbents to remove Dy from rare earth mine wastewater 3+ Adsorption and recovery are carried out;

[0058] The adsorbent includes the ZIF-8 adsorbent modified with tributyl phosphonate as described in the above technical solution.

[0059] In the recycling method provided by this invention, the rare earth mine wastewater contains Dy 3+ Preferably, K is also included. + Na + Mg 2+ Ca 2+ Ni 2+ Cu 2+ and Nd 3+ One or more of them.

[0060] In the recycling method provided by this invention, the rare earth mine wastewater undergoes Dy... 3+ Before recycling, it is preferable to adjust its pH value to 5-6, more preferably to 5.5; the reagent for adjusting the pH value is preferably HCl and / or NaOH.

[0061] In the recycling method provided by this invention, the rare earth mine wastewater undergoes Dy... 3+ Before recycling, it is preferable to filter and remove impurities.

[0062] In the recycling method provided by the present invention, the water body is preferably stirred during the adsorption and recycling process, and the stirring speed is preferably 300~800 rpm, more preferably 500 rpm; the adsorption and recycling temperature is preferably 10~40℃, more preferably 25℃ (room temperature); the adsorption and recycling time is preferably 4~16h, specifically 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h.

[0063] The technical solution provided by this invention first synthesizes ZIF-8, and then modifies tributyl phosphonate (TBP) via a solvothermal method, ensuring high selectivity and structural stability of the material. The synthesis steps are simple, do not use toxic or harmful reagents, and the synthesis conditions are mild, not involving high-temperature or high-pressure reactions, making it energy-saving and environmentally friendly. While maintaining the structural stability of ZIF-8, the technical solution provided by this invention effectively modifies its surface with TBP groups, ensuring sufficient adsorption sites for the adsorbent. Simultaneously, it utilizes the phosphooxy functional groups in the TBP groups for Dy... 3+ It has a strong affinity and can bind to it through coordination, making the prepared adsorbent effective against Dy. 3+It exhibits specific selectivity. The adsorbent prepared in this invention is effective for Dy 3+ The selectivity is significantly improved, and it can effectively separate Dy when multiple monovalent and divalent interfering ions coexist. 3+ Therefore, it is possible to selectively and efficiently recover high-value lanthanide ions (Dy) from rare earth mine wastewater. 3+ More specifically, the technical solution of the present invention has the following advantages:

[0064] (1) ZIF-8 as the substrate has a large specific surface area and good stability, providing excellent adsorption capacity;

[0065] (2) The synthesis method of ZIF-8 substrate is simple, safe and easy to operate. It does not require a high temperature, strong acid and strong base synthesis environment. The synthesis technology is mature and the cost is easy to control. It has the potential for large-scale commercial use.

[0066] (3) The synthesized ZIF-8-TBP is suitable for high-value heavy rare earth ions Dy 3+ It exhibits significant selectivity, enabling rapid and highly selective recovery of target ions from rare earth mine wastewater.

[0067] Figure 1 This invention demonstrates the preparation route of ZIF-8-TBP and its selective adsorption of Dy provided in the embodiments of the present invention. 3+ The process; for clarity, the following examples will provide a detailed description.

[0068] Example 1

[0069] The preparation process of TBP-modified ZIF-8 adsorbent is as follows:

[0070] 1.23 g of 2-methylimidazole was dissolved in 30 mL of methanol and stirred until completely dissolved. 1.91 g of zinc nitrate hexahydrate was dissolved in 60 mL of methanol and stirred until completely dissolved. The methanol solution of zinc nitrate hexahydrate was poured into the methanol solution of 2-methylimidazole and stirred vigorously for 30 minutes until the solution changed from clear and transparent to milky white. The milky white solution was transferred to a 70 mL stainless steel hydrothermal reactor lined with Teflon®, the reactor lid was tightened, and the reactor was placed in a 120°C forced-air drying oven for 4 hours. After the reaction was completed, the reactor was allowed to cool naturally to room temperature and then filtered to obtain ZIF-8 filter cake. After washing the filter cake three times with methanol, it was dried in a 70°C vacuum drying oven for 12 hours and then ground to obtain ZIF-8 powder.

[0071] 40 mg of ZIF-8 powder was poured into 20 mL of DMF solution containing 20 vol% TBP, placed in an oil bath, and heated at 80 °C with stirring for 12 hours. After naturally cooling to room temperature, the ungrafted TBP was washed away three times by DMF filtration, and then dried in a vacuum drying oven at 60 °C for 12 hours. After drying, ZIF-8-TBP was obtained by grinding.

[0072] The ZIF-8 and ZIF-8-TBP prepared in this embodiment were observed by scanning electron microscopy (SEM), and the results are as follows: Figure 2 and Figure 3 As shown, Figure 2 This is a SEM image of ZIF-8 provided in Embodiment 1 of the present invention. Figure 3 This is a SEM image of ZIF-8-TBP provided in Embodiment 1 of the present invention.

[0073] X-ray diffraction and infrared spectroscopy analyses were performed on the ZIF-8 and ZIF-8-TBP prepared in this embodiment, and the results are as follows: Figure 4 and Figure 5 As shown, Figure 4 These are the X-ray diffraction patterns of ZIF-8 and ZIF-8-TBP provided in Embodiment 1 of the present invention. Figure 5 These are the infrared spectra of ZIF-8 and ZIF-8-TBP provided in Embodiment 1 of the present invention. (The last sentence appears to be incomplete and possibly refers to a technical specification or method.) Figures 4-5 It can be seen that the ZIF-8 structure remains stable before and after TBP modification, and TBP is successfully modified on ZIF-8.

[0074] Example 2

[0075] ZIF-8-TBP at different pH values ​​regarding Dy 3+ The applications of adsorption recovery are as follows:

[0076] Weigh out 621.68 mg of NdCl3. . 6H2O and 579.92 mg DyCl3 . Dissolve 6H2O in 50 mL of deionized water to prepare a solution of 5000 mg / L Nd. 3+ and Dy 3+ The mother liquor was kept for later use; the adsorbent ZIF-8-TBP was tested for its effect on Dy at different solution pH values. 3+ The effect of adsorption recovery capacity is detailed in the following steps: Add DyCl3... . A solution of 50 mg / L Dy was prepared using 6H2O. 3 mL of this solution was drawn using a syringe, filtered through a 0.22 μm filter, and injected into a 10 mL centrifuge tube for storage in the dark. The initial concentration was then tested using inductively coupled plasma atomic emission spectrometry (ICP-AES). 10 mL of the 50 mg / L Dy solution was then transferred using a 5 mL pipette. 3+The solution was poured into several 25 mL screw-top vials. The pH of the solutions in the different vials was adjusted to 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and 5.5 using 0.1 mol / L HCl and 0.1 mol / L NaOH. Then, 5 mg of the adsorbent ZIF-8-TBP synthesized in Example 1 (adsorbent dosage of 0.5 g / L) was weighed and added to the vials containing solutions of different pH values. After adding a magnetic stir bar, the mixture was stirred at 500 rpm for 8 hours. After adsorption was completed, 3 mL of the solution was drawn with a syringe, filtered through a 0.22 μm filter membrane, injected into a 10 mL centrifuge tube, and stored in the dark. The concentration was then tested using ICP-AES.

[0077] Experimental results are as follows Figure 6 As shown, Figure 6 The ZIF-8-TBP provided in Example 2 of this invention is effective for Dy at different pH values. 3+ Adsorption capacity diagram. (By...) Figure 6 It can be seen that during the process of increasing the pH of the solution with added NaOH, the amount of negative charge on the surface of the adsorbent gradually increases, enhancing the interaction between the adsorbent ZIF-8-TBP and Dy. 3+ The electrostatic interaction between them promoted Dy 3+ Enrichment of the material enhances the adsorbent's ability to process Dy. 3+ Adsorption capacity.

[0078] Example 3

[0079] ZIF-8-TBP is used for light and heavy rare earth ion Nd. 3+ Dy 3+ The applications of separation are as follows:

[0080] Nd is prepared using the above mother liquor 3+ and Dy 3+ A mixed solution with a concentration of 25 mg / L was prepared. 3 mL of the solution was drawn using a syringe, filtered through a 0.22 μm filter, and injected into a 10 mL centrifuge tube for storage in the dark. The initial concentration was then tested using inductively coupled plasma atomic emission spectrometry (ICP-AES). 10 mL of the mixed solution was transferred to a 25 mL capillary vial using a 5 mL pipette. 5 mg of the adsorbent ZIF-8-TBP synthesized in Example 1 (adsorbent dosage of 0.5 g / L) was weighed and added to the capillary vial containing the mixed solution. The mixture was stirred at 500 rpm for 8 hours. After adsorption, 3 mL of the solution was drawn using a syringe, filtered through a 0.22 μm filter, and injected into a 10 mL centrifuge tube for storage in the dark. The concentration was then tested using ICP-AES.

[0081] Experimental results are as follows Figure 7 As shown, Figure 7 This is a distribution coefficient diagram of ZIF-8-TBP for different cations in simulated wastewater, provided in Embodiment 3 of the present invention. (Through...) Figure 7 It can be seen that the adsorbent ZIF-8-TBP is effective for heavy rare earth ions Dy 3+ The partition coefficient is as high as 35713 ml / g, which is the highest among light rare earth ions, Nd. 3+ The prepared adsorbent ZIF-8-TBP is 24 times more effective than Dy 3+ Exhibiting significant selectivity, the adsorbent ZIF-8-TBP developed in this invention has a significantly improved selectivity for light and heavy rare earth elements compared to existing adsorbents, enabling effective separation of the two.

[0082] Example 4

[0083] ZIF-8-TBP was used to simulate heavy rare earth ions (Dy) in wastewater. 3+ The recycling process is detailed below:

[0084] Add 19.06 mg KCl, 25.42 mg NaCl, and 83.63 mg MgCl2 to 1000 mL of deionized water. . 6H2O, 27.69 mg CaCl2, 40.50 mg NiCl2 . 6H2O, 26.83 mg CuCl2 . 2H2O, 23.20 mg DyCl3 . 6H2O, prepared as K + Na + Mg 2+ Ca 2+ Ni 2+ Cu 2+ Dy 3+ A mixed solution with a concentration of 10 mg / L was prepared. 3 mL of the solution was drawn with a syringe, filtered through a 0.22 μm filter, and injected into a 10 mL centrifuge tube for storage in the dark. The initial concentration was then tested using ICP-AES. 10 mL of the mixed solution was transferred to a 25 mL screw-top vial using a 5 mL pipette. 5 mg of the adsorbent ZIF-8-TBP synthesized in Example 1 (adsorbent dosage of 0.5 g / L) was weighed and added to the vial containing the mixed solution. A magnetic stir bar was added, and the mixture was stirred at 500 rpm. After 8 hours of adsorption, 3 mL of the solution was drawn with a syringe, filtered through a 0.22 μm filter, and injected into a 10 mL centrifuge tube for storage in the dark. The concentration was tested using ICP-AES, and the partition coefficient of the adsorbent for each ion was calculated.

[0085] Experimental results are as follows Figure 8 As shown, Figure 8 The ZIF-8-TBP provided in Embodiment 4 of this invention is for Nd 3+ Dy 3+ The distribution coefficient diagram. (Through) Figure 8It can be seen that the ZIF-8-TBP adsorbent, due to its modification with heavy rare earth ions Dy 3+ The TBP groups, possessing selective binding capabilities, exhibit excellent selectivity in mixed solutions. The adsorbent ZIF-8-TBP synthesized in Example 1 demonstrates excellent selectivity for the target ion Dy. 3+ The partition coefficient reached 39286 ml / g, significantly higher than that of the coexisting monovalent and divalent interfering ions, effectively realizing the simulation of high-value Dy in rare earth mine wastewater. 3+ Effective recycling.

[0086] Example 5

[0087] ZIF-8-TBP is used for the treatment of heavy rare earth ions (Dy) in wastewater from actual rare earth mines. 3+ The recycling process is detailed below:

[0088] Using wastewater from rare earth mines in Ganzhou City, Jiangxi Province as the target, this study investigated the Dy content of heavy rare earth ions in actual rare earth mine wastewater. 3+ The recycling application was carried out. Insoluble impurities in the mine wastewater were removed by filtration with filter paper. The pH of the filtered rare earth mine wastewater was adjusted to 5.5 using 0.1 mol / L HCl and NaOH solutions to obtain treated mine wastewater. 3 ml of the solution was drawn with a syringe, filtered through a 0.22 μm filter membrane, and injected into a 10 ml centrifuge tube for storage in the dark. The initial concentration of the mine wastewater was tested using ICP-AES. 10 ml of the treated mine wastewater was transferred to a 25 ml screw-top vial using a 5 ml pipette. 5 mg of the adsorbent ZIF-8-TBP synthesized in Example 1 (adsorbent dosage of 0.5 g / L) was weighed and added to the screw-top vial containing the treated rare earth mine wastewater. The mixture was stirred at 500 rpm and after 8 hours of adsorption, 3 ml of the solution was drawn with a syringe, filtered through a 0.22 μm filter membrane, and injected into a 10 ml centrifuge tube for storage in the dark. The concentration was then tested using ICP-AES, and the partition coefficient of the adsorbent for each ion was calculated.

[0089] Experimental results are as follows Figure 9 As shown, Figure 9 This is a distribution coefficient diagram of ZIF-8-TBP for different cations in rare earth mine wastewater, provided in Embodiment 5 of the present invention. (Through...) Figure 9 It can be seen that, in actual rare earth mine wastewater, in addition to the common monovalent and divalent interferences, there are a relatively large number of light rare earth ions, whose market value is lower than that of heavy rare earth ions (Dy). 3+ In actual mine wastewater systems, the adsorbent ZIF-8-TBP synthesized in Example 1 showed good performance for the target ion Dy. 3+ The distribution coefficient reached 22,688 ml / g, which is much higher than that of divalent impurity ions (Mn) coexisting in mine wastewater. 2+ Ca 2+ Mn2+ Pb 2+ ) and light rare earth ions with lower economic value (La) 3+ Ce 3+ 、Nd 3+ In practical systems, it can effectively achieve the target ion Dy. 3+ Effective recycling.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a ZIF-8 adsorbent modified with tributyl phosphonate, characterized in that, Includes the following steps: ZIF-8 metal-organic framework particles were synthesized by heating and mixing the ZIF-8 metal-organic framework particles with an organic solution of tributyl phosphonate, followed by filtration, washing, drying, and crushing to obtain a tributyl phosphonate-modified ZIF-8 adsorbent.

2. The preparation method according to claim 1, characterized in that, The specific steps for synthesizing the ZIF-8 metal-organic framework particles include: i) The organic ligand and zinc salt are mixed in an organic solvent to obtain a milky white mixed solution; ii) The milky white mixed solution was heated in a sealed environment, then filtered, washed, dried and crushed to obtain ZIF-8 metal-organic framework particles.

3. The preparation method according to claim 2, characterized in that, Step i) specifically includes: i-1) Mix the organic ligand with an organic solvent to obtain a solution of the organic ligand; mix the zinc salt with an organic solvent to obtain a solution of the zinc salt; i-2) The solution of the organic ligand is mixed with the solution of the zinc salt. During the mixing process, the solution changes from transparent to milky white, resulting in a milky white mixed solution.

4. The preparation method according to claim 2, characterized in that, In step ii), the heating temperature is 100–150°C; the heating time is 2–8 hours.

5. The preparation method according to claim 1, characterized in that, The ZIF-8 metal-organic framework particles are first heated and dried before being involved in the heating and mixing process.

6. The preparation method according to claim 1, characterized in that, The heating and mixing temperature is 60–100°C; the heating and mixing time is 8–16 hours.

7. A ZIF-8 adsorbent modified with tributyl phosphonate, characterized in that, It is prepared according to the preparation method according to any one of claims 1 to 6.

8. A rare earth mine wastewater containing Dy 3+ The recycling method is characterized by, Includes the following steps: Using adsorbents to remove Dy from rare earth mine wastewater 3+ Adsorption and recovery are carried out; The adsorbent includes the ZIF-8 adsorbent modified with tributyl phosphonate as described in claim 7.

9. The recycling method according to claim 8, characterized in that, The rare earth mine wastewater is undergoing Dy 3+ Before recycling, adjust its pH value to 5-6.

10. The recycling method according to claim 8, characterized in that, The rare earth mine wastewater is undergoing Dy 3+ Before recycling, it is filtered to remove impurities.

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