Metal-organic framework glass material for solidifying radionuclide and preparation method of metal-organic framework glass material

Abstract

The invention discloses a preparation method for adsorbing and curing radionuclides by using a metal-organic framework material, and relates to the technical field of environmental protection and governance, the preparation method comprises the following steps: S1, adding a pre-synthesized crystalline metal-organic framework into a solution containing radionuclides until adsorption equilibrium, and then adding a metal-organic framework into the solution containing radionuclides; separating and drying to obtain a radionuclide adsorbed metal-organic framework powder material sample; and S2, placing the material obtained in S1 in an inert gas atmosphere, and carrying out heat treatment to obtain the metal-organic framework glass for curing radionuclide. The metal-organic framework firmly adsorbs radionuclides by virtue of the chemical complexing action of the network skeleton group, the vitrified network solidifies and seals the radionuclides, and meanwhile, the metal-organic framework glass with the compact structure can withstand underground water erosion, prevent radionuclide leakage and improve the safety of the radionuclides. And compared with borosilicate glass, the metal-organic framework glass has lower melting temperature, can effectively reduce the volatilization of radionuclides, and reduces the energy consumption of the treatment process.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection and treatment, in particular to a preparation method for metal-organic framework materials to adsorb and solidify radioactive nuclides. Background Art

[0002] With the rapid development of nuclear science and technology in the fields of industry, medicine, agriculture, and military, waste containing radioactive nuclides is inevitably generated. As we all know, the radioactive nuclides in these wastes can be enriched through soil or water bodies through plants and animals, and enter the human body through the food chain, causing serious harm to the ecological environment and human health. How to safely and effectively deal with these radioactive nuclear wastes has become one of the more difficult environmental problems.

[0003] Common radionuclides in radioactive pollutants include radium, uranium, cobalt, polonium, deuterium, argon, krypton, xenon, iodine, strontium, cesium, plutonium, etc. At present, the more conventional methods for treating radionuclides include reverse osmosis concentration, evaporation concentration, ultrafiltration, coagulation precipitation, ion exchange, biological treatment, solidification, adsorption, etc. Among them, adsorption has become the mainstream treatment method because of its simplicity, high efficiency and low cost. In recent years, porous material adsorption is considered to be one of the most effective strategies for achieving waste liquid volume reduction and radionuclide removal.

[0004] Metal-organic framework materials are porous crystalline materials formed by metal ions and organic ligands connected by coordination. Functionalized adsorption materials with high specific surface area and high porosity can be obtained by adjusting metal ions and ligands, which can achieve efficient adsorption of radioactive ions. However, due to the inherent crystal structure defects and low mechanical stability of crystalline MOF materials, under long-term storage conditions, the influence of external heat and stress factors causes the collapse of its framework, resulting in the leakage of radionuclides. Therefore, a preparation method for metal-organic framework materials to adsorb and solidify radionuclides is proposed. Summary of the invention

[0005] The object of the present invention is to provide a preparation method for metal-organic framework materials for adsorbing and immobilizing radioactive nuclides, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a preparation method for metal-organic framework material adsorbing and immobilizing radioactive nuclides, the preparation method comprising the following steps:

[0007] S1. Adding the pre-synthesized crystalline metal-organic framework into a solution containing radioactive nuclides, and after reaching adsorption equilibrium, separating and drying to obtain a metal-organic framework powder material sample adsorbing radioactive nuclides;

[0008] S2, placing the sample obtained in step S1 in a furnace under an inert gas atmosphere and heat treating it at 100-600° C. for 1 min-3 h to obtain a metal-organic framework glass with solidified radionuclides.

[0009] Preferably, the crystalline metal-organic framework in step S1 includes but is not limited to crystalline metal-organic framework including but not limited to phosphate-imidazole series (such as [Zn(HPO4)(H2PO4)](H2Im)2, [Zn3(H2PO4)6(H2O)3](HbIm), [Zn3(H2PO4)6(H2O)3]H(2-MebIm), [Zn3(H2PO4)6(H2O)3](BTA) etc.), zeolite imidazole salt series (such as ZIF-7, ZIF-8, ZIF-62, ZIF-76 etc.), titanium oxide cluster-hydroquinone series (such as Ti 16 O 16 (OEt) 32 、Ti 12 O 16 (O-iPr) 16 etc.), thiocyanates (such as Cu2(SCN)3(C4bpy), [Co(μ-NCS)2(C5H5N3O)2]·C5H5N3O) and bis(fluorosulfonyl)imide-nitrile framework series (such as Li[N(SO2F)2](NCCH2CH2CN)2), metal-bis(acetamide) framework (such as Co(hmba)3[Co(NCS)4], Co(bba)3[CoCl4], Co(hmba)3[CoBr4]), carboxylic acid metal-organic framework (such as UiO-67, UiO-68, DUT-5, [Mg4(adipate)4(DMA)(H2O),) pyridine-carboxylic acid metal-organic framework (such as [Mn3(peb)6]·2DMF) or at least one of them.

[0010] Preferably, in step S1, the mass concentration of the crystalline metal-organic framework material relative to the radioactive nuclide solution is 1.5 to 5 g / L.

[0011] Preferably, the radioactive nuclides in step S1 include but are not limited to thorium, radium, uranium, cobalt, polonium, iodine, cesium, plutonium or at least one thereof.

[0012] Preferably, the pH of the radionuclide solution in step S1 is 2-11.

[0013] Preferably, the heating rate of the crystalline metal-organic framework that adsorbs radioactive nuclides during vitrification in step S2 is 1-20° C. / min.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The metal-organic framework of the present invention firmly adsorbs radionuclides by virtue of the chemical complexation of its network skeleton groups, and the vitrified network solidifies and seals the radionuclides; at the same time, the metal-organic framework glass with a dense structure can withstand groundwater erosion and prevent leakage of radionuclides; and the metal-organic framework glass has a lower melting temperature than borosilicate glass, which can effectively reduce the volatilization of radionuclides and reduce the energy consumption of the treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram of the radionuclide metal-organic framework glass adsorption-curing steps of the present invention;

[0017] Figure 2 This is the measured XRD diagram of the metal-organic framework glass before and after the adsorption and solidification of nuclides in Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Embodiment 1

[0020] (1) See Figure 1 , 5 g of the pre-synthesized crystalline metal-organic framework ZIF-4 was added to a 2 L solution containing radioactive nuclides, wherein the radioactive nuclide concentration was 1.5 g / L and the solution pH was 7, after oscillation to reach adsorption equilibrium, the ZIF-4 powder material adsorbing radioactive nuclides was obtained by separation and drying at 120°C;

[0021] (2) placing the sample obtained in step (1) in a furnace under an inert gas atmosphere, and heat treating it at 550° C. for 5 min at a rate of 3° C. / min to obtain a metal-organic framework glass with solidified radionuclides, whose XRD is as follows Figure 2 shown.

[0022] Embodiment 2

[0023] (1) See Figure 1 , 3 g of pre-synthesized crystalline metal-organic framework ZIF-76 was added to 1 L of a solution containing radioactive nuclides, wherein the concentration of the radioactive nuclides was 2.5 g / L and the pH of the solution was 4, after oscillation to reach adsorption equilibrium, the material was separated and dried at 120°C to obtain a ZIF-76 powder material adsorbing radioactive nuclides;

[0024] (2) placing the sample obtained in step (1) in a furnace under an inert gas atmosphere, and heat treating it at 480° C. for 15 min at a rate of 2° C. / min to obtain a metal-organic framework glass with solidified radionuclides.

[0025] Embodiment 3

[0026] (1) See Figure 1 , 2g of the pre-synthesized crystalline metal-organic framework Ti 16 O 16 (OEt) 32 Add to 2L solution containing radioactive nuclides, where the radioactive nuclide concentration is 2g / L and the solution pH is 8. After oscillation to reach adsorption equilibrium, separate and dry at 120℃ to obtain the adsorbed radioactive nuclide Ti 16 O 16 (OEt) 32 Powder materials;

[0027] (2) placing the sample obtained in step (1) in a furnace under an inert gas atmosphere, and heat treating it at 200° C. for 20 min at a rate of 2° C. / min to obtain a metal-organic framework glass with solidified radionuclides.

[0028] Embodiment 4

[0029] (1) See Figure 1 , 6 g of the pre-synthesized crystalline metal-organic framework Cu2(SCN)3(C4bpy) was added to a 3 L solution containing radioactive nuclides, wherein the radioactive nuclide concentration was 2.5 g / L and the solution pH was 7. After oscillation to reach adsorption equilibrium, the adsorbed radioactive nuclide Cu2(SCN)3(C4bpy) powder material was obtained by separation and drying at 120°C;

[0030] (2) The sample obtained in step (1) is placed in a furnace under an inert gas atmosphere, and heat treated at 350° C. for 10 min at a rate of 5° C. / min to obtain Cu2(SCN)3(C4bpy) glass with solidified radioactive nuclides.

[0031] Embodiment 5

[0032] (1) See Figure 1 , add 6 g of pre-synthesized crystalline metal-organic framework Li[N(SO2F)2](NCCH2CH2CN)2 into 2.5 L of solution containing radionuclides, wherein the radionuclides concentration is 2 g / L and the solution pH is 5, after oscillation to reach adsorption equilibrium, separate and dry at 120°C to obtain powder material adsorbing radionuclides Li[N(SO2F)2](NCCH2CH2CN)2;

[0033] (2) The sample obtained in step (1) is placed in a furnace under an inert gas atmosphere and heat treated at 250°C for 30 min at a rate of 5°C / min to obtain Li[N(SO2F)2](NCCH2CH2CN)2, which is a solidified radioactive nuclide.

[0034] Embodiment 6

[0035] (1) See Figure 1 , 5 g of the pre-synthesized crystalline metal-organic framework ZIF-68 was added to a 2 L solution containing radioactive nuclides, wherein the radioactive nuclide concentration was 1.5 g / L and the solution pH was 10, after oscillation to reach adsorption equilibrium, the ZIF-68 powder material adsorbing radioactive nuclides was obtained by separation and drying at 120°C;

[0036] (2) The sample obtained in step (1) is placed in a furnace under an inert gas atmosphere, and heat treated at 450° C. for 5 min at a rate of 3° C. / min to obtain ZIF-68 glass with solidified radionuclides.

[0037] Embodiment 7

[0038] (1) See Figure 1 , 4 g of the pre-synthesized crystalline metal-organic framework ZIF-UC-5 was added to a 2 L solution containing radioactive nuclides, wherein the radioactive nuclide concentration was 2.5 g / L and the solution pH was 6, after oscillation to reach adsorption equilibrium, the ZIF-UC-5 powder material adsorbing radioactive nuclides was obtained by separation and drying at 120°C;

[0039] (2) The sample obtained in step (1) is placed in a furnace under an inert gas atmosphere, and heat treated at 580° C. for 2 h at a rate of 10° C. / min to obtain ZIF-UC-5 glass with solidified radionuclides.

[0040] Embodiment 8

[0041] (1) See Figure 1 , 3 g of the pre-synthesized crystalline metal-organic framework Co(hmba)3[Co(NCS)4) was added to 1.5 L of a solution containing radioactive nuclides, wherein the radioactive nuclide concentration was 1.5 g / L and the solution pH was 2. After oscillation to reach adsorption equilibrium, the adsorbed radioactive nuclide Co(hmba)3[Co(NCS)4) powder material was obtained by separation and drying at 120°C;

[0042] (2) The sample obtained in step (1) is placed in a furnace under an inert gas atmosphere, and heat treated at 500°C for 1 hour at a rate of 10°C / min to obtain Co(hmba)3[Co(NCS)4] glass containing solidified radionuclides.

[0043] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a metal-organic framework material for adsorbing and immobilizing radionuclides, characterized in that: The preparation method comprises the following steps: A. adding the pre-synthesized crystalline metal-organic framework into a solution containing radioactive nuclides, and after reaching adsorption equilibrium, separating and drying to obtain a metal-organic framework powder material sample adsorbing radioactive nuclides; B. The sample obtained in step S1 is placed in a furnace under an inert gas atmosphere and subjected to heat treatment at 100 to 600° C. for 1 min to 3 h to obtain a metal-organic framework glass with solidified radionuclides.

2. The method for preparing a metal-organic framework material for adsorption and immobilization of radionuclides according to claim 1, characterized in that: The crystalline metal-organic framework in step S1 includes but is not limited to phosphate-imidazole series (such as [Zn(HPO4)(H2PO4)](H2Im)2, [Zn3(H2PO4)6(H2O)3](HbIm), [Zn3(H2PO4)6(H2O)3]H(2-MebIm), [Zn3(H2PO4)6(H2O)3](BTA) etc.), zeolite imidazole salt series (such as ZIF-7, ZIF-8, ZIF-62, ZIF-76 etc.), hydroquinone series (such as Ti 16 O 16 (OEt) 32 、Ti 12 O 16 (O-iPr) 16 etc.), thiocyanates (such as Cu2(SCN)3(C4bpy), [Co(μ-NCS)2(C5H5N3O)2]·C5H5N3O) and bis(fluorosulfonyl)imide-nitrile framework series (such as Li[N(SO2F)2](NCCH2CH2CN)2), metal-bis(acetamide) framework (such as Co(hmba)3[Co(NCS)4), Co(bba)3[CoCl4], Co(hmba)3[CoBr4]), carboxylic acid metal-organic framework (such as UiO-67, UiO-68, DUT-5, [Mg4(adipate)4(DMA)(H2O),) pyridine-carboxylic acid metal-organic framework (such as [Mn3(peb)6]·2DMF) or at least one of them.

3. The method for preparing a metal-organic framework material for adsorbing and immobilizing radionuclides according to claim 1, characterized in that: In the step S1, the mass concentration of the crystalline metal-organic framework material relative to the radioactive nuclide solution is 1.5 to 5 g / L.

4. The method for preparing a metal-organic framework material for adsorbing and immobilizing radionuclides according to claim 1, characterized in that: The radioactive nuclides in step S1 include but are not limited to thorium, radium, uranium, cobalt, polonium, iodine, cesium, plutonium or at least one of them.

5. The method for preparing a metal-organic framework material for adsorbing and immobilizing radionuclides according to claim 1, characterized in that: In step S1, the pH value of the radionuclide solution is 2-11.

6. The method for preparing a metal-organic framework material for adsorbing and immobilizing radionuclides according to claim 1, characterized in that: The heating rate of the crystalline metal-organic framework that adsorbs radioactive nuclides during vitrification in step S2 is 1-20° C. / min.

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