A bowl-shaped uranium peroxide cluster and its preparation method and application

Abstract

The present invention belongs to the field of polyoxometalates, and specifically discloses a uranium peroxo cluster with a bowl-shaped structure, its preparation method and application. The chemical formula of the uranium peroxo cluster is [(UO2) 15 (O2) 10 (HC3O5) 10 ‑20 , and the negative charge of the uranium peroxo cluster is neutralized by lithium ions, potassium ions or tetraethylammonium hydroxide ions. The present invention successfully synthesizes a uranium peroxo cluster with a bowl-shaped structure using uranyl nitrate, hydrogen peroxide, malonic acid, etc., and is expected to be used in fields such as nuclear fuel cycle and catalysis.​

Description

Technical Field

[0001] The invention belongs to the field of polymetallic oxygen clusters, and specifically discloses a uranium peroxide cluster with a bowl-shaped structure and a preparation method and application thereof. Background Art

[0002] The properties and applications of a substance are closely related to its structure. The preparation of substances with new structures is the basis for obtaining substances with novel properties and applications. Therefore, synthesizing substances with new structures by chemical methods and studying the relationship between their structure and performance is one of the important basic research topics in the fields of chemistry and materials. For uranium minerals and compounds, studying their structure is of great significance for understanding the origin of uranium ores and the migration and diffusion behavior of uranium in the environment, evaluating the safety of nuclear waste when stored in geological disposal repositories, developing new spent fuel reprocessing technologies, and developing new uranium materials.

[0003] Uranium has multiple oxidation states such as +3, +4, +5 and +6. Under normal conditions, the most stable is +6. The +6 uranium ion often combines with two oxygen atoms to form two strong U≡O bonds, in the form of linear UO2 2+ It exists in the form of ions (uranyl ions), and the two oxygen atoms bound to the uranium ions are called "uranyl oxygens". Generally speaking, a uranyl ion can coordinate with four, five or six ligand atoms dispersed in its equatorial plane to form tetragonal, pentagonal and hexagonal bipyramidal polyhedral configurations. The unique coordination chemistry of uranyl ions makes uranium ores and uranium compounds mostly have a two-dimensional layered structure, and it is difficult to form a zero-dimensional structure. It was not until 2003 that Professor Peter C. Burns reported the structure of a special uranium ore, uranyl hydridosite. They found that uranyl hydridosite is a peroxide, and that the peroxide formed a curved structural unit UO2 after coordinating with the uranyl ion. 2+ -O2 2- -UO2 2+, and this curved unit can provide the necessary curved surface for the formation of zero-dimensional spherical structure. Therefore, they subsequently carried out more research on uranium peroxides, and in 2005, they prepared uranium peroxide clusters with zero-dimensional cage structures for the first time. The molecular weight of uranium peroxide clusters is much larger than that of conventional inorganic ions. Therefore, uranium in uranium ore, nuclear waste, spent fuel and other materials can be converted into uranium peroxide clusters, and then the uranium can be separated by using the size difference between uranium clusters and other components, and uranium separation technology based on uranium clusters can be developed. In view of this important application of uranium peroxide clusters in the nuclear fuel cycle, researchers have carried out some work on the design and preparation of uranium peroxide clusters, and prepared dozens of uranium peroxide clusters (Dalton Trans. 2018, 47 (17), 5916-5927). However, most of these clusters have closed cage structures, and their structures and properties are relatively similar.

[0004] Uranium peroxy clusters are essentially uranium complexes formed by the coordination of uranyl ions with ligands such as peroxides and hydroxides, so their structure and properties can be regulated by changing the ligands. In the work that has been reported, researchers have synthesized uranium peroxy clusters by replacing some peroxides or hydroxides with ligands such as pyrophosphates and oxalates. However, since the connection between ligands such as pyrophosphates and oxalates and uranyl ions is very similar to the connection between peroxides and uranyl ions, that is, one ligand is connected to two uranyl ions in a "side-on" manner, the structure of these clusters is very similar to that of uranium clusters containing only peroxides, and they are all four-membered, five-membered or six-membered ring structural units containing uranium (Chem. Rev. 2013, 113 (2), 1097-1120).

[0005] Therefore, the present invention is intended to provide a uranium peroxo cluster with different configurations. Summary of the invention

[0006] Based on the above technical problems, the present invention uses malonate and other ligands with non-side-on coordination mode with uranyl ions to carry out synthesis experiments and successfully synthesizes a new type of uranium peroxide cluster U with a "bowl-shaped" structure. 15 -tartronate.

[0007] The first object of the present invention is to provide a novel uranium peroxide cluster with a bowl-shaped structure, the chemical formula of which is [(UO2) 15 (O2) 10 (HC3O5) 10 ] -20 The negative charge of the cluster is neutralized by lithium ions, potassium ions or tetraethylammonium hydroxide ions.

[0008] Preferably, the structure of the uranium peroxo cluster contains 15 uranyl ions and 10 hydroxymalonate ligands;

[0009] The uranium peroxide cluster is a bowl-shaped cluster compound formed by connecting a ten-membered ring structure unit and a five-membered ring structure unit through five hydroxymalonic acid groups;

[0010] The ten-membered ring structural unit is formed by connecting 10 monouranyl peroxide polyhedrons by sharing edges, and each of the monouranyl peroxide polyhedrons is a hexagonal bipyramidal structure formed by the coordination of a uranyl ion, a peroxide and four oxygen atoms from hydroxymalonate ligands;

[0011] The five-membered ring structural unit is formed by connecting five uranium diperoxide polyhedrons in a shared edge manner, and each of the uranium diperoxide polyhedrons is a hexagonal bipyramidal structure formed by the coordination of a uranyl ion with two peroxide radicals and two oxygen atoms from hydroxymalonate radicals.

[0012] Preferably, only the hydroxyl oxygen and two carboxyl oxygens in each hydroxymalonate are coordinated with two uranyl ions at the same time.

[0013] Preferably, in each of the hydroxymalonic acid radicals connecting the ten-membered cyclic structural unit and the five-membered cyclic structural unit, two carboxyl oxygen atoms are coordinated to the same uranyl ion in the five-membered cyclic structural unit, the other two carboxyl oxygen atoms are respectively coordinated to two adjacent uranyl ions in the ten-membered cyclic structural unit, and the hydroxyl oxygen is simultaneously coordinated to two adjacent uranyl ions in the ten-membered cyclic structural unit;

[0014] The remaining five hydroxymalonic acid groups are connected to the ten-membered ring structural unit.

[0015] Preferably, the uranium peroxo cluster forms yellow block crystals after crystallization, and the crystals are monoclinic, which include the following unit cell parameters: α=90°,β=108.6320(10)°,γ=90°,Z=4,the unit cell volume is The crystal space group of the uranium peroxo cluster is P21 / m.

[0016] The second object of the present invention is to provide a method for preparing the uranium peroxo cluster, comprising the following steps:

[0017] Under stirring conditions, hydrogen peroxide, alkali solution, malonic acid solution and salt solution containing potassium ions are added to the solution containing uranyl ions in sequence, and evaporated at room temperature to obtain crystals of uranium peroxy clusters.

[0018] Preferably, the solution containing uranyl ions is a uranyl nitrate solution, the alkali solution is a lithium hydroxide solution or a tetraethylammonium hydroxide solution, and the salt solution containing potassium ions is a potassium chloride solution or a potassium nitrate solution.

[0019] Preferably, the concentration of the uranyl nitrate solution is 0.5 mol / L, the mass fraction of the hydrogen peroxide is 30%, the concentration of the lithium hydroxide solution is 2.4 mol / L, the mass concentration of the tetraethylammonium hydroxide solution is 40%, and the concentrations of the malonic acid solution and the salt solution containing potassium ions are both 0.5 mol / L.

[0020] Preferably, the volume ratio of the uranyl nitrate solution, the hydrogen peroxide, the alkali solution, the malonic acid solution and the salt solution containing potassium ions is 1:1:0.75-1:1.5-2:0.5-3.

[0021] The fourth object of the present invention is to provide a use of the uranium peroxo cluster in the field of nuclear fuel cycle or catalysis.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The present invention uses malonic acid as a reaction reagent, and the reagent is in situ oxidized to hydroxymalonic acid. The hydroxymalonic acid and uranyl ions promote the formation of a ten-membered ring structural unit of uranium in a non-side-on coordination manner, and the final cluster U 15 -tartronate contains an odd number of uranyl ions and presents an unusual "bowl-shaped" structure. The successful preparation of this cluster compound enriches the types, structures and properties of uranium peroxide clusters, and also enriches the crystal chemistry of uranium. At the same time, this cluster compound is expected to be used in the fields of nuclear fuel cycle and catalysis.

[0024] 2. U provided by the present invention 15 -tartronate is the only cluster compound in the field of uranium peroxoclusters that contains a ten-membered ring structural unit of uranium.

[0025] 3. U provided by the present invention 15 The hydroxymalonate ligand in -tartronate is formed by an in situ redox reaction during the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a new type of cluster compound U 15 -tartronate structure (a) and its ten-membered ring (b, c) and five-membered ring structural units (d, e); wherein U is uranyl ion, C is carbon atom, and O is oxygen atom;

[0027] Figure 2 It's U 15 -tartronate structure: (a) the connection mode between the ligand hydroxymalonate and the uranyl ion; (b) polyhedral model, (c) ball-and-stick model; where U is the uranyl ion, C is the carbon atom, and O is the oxygen atom. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0029] The experimental methods and detection methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0030] The present invention provides a bowl-shaped uranium peroxide cluster, the chemical formula of which is [(UO2) 15 (O2) 10 (HC3O5) 10 ] -20 The negative charge of the uranium peroxo cluster is neutralized by lithium ions, potassium ions or tetraethylammonium hydroxide ions.

[0031] Example 1

[0032] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0033] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0034] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.8.

[0035] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0036] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0037] Example 2

[0038] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0039] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 40% tetraethylammonium hydroxide solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0040] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 75 μL of tetraethylammonium hydroxide solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.2.

[0041] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0042] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0043] Example 3

[0044] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0045] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 40% tetraethylammonium hydroxide solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0046] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of tetraethylammonium hydroxide solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 9.1.

[0047] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0048] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0049] Example 4

[0050] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0051] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KNO3 aqueous solution.

[0052] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 100 μL of KNO3 aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.9.

[0053] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0054] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0055] Example 5

[0056] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0057] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0058] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 50 μL of KCl aqueous solution to a 5 ml glass reaction bottle in sequence under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.9.

[0059] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0060] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0061] Example 6

[0062] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0063] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0064] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 200 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.8.

[0065] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0066] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0067] Example 7

[0068] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0069] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0070] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 100 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.8.

[0071] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0072] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0073] Example 8

[0074] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0075] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0076] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 175 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.7.

[0077] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0078] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0079] Example 9

[0080] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0081] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0082] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 225 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in sequence under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.5.

[0083] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0084] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0085] Example 10

[0086] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0087] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0088] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 150 μL of malonic acid solution, and 200 μL of KNO3 aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 9.1.

[0089] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes in the membrane to allow the solution to evaporate slowly at room temperature. After five or six weeks, yellow block crystals will appear in the bottle.

[0090] Step 4: Separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0091] Comparative Example 1

[0092] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0093] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L NaCl aqueous solution.

[0094] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of NaCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0095] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0096] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0097] Comparative Example 2

[0098] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0099] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L NaNO3 aqueous solution.

[0100] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of NaNO3 aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix well before adding the next solution.

[0101] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0102] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0103] Comparative Example 3

[0104] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0105] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L NaOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0106] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of NaOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0107] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0108] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0109] Comparative Example 4

[0110] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0111] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L MgOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0112] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of MgOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0113] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0114] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0115] Comparative Example 5

[0116] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0117] Step 1: Prepare 0.2 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0118] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0119] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0120] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0121] Comparative Example 6

[0122] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0123] Step 1: Prepare 1 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0124] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0125] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0126] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0127] Comparative Example 7

[0128] A bowl-shaped U15 -tartronate, the specific preparation process includes the following steps:

[0129] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 15% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0130] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0131] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0132] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0133] Comparative Example 8

[0134] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0135] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 10% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0136] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution. The pH of the final reaction solution is 8.8.

[0137] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0138] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0139] Comparative Example 9

[0140] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0141] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 1.5 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0142] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0143] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0144] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0145] Comparative Example 10

[0146] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0147] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 1 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0148] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0149] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0150] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0151] Comparative Example 11

[0152] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0153] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.2 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0154] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0155] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0156] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0157] Comparative Example 12

[0158] A bowl-shaped U15 -tartronate, the specific preparation process includes the following steps:

[0159] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 1 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0160] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 100 μL of LiOH aqueous solution, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0161] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0162] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0163] Comparative Example 13

[0164] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0165] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0166] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of LiOH aqueous solution, 100 μL of hydrogen peroxide, 200 μL of malonic acid solution, and 300 μL of KCl aqueous solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0167] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0168] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0169] Comparative Example 14

[0170] A bowl-shaped U 15 -tartronate, the specific preparation process includes the following steps:

[0171] Step 1: Prepare 0.5 mol / L uranyl nitrate aqueous solution, 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution.

[0172] Step 2: Use a pipette to add 100 μL of uranyl nitrate aqueous solution, 100 μL of hydrogen peroxide, 300 μL of KCl aqueous solution, 100 μL of LiOH aqueous solution, and 200 μL of malonic acid solution to a 5 ml glass reaction bottle in order under stirring. After each solution is added, stir and mix the solution before adding the next solution.

[0173] Step 3: Cover the bottle mouth with a polytetrafluoroethylene membrane and poke 5 to 6 small holes on the membrane. Allow the solution to evaporate slowly at room temperature and observe whether crystalline substances appear.

[0174] Step 4: If a crystalline substance is obtained, separate the crystal from the solution, stick a crystal of suitable size and good appearance to the Cryoloop under a microscope, place the Cryoloop on the sample stage of the X-ray single crystal diffractometer, and then test the crystal under liquid nitrogen purge. Based on the collected data, calculate the unit cell parameters of the crystal and analyze the structure of the crystal.

[0175] The results show that comparative examples 1 to 4 and 13 to 14 did not form crystals, while comparative examples 5 to 12 formed crystals. By analyzing the crystals separated from comparative examples 5 to 12, it was found that comparative examples 5 to 12 could not obtain the same uranium clusters as the embodiments of the present invention, indicating that only under the conditions of the present invention can the uranium clusters with the chemical formula [(UO2) 15 (O2) 10 (HC3O5) 10 ] -20 , and the cluster compound U is a bowl-shaped 15 -tartronate.

[0176] The main crystallographic parameters of the crystals formed in Examples 1 to 10 are shown in Table 1.

[0177] Table 1: Cluster U 15 -The main crystallographic parameters of tartronate

[0178]

[0179]

[0180] U 15 -Tartronate structure

[0181] The structure of the yellow crystal can be analyzed through X-ray single crystal diffraction data. Figure 1 As shown in the figure, the structure of the yellow crystal is an unusual "bowl-shaped" cluster. Specifically, the structure of the cluster contains 15 uranyl ions and 10 tartronate ligands. Therefore, it is named U 15 -tartronate.

[0182] Among the dozens of uranium peroxide clusters reported, most contain an even number of uranyl ions, and only U 19 (J.Am.Chem.Soc.2019,141(32),12780-12788), U 21 Pp9(Cryst.Growth Des.2018,18(12),7720-7729) and U 45 Pp 23 (Chem. Rev. 2013, 113(2), 1097-1120) These three clusters contain an odd number of uranyl ions. 15 -tartronate is an unusual cluster compound. In addition, among the reported uranium peroxide clusters, only the cluster U 16 (Inorg.Chem.2009,48(23),10907-10909) has a bowl-shaped structure, so from the perspective of configuration, U 15 -tartronate is also an unusual cluster compound. It is worth mentioning that the reagent added in the reaction of the present invention is malonic acid, but in U 15 The ligand in the -tartronate structure is hydroxymalonic acid, which means that malonic acid is oxidized in the reaction solution to generate hydroxymalonic acid. The ligand undergoes an in-situ redox reaction in the reaction, which is also rare in the previously reported synthesis reactions of cluster compounds.

[0183] U 15 The 15 uranyl ions in the -tartronate structure can be divided into two groups. Figure 1 As shown in Figures b and c, the coordination modes of the 10 uranyl ions are the same. Each uranyl ion is coordinated with a peroxide and four oxygen atoms from the hydroxymalonate ligand to form a hexagonal bipyramidal monoperoxyuranyl polyhedron of uranium. These 10 monoperoxyuranyl polyhedrons are connected by sharing edges to form a ten-membered ring structural unit. This structural unit has not appeared in the reported structures of uranium peroxide clusters. From the perspective of structural units, U 15 -tartronate is also an uncommon uranium peroxy cluster. Figure 1 As shown in d and e, the coordination mode of the remaining five uranyl ions is the same. Each uranyl ion coordinates with two peroxides and two oxygen atoms from hydroxymalonate to form a hexagonal bipyramidal diperoxyuranium polyhedron. These five diperoxyuranium polyhedrons are connected by sharing edges to form a five-membered ring structural unit. The two structural units of the ten-membered ring and the five-membered ring are connected by five hydroxymalonate groups to form a "bowl-shaped" cluster.

[0184] like Figure 2 As shown, U 15 The 10 hydroxymalonates in the -tartronate structure have two coordination modes. Among them, the five hydroxymalonates located between the ten-membered ring and the five-membered ring structural units have the same coordination mode: for each hydroxymalonate, two carboxyl oxygen atoms are coordinated with one uranyl ion, while the hydroxyl oxygen and the other two carboxyl oxygens are coordinated with two uranyl ions. This asymmetric coordination mode of hydroxymalonate may be the reason for the formation of the ten-membered ring structural unit. The remaining five hydroxymalonates are only connected to the ten-membered ring structural unit, showing the second coordination mode. Specifically, only the hydroxyl oxygen and two carboxyl oxygens in each acid radical are coordinated with two uranyl ions.

[0185] U 15 -tartronate is different from the reported uranium peroxy clusters:

[0186] As mentioned above, in addition to U 15 In previous work, the present invention team and peers have synthesized and reported three uranium peroxide clusters containing an odd number of uranyl ions: U 19 (J.Am.Chem.Soc.2019,141(32),12780-12788; ligand: o-phthalic acid), U 21 Pp9 (Cryst. Growth Des. 2018, 18(12), 7720-7729; ligand: pyrophosphate) and U 45 Pp 23(Chem. Rev. 2013, 113(2), 1097-1120; ligand: pyrophosphate) and a cluster with a "bowl-shaped" configuration U 16 (Inorg. Chem. 2009, 48 (23), 10907-10909). These clusters are similar to the U 15 -The differences of tartronate are as follows:

[0187] (1) The synthetic formulas and structures of these clusters are different;

[0188] (2)With U 19 , U 21 Pp9 and U 45 Pp 23 In comparison, although U 15 -tartronate also contains an odd number of uranyl ions, but the number of uranyl ions in these cluster structures is different; the types of ligands in the clusters are also different, with U 19 Contains phthalate ligand, U 21 Pp9 and U 45 Pp 23 Contains pyrophosphate ligands, while U 15 -tartronate contains a hydroxymalonate ligand that is generated in situ during the reaction.

[0189] (3)With U 16 In comparison, although U 15 -tartronate also presents a "bowl-shaped" configuration, but the structural units of the two clusters are different, U 16 It is composed of common uranium four-membered ring and six-membered ring structural units; U 15 -tartronate contains two structural units: a five-membered ring and an unusual ten-membered ring. The ligands of the two clusters are also different, U 16 The structure of U contains two ligands: peroxide and hydroxide; 15 The structure of -tartronate contains two ligands: peroxide and hydroxymalonate.

[0190] (4)U 15 -tartronate is the only cluster compound in the field of uranium peroxoclusters that contains the structural unit of uranium's ten-membered ring.

[0191] In summary, the successful preparation of uranium peroxoclusters provided by the present invention enriches the types, structures and properties of uranium peroxoclusters, and also enriches the crystal chemistry of uranium, and is expected to be applied to spent fuel reprocessing, uranium mining and metallurgy, catalysis and materials.

[0192] U 15- Application of tartronate in spent fuel reprocessing

[0193] The molecular weight of uranium peroxide clusters is much larger than that of conventional inorganic ions. Therefore, uranium in uranium ore, nuclear waste, spent fuel and other materials can be converted into uranium peroxide clusters in the present invention using the method provided by the present invention, and then the uranium clusters can be separated out by using the size difference between the uranium clusters and other components, thereby developing uranium separation technology based on uranium clusters. The specific separation process includes the following steps:

[0194] S1. Add 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution, and 0.5 mol / L KCl aqueous solution to the crushed spent fuel in sequence. After each solution is added, stir and mix the solution thoroughly before adding the next solution.

[0195] The mixing volume ratio of 30% hydrogen peroxide, 2.4 mol / L LiOH aqueous solution, 0.5 mol / L malonic acid solution and 0.5 mol / L KCl aqueous solution is 1:1:2:3;

[0196] UO2 in the spent fuel is dissolved into uranyl ions under the oxidation of hydrogen peroxide (ensuring that the concentration of uranyl ions is controlled at 0.5 mol / L after dissolution). Uranyl ions coordinate with peroxide and hydroxymalonate ions generated by the in-situ oxidation and reduction of malonic acid to form uranium peroxide clusters (i.e., U 15 -tartronate);

[0197] Pu, some minor actinides and fission products are reacted in the alkaline reaction solution as Pu 4+ 、MoO4 2- , Cs + Insoluble actinide products and fission products are separated and stored as high-level solid waste.

[0198] S2. Utilizing the different migration directions or speeds between uranium cluster ions and Pu, minor actinides and fission product ions in gel electrophoresis, uranium is extracted in the form of clusters, while Pu, minor actinides and fission products are stored as high-level liquid waste;

[0199] In the gel electrophoresis system, the gel is agar, the buffer is NaOH-Na2CO3 solution, and the reaction solution separated in S1 is slowly added. A voltage of 100V is applied to the two electrodes, and the cations in the solution move to the cathode. Since the precipitation rate of the impurity anions is slower than that of the uranium cluster anions, the uranium cluster solution is first precipitated from the anode. The above operation is repeated many times to achieve the separation of uranium clusters. The crystals formed by the separated uranium clusters are subjected to X-ray single crystal diffraction, and it is found that they have the same crystallographic parameters as Table 1, indicating that the cluster U in the present invention can indeed be obtained by using the spent fuel as the post-processing raw material according to the method in S1. 15 -tartronate, the cluster compound U 15 -tartronate is feasible for use in uranium separation technology for spent fuel reprocessing.

[0200] S3. Add 1 volume of 0.1 mol / L dilute nitric acid and two volumes of 30% hydrogen peroxide to the separated uranium cluster solution, control the solution pH at about 1, and convert the uranium peroxide cluster into uranium ore (UO2)O2(H2O)4 precipitate. A small amount of fission product ions adsorbed on the surface of the uranium peroxide cluster remain in the solution, filter, separate the uranium ore precipitate, and store the filtrate properly. Compared with the uranium content in the original spent fuel, the uranium recovery efficiency can reach 96.4%.

[0201] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, they are also intended to be included.

Claims

1. A bowl-shaped uranium peroxide cluster, characterized in that: The chemical formula of the uranium peroxo cluster is [(UO2) 15 (O2) 10 (HC3O5) 10 ] -20 The negative charge of the uranium peroxo cluster is neutralized by lithium ions, potassium ions or tetraethylammonium hydroxide ions.

2. The uranium peroxy cluster according to claim 1, characterized in that The structure of the uranium peroxo cluster contains 15 uranyl ions and 10 hydroxymalonate ligands; The uranium peroxide cluster is a bowl-shaped cluster compound formed by connecting a ten-membered ring structure unit and a five-membered ring structure unit through five hydroxymalonic acid groups; The ten-membered ring structural unit is formed by connecting 10 monouranyl peroxide polyhedrons by sharing edges, and each monouranyl peroxide polyhedron is a hexagonal bipyramidal structure formed by the coordination of a uranyl ion, a peroxide and four oxygen atoms from hydroxymalonate ligands; The five-membered ring structural unit is formed by connecting five uranium diperoxide polyhedrons in a shared edge manner, and each of the uranium diperoxide polyhedrons is a hexagonal bipyramidal structure formed by the coordination of a uranyl ion with two peroxide radicals and two oxygen atoms from hydroxymalonate radicals.

3. The uranium peroxy cluster according to claim 1, characterized in that In each of the hydroxymalonic acid radicals connecting the ten-membered cyclic structural unit and the five-membered cyclic structural unit, two carboxyl oxygen atoms are coordinated with the same uranyl ion in the five-membered cyclic structural unit, the other two carboxyl oxygen atoms are respectively coordinated with two adjacent uranyl ions in the ten-membered cyclic structural unit, and the hydroxyl oxygen is simultaneously coordinated with two adjacent uranyl ions in the ten-membered cyclic structural unit; The remaining five hydroxymalonic acid groups are connected to the ten-membered ring structural unit.

4. The uranium peroxy cluster according to claim 1, characterized in that The uranium peroxide cluster forms yellow block crystals after crystallization. The crystals are monoclinic and include the following unit cell parameters: a=26.1830 (15) Å, b=21.9950 (13) Å, c=31.2214 (18) Å, α=90°, β=108.6320 (10)°, γ=90°, Z=4, and the unit cell volume is 17037.9 (17) Å 3 ; The crystal space group of the uranium peroxide cluster is P21 / m.

5. A method for preparing uranium peroxo clusters according to claim 1, characterized in that: The following steps are involved: Under stirring conditions, hydrogen peroxide, alkali solution, malonic acid solution and salt solution containing potassium ions are sequentially added to the solution containing uranyl ions, and evaporated at room temperature to obtain crystals of uranium peroxide clusters; The alkali solution is a lithium hydroxide solution or a tetraethylammonium hydroxide solution, and the salt solution containing potassium ions is a potassium chloride solution or a potassium nitrate solution; The solution containing uranyl ions is a uranyl nitrate solution, the concentration of the uranyl nitrate solution is 0.5 mol / L, the mass fraction of the hydrogen peroxide is 30%, the concentration of the lithium hydroxide solution is 2.4 mol / L, the mass concentration of the tetraethylammonium hydroxide solution is 40%, and the concentrations of the malonic acid solution and the salt solution containing potassium ions are both 0.5 mol / L; the volume ratio of the uranyl nitrate solution, the hydrogen peroxide, the alkali solution, the malonic acid solution and the salt solution containing potassium ions is 1:1:0.75~1:1.5~2:0.5~3.

6. Use of the uranium peroxo cluster according to any one of claims 1 to 4 in a nuclear fuel cycle.

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