An ammonium thio stannate salt, its preparation method and application

Abstract

The application provides an ammonium thio stannate salt and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a sulfur source, a tin source, a soluble metal salt and water to perform a hydrothermal reaction, so as to obtain a thio stannate salt; and mixing the obtained thio stannate salt with an ammonium salt, so as to obtain the ammonium thio stannate salt. The ammonium thio stannate salt provided by the application has high selectivity, high adsorption capacity, fast kinetics and good cycle stability in sodium, potassium, rubidium, magnesium, calcium and other ions, and has high efficiency in adsorbing cesium ions in salt lake brine, especially high selectivity for cesium in extremely difficult rubidium and cesium separation. Compared with multi-stage extraction separation, the process is simple, and pollution of organic solvents to water and high alkali consumption are avoided. The preparation method is simple, the conditions are mild, no noble metal or organic amine doping is needed, and the method is convenient for realization and scale-up.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material technology, and relates to a thiostannate, and more particularly to an ammonium thiostannate salt and its preparation method and application. Background Technology

[0002] Cesium is an important rare and precious metal resource, widely used in communications, batteries, and medicine, and holds significant economic and strategic importance. Currently, cesium resources mainly come from solid minerals such as lepidolite and cesium garnet, but ore reserves are limited and extraction processes are complex. In contrast, the abundant cesium resources in cesium-bearing brines have not yet been extensively developed; therefore, cesium separation from salt lakes holds great promise. However, most salt lake brines have low cesium ion concentrations and coexist with high-concentration competing ions such as sodium, potassium, magnesium, and calcium, posing a significant challenge to large-scale exploitation of cesium resources in salt lakes. Currently, technologies for extracting cesium resources from aqueous solutions mainly include solvent extraction, co-precipitation, membrane separation, and adsorption. Among these, adsorption technology offers advantages such as high selectivity, low production costs, excellent thermal stability, and environmental friendliness, thus possessing great potential for large-scale industrial application in cesium extraction from salt lakes.

[0003] Compared to common cesium adsorbents such as titanosilicones, heteropolyacids, and ferricyanides, thiostannates have the structural formula A. n M z Sn x-z S y Where A is an intercalated cation, M is a doped metal, and [Sn x-z S y ] n- As a large anionic layer, it possesses advantages such as structural stability, large adsorption capacity, fast kinetics, and high cesium selectivity, making it one of the most promising adsorbents for extracting cesium resources from high-salt systems, and has been extensively studied in the past decade. To date, many different thiostannates have been investigated, with anions including [Sn₂S₅]. 2- [Sn2S6] 4- [Sn3S6] 2- [Sn3S7] 2- Various types of metals are used, including manganese, magnesium, aluminum, and indium. The intercalated cations are mainly sodium, potassium, and organic amines. For example, CN114588873A discloses an adsorbent for cesium extraction from brine and groundwater and its preparation method. This adsorbent uses potassium (K) as the intercalated cation and is doped with rare metals such as Zr, Ti, Nb, and In to form a layered main structure for cesium extraction from brine and groundwater. CN116688949A discloses a metal-doped organic amine tin sulfide adsorbent, its preparation method, and its application in cesium extraction. This adsorbent uses organic amines as intercalated cations and is doped with Sn... 4+Metals with similar radii are called doped metals and are used for the separation and extraction of cesium from liquids.

[0004] In existing technologies, thiostannate adsorbents are typically doped with organic amines or noble metals. Organic amine ligands are complex to synthesize, while noble metals are scarce and expensive. Furthermore, current thiostannate adsorbents are primarily used in high-level radioactive waste systems, mainly targeting sodium ions, but exhibiting insufficient selectivity for potassium, calcium, and magnesium ions. Additionally, some thiostannate adsorbents cannot be eluted and regenerated after adsorbing cesium ions.

[0005] Furthermore, rubidium and cesium ions are both rare metals with similar properties and often coexist in brine or other leaching tailings. However, due to their very similar physicochemical properties, the separation of rubidium and cesium ions remains an industrial challenge. Currently, multi-stage extraction processes are generally used for separation, but commonly used phenolic extractants are readily soluble in water and require large amounts of alkali, making the process complex and costly. Therefore, developing novel, highly selective cesium adsorbents to achieve rubidium-cesium separation through a simple adsorption process has significant industrial value.

[0006] Therefore, for the need for cesium extraction and selective separation of rubidium and cesium in high-salt systems such as salt lakes, there is an urgent need to develop a thiostannate adsorbent that has excellent selectivity for cesium ions and can be regenerated. Summary of the Invention

[0007] The purpose of this invention is to provide an ammonium thiostannate salt that is simple to prepare, has high selectivity for cesium adsorption, and can be regenerated and used, as well as its preparation method and application.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing ammonium thiostannate salt, the method comprising the following steps:

[0010] (1) A sulfur source, a tin source, a soluble metal salt and water are mixed and subjected to a hydrothermal reaction to obtain thiostannate;

[0011] (2) Mix the thiostanate obtained in step (1) with an ammonium salt to obtain ammonium thiostanate.

[0012] The preparation method provided by this invention uses a hydrothermal method to prepare [Sn] x S y ] 2- The ammonium thiostannate with a large anionic layer (x:y = 0.2-0.8) is prepared by replacing the interlayer cations with ammonium ions through post-treatment. This avoids the high-temperature calcination process (>500℃) and the risks associated with using hazardous chemicals such as hydrazine hydrate to introduce ammonium ions in conventional one-step methods.x S y It has high stability, and the soft alkali S in it 2- Can be combined with soft acid Cs + Affinity coordination, at the same time, NH4 + The presence of competing ions Li + Na + K + and Rb + The exchange process is inhibited, and its layered structure can inhibit large-sized hydrated ions Mg. 2+ Ca 2+ The sieve has high selectivity for cesium and is easy to regenerate.

[0013] Preferably, the sulfur source in step (1) includes any one or a combination of at least two of thiourea, thioacetamide, glutathione, sodium sulfide, or elemental sulfur. Typical but non-limiting combinations include combinations of thiourea and thioacetamide, combinations of thioacetamide and glutathione, combinations of glutathione and sodium sulfide, combinations of sodium sulfide and elemental sulfur, combinations of thiourea, thioacetamide, and glutathione, combinations of glutathione, sodium sulfide, and elemental sulfur, or combinations of thiourea, thioacetamide, glutathione, sodium sulfide, and elemental sulfur.

[0014] Preferably, the tin source in step (1) includes any one or a combination of at least two of sodium stannate, potassium stannate, sodium stanoxide, potassium stanoxide, sodium hydroxystannate, potassium hydroxystannate, or elemental tin. Typical but non-limiting combinations include a combination of sodium stannate and sodium stanoxide, a combination of potassium stannate and sodium hydroxystannate, a combination of potassium hydroxystannate and elemental tin, a combination of sodium stannate, potassium stanoxide, and sodium hydroxystannate, or a combination of sodium stannate, sodium stanoxide, potassium hydroxystannate, and elemental tin.

[0015] Preferably, the soluble metal salt in step (1) includes any one or a combination of at least two of sodium, potassium, rubidium, magnesium, or calcium salts. Typical but non-limiting combinations include combinations of sodium and potassium salts, combinations of potassium and rubidium salts, combinations of rubidium and magnesium salts, combinations of magnesium and calcium salts, combinations of sodium, potassium, and rubidium salts, or combinations of rubidium, magnesium, and calcium salts.

[0016] For example, the sodium salt includes sodium chloride, sodium nitrate, sodium carbonate, or sodium sulfate.

[0017] For example, the potassium salt includes potassium chloride, potassium nitrate, potassium carbonate, or potassium sulfate.

[0018] For example, the rubidium salt includes rubidium chloride, rubidium nitrate, rubidium carbonate, or rubidium sulfate.

[0019] For example, the magnesium salt includes magnesium chloride or magnesium nitrate.

[0020] For example, the calcium salt includes calcium chloride or calcium nitrate.

[0021] Preferably, the molar ratio of the metal element in the soluble metal salt to the tin element in the tin source in step (1) is (0.5-6):1, for example, it can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, in step (1), the molar ratio of sulfur to tin in the sulfur source and tin source is (1-6):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the amount of water used in step (1) is 5-80% of the total mass of the sulfur source, tin source, soluble metal salt and water. For example, it can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 10-60%.

[0024] Preferably, the temperature of the hydrothermal reaction in step (1) is 120-260℃, for example, it can be 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, 220℃, 240℃, 250℃ or 260℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 160-240℃.

[0025] Preferably, the hydrothermal reaction time in step (1) is ≥12h, for example, it can be 12h, 18h, 20h, 24h, 25h, 30h, 35h, 36h, 40h, 42h, 48h, 50h, 54h, 60h, 66h, 72h, 80h, 90h or 100h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 24-72h.

[0026] Preferably, the ammonium salt in step (2) includes any one or a combination of at least two of ammonium chloride, ammonium nitrate or ammonium sulfate. Typical but non-limiting combinations include a combination of ammonium chloride and ammonium nitrate, a combination of ammonium nitrate and ammonium sulfate, a combination of ammonium chloride and ammonium sulfate, or a combination of ammonium chloride, ammonium nitrate and ammonium sulfate.

[0027] Preferably, the concentration of ammonium ions in the ammonium salt in step (2) is ≥0.05 mol / L, for example, it can be 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 5 mol / L, 10 mol / L or 20 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, after mixing in step (2), the mixture is stirred, separated, and dried in sequence.

[0029] Preferably, the drying temperature is 40-100℃, for example, it can be 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] As a preferred embodiment of the preparation method provided by the present invention, the preparation method includes the following steps:

[0031] (1) Mix sulfur source, tin source, soluble metal salt and water, wherein the molar ratio of sulfur to tin is (1-6):1, the molar ratio of metal element to tin in soluble metal salt is (0.5-6):1, and the amount of water is 10-60% of the total mass of sulfur source, tin source, soluble metal salt and water. Carry out hydrothermal reaction at 160-240℃ for 24-72h to obtain thiostannate.

[0032] (2) The thiostannate obtained in step (1) is mixed with an ammonium salt with an ammonium ion concentration ≥0.05mol / L and stirred. Then the mixture is separated and dried at 40-100℃ to obtain ammonium thiostannate.

[0033] In a second aspect, the present invention provides an ammonium thiostannate salt, which is prepared by the preparation method described in the first aspect.

[0034] The ammonium thiostannate salt provided by this invention has high selectivity for cesium, high adsorption capacity, rapid kinetics and good cycling stability, thereby improving the efficiency of cesium ion extraction from salt lake brine.

[0035] Thirdly, the present invention provides an application of the ammonium thiostannate salt described in the second aspect, wherein the ammonium thiostannate salt is used for the adsorption of cesium ions and / or the separation of rubidium and cesium in salt lake brine.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The ammonium thiostannate salt provided by this invention exhibits high selectivity, high adsorption capacity, rapid kinetics, and good cycling stability for cesium ions such as sodium, potassium, rubidium, magnesium, and calcium. It demonstrates high efficiency in adsorbing cesium ions in salt lake brines, particularly in the highly challenging separation of rubidium and cesium, where cesium selectivity is exceptionally high. Compared to multi-stage extraction separation, this method is not only simpler but also avoids water pollution from organic solvents and high alkali consumption. The preparation method is simple, operates under mild conditions, requires no precious metal or organic amine doping, and is easy to implement and scale up. Attached Figure Description

[0038] Figure 1 This is a SEM image of the ammonium thiostannate salt prepared in Example 1.

[0039] Figure 2 These are the XRD patterns of ammonium thiostannate salts prepared in Examples 1-2, 6 and 10. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0041] Example 1

[0042] This embodiment provides a method for preparing ammonium thiostannate, the method comprising the following steps:

[0043] (1) Sodium stannate, thiourea and sodium chloride are mixed in a molar ratio of 1:2:1. The amount of deionized water added is 60% of the total mass of sodium stannate, thiourea, sodium chloride and water. After stirring thoroughly, the mixture is placed in a hydrothermal reactor and reacted at 180°C for 24 hours to obtain a solid product. The solid product is washed with water 3 times and placed in a vacuum drying oven. After drying at 90°C for 4 hours, sodium thiostannate solid is obtained.

[0044] (2) Add the sodium thiostannate obtained in step (1) to 25 mL of 1 mol / L ammonium chloride solution, stir for 30 min, filter, wash 3 times with deionized water, put it in a vacuum drying oven, and dry at 90 °C for 4 h to obtain solid ammonium thiostannate.

[0045] Example 2

[0046] This embodiment provides a method for preparing ammonium thiostannate, the method comprising the following steps:

[0047] (1) Sodium stannate, thiourea and sodium chloride are mixed in a molar ratio of 1:1:6. The amount of deionized water added is 10% of the total mass of sodium stannate, thiourea, sodium chloride and water. After stirring thoroughly, the mixture is placed in a hydrothermal reactor and reacted at 160°C for 72 hours to obtain a solid product. The solid product is washed with water three times and placed in a vacuum drying oven. After drying at 40°C for 4 hours, sodium thiostannate solid is obtained.

[0048] (2) Add the sodium thiostannate obtained in step (1) to 25 mL of 5 mol / L ammonium chloride solution, stir for 30 min, filter, wash 3 times with deionized water, put it in a vacuum drying oven, and dry at 40 °C for 4 h to obtain solid ammonium thiostannate.

[0049] Example 3

[0050] This embodiment provides a method for preparing ammonium thiostannate, the method comprising the following steps:

[0051] (1) Sodium stannate, thiourea and sodium chloride are mixed in a molar ratio of 1:6:0.5. The amount of deionized water added is 40% of the total mass of sodium stannate, thiourea, sodium chloride and water. After stirring thoroughly, the mixture is placed in a hydrothermal reactor and reacted at 240°C for 48 hours to obtain a solid product. The solid product is washed with water three times and placed in a vacuum drying oven. After drying at 100°C for 4 hours, sodium thiostannate solid is obtained.

[0052] (2) Add the sodium thiostannate obtained in step (1) to 25 mL of 1 mol / L ammonium chloride solution, stir for 30 min, filter, wash 3 times with deionized water, put it in a vacuum drying oven, and dry at 100 °C for 4 h to obtain solid ammonium thiostannate.

[0053] Example 4

[0054] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, the sodium chloride in step (1) is replaced with potassium chloride in equal amounts, and the rest is the same as in Example 1.

[0055] Example 5

[0056] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, sodium chloride in step (1) is replaced with sodium sulfate in equal amounts, while the rest is the same as in Example 1.

[0057] Example 6

[0058] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, the amount of water added in step (1) is controlled to be 90%, while the rest is the same as in Example 1.

[0059] Example 7

[0060] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, the temperature of the hydrothermal reaction in step (1) is controlled at 120°C, and the rest is the same as in Example 1.

[0061] Example 8

[0062] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, the hydrothermal reaction time in step (1) is controlled to be 12 hours, while the rest is the same as in Example 1.

[0063] Example 9

[0064] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, the concentration of ammonium chloride solution in step (2) is controlled to be 0.02 mol / L, and the rest is the same as in Example 1.

[0065] Example 10

[0066] This embodiment provides a method for preparing ammonium thiostannate salt. Compared with Example 1, the drying temperature in step (2) is controlled at 120°C, and the rest is the same as in Example 1.

[0067] Comparative Example 1

[0068] This comparative example provides a method for preparing thiostannate, which, compared with Example 1, does not perform step (2), and the rest is the same as Example 1.

[0069] Performance Characterization

[0070] The adsorption performance of the thiostannates provided in the examples and comparative examples was tested using the following methods:

[0071] The yield was calculated based on the mass of tin powder added. 5 mg of thiostannate was added to 10 mL of a cesium chloride solution with a concentration of 500 mg / L, and the change in cesium ion concentration before and after adsorption was tested by ICP-OES to calculate the adsorption amount. 5 mg of thiostannate adsorbent was added to 10 mL of a mixed solution with a potassium (or sodium, rubidium, magnesium, calcium) ion concentration of 10 mmol / L and a cesium ion concentration of 0.1 mmol / L, and the change in cesium ion concentration before and after adsorption was tested by ICP-OES to calculate the cesium partition coefficient. The results are listed in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] As shown in Table 1, the ammonium thiostannate salt provided by this invention exhibits high yield, large adsorption capacity, and high selectivity for cesium among sodium, potassium, rubidium, magnesium, and calcium ions. Compared to Example 1, changes in the metal salt feed ratio and type, the amount of deionized water added, and the reaction temperature and time directly affect the product performance; the concentration of ammonium chloride solution affects the ammonium ion content in the final ammonium thiostannate, thus affecting its adsorption performance; excessively high drying temperature affects the adsorption performance of ammonium thiostannate. Therefore, the ammonium thiostannate prepared using the preferred preparation conditions of this invention can achieve optimal adsorption performance.

[0076] Depend on Figure 1 It can be seen that the microstructure of the ammonium thiostannate salt provided by this invention is a solid with a regular cuboid shape. Combined with the adsorption properties in Table 1 and... Figure 2 Material structure characterization: The crystallinity of materials synthesized within the preferred process parameter range provided by the present invention may vary, but their structure and adsorption performance are not affected, as in Examples 1 and 2; when the synthesis process conditions deviate significantly, the structure of the material will change and the adsorption performance will decrease, as in Examples 6 and 10.

[0077] In summary, the ammonium thiostannate salt provided by this invention exhibits high selectivity, high adsorption capacity, rapid kinetics, and good cycling stability for cesium ions such as sodium, potassium, rubidium, magnesium, and calcium. It is highly efficient for adsorbing cesium ions in salt lake brines without the need for doping with precious metals or organic amines. When used for rubidium-cesium separation, it exhibits good cesium selectivity. Compared with multi-stage extraction separation, it is not only simple in process but also avoids water pollution by organic solvents and high alkali consumption. The preparation method is simple, the conditions are mild, and it is easy to implement and scale up.

[0078] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing an ammonium thiostannate salt, characterized in that, The preparation method includes the following steps: (1) A sulfur source, a tin source, a soluble metal salt and water are mixed and subjected to a hydrothermal reaction to obtain thiostannate; (2) Mix the thiostanate obtained in step (1) with the ammonium salt to obtain ammonium thiostanate.

2. The preparation method according to claim 1, characterized in that, The sulfur source in step (1) includes any one or a combination of at least two of thiourea, thioacetamide, glutathione, sodium sulfide, or elemental sulfur.

3. The preparation method according to claim 1, characterized in that, The tin source in step (1) includes any one or a combination of at least two of sodium stannate, potassium stannate, sodium stanoxide, potassium stanoxide, sodium hydroxystannate, potassium hydroxystannate, or elemental tin.

4. The preparation method according to claim 1, characterized in that, The soluble metal salt in step (1) includes any one or a combination of at least two of sodium, potassium, rubidium, magnesium, or calcium salts.

5. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of the metal element in the soluble metal salt to the tin element in the tin source is (0.5-6):

1.

6. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of sulfur to tin in the sulfur source and tin source is (1-6):

1.

7. The preparation method according to claim 1, characterized in that, The amount of water used in step (1) is 5-80% of the total mass of the sulfur source, tin source, soluble metal salt and water.

8. The preparation method according to claim 1, characterized in that, The temperature of the hydrothermal reaction in step (1) is 120-260℃.

9. The preparation method according to claim 1, characterized in that, The hydrothermal reaction time in step (1) is ≥12h.

10. The preparation method according to claim 1, characterized in that, The ammonium salt in step (2) includes any one or a combination of at least two of ammonium chloride, ammonium nitrate or ammonium sulfate.

11. The preparation method according to claim 1, characterized in that, The concentration of ammonium ions in the ammonium salt in step (2) is ≥0.05mol / L.

12. The preparation method according to claim 1, characterized in that, After mixing in step (2), the mixture is stirred, separated, and dried in sequence.

13. The preparation method according to claim 12, characterized in that, The drying temperature is 40-100℃.

14. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix sulfur source, tin source, soluble metal salt and water, wherein the molar ratio of sulfur to tin is (1-6):1, the molar ratio of metal element to tin in soluble metal salt is (0.5-6):1, and the amount of water is 10-60% of the total mass of sulfur source, tin source, soluble metal salt and water. Carry out hydrothermal reaction at 160-240℃ for 24-72h to obtain thiostannate. (2) The thiostannate obtained in step (1) is mixed with an ammonium salt with an ammonium ion concentration ≥0.05mol / L and stirred, then separated and dried at 40-100℃ to obtain ammonium thiostannate.

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