A sodium ion adsorbent, a preparation method and application thereof

Abstract

The application provides a sodium ion adsorbent and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a titanium source, an organic acid and an acidic solvent, and performing reaction to obtain a reaction product; (2) mixing the reaction product, an aluminum source, a magnesium source and a phosphorus source, and performing reaction to obtain a gel; and (3) calcining the gel to obtain the sodium ion adsorbent. The application proposes a method combining a sol-gel method and a calcination method, and the method has the advantages of low energy consumption, short cycle, large production scale and simple operation, and the sodium ion adsorbent prepared based on the method has the advantages of high efficiency and reversibility.

Description

Technical Field

[0001] This invention belongs to the field of sodium ion separation technology, specifically relating to a sodium ion adsorbent, its preparation method, and its application. Background Technology

[0002] As is well known, the precipitation of sodium ions in bauxite slag can lead to poor appearance of building surfaces when it is used on a large scale in building materials. In severe cases, it can even cause quality problems such as peeling and cracking of building surfaces. Therefore, the removal of sodium ions is imperative.

[0003] In existing technologies, sodium ion adsorbents are often used to remove sodium ions. Traditional methods for preparing sodium ion adsorbents include high-temperature solid-phase methods. For example, Sun Jianzhi et al. used a high-temperature solid-phase method to synthesize a novel, highly effective sodium ion adsorbent, Li. 1+x M x N 2-x (PO4)3 (M = Al, Cr, La; N = Ti, Zr), that is, using Li2CO3, Al2O3, NH4H2PO4 and TiO2 as raw materials, pre-calcination and high-temperature solid-phase reaction are carried out to obtain the novel special sodium ion adsorbent.

[0004] However, the traditional high-temperature solid-phase method for preparing sodium ion adsorbents has problems such as high energy consumption, long cycle time, low yield, and difficulty in post-processing.

[0005] Therefore, how to reduce manufacturing costs and production cycle, increase yield, and obtain a high-performance sodium ion adsorbent is a key area that urgently needs to be studied. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a sodium ion adsorbent, its preparation method, and its applications. This invention proposes a method combining the sol-gel method and the calcination method. This method has advantages such as low energy consumption, short cycle time, large production scale, and simple operation. The sodium ion adsorbent prepared based on this method has the advantages of high efficiency and reversibility.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a sodium ion adsorbent, the method comprising the following steps:

[0009] (1) Mix titanium source, organic acid and acidic solvent, and react to obtain reaction product;

[0010] (2) The reaction product, aluminum source, magnesium source and phosphorus source are mixed and reacted to obtain a gel;

[0011] (3) The gel is calcined to obtain the sodium ion adsorbent.

[0012] This invention proposes a method combining sol-gel and calcination methods, which has the advantages of low energy consumption, short cycle, large production scale and simple operation. The sodium ion adsorbent prepared based on this method has the advantages of high efficiency and reversibility.

[0013] In this invention, reacting a titanium source with an organic acid can inhibit TiO2 formation. + It was transformed into TiO2, and the adsorbent precursor was successfully synthesized.

[0014] In this invention, the reaction product of step (1) is mixed with aluminum source, magnesium source and phosphorus source and reacted. The magnesium source and phosphorus source can help synthesize the adsorbent body, which has a stable skeleton structure. The PO4 tetrahedron and TiO6 octahedron are connected by oxygen atoms at shared vertices to form a three-dimensional network structure, which allows sodium ions to transfer in the channels. Adding aluminum source can increase the number of active sites in the adsorbent body structure that allow sodium ions to attach.

[0015] As a preferred technical solution of the present invention, the titanium source in step (1) includes Ti(OH)4.

[0016] Preferably, the organic acid in step (1) includes citric acid.

[0017] Preferably, the mass ratio of the titanium source and the organic acid in step (1) is (6-14):(16-35), wherein the titanium source is selected in the range of "6-14", for example, 6, 8, 10, 12 or 14, and the organic acid is selected in the range of "16-35", for example, 16, 19, 20, 25, 30 or 35.

[0018] In this invention, if the mass ratio of titanium source to organic acid is too small, i.e., the amount of organic acid is too large, it will affect the adsorption of sodium ions, thus leading to a decrease in the adsorption rate of the sodium ion adsorbent; if the mass ratio of titanium source to organic acid is too large, i.e., the amount of organic acid is too small, it will be difficult to prevent TiO2 in the solution from adsorbing. 2+ The conversion to TiO2 hinders the synthesis of adsorbent precursors.

[0019] As a preferred technical solution of the present invention, the acidic solvent in step (1) includes a strong acid.

[0020] Preferably, the strong acid includes concentrated nitric acid.

[0021] It should be noted that concentrated nitric acid refers to nitric acid solutions with a molar concentration of 8 mol / L or higher.

[0022] Preferably, the acidic solvent in step (1) further includes water, and the volume ratio of the strong acid to water is 1:(2-5), for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc.

[0023] As a preferred technical solution of the present invention, the mixing process in step (1) is accompanied by stirring.

[0024] Preferably, the temperature of the reaction in step (1) is 23-27°C, for example, 23°C, 25°C or 27°C.

[0025] Preferably, the reaction time in step (1) is 1-3 hours, for example, 1 hour, 2 hours or 3 hours.

[0026] As a preferred technical solution of the present invention, the aluminum source in step (2) includes aluminum nitrate nonahydrate.

[0027] Preferably, the magnesium source in step (2) includes magnesium nitrate hexahydrate.

[0028] Preferably, the phosphorus source in step (2) includes ammonium dihydrogen phosphate.

[0029] Preferably, the molar ratio of the reaction product, aluminum source, magnesium source and phosphorus source in step (2) is 1:(1.5-7.5):(2.5-5.5):(6-7), wherein the range of aluminum source selection “1.5-7.5” can be, for example, 1.5, 2, 3, 4, 5, 6 or 7, the range of magnesium source selection “2.5-5.5” can be, for example, 2.5, 3, 3.5, 4, 4.5 or 5, and the range of phosphorus source selection “6-7” can be, for example, 6, 6.5 or 7.

[0030] As a preferred technical solution of the present invention, the mixing process in step (2) is accompanied by stirring.

[0031] Preferably, the mixing method in step (2) includes dropwise addition.

[0032] It should be noted that the dropwise addition method can involve adding aluminum, magnesium, and phosphorus sources dropwise to the reaction products.

[0033] Preferably, the reaction temperature in step (2) is 23-27°C, for example, 23°C, 25°C or 27°C.

[0034] Preferably, the reaction time in step (2) is 1-3 hours, for example, 1 hour, 2 hours or 3 hours.

[0035] As a preferred technical solution of the present invention, the gel in step (3) is dried before calcination.

[0036] Preferably, the drying temperature is 60-100℃, for example, it can be 60℃, 70℃, 80℃, 90℃ or 100℃.

[0037] Preferably, the drying time is 10-14 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, etc.

[0038] Preferably, the calcination temperature in step (3) is 300-500℃, for example, it can be 300℃, 350℃, 400℃, 450℃ or 500℃.

[0039] In this invention, if the calcination temperature is too low, the removal effect of sodium ions will not be significantly improved; if the calcination temperature is too high, the structure and microstructure of the adsorbent will change, which will be detrimental to the removal of sodium ions.

[0040] Preferably, the calcination time in step (3) is 3-5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0041] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0042] (I) Mixing titanium-based organic matter with water yields a hydrolyzed precipitate;

[0043] Among them, the titanium-based organic compounds include tetrabutyl titanate, and the hydrolysis precipitate is Ti(OH)4;

[0044] (II) The hydrolyzed precipitate, citric acid and acidic solvent are stirred and mixed, and the reaction is carried out at 23-27°C for 1-3 hours to obtain the reaction product;

[0045] The acidic solvent includes a strong acid and water in a volume ratio of 1:(2-5), and the mass ratio of the hydrolysate to citric acid is (6-14):(16-35).

[0046] (III) Under stirring conditions, aluminum source, magnesium source and phosphorus source are added dropwise to the reaction product and the reaction is carried out at 23-27℃ for 1-3 hours to obtain gel;

[0047] The molar ratio of the reaction product, aluminum source, magnesium source and phosphorus source is 1:(1.5-7.5):(2.5-5.5):(6-7);

[0048] (IV) The gel is dried at 60-100℃ for 10-14 hours to obtain a dry gel, and the dry gel is calcined at 300-500℃ for 3-5 hours to obtain the sodium ion adsorbent.

[0049] It should be noted that the present invention does not specifically limit the titanium-based organic compounds; for example, it may be tetrabutyl titanate, etc.

[0050] Secondly, the present invention provides a sodium ion adsorbent prepared by the preparation method described in the first aspect, wherein the general chemical formula of the sodium ion adsorbent is Mg. 0.5+0.5x Al x Ti 2-x (PO4)3, 0 < x ≤ 1.

[0051] In this invention, 0 < x ≤ 1, for example, it can be 0.2, 0.4, 0.6 or 0.8, etc.

[0052] Preferably, the particle size D50 of the sodium ion adsorbent is 20-70 nm, for example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm or 70 nm.

[0053] Thirdly, the present invention provides an application of the sodium ion adsorbent as described in the second aspect, wherein the sodium ion adsorbent is used for adsorbing and removing sodium.

[0054] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] This invention proposes a method combining sol-gel and calcination methods, which has the advantages of low energy consumption, short cycle, large production scale and simple operation. The sodium ion adsorbent prepared based on this method has the advantages of high efficiency and reversibility. Attached Figure Description

[0057] Figure 1 This is a process flow diagram for preparing sodium ion adsorbent in Example 1 of the present invention.

[0058] Figure 2 This is a graph showing the regeneration performance of the sodium ion adsorbent prepared in Example 1 of this invention. Detailed Implementation

[0059] 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.

[0060] In the following examples, the concentration of concentrated nitric acid is 10 mol / L.

[0061] Example 1

[0062] This embodiment provides a method for preparing a sodium ion adsorbent, the process flow diagram of which is shown below. Figure 1 As shown, the preparation method includes the following steps:

[0063] (1) Tetrabutyl titanate was added to deionized water under stirring conditions to obtain hydrolyzed precipitate Ti(OH)4;

[0064] (2) After filtration, Ti(OH)4 was transferred to an acidic solvent (including concentrated nitric acid and deionized water in a volume ratio of 1:3), and then citric acid was added. The reaction was carried out at 25°C for 2 hours to obtain the reaction product.

[0065] The mass ratio of Ti(OH)4 to citric acid is 10:25.

[0066] (3) Dissolve aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium dihydrogen phosphate in deionized water and slowly add them dropwise to the reaction product under stirring. Keep warm at 25°C for 2 hours to obtain a gel.

[0067] The molar ratio of the reaction product, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and ammonium dihydrogen phosphate is 1:4.5:4:6.5.

[0068] (4) The gel was dried in a forced-air drying oven at 80°C for 12 hours to obtain a dry gel. The dry gel was then transferred to a muffle furnace and calcined at 400°C for 4 hours to obtain a product with the chemical composition Mg. 0.7 Al 0.4 Ti 1.6 The sodium ion adsorbent of (PO4)3 has a particle size D50 of 30.4 nm.

[0069] Figure 2 The figure shows the adsorption performance of the sodium ion adsorbent prepared in this embodiment after regeneration. As can be seen from the figure, the sodium ion adsorbent prepared by this method has the advantages of high efficiency and reversibility.

[0070] Example 2

[0071] This embodiment provides a method for preparing a sodium ion adsorbent, the method comprising the following steps:

[0072] (1) Tetrabutyl titanate was added to deionized water under stirring conditions to obtain hydrolyzed precipitate Ti(OH)4;

[0073] (2) After filtration, Ti(OH)4 was transferred to an acidic solvent (including concentrated nitric acid and deionized water in a volume ratio of 1:4), and then citric acid was added. The reaction was carried out at 25°C for 2 hours to obtain the reaction product.

[0074] The mass ratio of Ti(OH)4 to citric acid is 8:30.

[0075] (3) Dissolve aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium dihydrogen phosphate in deionized water and slowly add them dropwise to the reaction product under stirring. Keep warm at 25°C for 2 hours to obtain a gel.

[0076] The molar ratio of the reaction product, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and ammonium dihydrogen phosphate is 1:4.5:4:6.5.

[0077] (4) The gel was dried in a forced-air drying oven at 70°C for 13 hours to obtain a dry gel. The dry gel was then transferred to a muffle furnace and calcined at 400°C for 4 hours to obtain a product with the chemical composition Mg. 0.5+ 0.5x Al x Ti 2-x Sodium ion adsorbent of (PO4)3 with x = 0.5 and particle size D50 = 30.0 nm.

[0078] Example 3

[0079] This embodiment provides a method for preparing a sodium ion adsorbent, the method comprising the following steps:

[0080] (1) Tetrabutyl titanate was added to deionized water under stirring conditions to obtain hydrolyzed precipitate Ti(OH)4;

[0081] (2) After filtration, Ti(OH)4 was transferred to an acidic solvent (including concentrated nitric acid and deionized water in a volume ratio of 1:2), and then citric acid was added. The reaction was carried out at 25°C for 2 hours to obtain the reaction product.

[0082] The mass ratio of Ti(OH)4 to citric acid is 12:20.

[0083] (3) Dissolve aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium dihydrogen phosphate in deionized water and slowly add them dropwise to the reaction product under stirring. Keep warm at 25°C for 2 hours to obtain a gel.

[0084] The molar ratio of the reaction product, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and ammonium dihydrogen phosphate is 1:4.5:4:6.5.

[0085] (4) The gel was dried in a 90°C oven for 11 hours to obtain a dry gel. The dry gel was then transferred to a muffle furnace and calcined at 400°C for 4 hours to obtain a product with the chemical composition Mg. 0.5+ 0.5x Alx Ti 2-x The sodium ion adsorbent of (PO4)3 has an x ​​of 0.3 and a particle size D50 of 50 nm.

[0086] Example 4

[0087] This embodiment provides a method for preparing a sodium ion adsorbent, the method comprising the following steps:

[0088] (1) Tetrabutyl titanate was added to deionized water under stirring conditions to obtain hydrolyzed precipitate Ti(OH)4;

[0089] (2) After filtration, Ti(OH)4 was transferred to an acidic solvent (including concentrated nitric acid and deionized water in a volume ratio of 1:5), and then citric acid was added. The reaction was carried out at 23°C for 3 hours to obtain the reaction product.

[0090] The mass ratio of Ti(OH)4 to citric acid is 6:35.

[0091] (3) Dissolve aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium dihydrogen phosphate in deionized water and slowly add them dropwise to the reaction product under stirring. Keep the mixture at 23°C for 3 hours to obtain a gel.

[0092] The molar ratio of the reaction product, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and ammonium dihydrogen phosphate is 1:1.5:2.5:6.

[0093] (4) The gel was dried in a forced-air drying oven at 60°C for 14 hours to obtain a dry gel. The dry gel was then transferred to a muffle furnace and calcined at 300°C for 5 hours to obtain a product with the chemical composition Mg. 0.5+ 0.5x Al x Ti 2-x The sodium ion adsorbent of (PO4)3 has an x ​​of 0.8 and a particle size D50 of 25 nm.

[0094] Example 5

[0095] This embodiment provides a method for preparing a sodium ion adsorbent, the method comprising the following steps:

[0096] (1) Tetrabutyl titanate was added to deionized water under stirring conditions to obtain hydrolyzed precipitate Ti(OH)4;

[0097] (2) After filtration, Ti(OH)4 was transferred to an acidic solvent (including concentrated nitric acid and deionized water in a volume ratio of 1:3), and then citric acid was added. The reaction was carried out at 27°C for 1 hour to obtain the reaction product.

[0098] The mass ratio of Ti(OH)4 to citric acid is 14:16.

[0099] (3) Dissolve aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium dihydrogen phosphate in deionized water and slowly add them dropwise to the reaction product under stirring. Keep warm at 27°C for 1 hour to obtain a gel.

[0100] The molar ratio of the reaction product, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and ammonium dihydrogen phosphate is 1:7.5:5.5:7.

[0101] (4) The gel was dried in a forced-air drying oven at 100°C for 10 hours to obtain a dry gel. The dry gel was then transferred to a muffle furnace and calcined at 500°C for 3 hours to obtain a product with the chemical composition Mg. 0.5+ 0.5x Al x Ti 2-x Sodium ion adsorbent of (PO4)3, with x = 1 and particle size D50 = 20 nm.

[0102] Example 6

[0103] The difference between this embodiment and embodiment 1 is that the mass ratio of Ti(OH)4 to citric acid in step (2) is 5:35.

[0104] The remaining preparation methods and parameters are consistent with those in Example 1.

[0105] Example 7

[0106] The difference between this embodiment and embodiment 1 is that the mass ratio of Ti(OH)4 to citric acid in step (2) is 15:15.

[0107] The remaining preparation methods and parameters are consistent with those in Example 1.

[0108] Example 8

[0109] The difference between this embodiment and embodiment 1 is that the calcination temperature in step (4) is 250°C.

[0110] The remaining preparation methods and parameters are consistent with those in Example 1.

[0111] Example 9

[0112] The difference between this embodiment and embodiment 1 is that the calcination temperature in step (4) is 550°C.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 is that in step (2), citric acid is replaced with dilute hydrochloric acid with a mass fraction of 15%.

[0116] The remaining preparation methods and parameters are consistent with those in Example 1.

[0117] Comparative Example 2

[0118] The difference between this comparative example and Example 1 is that citric acid is not added in step (2).

[0119] The remaining preparation methods and parameters are consistent with those in Example 1.

[0120] Comparative Example 3

[0121] The difference between this comparative example and Example 1 is that magnesium nitrate hexahydrate is not added in step (3).

[0122] The remaining preparation methods and parameters are consistent with those in Example 1.

[0123] Comparative Example 4

[0124] The difference between this comparative example and Example 1 is that aluminum nitrate nonahydrate is not added in step (3).

[0125] The remaining preparation methods and parameters are consistent with those in Example 1.

[0126] Performance testing

[0127] The sodium ion adsorbents prepared in Examples 1-9 and Comparative Examples 1-4 were used to adsorb sodium ions in bauxite slag, and then the remaining sodium ion content in the bauxite slag was detected to obtain the adsorption rate of the sodium ion adsorbents.

[0128] After adsorption is complete, the sodium ion adsorbent is regenerated, and the regenerated adsorbent is used to adsorb the same bauxite slag again to obtain the adsorption rate of the regenerated sodium ion adsorbent.

[0129] The test results are shown in Table 1.

[0130] Table 1

[0131]

[0132]

[0133] analyze:

[0134] As shown in the table above, the sodium ion adsorbent prepared by the combination of sol-gel method and calcination method of the present invention has the advantages of high efficiency and reversibility, and does not introduce other impurity ions.

[0135] The data from Examples 1 and 6-7 show that if the mass ratio of Ti(OH)4 to citric acid is too small, i.e., the amount of citric acid is too large, it will affect the adsorption of sodium ions, thus leading to a decrease in the adsorption rate of the sodium ion adsorbent; if the mass ratio of Ti(OH)4 to citric acid is too large, i.e., the amount of citric acid is too small, it will be difficult to prevent TiO2 in the solution from adsorbing sodium ions. 2+ The conversion to TiO2 hinders the synthesis of the adsorbent precursor, thus affecting the adsorption rate of the sodium ion adsorbent.

[0136] The data from Examples 1 and 8-9 show that if the calcination temperature is too low, the removal effect of sodium ions will not be significantly improved; if the calcination temperature is too high, the structure and microstructure of the adsorbent will change, which will be detrimental to the removal of sodium ions.

[0137] The data from Example 1 and Comparative Example 1 show that if the organic acid is replaced with an inorganic acid, the adsorption rate of sodium ions decreases significantly.

[0138] The data from Example 1 and Comparative Example 2 show that if no organic acid is added, the adsorption rate of sodium ions and the adsorption rate after regeneration both show a significant downward trend.

[0139] The data from Example 1 and Comparative Examples 3-4 show that if magnesium nitrate hexahydrate or aluminum nitrate nonahydrate is not added, the adsorption rate of sodium ions and the adsorption rate after regeneration both show a significant downward trend.

[0140] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An application of a sodium ion adsorbent in sodium adsorption and removal, characterized in that, The preparation method of the sodium ion adsorbent includes the following steps: (1) Mix titanium source, organic acid and acidic solvent, and react to obtain reaction product; (2) The reaction product, aluminum source, magnesium source and phosphorus source are mixed and reacted to obtain a gel; (3) The gel is calcined to obtain the sodium ion adsorbent.

2. The application according to claim 1, characterized in that, The titanium source in step (1) includes Ti(OH)4.

3. The application according to claim 1, characterized in that, The organic acid mentioned in step (1) includes citric acid.

4. The application according to claim 1, characterized in that, The mass ratio of the titanium source and organic acid in step (1) is (6-14):(16-35).

5. The application according to claim 1, characterized in that, The acidic solvent in step (1) includes strong acids.

6. The application according to claim 5, characterized in that, The strong acid includes concentrated nitric acid.

7. The application according to claim 5, characterized in that, The acidic solvent in step (1) also includes water, and the volume ratio of the strong acid to water is 1:(2-5).

8. The application according to claim 1, characterized in that, The mixing process described in step (1) is accompanied by stirring.

9. The application according to claim 1, characterized in that, The reaction temperature in step (1) is 23-27℃.

10. The application according to claim 1, characterized in that, The reaction time in step (1) is 1-3 hours.

11. The application according to claim 1, characterized in that, The aluminum source in step (2) includes aluminum nitrate nonahydrate.

12. The application according to claim 1, characterized in that, The magnesium source in step (2) includes magnesium nitrate hexahydrate.

13. The application according to claim 1, characterized in that, The phosphorus source in step (2) includes ammonium dihydrogen phosphate.

14. The application according to claim 1, characterized in that, The molar ratio of the reaction product, aluminum source, magnesium source and phosphorus source in step (2) is 1:(1.5-7.5):(2.5-5.5):(6-7).

15. The application according to claim 1, characterized in that, The mixing process described in step (2) is accompanied by stirring.

16. The application according to claim 1, characterized in that, The mixing method described in step (2) includes dropwise addition.

17. The application according to claim 1, characterized in that, The reaction temperature in step (2) is 23-27℃.

18. The application according to claim 1, characterized in that, The reaction time in step (2) is 1-3 hours.

19. The application according to claim 1, characterized in that, Before calcining the gel described in step (3), the gel is first dried.

20. The application according to claim 19, characterized in that, The drying temperature is 60-100℃.

21. The application according to claim 19, characterized in that, The drying time is 10-14 hours.

22. The application according to claim 1, characterized in that, The calcination temperature in step (3) is 300-500℃.

23. The application according to claim 1, characterized in that, The calcination time in step (3) is 3-5 hours.

24. The application according to claim 1, characterized in that, The preparation method includes the following steps: (I) Mixing titanium-based organic matter with water yields a hydrolyzed precipitate; Among them, the titanium-based organic compounds include tetrabutyl titanate, and the hydrolysis precipitate is Ti(OH)4; (II) The hydrolyzed precipitate, citric acid and acidic solvent are stirred and mixed, and the reaction is carried out at 23-27°C for 1-3 hours to obtain the reaction product; The acidic solvent includes a strong acid and water in a volume ratio of 1:(2-5), and the mass ratio of the hydrolysate to citric acid is (6-14):(16-35). (III) Under stirring conditions, aluminum source, magnesium source and phosphorus source are added dropwise to the reaction product and the reaction is carried out at 23-27℃ for 1-3 hours to obtain gel; The molar ratio of the reaction product, aluminum source, magnesium source and phosphorus source is 1:(1.5-7.5):(2.5-5.5):(6-7); (IV) The gel is dried at 60-100℃ for 10-14 hours to obtain a dry gel, and the dry gel is calcined at 300-500℃ for 3-5 hours to obtain the sodium ion adsorbent.

25. The application according to claim 1, characterized in that, The general chemical formula of the sodium ion adsorbent is Mg. 0.5+ 0.5x Al x Ti 2-x (PO4)3, 0 < x ≤ 1.

26. The application according to claim 25, characterized in that, The particle size D50 of the sodium ion adsorbent is 20-70 nm.

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