A method for preparing offretite from natural analcime, offretite and application thereof

Abstract

The application provides a method for preparing offretite by using natural analcime as a raw material, the offretite and application thereof, and relates to the technical field of zeolite materials. The natural analcime is mixed with an aqueous solution of an ammonium salt to perform ion exchange, so that ammonium-type analcime is obtained; the ammonium-type analcime is calcined to obtain hydrogen-type analcime; and the hydrogen-type analcime is mixed with sodium hydroxide, potassium hydroxide and water to perform hydrothermal reaction, so that the offretite is obtained. The natural analcime is a kind of zeolite mineral widely existing in nature, and the application uses the natural analcime as a raw material, so that the application has the remarkable advantages of low price and environmental friendliness; and the traditional hydrothermal method needs 7-10 days to synthesize offretite with high crystallinity, while the application uses the natural analcime as a raw material to perform crystal transformation synthesis of offretite, so that offretite with high crystallinity can be obtained in 0.5-2 days. Moreover, the offretite provided by the application can efficiently adsorb heavy metal ions in wastewater.

Description

Technical Field

[0001] This invention relates to the field of zeolite materials technology, and in particular to a method for preparing potassium zeolite from natural zeolite, potassium zeolite and its applications. Background Technology

[0002] The rapid development of industrial production has generated a large amount of wastewater containing heavy metal ions. Heavy metal wastewater has become one of the major problems hindering environmental development, attracting significant attention due to its high toxicity and difficulty in degradation, posing potential hazards to the ecological environment and human health. Therefore, it is essential to develop a simple and efficient technology for removing toxic heavy metals from wastewater. Methods for removing heavy metal ions from wastewater include ion exchange, physical and chemical treatment, electrochemical treatment, and reverse osmosis. Among these, ion exchange (adsorption) has advantages such as high selectivity, fast removal rate, and low operating cost, and is widely used.

[0003] Zeolite molecular sieves are a series of aluminosilicate crystals with a well-defined microporous structure, formed by the orderly arrangement of alumina and silica tetrahedra. Because the negatively charged cations in the zeolite framework can exchange with heavy metal cations in wastewater, zeolites possess excellent heavy metal cation capture performance. In recent years, research on the application of zeolite molecular sieves such as LTA, CHA, HEU, and MER in wastewater treatment has been abundant.

[0004] MER-type zeolite molecular sieves have a Si / Al ratio between 1 and 4 and feature four different sizes of 8-membered ring channels. Potassium hydroxide has important potential applications in the adsorption and separation of small molecules and the adsorption of heavy metal ions in wastewater. However, at present, the synthesis of potassium hydroxide zeolite usually uses chemical raw materials such as aluminum hydroxide and silica sol, which are not environmentally friendly and have a long crystallization time, mostly requiring 7 to 10 days. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing potassium zeolite from natural pyroxene, potassium zeolite itself, and its applications. This invention prepares potassium zeolite from natural pyroxene, which is inexpensive, environmentally friendly, shortens crystallization time, and the prepared potassium zeolite can efficiently adsorb heavy metal ions from wastewater.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing potassium zeolite from natural zeolite, comprising the following steps:

[0008] Natural zeolite was mixed with an aqueous solution of ammonium salt and subjected to ion exchange to obtain ammonium-type zeolite.

[0009] The ammonium-type zeolite was calcined to obtain hydrogen-type zeolite;

[0010] The hydrogen-form zeolite is mixed with sodium hydroxide, potassium hydroxide and water and subjected to a hydrothermal reaction to obtain the potassium hydroxide zeolite; the sodium hydroxide is calculated as Na2O, the potassium hydroxide as K2O, the hydrogen-form zeolite as Al2O3 and SiO2, and the molar ratio of the hydrogen-form zeolite, sodium hydroxide, potassium hydroxide and water satisfies Na2O:K2O:Al2O3:SiO2:H2O=(0~12):(0.1~12):1:(4~10):(100~1000).

[0011] Preferably, the ammonium salt in the ammonium salt aqueous solution includes one or more of ammonium chloride, ammonium sulfate and ammonium nitrate, and the concentration of the ammonium salt aqueous solution is 0.5 to 5 mol / L.

[0012] Preferably, the temperature of the ion exchange is 25–90°C, the number of ion exchanges is 1–4, and the time for a single ion exchange is 1–5 hours.

[0013] Preferably, the calcination temperature is 500–600°C and the time is 2–8 hours.

[0014] Preferably, the hydrothermal reaction is carried out at a temperature of 90–200°C for 0.5–10 days.

[0015] This invention provides potassium zeolite prepared by the method described in the above technical solution.

[0016] This invention provides the application of potassium zeolite as described above in the adsorption of heavy metal ions in wastewater.

[0017] Preferably, the heavy metal ions include lead ions and / or cadmium ions.

[0018] Preferably, the concentration of heavy metal ions in the wastewater is 0.1 to 1000 ppm.

[0019] Preferably, the mass ratio of potassium zeolite to wastewater is 1g:100mL to 1g:10000mL, the adsorption temperature is 25 to 80℃, and the time is 10 to 600min.

[0020] This invention provides a method for preparing potassium zeolite from natural zeolite, comprising the following steps: mixing natural zeolite with an ammonium salt aqueous solution for ion exchange to obtain ammonium-type zeolite; calcining the ammonium-type zeolite to obtain hydrogen-type zeolite; and mixing the hydrogen-type zeolite with sodium hydroxide, potassium hydroxide, and water for a hydrothermal reaction to obtain potassium zeolite. This invention pretreats natural zeolite by converting it from calcium-type zeolite to hydrogen-type zeolite through ion exchange and calcination, obtaining a raw material for the transcrystalline synthesis of potassium zeolite; then mixing it with sodium hydroxide, potassium hydroxide, and water under hydrothermal conditions to obtain potassium zeolite. Natural zeolite is a zeolite mineral widely found in nature. This invention uses natural zeolite as a raw material, which has significant advantages such as low cost and environmental friendliness. Furthermore, the traditional hydrothermal synthesis of highly crystalline potassium zeolite requires 7–10 days, while this invention, using natural zeolite as a raw material for transcrystalline synthesis of potassium zeolite, can obtain highly crystalline potassium zeolite in 0.5–2 days.

[0021] This invention provides potassium zeolite prepared by the method described in the above technical solution. The potassium zeolite provided by this invention can efficiently adsorb heavy metal ions in wastewater. Example results show that when the potassium zeolite provided by this invention is used to adsorb lead ions in wastewater, it still maintains a high adsorption rate of 99.9% even at a high solid-liquid ratio of 1:3000; when used to adsorb cadmium ions in wastewater, it can achieve a high adsorption rate of 99.9% at a solid-liquid ratio of 1:500 and a high adsorption rate of 89.8% at a solid-liquid ratio of 1:1000. Attached Figure Description

[0022] Figure 1 The XRD patterns of the zeolite products prepared in Examples 1-8 and Comparative Example 4 are shown below.

[0023] Figure 2 SEM images of potassium zeolite prepared in Examples 1-8. Detailed Implementation

[0024] This invention provides a method for preparing potassium zeolite from natural zeolite, comprising the following steps:

[0025] Natural zeolite was mixed with an aqueous solution of ammonium salt and subjected to ion exchange to obtain ammonium-type zeolite.

[0026] The ammonium-type zeolite was calcined to obtain hydrogen-type zeolite;

[0027] The hydrogen-form zeolite is mixed with sodium hydroxide, potassium hydroxide and water and subjected to a hydrothermal reaction to obtain the potassium hydroxide zeolite; the sodium hydroxide is calculated as Na2O, the potassium hydroxide as K2O, the hydrogen-form zeolite as Al2O3 and SiO2, and the molar ratio of the hydrogen-form zeolite, sodium hydroxide, potassium hydroxide and water satisfies Na2O:K2O:Al2O3:SiO2:H2O=(0~12):(0.1~12):1:(4~10):(100~1000).

[0028] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known in the art.

[0029] This invention involves mixing natural zeolite (STI-type zeolite) with an aqueous solution of ammonium salt and then performing ion exchange to obtain ammonium-type zeolite. Natural zeolite is a zeolite mineral widely found in nature. This invention uses natural zeolite as a raw material, which has the significant advantages of being inexpensive and environmentally friendly.

[0030] In this invention, the ammonium salt in the ammonium salt aqueous solution preferably includes one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate, and the concentration of the ammonium salt aqueous solution is preferably 0.5–5 mol / L, more preferably 1–2 mol / L. This invention does not have particular requirements on the amount of the ammonium salt aqueous solution, as long as it completely submerges the natural zeolite.

[0031] In this invention, the temperature of the ion exchange is preferably 25–90°C, more preferably 50–80°C; the number of ion exchanges is preferably 1–4 times, more preferably 2–3 times; and the time for a single ion exchange is preferably 1–5 hours, more preferably 2–3 hours. In this invention, the ion exchange is preferably carried out under water bath and stirring conditions.

[0032] After the ion exchange is completed, the present invention preferably performs solid-liquid separation, solid-phase washing, and drying on the obtained reaction solution in sequence to obtain the ammonium-type zeolite. In the present invention, the solid-liquid separation is preferably performed by vacuum filtration, and the washing is preferably performed by water washing.

[0033] After obtaining ammonium-type zeolite, the present invention calcines the ammonium-type zeolite to obtain hydrogen-type zeolite. In the present invention, the calcination temperature is preferably 500-600℃, more preferably 550℃, and the calcination time is preferably 2-8h, more preferably 4-5h.

[0034] This invention involves ion exchange and calcination of natural zeolite to transform it from calcium-type zeolite to hydrogen-type zeolite, thereby obtaining raw materials for the synthesis of potassium zeolite by the crystallization method.

[0035] After obtaining the hydrogen-form zeolite, the present invention mixes the hydrogen-form zeolite with sodium hydroxide, potassium hydroxide and water to carry out a hydrothermal reaction to obtain the MER-type zeolite.

[0036] In this invention, the sodium hydroxide is calculated as Na2O, the potassium hydroxide as K2O, and the hydrogen-form zeolite as Al2O3 and SiO2. The molar ratio of the hydrogen-form zeolite, sodium hydroxide, potassium hydroxide, and water satisfies Na2O:K2O:Al2O3:SiO2:H2O=(0~12):(0.1~12):1:(4~10):(100~1000), preferably (1.5~8):(0.5~5):1:(5~9):(200~600), and more preferably (2~6):(0.5~4):1:(5~8):(250~500).

[0037] In this invention, the mixing is preferably carried out by stirring. This invention does not have special requirements for the stirring conditions, as long as the mixture is stirred evenly. After mixing, a reaction gel is obtained.

[0038] In this invention, the temperature of the hydrothermal reaction is preferably 90-200°C, more preferably 100-180°C, and the time is preferably 0.5-10 days, more preferably 1-2 days.

[0039] After the hydrothermal reaction is completed, the product is preferably subjected to solid-liquid separation, solid-phase washing, and drying in sequence to obtain the potassium zeolite. In this invention, the solid-liquid separation method is preferably vacuum filtration, and the solid-phase washing is preferably water washing.

[0040] This invention provides potassium zeolite prepared by the method described in the above technical solution.

[0041] This invention provides the application of potassium zeolite as described above in the adsorption of heavy metal ions in wastewater.

[0042] In this invention, the heavy metal ions preferably include lead ions and / or cadmium ions; the concentration of heavy metal ions in the wastewater is preferably 0.1 to 1000 ppm, more preferably 0.5 to 300 ppm, and the pH value of the wastewater is preferably 2 to 7.

[0043] In this invention, the mass ratio of potassium zeolite to the volume of wastewater (i.e., solid-liquid ratio) is preferably 1g:100mL to 1g:10000mL. When the heavy metal ion is lead ion, the solid-liquid ratio is further preferably 1g:3000mL to 1g:5000mL. When the heavy metal ion is cadmium ion, the solid-liquid ratio is further preferably 1g:500mL to 1g:1000mL. In this invention, the adsorption temperature is preferably 25 to 80°C, and the adsorption time is preferably 10 to 600 min, more preferably 120 to 180 min.

[0044] In this invention, the preferred specific operation for adsorption is to place the potassium zeolite in wastewater containing heavy metal ions and stir it at a temperature of 25–80°C for adsorption.

[0045] The potassium zeolite provided by this invention can efficiently adsorb heavy metal ions in wastewater.

[0046] To further illustrate the present invention, the following detailed description, in conjunction with examples, describes the method for preparing potassium zeolite from natural zeolite, the potassium zeolite itself, and its applications, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] 10g of natural zeolite (purchased from Guilin Hsinchu Nature Biomaterials Co., Ltd.) was stirred in a 1mol / L ammonium chloride aqueous solution at 80℃ for 2h, and this process was repeated twice. The resulting solid was filtered, washed, dried, and then calcined at 550℃ for 4h to obtain hydrogen-form zeolite.

[0049] 8.1 g of hydrogen-form zeolite, 78 g of water, 3.5 g of sodium hydroxide, and 5.7 g of potassium hydroxide (85 wt%) were mixed and stirred until homogeneous to obtain a reaction gel (meeting the molar ratio Na₂O:K₂O:Al₂O₃:SiO₂:H₂O = 2.9:2.9:1:6.8:300). This gel was heated at 180 °C for 2 days to crystallize. After filtration, washing, and drying, the resulting product, potassium zeolite, was designated A1, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0050] Example 2

[0051] Other conditions were the same as in Example 1, but the crystallization temperature of potassium zeolite was changed to 90°C. The resulting potassium zeolite product was designated A2, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0052] Example 3

[0053] Other conditions were the same as in Example 1, but the crystallization temperature of potassium zeolite was changed to 200°C. The resulting potassium zeolite product was designated A3, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0054] Example 4

[0055] Other conditions were the same as in Example 1, but the crystallization time of potassium zeolite was changed to 0.5 days. The resulting potassium zeolite product was designated A4, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0056] Example 5

[0057] Other conditions were the same as in Example 1, but the crystallization time of potassium zeolite was changed to 10 days. The resulting potassium zeolite product was designated A5, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0058] Example 6

[0059] Other conditions were the same as in Example 1, except that the sodium hydroxide used in the synthesis was replaced with 1.8 g and the potassium hydroxide with 8.6 g. The resulting product, potassium zeolite, was designated A6, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0060] Example 7

[0061] Other conditions were the same as in Example 1, except that the sodium hydroxide used in the synthesis was replaced with 5.3 g and the potassium hydroxide with 2.9 g. The resulting product, potassium zeolite, was designated A7, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0062] Example 8

[0063] Other conditions were the same as in Example 1, except that sodium hydroxide used in the synthesis was replaced with an equal molar amount of potassium hydroxide. The resulting product, potassium zeolite, was designated A8, and its XRD pattern is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown.

[0064] Depend on Figure 1 It can be seen that A1 to A8 prepared in Examples 1 to 8 are all highly crystalline potassium zeolite.

[0065] Application Example 1

[0066] A certain amount of potassium zeolite A1 prepared in Example 1 was added to lead-containing wastewater with a lead concentration of 100 ppm and pH = 7 at a solid-liquid ratio of 1 g: 3000 mL (mass of potassium zeolite:volume of wastewater), and stirred at 25°C for 120 min. The content of residual lead ions in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0067] Application Example 2

[0068] Other conditions were the same as in Application Example 1, but the pH of the lead-containing wastewater was adjusted to 2. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0069] Application Example 3

[0070] Other conditions were the same as in Application Example 1, but the temperature was adjusted to 80°C. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0071] Application Example 4

[0072] Other conditions were the same as in Application Example 1, but the time was adjusted to 10 min. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0073] Application Example 5

[0074] Other conditions were the same as in Application Example 1, but the lead concentration in the lead-containing wastewater was adjusted to 300 ppm. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0075] Application Example 6

[0076] Other conditions were the same as in Application Example 1, but the solid-liquid ratio was adjusted to 1 g: 5000 mL. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0077] Application Example 7

[0078] Other conditions were the same as in Application Example 1, but the lead-containing wastewater was replaced with lead-containing wastewater containing 0.5 ppm lead, 1250 ppm sodium, 1250 ppm potassium, 1250 ppm calcium, and 1250 ppm magnesium. The resistance of the prepared potassium zeolite to ion interference was tested. The content of residual lead ions in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 1.

[0079] Application Example 8

[0080] A certain amount of potassium zeolite A1 prepared in Example 1 was added to cadmium-containing wastewater with a cadmium concentration of 100 ppm and pH = 7 at a solid-liquid ratio of 1 g: 500 mL, and stirred at 25 °C for 180 min. The content of residual cadmium ions in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0081] Application Example 9

[0082] Other conditions were the same as in Application Example 8, but the pH was adjusted to 2. The residual cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0083] Application Example 10

[0084] Other conditions were the same as in Application Example 8, but the temperature was adjusted to 80°C. The remaining cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0085] Application Example 11

[0086] Other conditions were the same as in Application Example 8, but the time was adjusted to 10 min. The remaining cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0087] Application Example 12

[0088] Other conditions were the same as in Application Example 8, but the cadmium concentration in the cadmium-containing wastewater was adjusted to 300 ppm. The residual cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0089] Application Example 13

[0090] Other conditions were the same as in Application Example 8, but the solid-liquid ratio was adjusted to 1 g: 1000 mL. The content of residual cadmium ions in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0091] Application Example 14

[0092] Other conditions were the same as in Application Example 8, but the cadmium-containing wastewater was replaced with cadmium-containing wastewater containing 0.5 ppm cadmium, 1250 ppm sodium, 1250 ppm potassium, 1250 ppm calcium, and 1250 ppm magnesium. The residual cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 2.

[0093] Table 1 shows the lead ion removal rates of potassium zeolite in Application Examples 1-7.

[0094]

[0095] Table 2 shows the removal rate of cadmium ions by potassium zeolite in Application Examples 8-14.

[0096]

[0097] Comparative Example 1

[0098] Other conditions were the same as in Example 1, except that potassium hydroxide used in the synthesis was replaced with an equal molar amount of sodium hydroxide, and potassium zeolite was not obtained.

[0099] Comparative Example 2

[0100] Other conditions were the same as in Example 1, but the crystallization temperature was changed to 80°C, and potassium zeolite was not obtained.

[0101] Comparative Example 3

[0102] Other conditions were the same as in Example 1, except that the hydrogen-type zeolite used for crystallization was replaced with an equal molar amount of boehmite and silica sol, and potassium zeolite was not obtained.

[0103] Comparative Example 4

[0104] 8.1g of natural zeolite (purchased from Guilin Hsinchu Nature Biomaterials Co., Ltd.), 78g of water, 3.5g of sodium hydroxide, and 5.7g of potassium hydroxide were mixed and stirred until homogeneous to obtain a reaction gel. This gel was then heated at 180℃ for crystallization for 2 days. After filtration, washing, and drying, the resulting product was designated A9, and its XRD pattern is shown below. Figure 1 As shown.

[0105] Depend on Figure 1 It can be seen that the product A9 prepared in Comparative Example 4 is a mixture of potassium zeolite and zeolite.

[0106] Comparative Example 5

[0107] Potassium zeolite was synthesized using the method described in Verified Syntheses of Zeolitic Materials Third Revised Edition, and is designated as B1.

[0108] Comparative Application Example 1

[0109] Other conditions were the same as in Application Example 1, except that the potassium zeolite added to the lead-containing wastewater was replaced with B1. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 3.

[0110] Comparative Application Example 2

[0111] Other conditions were the same as in Application Example 6, except that the potassium zeolite added to the lead-containing wastewater was replaced with B1. The residual lead ion content in the liquid was measured to calculate the lead ion removal rate, and the results are shown in Table 3.

[0112] Comparative Application Example 3

[0113] Other conditions were the same as in Application Example 8, except that the potassium zeolite added to the cadmium-containing wastewater was replaced with B1. The residual cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 4.

[0114] Comparative Application Example 4

[0115] Other conditions were the same as in Application Example 13, except that the potassium zeolite added to the cadmium-containing wastewater was replaced with B1. The residual cadmium ion content in the liquid was measured to calculate the cadmium ion removal rate, and the results are shown in Table 4.

[0116] Table 3 compares the lead ion removal rates of potassium zeolite in application examples 1 and 2.

[0117] Comparative application examples Comparative Application Example 1 Comparative Application Example 2 Lead ion removal rate 98.8％ 80.4％

[0118] Table 4 compares the removal rates of cadmium ions by potassium zeolite in application examples 3 and 4.

[0119] Comparative application examples Comparative Application Example 3 Comparative Application Example 4 Cadmium ion removal rate 97.1％ 78.3％

[0120] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing potassium zeolite from natural zeolite, characterized in that, Includes the following steps: Natural zeolite was mixed with an aqueous solution of ammonium salt and subjected to ion exchange to obtain ammonium-type zeolite. The ammonium-type zeolite was calcined to obtain hydrogen-type zeolite; The hydrogen-form zeolite is mixed with sodium hydroxide, potassium hydroxide, and water and subjected to a hydrothermal reaction to obtain the potassium hydroxide zeolite; the sodium hydroxide is calculated as Na2O, the potassium hydroxide as K2O, and the hydrogen-form zeolite as Al2O3 and SiO2; the molar ratio of the hydrogen-form zeolite, sodium hydroxide, potassium hydroxide, and water satisfies Na2O:K2O:Al2O3:SiO2:H2O=(0~12):(0.1~12):1:(4~10):(100~1000); the temperature of the hydrothermal reaction is 90~200℃.

2. The method according to claim 1, characterized in that, The ammonium salt in the aqueous solution includes one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate, and the concentration of the aqueous solution is 0.5~5 mol / L.

3. The method according to claim 1 or 2, characterized in that, The ion exchange temperature is 25~90℃, the number of ion exchanges is 1~4 times, and the time for a single ion exchange is 1~5 hours.

4. The method according to claim 1, characterized in that, The calcination temperature is 500~600℃, and the time is 2~8h.

5. The method according to claim 1, characterized in that, The hydrothermal reaction takes 0.5 to 10 days.

6. Potassium zeolite prepared by the method according to any one of claims 1 to 5.

7. The application of the potassium zeolite according to claim 6 in the adsorption of heavy metal ions in wastewater.

8. The application according to claim 7, characterized in that, The heavy metal ions include lead ions and / or cadmium ions.

9. The application according to claim 7 or 8, characterized in that, The concentration of heavy metal ions in the wastewater is 0.1~1000ppm.

10. The application according to claim 7, characterized in that, The mass ratio of potassium zeolite to wastewater is 1g:100mL to 1g:10000mL, the adsorption temperature is 25~80℃, and the time is 10~600min.

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