A PF6-intercalated layered Zn-Al-LDH and its preparation method

Abstract

This invention proposes a PF6 ‑ Intercalated layered Zn-Al-LDH and its preparation method belong to the technical field of hydrotalcite compounds. This invention addresses the technical problems encountered in the hydrothermal preparation of LDH, which requires the use of surfactants, leading to LDH agglomeration, large particle size, wide particle size distribution, and small specific surface area. The invention includes the following steps: (1) mixing a polar ionic liquid, a non-polar ionic liquid, and a dual-solvent ionic liquid to prepare a reversed-phase ionic liquid microemulsion; (2) adding a zinc source, an aluminum source, and a precipitant to the reversed-phase ionic liquid microemulsion, followed by a hydrothermal reaction to obtain layered Zn-Al-LDH. The reversed-phase ionic liquid microemulsion of this invention does not contain surfactants, greatly reducing environmental pollution and meeting the requirements of green development. Furthermore, the preparation process is simple, using common equipment, thus reducing production costs.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrotalcite compounds, and particularly relates to a PF6... - Intercalated layered Zn-Al-LDH and its preparation method. Background Technology

[0002] Layered hydrotalcite (LDH) is a class of bimetallic or polymetallic hydroxides with a special layered structure, and its molecular formula is [M]. 2+ 1-x M 3+ x (OH)2] x+ (A n- ) x / n ·mH2O(M 2+ It is a divalent cation, M 3+ LDH (a trivalent cation) exhibits promising applications in organic catalysis, biomedicine, and pollutant adsorption due to its uniform elemental distribution, adjustable types and proportions of elements, tunable interlayer anions, and diverse morphologies. Furthermore, LDH's numerous active sites, large specific surface area and pore volume, interlayer ion exchangeability, and high stability in water make it a potential adsorbent for water purification and remediation. The M in the LDH structure... 2+ M 3+ After isomorphous substitution, the interlayer plates become positively charged. Therefore, to maintain the electroneutrality of LDHs, there must be anions between the interlayer plates to balance the positive charges on the plates. To meet different application requirements, the type and quantity of interlayer anions and the interlayer spacing can be changed through ion exchange, thereby altering the performance of LDHs.

[0003] Currently, methods for preparing LDH nanomaterials with different morphologies include coprecipitation, microwave radiation, and hydrothermal methods. For example, Benhiti, R. et al. prepared MgAl-LDHs using traditional coprecipitation techniques and applied them to phosphate removal. (Benhiti, R., Ait Ichou, A., Zaghloul, A. et al. Synthesis, characterization, and comparative study of MgAl-LDHs prepared by standard coprecipitation and urea hydrolysis methods for phosphate removal[J]. Environmental Science and Pollution Research, 2020, 27; 45767-45774.) Li Longfeng et al. prepared well-crystallized, structurally regular Mg-Al binary hydrotalcite nanomaterials using microwave heating and reflux technology. (Li Longfeng, Gao Yuan, Zhang Maolin.) Synthesis of Mg-Al binary hydrotalcite compounds by microwave heating reflux method [J]. Journal of Huaibei Normal University (Natural Science Edition), 2011, 32(04): 36-38. Hu et al. prepared C / NiFe-LDH composite nanomaterials by a simple hydrothermal method and used them for the effective removal of methyl orange (MO) and Congo red (CR) anionic dyes. Haojun Hu, S. Wageh, Ahmed A. Al-Ghamdi, et al. NiFe-LDH nanosheet / carbonfiber nanocomposite with enhanced anionic dye adsorption performance [J]. Applied Surface Science, 2022, 511: 145570. Wang et al. prepared 3D flower-like Mg-Al hydrotalcite nanomaterials by hydrothermal technology and used them for the efficient removal of U(VI) from wastewater. XinWang,YawenCai,TianhaoHan,etal.Phosphate functionalized layered double hydroxides(phos-LDH)for ultrafast and efficient U(VI)uptake from pollutedsolutions[J].JournalofHazardousMaterials,2020,399:123081.

[0004] The performance of LDH is closely related to its particle size and particle size distribution. However, the LDH nanomaterials prepared by the above method have low crystallinity, uneven particle size, and are prone to agglomeration, which limits the application of LDH in the field of adsorption. Summary of the Invention

[0005] To address the technical problems of poor reaction stability and environmental pollution caused by the use of surfactants in the hydrothermal preparation of LDH, this invention proposes a PF6... - Intercalated layered Zn-Al-LDH and its preparation method: A microemulsion-hydrothermal coupling method is used to confine the precursors zinc nitrate hexahydrate, magnesium nitrate nonahydrate, and urea within tiny water droplets of a reverse microemulsion, restricting precursor nucleation and growth, resulting in Zn₂Al layered double hydroxides with good morphology. The reverse ionic liquid microemulsion is surfactant-free, significantly reducing environmental pollution and meeting the requirements of green development. Furthermore, the preparation process is simple, using readily available equipment, thus reducing production costs.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A PF6 - The preparation method of intercalated layered Zn-Al-LDH includes the following steps:

[0008] (1) Mix polar phase ionic liquid, nonpolar phase ionic liquid and dual solvent ionic liquid to prepare reverse phase ionic liquid microemulsion;

[0009] (2) Zinc source, aluminum source and precipitant were added to the reverse ionic liquid microemulsion, and then a hydrothermal reaction was carried out to obtain layered Zn-Al-LDH.

[0010] The polar phase ionic liquid is N-methylethanolamine glycolate ([MEOA][HOCH2COO]) or N-methylethanolamine nitrate ([MEOA][NO3]).

[0011] The nonpolar ionic liquid phase is: N-butylpyridine hexafluorophosphate ([Bpy][PF6]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]).

[0012] The dual-solvent ionic liquid is N,N-dimethylethanolamine trifluoroacetate ([DMEOA][CF3COO]) or N,N-dimethylethanolamine nitrate ([DMEOA][NO3]).

[0013] The volume ratio of the polar phase ionic liquid, the nonpolar phase ionic liquid, and the dual-solvent ionic liquid is (0.45–1.5):(3–4):1.5.

[0014] The zinc source is zinc nitrate; the aluminum source is aluminum nitrate; and the precipitant is urea.

[0015] The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant is (1-5):1:(5-12).

[0016] In step (2), the concentration of zinc in the reverse ionic liquid microemulsion is 0.01–0.05 mmol·mL. -1 .

[0017] The hydrothermal reaction is carried out at a temperature of 90–120°C for 1–3 hours.

[0018] The beneficial effects of this invention are:

[0019] Microemulsions are macroscopically homogeneous, optically isotropic, transparent, and thermodynamically stable single-phase media formed by two or more immiscible components under the action of surfactants and co-surfactants. Reverse microemulsions, on the other hand, are microreactors formed by numerous small, stable micro-droplets dispersed in an oil phase medium. Reverse microemulsion droplets, acting as micro-nanoreactors, can restrict the nucleation, growth, and crystallization of LDH nanomaterials. This reaction does not use organic solvents or alkaline solutions, reducing environmental pollution. Simultaneously, the aqueous phase uses a high-temperature resistant ionic liquid, resulting in a distinct layered structure and uniform particle size distribution in the prepared Mg-Al-LDH. This avoids the problems of water or organic solvent evaporation, demulsification, agglomeration, and misshapen structures in reverse microemulsions caused by excessively high temperatures during hydrothermal reactions. Therefore, using reverse microemulsion droplets as soft templates not only effectively solves the problems associated with traditional LDH preparation methods but also allows for precise control of the particle size and morphology of LDH nanomaterials to improve their adsorption performance, providing an ideal platform for constructing LDH nanomaterials.

[0020] Traditional surfactant microemulsions (SBMEs) suffer from drawbacks such as component volatility, poor thermal stability, weak self-assembly ability, and difficulty in surfactant removal. Furthermore, when used as soft templates to prepare LDH nanomaterials, the large presence of surfactants reduces the purity and surface activity of the nanomaterials, significantly limiting the application of SBMEs. Green surfactant-free microemulsion (SFME) systems, constructed by replacing surfactants with "dual solvents," contain no surfactants and possess similar microstructures and physicochemical properties to SBMEs. Therefore, replacing SBMEs with SFME systems not only reduces manufacturing costs but is also more environmentally friendly and can even enable the recycling of raw materials. Ionic liquids (ILs), as a novel type of green solvent, possess unique physicochemical properties, such as negligible vapor pressure, good thermal stability, and a wide electrochemical window. In particular, ionic liquids exhibit structural tunability, allowing them to function as polar phases, non-polar phases, or surfactants within IL-SFMEs. Introducing ionic liquids into SFMEs not only solves the problems of component volatility and poor stability inherent in SFMEs, but also enables SFMEs to simultaneously possess the characteristics of ILs and microemulsions, effectively improving the structural size and thermodynamic stability of microemulsions. Therefore, using the IL-SFME system as a soft template for the directional regulation of LDH nanomaterials has significant theoretical and practical implications for the efficient and reversible adsorption of organic dyes and phosphates by LDH nanomaterials. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 Phase diagram for [MEOA][HOCH2COO] / [Bmim][PF6] / [DMEOA][CF3COO]IL-SFMEs.

[0023] Figure 2 The XRD pattern of Zn-Al-LDH prepared in Example 1.

[0024] Figure 3 XPS image of Zn-Al-LDH prepared in Example 1.

[0025] Figure 4 SEM image of Zn-Al-LDH prepared in Example 1. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal combined method. - Intercalated layered Zn-Al-LDH.

[0029] The specific dosage and operating steps are as follows:

[0030] 1. Configure m [MEOA][HOCH2COO] :m [Bmim][PF6] :m [DMEOA][CF3COO] =1.5:3.715:1.5 W / O type microemulsion, 10 mL total;

[0031] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0032] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0033] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0034] Example 2

[0035] A PF6 -Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal combined method. - Intercalated layered Zn-Al-LDH.

[0036] The specific dosage and operating steps are as follows:

[0037] 1. Configure m [MEOA][HOCH2COO] :m [Bmim][PF6] :m [DMEOA][CF3COO] =1.5:4:1.5 W / O type microemulsion, 10 mL in total;

[0038] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0039] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0040] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0041] Example 3

[0042] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal combined method. - Intercalated layered Zn-Al-LDH.

[0043] The specific dosage and operating steps are as follows:

[0044] 1. Configure m [MEOA][HOCH2COO] :m [Bmim][PF6] :m [DMEOA][CF3COO] =1.5:3.5:1.5 W / O type microemulsion, 10 mL in total;

[0045] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0046] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0047] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0048] Example 4

[0049] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal combined method. - Intercalated layered Zn-Al-LDH.

[0050] The specific dosage and operating steps are as follows:

[0051] 1. Configure m [MEOA][HOCH2COO] :m [Bmim][PF6] :m [DMEOA][CF3COO] =1.5:3.25:1.5 W / O type microemulsion, 10 mL total;

[0052] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0053] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0054] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0055] Example 5

[0056] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal combined method. - Intercalated layered Zn-Al-LDH.

[0057] The specific dosage and operating steps are as follows:

[0058] 1. Configure m [MEOA][HOCH2COO] :m [Bmim][PF6] :m [DMEOA][CF3COO] =1.5:3:1.5 W / O type microemulsion, 10 mL in total;

[0059] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0060] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0061] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0062] Example 6

[0063] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][NO3] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal coupling method. - Intercalated layered Zn-Al-LDH.

[0064] The specific dosage and operating steps are as follows:

[0065] 1. Configure m [MEOA][NO3] :m [Bmim][PF6] :m [DMEOA][CF3COO] =1.5:3.715:1.5 W / O type microemulsion, 10 mL total;

[0066] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0067] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0068] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0069] Example 7

[0070] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bpy][PF6] as the nonpolar phase, and [DMEOA][CF3COO] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal combined method. - Intercalated layered Zn-Al-LDH.

[0071] The specific dosage and operating steps are as follows:

[0072] 1. Configure m [MEOA][HOCH2COO] :m [Bpy][PF6] :m [DMEOA][CF3COO] =1.5:3.715:1.5 W / O type microemulsion, 10 mL total;

[0073] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL-1 ).

[0074] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0075] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0076] Example 9

[0077] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][NO3] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal coupling method. - Intercalated layered Zn-Al-LDH.

[0078] The specific dosage and operating steps are as follows:

[0079] 1. Configure m [MEOA][HOCH2COO] :m [Bpy][PF6] :m [DMEOA][NO3] =1.5:3.715:1.5 W / O type microemulsion, 10 mL total;

[0080] Zinc nitrate hexahydrate (0.1190 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.135 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.4 mmol:0.2 mmol:2.2 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.04 mmol·mL.) -1 0.02 mmol·mL -1 0.22 mmol·mL -1 ).

[0081] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 120°C for 3 hours. The final product was obtained by washing with anhydrous ethanol.

[0082] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0083] Example 10

[0084] A PF6 -Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][NO3] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal coupling method. - Intercalated layered Zn-Al-LDH.

[0085] The specific dosage and operating steps are as follows:

[0086] 1. Configure m [MEOA][HOCH2COO] :m [Bpy][PF6] :m [DMEOA][NO3] =0.45:3.715:1.5 W / O type microemulsion, 20 mL total;

[0087] Zinc nitrate hexahydrate (0.0595 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.0614 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.2 mmol:0.2 mmol:1 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.01 mmol·mL, respectively.) -1 0.01 mmol·mL -1 0.05 mmol·mL -1 ).

[0088] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 100°C for 1 hour. The final product was obtained by washing with anhydrous ethanol.

[0089] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0090] Example 11

[0091] A PF6 - Intercalated layered Zn-Al-LDH was used to construct an IL-SFME with [MEOA][HOCH2COO] as the polar phase, [Bmim][PF6] as the nonpolar phase, and [DMEOA][NO3] as the "dual solvent". PF6 was prepared using a microemulsion-hydrothermal coupling method. - Intercalated layered Zn-Al-LDH.

[0092] The specific dosage and operating steps are as follows:

[0093] 1. Configure m [MEOA][HOCH2COO] :m [Bpy][PF6] :m [DMEOA][NO3] =1:3.715:1.5 W / O type microemulsion, 10 mL total;

[0094] Zinc nitrate hexahydrate (0.1488 g), aluminum nitrate hexahydrate (0.075 g), and urea (0.0859 g) were added sequentially to the microemulsion, and the mixture was stirred at room temperature for 0.5 h. (The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant was 0.5 mmol:0.2 mmol:1.4 mmol; the concentrations of zinc in the zinc source, aluminum in the aluminum source, and precipitant were 0.05 mmol·mL, respectively.) -1 0.02 mmol·mL -1 0.14 mmol·mL -1 ).

[0095] 2. The aged mixture was transferred to a reaction vessel and hydrothermally heated at 90°C for 1 hour. The final product was obtained by washing with anhydrous ethanol.

[0096] 3. The product is placed in a vacuum drying oven at 60°C for 6 hours to remove residual solvent and obtain the final product.

[0097] Test case

[0098] The ternary phase diagram of the surfactant-free ionic liquid microemulsion system [MEOA][HOCH2COO] / [Bmim][PF6] / [DMEOA][CF3COO] was determined by visual titration. The results are as follows: Figure 1 As shown. By Figure 1 As can be seen, the ternary phase diagram is divided into two regions. The upper single-phase region is a transparent and homogeneous microemulsion region, while the lower region is a turbid multiphase region. After standing, the microemulsion will separate into layers. This proves that by selecting appropriate polar phases, non-polar phases, and dual solvents, the present invention can obtain stable reverse microemulsions even without the use of surfactants.

[0099] The crystal structure of the intercalated Zn-Al-LDH synthesized in Example 1 using an ionic liquid surfactant-free microemulsion system as a soft template was studied using X-ray diffraction (XRD). The results are as follows: Figure 2 As shown in the figure, Zn-Al-LDH not only possesses typical hydrotalcite diffraction planes, but also exhibits corresponding intercalated PF6 layers. - Characteristic diffraction peaks.

[0100] The elemental composition of the Zn-Al-LDH nanomaterials prepared in Example 1 was analyzed using X-ray photoelectron spectroscopy (XPS), and the results are as follows: Figure 3 As shown. From Figure 3 It can be seen that Zn-Al-LDH is mainly composed of Zn, Al, C, N, O, P, and F elements, which further proves that PF6 - Successfully inserted between the layers of Zn-Al-LDH.

[0101] The Zn-Al-LDH prepared in Example 1 was characterized using scanning electron microscopy (SEM), and the results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the material has a distinct layered structure, which to some extent increases the specific surface area of ​​Zn-Al-LDH, making it more suitable for its application in wastewater treatment.

[0102] Furthermore, in Examples 1-5, by controlling the volumes of both the polar and nonpolar ionic liquid phases, the particle size and morphology of the prepared LDH can be effectively controlled. Moreover, since the reaction system does not contain surfactants, the hydrothermal reaction process is more stable.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PF6 - A method for preparing intercalated layered Zn-Al-LDH, characterized in that, Includes the following steps: (1) Mix polar phase ionic liquid, nonpolar phase ionic liquid and dual solvent ionic liquid to prepare reverse phase ionic liquid microemulsion; (2) Zinc source, aluminum source and precipitant were added to the reverse ionic liquid microemulsion, and then a hydrothermal reaction was carried out to obtain layered Zn-Al-LDH; The polar phase ionic liquid is N-methylethanolamine glycolate or N-methylethanolamine nitrate; The nonpolar ionic liquid phase is N-butylpyridine hexafluorophosphate or 1-butyl-3-methylimidazolium hexafluorophosphate; The dual-solvent ionic liquid is N,N-dimethylethanolamine trifluoroacetate or N,N-dimethylethanolamine nitrate; The volume ratio of the polar phase ionic liquid, the nonpolar phase ionic liquid, and the dual-solvent ionic liquid is (0.45–1.5):(3–4):1.

5.

2. The PF6 according to claim 1 - A method for preparing intercalated layered Zn-Al-LDH, characterized in that, The zinc source is zinc nitrate; the aluminum source is aluminum nitrate; and the precipitant is urea.

3. The PF6 according to claim 2 - A method for preparing intercalated layered Zn-Al-LDH, characterized in that, The molar ratio of zinc in the zinc source, aluminum in the aluminum source, and precipitant is (1-5):1:(5-12).

4. The PF6 according to claim 3 - A method for preparing intercalated layered Zn-Al-LDH, characterized in that, In step (2), the concentration of zinc in the reverse ionic liquid microemulsion is 0.01–0.05 mmol·mL. -1 .

5. The PF6 according to claim 4 - A method for preparing intercalated layered Zn-Al-LDH, characterized in that, The hydrothermal reaction is carried out at a temperature of 90–120 °C for a time of 1–3 h.

6. PF6 prepared by the method according to any one of claims 1-5 - Intercalated layered Zn-Al-LDH.

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