Porous nano material as well as preparation method and application thereof

Abstract

The invention belongs to the field of material science, and particularly relates to a porous nano-material and a preparation method and application thereof.The porous nano-material is prepared by taking a nano-emulsion composed of a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, a polyethylene glycol polypropylene glycol polyethylene glycol triblock copolymer, a pore-enlarging agent and water as a template; a zirconium source and an organic ligand are subjected to a coordination reaction on an emulsion interface, and the porous nano material is obtained. The porous nano-material provided by the invention can be used as an efficient and stable heavy metal adsorbent, the mercury ion removal rate reaches up to 99.98%, saturated adsorption can be achieved within a short time, and the porous nano-material has relatively strong regeneration capacity, good selectivity and cycling stability.

Description

Technical Field

[0001] The present invention belongs to the field of material science, and specifically relates to a porous nanomaterial and a preparation method and application thereof. Background Art

[0002] With the intensification of industrial activities, mercury pollution has become a global environmental challenge. 2+ Mercury ions (Hg) pose a serious threat to aquatic ecosystems and human health due to their high toxicity, bioaccumulation, and environmental persistence. Industrial wastewater (e.g., from electroplating, mining, and pharmaceutical industries) is a major source of mercury pollution, with concentrations far exceeding national emission standards. Traditional water treatment technologies face significant challenges: mercury ions readily form soluble complexes in water, making them difficult to completely remove using conventional methods. Furthermore, even trace amounts can amplify their toxic effects through the food chain. Therefore, the development of efficient and highly selective mercury ion adsorption materials is urgent.

[0003] Current mercury ion removal technologies include physical adsorption, chemical precipitation, electrochemical, and biological treatment. Physical adsorption often uses adsorbents such as activated carbon and zeolite, but their adsorption capacity and selectivity are limited, making them ineffective in treating high-concentration mercury ions. Furthermore, traditional adsorbents have poor regeneration capabilities. Chemical precipitation is susceptible to solubility limitations when treating wastewater with high mercury concentrations, and the use of chemical reagents also poses a risk of secondary pollution. Electrochemical methods are complex to operate and consume a lot of energy, and the electrolytic equipment is susceptible to mercury ion contamination, resulting in poor reaction stability.

[0004] Biological treatment mainly relies on microbial metabolism and is suitable for low-concentration mercury ions. It has a slow treatment speed and is greatly affected by environmental conditions. It has limited effect in the treatment of high-concentration wastewater.

[0005] In recent years, metal-organic framework (MOF) materials have shown great potential in the field of heavy metal adsorption due to their high specific surface area and adjustable pore structure. Compared with traditional adsorbents such as activated carbon and zeolites, MOFs have a larger specific surface area and a richer functionalized surface, which can rapidly adsorb large amounts of mercury ions with higher adsorption capacity and selectivity. However, MOF materials also have problems such as complex synthesis processes and poor stability, which lead to reduced adsorption performance. Therefore, the development of a method for preparing an adsorbent material that can efficiently remove mercury ions and has good stability is an urgent need in the current field of environmental remediation. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a porous nanomaterial and its preparation method and application. The porous nanomaterial provided by the present invention can be used as an efficient and stable heavy metal adsorbent. Experiments show that this porous nanomaterial has a mercury ion removal rate of up to 99.98% and has good selectivity and stability.

[0007] To achieve the above purpose, the specific technical solutions of the present invention are as follows: The first aspect of the present invention provides a method for preparing a porous nanomaterial, wherein a zirconium source and an organic ligand undergo a coordination reaction at the interface of an emulsion to obtain the porous nanomaterial; the emulsion is composed of a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, a polyethylene glycol-polypropylene alcohol-polyethylene glycol triblock copolymer, a pore expander and water.

[0008] Furthermore, the method comprises the following steps: dissolving polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyethylene glycol polypropylene alcohol polyethylene glycol triblock copolymer in water, and then adding acetic acid, ClO4 - , a zirconium source and a pore-enlarging agent, and stirring to form a nanoemulsion; After adding the organic ligand into the nanoemulsion, stirring, centrifuging, collecting the solid precipitate, washing, removing impurities and drying, the porous nanomaterial is obtained.

[0009] Furthermore, the pore-enlarging agent is 1,3,5-trimethylbenzene; and the organic ligand is 2,5-dithiophthalic acid or 2-aminoterephthalic acid.

[0010] The zirconium source provides the metal nodes (zirconium clusters) in the MOF framework, and 2,5-dithiophthalic acid serves as the organic ligand. 4+ The coordination forms a three-dimensional framework structure of UiO-66-SH2, and the presence of its thiol functional group also has the effect of reducing the electrostatic potential of the material; ClO4 - It plays the role of a modulator in the synthesis of nanomaterials, regulating the pH and ionic environment of the solution through weakly coordinating anions, affecting the crystallization process of MOF; polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyethylene glycol polypropylene alcohol polyethylene glycol triblock copolymer act as surfactants, forming templates at the water-oil interface through self-assembly, and the size of the nanomaterial pores can be adjusted by adjusting the mixing ratio of the two surfactants to synergistically form a specific pore morphology; acetic acid reacts with Zr 4+ Competitive coordination slows down the crystallization rate of MOF, thereby helping the nanomaterial to form a more regular structure; 1,3,5-trimethylbenzene, as an oil phase component, forms a nanoemulsion with the water phase, providing a template for the formation of mesoporous structure.

[0011] Furthermore, the mixing ratio of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, polyethylene glycol polypropylene alcohol polyethylene glycol triblock copolymer, acetic acid, NaClO4·H2O, ZrOCl2·8H2O, 1,3,5-trimethylbenzene solution and 2,5-dithiophthalic acid in the nanomaterial is 10 mg~50 mg: 10 mg~50 mg: 0.5 mL~2.5 mL: 150 mg: 50 mg~170 mg: 50 μL~250 μL: 40 mg~120 mg.

[0012] Furthermore, the stirring speed is 400 rpm to 800 rpm, the temperature during stirring is 45° C. to 95° C., and the stirring time is 4 h to 8 h.

[0013] Furthermore, the stirring temperature is 70° C. and the stirring time is 5 h.

[0014] Furthermore, the centrifugal speed is 6000 rpm to 10000 rpm, the centrifugal temperature is 20° C. to 25° C., and the centrifugal time is 2 min to 5 min.

[0015] Furthermore, the washing is first washing with deionized water or ethanol solution, and then washing with dimethylformamide solution.

[0016] Furthermore, the impurity removal is performed by soaking the washed solid precipitate in an ethanol solution.

[0017] Furthermore, after the impurity removal, the solid precipitate after impurity removal needs to be vacuum dried.

[0018] The second aspect of the present invention provides a porous nanomaterial prepared by the above-mentioned preparation method.

[0019] The third aspect of the present invention provides a use of the porous nanomaterial described above in the preparation of a heavy metal adsorbent.

[0020] Furthermore, the heavy metal is mercury.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a porous nanomaterial. Using a nanoemulsion composed of a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, a polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer, a pore-enlarging agent, and water as a template, a zirconium source and an organic ligand undergo a coordination reaction at the emulsion interface to produce a porous nanomaterial. Compared to traditional MOF material synthesis methods, this invention utilizes nanoemulsion technology, which is simple and easy to use, capable of synthesizing MOF materials with uniform quality and a high specific surface area in a relatively short period of time. This method is widely applicable to large-scale production and has high industrial potential.

[0022] The preparation method provided by the present invention can be used to synthesize a porous nanomaterial with a uniform, multi-channel structure. This structure provides abundant adsorption sites in the porous body distributed over a large area, which makes the material have obvious advantages in terms of adsorption efficiency and selectivity. This porous nanomaterial has a high adsorption capacity for heavy metal ions, especially for heavy metal ions such as Hg (II). Experiments show that the removal rate of mercury ions by this porous nanomaterial is as high as 99.98%, and it can reach saturated adsorption in a short time and has strong regeneration ability. The porous nanomaterial provided by the present invention has excellent stability. Even in the process of multiple adsorption and desorption, its adsorption capacity does not show significant attenuation, and it has strong reusability. Therefore, the porous nanomaterial provided by the present invention and its preparation method have great application prospects in water treatment and environmental governance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a transmission electron microscope image of the Nic-UiO-66-SH1 material prepared in Example 1.

[0025] Figure 2 This is a scanning electron microscope image of the Nic-UiO-66-SH1 material prepared in Example 1.

[0026] Figure 3 This is the X-ray diffraction pattern of the Nic-UiO-66-SH1 material prepared in Example 1.

[0027] Figure 4 Does not contain surfactant and ClO4 - Characterization diagram of the synthesized nanomaterials, Figure a is the SEM image, and Figure b is the TEM image.

[0028] Figure 5 Characterization diagram of microporous UiO-66-SH crystals, Figure a is the SEM image, and Figure b is the TEM image.

[0029] Figure 6 Characterization diagram of nanomaterials synthesized without surfactant, Figure a is the SEM image, and Figure b is the TEM image.

[0030] Figure 7 Does not contain ClO4- Characterization diagrams of the synthesized nanomaterials, Figure a is the SEM image, and Figure b is the TEM image.

[0031] Figure 8 Figure a is a SEM image and Figure b is a TEM image of the nanomaterials synthesized using F127 as a single surfactant.

[0032] Figure 9 Characterization diagram of nanomaterials synthesized using P123 as a single surfactant. Figure a is the SEM image and Figure b is the TEM image.

[0033] Figure 10 The adsorption kinetics and isotherm fitting of Hg(II) ions on Nic-UiO-66-SH1 and microporous UiO-66-SH prepared in Example 1. Figure a is the adsorption kinetics fitting of Nic-UiO-66-SH1, Figure b is the adsorption kinetics fitting of microporous UiO-66-SH, Figure c is the adsorption isotherm fitting of Nic-UiO-66-SH1, and Figure d is the adsorption isotherm fitting of microporous UiO-66-SH.

[0034] Figure 11 Results of continuous adsorption-desorption cycles using Nic-UiO-66-SH1.

[0035] Figure 12 These are the experimental results of the effect of coexisting ions on the adsorption of Hg(II) by Nic-UiO-66-SH1. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following embodiments can be obtained from commercial sources unless otherwise specified.

[0037] Intensified industrial activity has made mercury pollution a global environmental challenge. Existing technologies for mercury ion removal include physical adsorption, chemical precipitation, electrochemical methods, and biological treatment. Physical adsorption has limited adsorption capacity and selectivity, and poor regeneration capacity; chemical precipitation is limited by solubility when treating high-concentration mercury wastewater, posing a risk of secondary pollution; electrochemical methods are complex to operate and energy-intensive, and electrolytic equipment is susceptible to mercury ion contamination, resulting in poor stability; biological treatment methods are slow, greatly affected by environmental conditions, and have limited effectiveness in treating high-concentration wastewater. Metal-organic framework materials have great potential in the field of heavy metal adsorption due to their high specific surface area and adjustable pore structure, but their complex synthesis process and poor stability make them susceptible to structural disintegration or pore collapse in aqueous environments, resulting in reduced adsorption performance. Therefore, there is an urgent need to develop a method for preparing an adsorption material that can efficiently remove mercury ions and has good cyclic stability.

[0038] The present invention provides a porous nanomaterial, its preparation method, and application. Using a nanoemulsion composed of a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, a polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer, a pore-expanding agent, and water as a template, a zirconium source and an organic ligand undergo a coordination reaction at the emulsion interface to produce a porous nanomaterial. The porous nanomaterial provided by the present invention can be used as a highly efficient and stable heavy metal adsorbent. Experimental results show that this porous nanomaterial has a mercury ion removal rate of up to 99.98%, can reach saturated adsorption within a short period of time, and exhibits strong regeneration ability, good selectivity, and cyclic stability.

[0039] Example 1: A method for preparing a porous nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification reaction: 10 mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and 50 mg of polyethylene glycol-polypropylene glycol triblock copolymer (F127) were dissolved in 6 mL of deionized water to obtain a mixed solution; then, 1.5 mL of 99 wt % glacial acetic acid solution, 150 mg of NaClO4·H2O, 110 mg of ZrOCl2·8H2O and 150 μL of 98 wt % 1,3,5-trimethylbenzene solution (TMB) were added to the mixed solution, and the solution was stirred at 70 °C and 700 rpm until a stable nanoemulsion was formed.

[0040] (2) Addition of ligand: 80 mg of 2,5-dithiophthalic acid (BDC-SH) was added to the nanoemulsion and stirred at 70 °C and 700 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0041] (3) Product separation and washing: After the reaction, centrifuge at 8000 rpm for 3 min at 23°C to collect the solid product, wash it once with deionized water, and then wash it twice with dimethylformamide solution (DMF) to remove unreacted raw materials and solvent.

[0042] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum oven at 60°C for 12 hours to obtain a porous nanomaterial, which was labeled as Nic-UiO-66-SH1.

[0043] Example 2: A method for preparing a porous nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification reaction: 20 mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and 40 mg of polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer were dissolved in 6 mL of deionized water to obtain a mixed solution; then, 0.5 mL of 99 wt % glacial acetic acid solution, 150 mg of NaClO4·H2O, 50 mg of ZrOCl2·8H2O and 50 μL of 98 wt % 1,3,5-trimethylbenzene solution were added to the mixed solution, and the solution was stirred at 70 °C and 400 rpm until a stable nanoemulsion was formed.

[0044] (2) Addition of ligand: 40 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 400 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0045] (3) Product separation and washing: After the reaction is completed, centrifuge at 20°C and 10,000 rpm for 2 min to collect the solid product, wash it once with anhydrous ethanol, and then wash it twice with dimethylformamide solution to remove unreacted raw materials and solvent.

[0046] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum oven at 60°C for 12 hours to obtain a porous nanomaterial.

[0047] Example 3: A method for preparing a porous nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification reaction: 30 mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and 30 mg of polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer were dissolved in 6 mL of deionized water to obtain a mixed solution; then, 1 mL of 99 wt % glacial acetic acid solution, 150 mg of NaClO4·H2O, 170 mg of ZrOCl2·8H2O and 250 μL of 98 wt % 1,3,5-trimethylbenzene solution were added to the mixed solution, and the solution was stirred at 70 °C and 800 rpm until a stable nanoemulsion was formed.

[0048] (2) Addition of ligand: 120 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 800 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0049] (3) Product separation and washing: After the reaction is completed, centrifuge at 6000 rpm for 5 min at 25°C to collect the solid product, wash it once with deionized water, and then wash it twice with dimethylformamide solution to remove unreacted raw materials and solvent.

[0050] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum oven at 60°C for 12 hours to obtain a porous nanomaterial.

[0051] Example 4: A method for preparing a porous nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification reaction: 40 mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and 20 mg of polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer were dissolved in 6 mL of deionized water to obtain a mixed solution; then, 2.5 mL of 99 wt % glacial acetic acid solution, 150 mg of NaClO4·H2O, 170 mg of ZrOCl2·8H2O and 250 μL of 98 wt % 1,3,5-trimethylbenzene solution were added to the mixed solution, and the solution was stirred at 70 °C and 800 rpm until a stable nanoemulsion was formed.

[0052] (2) Addition of ligand: 120 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 800 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0053] (3) Product separation and washing: After the reaction is completed, centrifuge at 6000 rpm for 5 min at 25°C to collect the solid product, wash it once with deionized water, and then wash it twice with dimethylformamide solution to remove unreacted raw materials and solvent.

[0054] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum oven at 60°C for 12 hours to obtain a porous nanomaterial.

[0055] Example 5: A method for preparing a porous nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification reaction: 50 mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and 10 mg of polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer were dissolved in 6 mL of deionized water to obtain a mixed solution; then, 3 mL of 99 wt % glacial acetic acid solution, 150 mg of NaClO4·H2O, 170 mg of ZrOCl2·8H2O and 250 μL of 98 wt % 1,3,5-trimethylbenzene solution were added to the mixed solution, and the solution was stirred at 70 °C and 800 rpm until a stable nanoemulsion was formed.

[0056] (2) Addition of ligand: 120 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 800 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0057] (3) Product separation and washing: After the reaction is completed, centrifuge at 6000 rpm for 5 min at 25°C to collect the solid product, wash it once with deionized water, and then wash it twice with dimethylformamide solution to remove unreacted raw materials and solvent.

[0058] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum oven at 60°C for 12 hours to obtain a porous nanomaterial.

[0059] Comparative Example 1: A method for preparing a nanomaterial, comprising the following steps: (1) Precursor dissolution: Dissolve 110 mg of ZrOCl2·8H2O in 6 mL of deionized water and stir until completely transparent.

[0060] (2) Ligand addition and reaction: Add 80 mg of BDC-SH and 1.5 mL of 99 wt% glacial acetic acid, and stir at 70 °C and 700 rpm for 5 hours.

[0061] (3) Product separation and washing: The reaction solution was centrifuged at 25 °C and 8000 rpm for 3 min to collect the solid. The solid product was collected and washed once with deionized water and then twice with DMF to remove unreacted raw materials and solvent.

[0062] (4) Drying treatment: The sample obtained in step (3) was placed in a vacuum dryer at 60°C for 12 hours.

[0063] Comparative Example 2: A method for preparing a nanomaterial, comprising the following steps: (1) Precursor dissolution: Dissolve 80 mg ZrCl4 and 80 mg BDC-SH in 10 mL DMF, add 1.0 mL 99 wt% glacial acetic acid, and stir at room temperature for 30 min.

[0064] (2) Solvothermal reaction: The mixed solution was transferred to a reactor and reacted at 120 °C for 24 h.

[0065] (3) Product separation and washing: After the reaction, centrifuge at 8000 rpm for 3 min at 23°C to collect the solid product, and wash the solid product once with deionized water and then twice with DMF.

[0066] (4) Drying treatment: The sample obtained in step (3) was placed in a vacuum dryer at 60°C for 12 hours to obtain microporous UiO-66-SH (micro-UiO-66-SH).

[0067] Comparative Example 3: A method for preparing a nanomaterial, comprising the following steps: (1) Precursor dissolution: Dissolve 110 mg of ZrOCl2·8H2O and 150 mg of NaClO4·H2O in 6 mL of deionized water and stir until completely dissolved. Add 1.5 mL of 99 wt% glacial acetic acid and 150 μL of 98 wt% TMB and stir at 70°C and 700 rpm to form a homogeneous solution.

[0068] (2) Addition of ligand: Add 80 mg of BDC-SH and stir at 70°C and 700 rpm for 5 hours.

[0069] (3) Product separation and washing: After the reaction, centrifuge at 8000 rpm for 3 min at 23°C to collect the solid product, and wash the solid product once with deionized water and then twice with DMF to remove unreacted raw materials and solvent.

[0070] (4) Drying: The sample obtained in step (3) was placed in a vacuum dryer at 60°C for 12 hours.

[0071] Comparative Example 4: A method for preparing a nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification: 10 mg of P123 and 50 mg of F127 were dissolved in 6 mL of water, and 1.5 mL of glacial acetic acid, 110 mg of ZrOCl2·8H2O, and 150 μL of 98 wt% TMB were added. The mixture was stirred at 70 °C and 700 rpm for emulsification.

[0072] (2) Addition of ligand: 80 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 700 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0073] (3) Product separation and washing: After the reaction, centrifuge at 8000 rpm for 3 min at 23°C to collect the solid product, and wash the solid product once with deionized water and then twice with DMF to remove unreacted raw materials and solvent.

[0074] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum oven at 60°C for 12 hours.

[0075] Comparative Example 5: A method for preparing a nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification: 60 mg of F127 was dissolved in 6 mL of water, and 1.5 mL of glacial acetic acid, 150 mg of NaClO4·H2O, 110 mg of ZrOCl2·8H2O, and 150 μL of 98 wt% TMB were added. Emulsification was carried out at 70 °C and 700 rpm.

[0076] (2) Addition of ligand: 80 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 700 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0077] (3) Product separation and washing: After the reaction, centrifuge at 8000 rpm for 3 min at 23°C to collect the solid product, and wash the solid product once with deionized water and then twice with DMF to remove unreacted raw materials and solvent.

[0078] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum dryer at 60°C for 12 hours.

[0079] Comparative Example 6: A method for preparing a nanomaterial, comprising the following steps: (1) Solvent mixing and emulsification: 60 mg of P123 was dissolved in 6 mL of water, and 1.5 mL of glacial acetic acid, 150 mg of NaClO4·H2O, 110 mg of ZrOCl2·8H2O, and 150 μL of 98 wt% TMB were added. Emulsification was carried out at 70 °C and 700 rpm.

[0080] (2) Addition of ligand: 80 mg of BDC-SH was added to the nanoemulsion and stirred at 70 °C and 700 rpm for 5 hours to promote the synthesis of the organic metal framework.

[0081] (3) Product separation and washing: After the reaction, centrifuge at 8000 rpm for 3 min at 23°C to collect the solid product, and wash the solid product once with deionized water and then twice with DMF to remove unreacted raw materials and solvent.

[0082] (4) Template removal and drying: The sample obtained in step (3) was immersed in an ethanol solution at 60°C for two days, during which the ethanol was replaced every other day, and then placed in a vacuum dryer at 60°C for 12 hours.

[0083] Experimental Example 1: Characterization of Porous Nanomaterials The present invention first characterized the nanomaterials prepared in Example 1 and Comparative Examples 1 to 6: a JEOL JEM-2100 transmission electron microscope (TEM) was used to record scanned sample images, a Hitachi SU8010 scanning electron microscope (SEM) was used to record scanned sample images, and an X-ray diffractometer (XRD) from Germany, a Bruker D8 ADVANCE wide-angle X-ray diffractometer (XRD), was used for X-ray diffraction analysis, with a Cu target (λ = 1.54 Å) and a scanning range of 0° to 10°.

[0084] Transmission electron microscopy images reveal radially arranged channels in Nic-UiO-66-SH1 with an average diameter of 7.2 nm ( Figure 1 ), these channels significantly increase the accessibility of adsorption sites on the particles; scanning electron microscopy images show that Nic-UiO-66-SH1 has a spherical structure with an average diameter of about 85nm, and mesopores are regularly distributed on the particle surface ( Figure 2 ); Powder X-ray diffraction results are as follows Figure 3 As shown in the figure, the diffraction pattern of Nic-UiO-66-SH1 has multiple significant diffraction peaks in the low-angle region (0° to 10°), and the peaks are sharp, indicating that the material has a high degree of crystallinity.

[0085] Figures 4 to 9 The characterization results of the nanomaterials prepared in Comparative Examples 1 to 6 are shown in the figure. It can be seen from the figure that in the absence of surfactant and ClO4 -UiO-66-SH synthesized in pure water system shows a certain crystal orientation ( Figure 4 ); However, its crystallinity is significantly lower than that of microporous UiO-66-SH synthesized using N, N-dimethylformamide (DMF) as solvent ( Figure 5 Removal of the surfactant alone yields irregular, non-mesoporous MOF nanoparticles ( Figure 6 ), which is attributed to ClO4 - Strong electrostatic interactions with metal cations compete with ligands for binding and further affect MOF crystallization. - ions, MOF nanoparticles with sparse surface pits are formed ( Figure 7 ), which indicates that the interaction between surfactant and MOF precursor is not sufficient to form MOF in the absence of ClO4 - Ionic guided nanoemulsion assembly. Figure 8 、 Figure 9 It shows that F127 has little effect on the pore size, while the short hydrophilic chain of P123 hinders it from forming a stable emulsion system with the MOF precursor.

[0086] Experimental Example 2: Determination of the removal rate of metal ions by porous nanomaterials The Hg(II) concentration in the solution after adsorption by porous nanomaterials was measured using the SL58-CG-1C intelligent mercury analyzer. The specific steps are as follows: Place 5 mL of a 1000 mg / L mercuric nitrate standard solution in a 50 mL beaker. Add an appropriate amount of deionized water to the beaker and adjust the pH of the solution to 2-8 to prepare a solution containing 400 mg / L mercuric ions. Finally, add 5 mg of the porous nanomaterial prepared in Examples 1-5 to the solution and stir for 60 minutes. Centrifuge the adsorbed solution for 10 minutes, and take 1 mL of the supernatant from the centrifugation into a 50 mL volumetric flask. Dose the solution to the same volume with anhydrous ethanol and shake well. The adsorption amount and removal rate of Hg(II) by the porous nanomaterial were determined according to the following formulas (1) and (2).

[0087] (1) (2) Where, Q e is the adsorption capacity of Hg(II) by porous nanomaterials (mg / g); C 0 and C e are the Hg(II) concentrations (mg / L) in the solution before and after adsorption by the porous nanomaterials; mis the mass of the porous nanomaterial (g); V is the volume of the solution (L); R is the Hg(II) removal rate in the solution (%).

[0088] The removal rate results are shown in Table 1.

[0089] Table 1 Removal rate of mercury ions by porous nanomaterials In order to elucidate the mechanism of ion channel adsorption control, the adsorption data of Hg(II) ions on Nic-UiO-66-SH1 and micro-UiO-66-SH (microporous UiO-66-SH) were kinetically fitted for comparison. The analysis included pseudo-first-order (PFO) and pseudo-second-order (PSO) models ( Figure 10 a, Figure 10 b), the parameter values ​​are shown in Tables 2 and 3. The correlation coefficients of the two kinetic models of Nic-UiO-66-SH1 ( R 2 ) are 0.9998 and 0.9997, respectively. The equilibrium adsorption capacity predicted by the PFO model Q e(cal) 780.52 mg·g -1 , while the PSO model predicts Q e(cal) 822.12 mg·g -1 ; Both are consistent with the measured equilibrium capacity Q e =799.32mg·g -1 This indicates that the adsorption rate of Hg(II) ions by Nic-UiO-66-SH1 is controlled by both physical adsorption and chemical adsorption. For micro-UiO-66-SH, the correlation coefficient and equilibrium adsorption capacity are closer to the PSO model (the PFO and PSO models predict Q e(cal) 377.13 mg·g -1 and 400.16 mg·g -1 Measured equilibrium capacity Q e =391.24mg·g -1 ), indicating that chemical adsorption is dominant. Three adsorption isotherm models—Sips, Langmuir, and Freundlich—were fitted to the experimental data by nonlinear regression ( Figure 10 c, Figure 10 d), parameters are shown in Tables 4 and 5. The adsorption data of Nic-UiO-66-SH1 is more consistent with the Sips model because R 2The high value (0.9993) and the Qm value are in good agreement with the experimental results, indicating that the adsorption process involves physical (multilayer) adsorption and chemical (monolayer) adsorption. In contrast, the adsorption data of micro-UiO-66-SH are consistent with the Langmuir model, indicating that chemical (monolayer) adsorption is the main process.

[0090] Table 2 Parameters of Nic-UiO-66-SH1 adsorption kinetic model Table 3 Parameters of micro-UiO-66-SH adsorption kinetic model Table 4 Langmuir Freundlich and Sips isotherm parameters (Nic-UiO-66-SH1) Table 5 Langmuir Freundlich and Sips isotherm parameters (micro-UiO-66-SH) Experimental Example 3: Stability Test of Porous Nanomaterials from Figure 11 It can be seen that after five adsorption cycles, the adsorption efficiency of Nic-UiO-66-SH1 still remains above 90%, further demonstrating its excellent application potential.

[0091] Experimental Example 4: Ion Selectivity of Porous Nanomaterials In actual emergency water treatment processes, relatively harmless metal ions (such as K(I), Mg(II), and Ca(II)) and toxic heavy metal ions (such as Pb(II) and Cd(II)) often compete with Hg(II) for adsorption sites, thereby affecting the overall adsorption efficiency. To investigate the competitive adsorption of Hg(II) on Nic-UiO-66-SH, the present invention introduced cations at the same concentration as Hg(II) into the solution as competing ions.

[0092] The experimental results show that the coexistence of metal ions K(I), Mg(II), Ca(II), Al(III), Cu(II), Ni(II) and Zn(II) does not significantly affect the adsorption capacity of porous nanomaterials for Hg(II) ( Figure 12 ).

[0093] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0094] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a porous nanomaterial, characterized in that: The nanoemulsion is used as a template, and a zirconium source and an organic ligand are coordinated and reacted at the interface of the emulsion to obtain the porous nanomaterial; the emulsion is composed of a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, a polyethylene glycol-polypropylene alcohol polyethylene glycol triblock copolymer, a pore expander and water.

2. The preparation method according to claim 1, characterized in that The method comprises the following steps: dissolving a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and a polyethylene glycol polypropylene alcohol polyethylene glycol triblock copolymer in water, and then adding acetic acid, ClO4 - 、Zr 4+ and a pore-enlarging agent, stirring to form a nanoemulsion; After adding the organic ligand into the nanoemulsion, stirring, centrifuging, collecting the solid precipitate, washing, removing impurities and drying, the porous nanomaterial is obtained.

3. The preparation method according to claim 2, characterized in that The pore-enlarging agent is 1,3,5-trimethylbenzene; and the organic ligand is 2,5-dithiophthalic acid or 2-aminoterephthalic acid.

4. The preparation method according to claim 3, characterized in that The mixing ratio of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, polyethylene glycol polypropylene alcohol polyethylene glycol triblock copolymer, acetic acid, NaClO4·H2O, ZrOCl2·8H2O, 1,3,5-trimethylbenzene solution and 2,5-dithiophthalic acid in the nanomaterial is 10 mg~50 mg: 10 mg~50 mg: 0.5 mL~2.5 mL: 150 mg: 50 mg~170 mg: 50 μL~250 μL: 40 mg~120 mg.

5. The preparation method according to claim 2, characterized in that The stirring speed is 400 rpm to 800 rpm, the temperature during stirring is 45° C. to 95° C., and the stirring time is 4 h to 8 h.

6. The preparation method according to claim 2, characterized in that The centrifugal speed is 6000 rpm to 10000 rpm, the centrifugal temperature is 20° C. to 25° C., and the centrifugal time is 2 min to 5 min.

7. A porous nanomaterial prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the porous nanomaterial according to claim 7 in preparing a heavy metal adsorbent.

9. The use according to claim 8, characterized in that The heavy metal is mercury.

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