A resin-based bimetallic oxide composite nanomaterial, its preparation method and application

Abstract

This invention discloses a resin-based bimetallic oxide composite nanomaterial, its preparation method, and its application. The composite nanomaterial comprises a strongly basic anion exchange resin carrier, first metal oxide nanoparticles loaded within the carrier, and molybdenum oxide nanoparticles doped with the first metal oxide. Preparation involves first dissolving the first metal oxide precursor in methanol to obtain solution A. A strongly basic anion exchange resin is added to solution A, stirred, and the reaction is carried out, with the resin filtered out. This resin is then added to a sodium molybdate solution, stirred, and the reaction is carried out, with the resin filtered out again. Finally, the resin is added to an alkaline solution and allowed to react fully. This composite nanomaterial can achieve efficient defluorination in neutral or weakly alkaline (pH 7-9) water; it can be stably recycled, and the molybdenum loss after alkaline desorption is less than 1%, requiring no further acid activation after desorption.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite material preparation, and particularly relates to a resin-based bimetallic oxide composite nanomaterial, its preparation method, and its application. Background Technology

[0002] Fluorine is widely present in the environment, including both natural sources and emissions from human activities. Weathering of fluoride-containing minerals and microbial mineralization promoting mineral dissolution are the main natural sources of fluoride, which enter the environment primarily as neutral or weakly alkaline water through groundwater circulation. Anthropogenic sources include smelting and electroplating, which mainly produce acidic fluoride-containing wastewater; however, passivation and galvanizing wastewater produce alkaline fluoride-containing wastewater. Low concentrations of fluoride are beneficial to human health, but excessive intake can lead to severe damage to teeth and bones, and even cause various adverse effects such as bone fluorosis. Today, fluoride pollution has become a global environmental problem.

[0003] To address the health hazards of fluoride pollution, various technologies for fluoride removal are available. Adsorption, with its advantages of high efficiency, ease of operation and maintenance, environmental friendliness, and low cost, is one of the most promising fluoride removal technologies. Nanocomposites prepared by immobilizing Zr(IV), La(III), and Ti(IV) nano-oxides within large-size carriers can selectively remove fluoride through the coordination of metal oxides with fluoride ions. This approach overcomes the drawbacks of nanoparticles, such as easy aggregation and operational inconvenience due to their small size, making it one of the most effective methods for practical application in fluoride-containing wastewater treatment (Environ. Sci. Technol. 2013, 47, 16, 9347–9354). However, while Zr(IV), La(III), and Ti(IV) oxides can achieve highly efficient fluoride ion removal under acidic conditions, under neutral or weakly alkaline conditions, the similar ion size, hydration energy, and charge density of hydroxide ions and fluoride ions create strong competition for the coordination between metal oxides and fluoride ions, significantly reducing the fluoride removal efficiency.

[0004] Therefore, there is an urgent need for a new type of material that can further achieve efficient removal of fluoride ions under neutral or weakly alkaline conditions, based on existing Zr(IV), La(III) and Ti(IV) oxides loaded on large-size supports to achieve efficient fluoride removal under acidic conditions. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a novel composite nanomaterial that can efficiently remove fluoride ions under neutral or weakly alkaline water conditions.

[0006] Technical solution: The resin-based bimetallic oxide composite nanomaterial of the present invention includes a strongly alkaline anion exchange resin carrier, first metal oxide nanoparticles loaded in the carrier, and molybdenum oxide nanoparticles doped in the first metal oxide.

[0007] This invention is based on resin and first metal oxide nanoparticles. By doping with molybdenum oxide nanoparticles, the first metal oxide is combined with molybdenum oxide nanoparticles. This allows the molybdenum oxide nanoparticles to impart an acidic surface to the first metal oxide under neutral or weakly alkaline water conditions. Since the first metal oxide particles themselves are alkaline, the surface of the prepared composite nanomaterial is made neutral, which enhances the ability of fluoride to diffuse to the surface of the composite nanomaterial and realizes the adsorption effect of the first metal oxide on fluoride ions under neutral or weakly alkaline conditions.

[0008] Furthermore, the molybdenum content in this composite nanomaterial is 0.10-0.30%, and the content of the first metallic element is 8.5-14.5%.

[0009] Furthermore, the strong basic anion exchange resin used in this composite nanomaterial has a skeleton of poly(styrene-co-divinylbenzene) and functional groups of trimethylamine, triethylamine or pyridine.

[0010] Furthermore, the first metal oxide nanoparticles used in this composite nanomaterial are hydrated zirconium oxide, hydrated lanthanum oxide, or hydrated titanium dioxide, with an average size of 15-30 nm.

[0011] The method for preparing the above-mentioned resin-based bimetallic oxide composite nanomaterials according to the present invention includes the following steps:

[0012] (1) Dissolve the first metal oxide precursor in methanol according to its content and stir until homogeneous to obtain solution A;

[0013] (2) Add a strong base anion exchange resin to solution A, stir and react for 6-12 hours, and then filter out the resin; wherein the solid-liquid ratio of the strong base anion exchange resin to solution A is 10-360 g / L.

[0014] (3) Dissolve the molybdenum oxide precursor according to the content to obtain solution B, add the resin prepared in step (2), stir and react for 6-12 hours, and then filter out;

[0015] (4) The resin prepared in step (3) is added to the alkaline solution and stirred for 1-5 hours to obtain the resin. After cleaning and drying, the resin-based bimetallic oxide composite nanomaterial is obtained.

[0016] In preparing this composite nanomaterial, the present invention first forms a resin loaded with a first metal oxide precursor, and then reacts it with a molybdenum oxide precursor solution. This allows the molybdenum oxide nanoparticles to be uniformly dispersed within the first metal oxide nanoparticles, improving the bonding force between the two and effectively preventing the detachment of molybdenum oxide. While maintaining an acidic surface on the first metal oxide, the invention does not introduce hydrogen ions into the water, thus avoiding significant pH changes and water quality alterations. Furthermore, in preparing this composite nanomaterial, the present invention uses an alkaline solution to fully react the resin loaded with the first metal oxide and molybdenum oxide particles. This allows the first metal oxide and molybdenum oxide to effectively precipitate within the resin pores, and the alkaline conditions further enhance the bonding ability between the first metal oxide and molybdenum oxide.

[0017] Furthermore, in step (1) of the preparation method, the concentration of solution A is 0.1-5 mol / L, preferably 0.1-1.6 mol / L.

[0018] Furthermore, in step (3) of the preparation method, the concentration of solution B is 0.02-0.50 mol / L, and the solid-liquid ratio of the resin prepared in step (2) to solution B is 16.5-500 g / L.

[0019] Furthermore, in step (4) of the preparation method, the mass fraction of the alkali solution is 2.5-10%, and the solid-liquid ratio of the resin prepared in step (3) to the alkali solution is 16.5-500 g / L.

[0020] The resin-based bimetallic oxide composite nanomaterials of the present invention are applied to the defluorination of neutral or weakly alkaline water.

[0021] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are as follows: The resin-based bimetallic oxide composite nanomaterial is based on resin and a first metal oxide loaded in the resin, with molybdenum oxide doped into the first metal oxide, thereby enabling the composite nanomaterial to achieve efficient defluorination in neutral or weakly alkaline (pH 7-9) water without causing significant changes in the pH of the water; in addition, the composite nanomaterial can be stably recycled, and the molybdenum element lost from the material after alkaline desorption is less than 1%, and it can be washed with clean water after desorption without the need for additional acid activation; furthermore, its preparation method is simple and highly operable. Attached Figure Description

[0022] Figure 1 An optical photograph of the resin-based bimetallic oxide composite nanomaterial prepared in Example 1 of this invention;

[0023] Figure 2 This is a transmission electron microscope (TEM) image of the resin-based bimetallic oxide composite nanomaterial prepared in Example 1 of the present invention.

[0024] Figure 3 The graphs show the fluoride removal effect of the resin-based bimetallic oxide composite nanomaterial prepared in Example 1 of this invention under different pH conditions and the pH change after adsorption.

[0025] Figure 4 The diagram shows the adsorption-regeneration cycle effect of the resin-based bimetallic oxide composite nanomaterial prepared in Example 1 of this invention and the amount of molybdenum leached out.

[0026] Figure 5 This is a transmission electron microscope (TEM) image of the resin-based bimetallic oxide composite nanomaterial prepared in Example 4 of the present invention.

[0027] Figure 6 This is a transmission electron microscope (TEM) image of the resin-based bimetallic oxide composite nanomaterial prepared in Example 7 of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] It should be noted that the strongly basic anion exchange resin used in this invention was purchased from Ningbo Zhengguang Resin Co., Ltd.; its backbone is poly(styrene-co-divinylbenzene), the functional groups are trimethylamine, triethylamine or pyridine, and its specific surface area is >50 m². 2 / g, average pore size >10nm, strong basic ion exchange capacity >3mmol / g.

[0030] Example 1

[0031] The resin-based bimetallic oxide composite nanomaterial of the present invention is prepared by the following steps:

[0032] (1) Dissolve 90g of zirconium oxychloride octahydrate in 200mL of methanol and stir until homogeneous to obtain a solution A with a concentration of 1.0mol / L;

[0033] (2) Add 100g of a strong base anion exchange resin with the functional group of trimethylamine to the solution A prepared in step (1), stir for 10h, filter out the resin, and dry it for later use; wherein, the solid-liquid ratio of the strong base anion exchange resin to solution A is 360g / L.

[0034] (3) Dissolve 5g of sodium molybdate dihydrate in 200mL of water to prepare a sodium molybdate solution with a concentration of 0.10mol / L. Then add the dried resin from step (2), stir for 10h and filter out. The solid-liquid ratio of the resin prepared in step (2) to the sodium molybdate solution is 500g / L.

[0035] (4) Add the resin filtered out in step (3) to 200 mL of 5% NaOH solution and stir for 2 h; wherein the solid-liquid ratio of the resin prepared in step (3) to the alkali solution is 500 g / L.

[0036] (5) Take out the resin from step (4), wash it with pure water until it is neutral, and then dry it to obtain bimetallic oxide composite nanomaterials.

[0037] Performance testing - structural characterization

[0038] The optical photographs of the composite nanomaterials prepared in this embodiment are as follows. Figure 1 As shown, the structure of the composite nanomaterial was characterized, and the results obtained are as follows. Figure 2 As shown. (Through) Figure 1 and Figure 2 It is known that the diameter of the composite nanomaterial is 0.45-0.60 mm, and the average size of the nanoparticles is 20 nm. The zirconium loading is 12.0% and the molybdenum loading is 0.15% as metallic elements, as measured by inductively coupled plasma atomic emission spectrometry.

[0039] Performance Testing -- Fluoride Ion Adsorption and Water Quality Testing

[0040] 0.025 g of the composite material was added to 50 mL of solutions with a fluoride ion concentration of 10 mg / L, a sulfate ion concentration of 1 g / L, and pH values ​​of 7, 8, and 9, respectively. The reaction was carried out for 24 h, and the results are as follows. Figure 3 As shown, the adsorption capacities of the composite nanomaterial for fluoride ions were 5.2 mg / g, 5.0 mg / g, and 4.6 mg / g, respectively, and further... Figure 3 It can be seen that the pH value of the water did not change significantly.

[0041] Performance Testing -- Adsorption-Regeneration Cycle and Mo Loss Rate Testing

[0042] The adsorption-regeneration cycle effect diagram and molybdenum leaching detection of the resin-based bimetallic oxide composite nanomaterials prepared in this embodiment are shown in the following results. Figure 4 As shown in the figure, the loss rate of molybdenum is less than 1%, and even after cyclic regeneration at pH 7, its adsorption capacity for fluoride ions can still reach over 5 mg / g.

[0043] Example 2

[0044] The basic steps are the same as in Example 1, except that the functional group used in the strongly basic anion exchange resin is triethylamine.

[0045] The bimetallic oxide composite nanomaterials prepared in this embodiment have a diameter of 0.45-0.60 mm and an average nanoparticle size of 20 nm. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis revealed a zirconium loading of 11.5% and a molybdenum loading of 0.15%.

[0046] 0.025 g of the composite material was added to 50 mL of solutions with a fluoride ion concentration of 10 mg / L, a sulfate ion concentration of 1 g / L, and pH values ​​of 7, 8, and 9, respectively. After reacting for 24 h, the experimental results showed that the loss rate of molybdenum was <1%, and the adsorption capacity of fluoride ions was 5.3 mg / g, 5.1 mg / g, and 4.8 mg / g, respectively.

[0047] Example 3

[0048] The basic steps are the same as in Example 1, except that the functional group used in the strongly basic anion exchange resin is pyridine.

[0049] The bimetallic oxide composite nanomaterials prepared in this embodiment have a diameter of 0.45-0.60 mm and an average nanoparticle size of 20 nm. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis revealed a zirconium loading of 11.8% and a molybdenum loading of 0.15%.

[0050] 0.025 g of the composite material was added to 50 mL of solutions with a fluoride ion concentration of 10 mg / L, a sulfate ion concentration of 1 g / L, and pH values ​​of 7, 8, and 9, respectively. After reacting for 24 h, the experimental results showed that the loss rate of molybdenum was <1%, and the adsorption capacity of fluoride ions was 5.6 mg / g, 5.4 mg / g, and 5.1 mg / g, respectively.

[0051] Example 4

[0052] The basic steps are the same as in Example 1, except that in step (1), 65g of lanthanum chloride heptahydrate is dissolved in 200mL of methanol and stirred evenly to obtain a solution A with a concentration of 0.69mol / L.

[0053] The structure of the composite nanomaterial prepared in this embodiment is as follows: Figure 5 As shown, the diameter of the composite nanomaterial is 0.45-0.60 mm, and the average size of the nanoparticles is 30 nm.

[0054] The lanthanum loading was determined to be 11.2% and the molybdenum loading to be 0.12% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 5.5 mg / g, 5.3 mg / g, and 5.0 mg / g, respectively.

[0055] Example 5

[0056] The basic steps are the same as in Example 4, except that the functional group used in the strongly basic anion exchange resin is triethylamine.

[0057] The bimetallic oxide composite nanomaterials prepared in this embodiment have a diameter of 0.45-0.60 mm and an average nanoparticle size of 30 nm.

[0058] The lanthanum loading was determined to be 11.0% and the molybdenum loading to be 0.12% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 5.8 mg / g, 5.6 mg / g, and 5.2 mg / g, respectively.

[0059] Example 6

[0060] The basic steps are the same as in Example 4, except that the functional group used in the strongly basic anion exchange resin is pyridine.

[0061] The bimetallic oxide composite nanomaterials prepared in this embodiment have a diameter of 0.45-0.60 mm and an average nanoparticle size of 30 nm. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis revealed a lanthanum loading of 10.5% and a molybdenum loading of 0.12%.

[0062] 0.025 g of the composite material was added to 50 mL of solutions with a fluoride ion concentration of 10 mg / L, a sulfate ion concentration of 1 g / L, and pH values ​​of 7, 8, and 9, respectively. After reacting for 24 h, the experimental results showed that the loss rate of molybdenum was <1%, and the adsorption capacity of fluoride ions was 6.0 mg / g, 5.8 mg / g, and 5.5 mg / g, respectively.

[0063] Example 7

[0064] The basic steps are the same as in Example 4, except that in step (1), 85g of titanium tetrachloride is dissolved in 200mL of methanol and stirred evenly to obtain a solution A with a concentration of 1.6mol / L.

[0065] The structure of the composite nanomaterial prepared in this embodiment is as follows: Figure 6 As shown in the figure, the average size of the nanoparticles in this composite nanomaterial is 15 nm.

[0066] The titanium loading was determined to be 10.2% and the molybdenum loading to be 0.2% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 4.8 mg / g, 4.5 mg / g, and 4.2 mg / g, respectively.

[0067] Example 8

[0068] The basic steps are the same as in Example 7, except that the functional group used in the strongly basic anion exchange resin is triethylamine.

[0069] The bimetallic oxide composite nanomaterials prepared in this embodiment have a diameter of 0.45-0.60 mm and an average nanoparticle size of 15 nm.

[0070] The titanium loading was determined to be 10.8% and the molybdenum loading to be 0.2% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 5.0 mg / g, 4.7 mg / g, and 4.5 mg / g, respectively.

[0071] Example 9

[0072] The basic steps are the same as in Example 7, except that the functional group used in the strongly basic anion exchange resin is pyridine.

[0073] The bimetallic oxide composite nanomaterials prepared in this embodiment have a diameter of 0.45-0.60 mm and an average nanoparticle size of 15 nm.

[0074] The titanium loading was determined to be 10.3% and the molybdenum loading to be 0.2% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 5.2 mg / g, 5.0 mg / g, and 4.7 mg / g, respectively.

[0075] Example 10

[0076] The resin-based bimetallic oxide composite nanomaterial of the present invention is prepared by the following steps:

[0077] (1) Dissolve 6.5g of zirconium oxychloride octahydrate in 200mL of methanol and stir until homogeneous to obtain a solution A with a concentration of 0.1mol / L;

[0078] (2) Add 20g of a strong base anion exchange resin with the functional group of trimethylamine to the solution A prepared in step (1), stir for 6 hours, filter out the resin, and dry it for later use; wherein, the solid-liquid ratio of the strong base anion exchange resin to solution A is 100g / L.

[0079] (3) Dissolve 0.9g of sodium molybdate dihydrate in 200mL of water to prepare a sodium molybdate solution with a concentration of 0.02mol / L. Then add the dried resin from step (2), stir for 6h and filter out. The solid-liquid ratio of the resin prepared in step (2) to the sodium molybdate solution is 100g / L.

[0080] (4) Add the resin filtered out in step (3) to 200 mL of 2.5% NaOH solution and stir for 1 h; wherein the solid-liquid ratio of the resin prepared in step (3) to the alkali solution is 100 g / L.

[0081] (5) Take out the resin from step (4), wash it with pure water until it is neutral, and then dry it to obtain bimetallic oxide composite nanomaterials.

[0082] The zirconium loading was determined to be 8.5% and the molybdenum loading to be 0.10% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 4.4 mg / g, 4.1 mg / g, and 3.9 mg / g, respectively.

[0083] Example 11

[0084] The resin-based bimetallic oxide composite nanomaterial of the present invention is prepared by the following steps:

[0085] (1) Dissolve 40g of zirconium oxychloride octahydrate in 200mL of methanol and stir until homogeneous to obtain a solution A with a concentration of 0.5mol / L;

[0086] (2) Add 11.5g of a strong base anion exchange resin with the functional group of trimethylamine to the solution A prepared in step (1), stir for 8 hours, filter out the resin, and dry it for later use; wherein, the solid-liquid ratio of the strong base anion exchange resin to solution A is 50g / L.

[0087] (3) Dissolve 12.5g of sodium molybdate dihydrate in 200mL of water to prepare a sodium molybdate solution with a concentration of 0.25mol / L. Then add the dried resin from step (2), stir for 8h and filter out. The solid-liquid ratio of the resin prepared in step (2) to the sodium molybdate solution is 57.5g / L.

[0088] (4) Add the resin filtered out in step (3) to 200 mL of 6% NaOH solution and stir for 3 h; wherein the solid-liquid ratio of the resin prepared in step (3) to the alkali solution is 57.5 g / L.

[0089] (5) Take out the resin from step (4), wash it with pure water until it is neutral, and then dry it to obtain bimetallic oxide composite nanomaterials.

[0090] The zirconium loading was determined to be 10.2% and the molybdenum loading to be 0.22% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 4.7 mg / g, 4.4 mg / g, and 4.2 mg / g, respectively.

[0091] Example 12

[0092] The resin-based bimetallic oxide composite nanomaterial of the present invention is prepared by the following steps:

[0093] (1) Dissolve 160g of zirconium oxychloride octahydrate in 200mL of methanol and stir until homogeneous to obtain a solution A with a concentration of 1.5mol / L;

[0094] (2) Add 3.3g of a strong base anion exchange resin with the functional group of trimethylamine to the solution A prepared in step (1), stir for 12h, filter out the resin, and dry it for later use; wherein, the solid-liquid ratio of the strong base anion exchange resin to solution A is 10g / L.

[0095] (3) Dissolve 25g of sodium molybdate dihydrate in 200mL of water to prepare a sodium molybdate solution with a concentration of 0.5mol / L. Then add the dried resin from step (2), stir for 12h and filter out. The solid-liquid ratio of the resin prepared in step (2) to the sodium molybdate solution is 16.5g / L.

[0096] (4) Add the resin filtered out in step (3) to 200 mL of 10% NaOH solution and stir for 5 h; wherein the solid-liquid ratio of the resin prepared in step (3) to the alkali solution is 16.5 g / L.

[0097] (5) Take out the resin from step (4), wash it with pure water until it is neutral, and then dry it to obtain bimetallic oxide composite nanomaterials.

[0098] The titanium loading was determined to be 14.5% and the molybdenum loading to be 0.3% by inductively coupled plasma atomic emission spectrometry. 0.025 g of the composite material was added to 50 mL solutions with fluoride ion concentrations of 10 mg / L, sulfate ion concentrations of 1 g / L, and pH values ​​of 7, 8, and 9, respectively, and reacted for 24 h. The experimental results showed that the molybdenum loss rate was <1%, and the adsorption capacities for fluoride ions were 5.4 mg / g, 5.1 mg / g, and 4.7 mg / g, respectively.

Claims

1. A resin-based bimetallic oxide composite nanomaterial, characterized in that: The composite nanomaterial comprises a strongly basic anion exchange resin carrier, first metal oxide nanoparticles loaded within the carrier, and molybdenum oxide nanoparticles doped within the first metal oxide nanoparticles; the first metal oxide nanoparticles are hydrated zirconium oxide, hydrated lanthanum oxide, or hydrated titanium dioxide, with an average nanoparticle size of 15-30 nm; the composite nanomaterial contains 0.10-0.30% molybdenum and 8.5-14.5% of the first metal element; This composite nanomaterial was prepared by the following steps: (1) Dissolve the first metal oxide precursor in methanol according to the content, and stir evenly to obtain solution A; the concentration of solution A is 0.1-5 mol / L; (2) Add a strong base anion exchange resin to solution A, stir and react for 6-12 h, and then filter out the resin; wherein the solid-liquid ratio of the strong base anion exchange resin to solution A is 10-360 g / L. (3) Dissolve the molybdenum oxide precursor according to the content to obtain solution B, add the resin prepared in step (2), stir and react for 6-12 hours, and then filter out; the concentration of solution B is 0.02-0.50 mol / L, and the solid-liquid ratio of the resin prepared in step (2) to solution B is 16.5-500 g / L. (4) The resin prepared in step (3) is added to the alkaline solution and stirred for 1-5 h to obtain the resin. After cleaning and drying, the resin-based bimetallic oxide composite nanomaterial is obtained. The mass fraction of the alkaline solution is 2.5-10%, and the solid-liquid ratio of the resin prepared in step (3) to the alkaline solution is 16.5-500 g / L.

2. The resin-based bimetallic oxide composite nanomaterial according to claim 1, characterized in that: The backbone of the strongly basic anion exchange resin is poly(styrene-) co (-Divinylbenzene), with functional groups of trimethylamine, triethylamine or pyridine.

3. The resin-based bimetallic oxide composite nanomaterial of claim 1 is used for defluorination in neutral or weakly alkaline water.

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