Acid-resistant noble metal ion adsorption film and preparation method therefor

Abstract

Disclosed in the present invention are an acid-resistant noble metal ion adsorption film and a preparation method therefor. The preparation method comprises: a) pretreatment of a base film: firstly, cleaning and drying a silicon carbide substrate to obtain a clean film; then performing oxidation treatment on the clean film to obtain a micro-oxidation film; and finally, placing the micro-oxidation film in a strong acid solution for acidification treatment, to obtain a base film modified with a hydroxyl functional group; b) the growth of an MOF seed crystal: placing the obtained base film modified with the hydroxyl functional group into a seed crystal growth solution, and reacting at 110-130°C for 12-24 hours to obtain a film loaded with the MOF seed crystal; and c) MOF secondary growth: placing the prepared film loaded with the MOF seed crystal into a secondary growth solution, and reacting at 110-130°C for 20-30 hours to obtain the acid-resistant noble metal ion adsorption film. The adsorption film prepared according to the present invention has good acid resistance, and can achieve efficient and stable recovery of rare noble metals in a strong acid environment.

Description

Acid-resistant noble metal ion adsorption membrane and preparation method thereof Technical Field

[0001] The invention relates to an acid-resistant noble metal ion adsorption membrane and a preparation method thereof, belonging to the technical field of noble metal ion adsorption membranes. Background Art

[0002] Platinum group metals (PGMs) are a class of highly reactive precious metals, crucial for applications in a wide range of fields, including catalysis, electronics, and biomedicine. Due to their rarity and high cost in the Earth's crust, their separation and recovery are crucial. Efficiently recovering precious metals such as gold, platinum, and palladium from highly acidic treatment solutions has become a pressing challenge.

[0003] Adsorption methods have been widely used for the enrichment and recovery of precious metals due to their advantages, including short process steps, low energy consumption, simple operation, and reusable adsorbents. Compared to traditional adsorbent materials (such as activated carbon, ion exchange resins, chitosan, and carbon nanotubes), MOFs (metal-organic frameworks), as a novel porous material, offer ultra-high surface area, designable pores, and ease of modification, providing a large number of adsorption sites. Zirconium-based MOFs, such as UiO-66 and UiO-66-NH2, exhibit exceptional precious metal adsorption performance, offering significant advantages over traditional adsorbents. However, these powdered adsorbents exhibit problems such as agglomeration in water, difficulty in recovery, and high recycling costs, limiting their practical applications. Therefore, integrating these MOFs with substrates to form functional membranes for precious metal recovery is a key research area in precious metal recovery.

[0004] Patent CN107398186B discloses a method for preparing a MOF separation layer membrane. This patent modifies the substrate surface through interfacial polymerization, followed by secondary growth on the surface-modified layer to form the MOF separation layer. The substrate mentioned in this patent is a polymer membrane, and its surface modifier is a polymer (alginic acid). Both the substrate and the modifier are organic components, and both have deficiencies in thermal, mechanical, and chemical stability.

[0005] Patent CN114433235A discloses a MOF-supported substrate composite material and its preparation method. This patent involves sequentially immersing an ultrasonically cleaned substrate into a metal salt and organic ligand solution to complete a self-assembly process. The resulting MOF-supported substrate composite material is then removed and dried. This patent involves direct MOF self-assembly on the substrate, resulting in an unstable bond between the MOF and the substrate.

[0006] Patent CN101890305B discloses a method for preparing a MOF membrane. This patent first modifies a carrier with a coupling agent and then applies a seed layer. Then, a continuous, dense, and defect-free MOF layer is prepared using a crystallization method from low temperature to high temperature. Patent CN112691553B discloses a method for preparing a polydopamine cross-linked MOF separation membrane. This patent utilizes the special properties of dopamine to prepare a dopamine-coated MOF material. Then, a MOF functional layer is formed on the substrate surface by means of filtration interception, physical deposition, and spraying. Both CN101890305B and CN112691553B involve the use of organic compounds as modifiers. The functional membranes prepared face the problem of weak bonding in strong acid environments, and there are problems with thermal stability and chemical stability.

[0007] Patent CN113041863A discloses a method for preparing and applying a defect-free, pollution-resistant zirconium-based MOF membrane. This patent improves the macroporous defects and surface chemical environment of the original ceramic support by introducing a titanium dioxide modification layer. A thin and dense layer of UiO-66 is prepared using in-situ seeding and secondary growth of nanocrystals. The preparation method mentioned in this patent requires repeated use of the "dip coating-sintering" process and the introduction of an intermediate inorganic modification layer (TiO2). This not only results in a complex and energy-intensive preparation method, but also poses bonding instability issues in the presence of strong acids.

[0008] As can be seen from the above, current MOF membrane (metal-organic framework) materials still have shortcomings in terms of stability. Because the treatment fluids used to process precious metal waste are typically highly acidic, stringent requirements are placed on the stability of MOF membrane materials, especially their acid resistance. However, current MOF membrane materials are difficult to maintain in such extreme operating conditions. Technical issues

[0009] In view of the above problems existing in the prior art, the purpose of the present invention is to provide an acid-resistant precious metal ion adsorption membrane with good stability and suitable for precious metal recovery in industrial strong acidic environments, and a preparation method thereof. Technical Solutions

[0010] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing an acid-resistant noble metal ion adsorption membrane comprises the following steps:

[0012] a) Basement membrane pretreatment

[0013] First, the silicon carbide substrate is cleaned and dried to obtain a clean membrane; then the clean membrane is oxidized in air or oxygen atmosphere to obtain a slightly oxidized membrane; then the slightly oxidized membrane is placed in a strong acidic solution for acidification, and finally the membrane is removed, cleaned, and dried to obtain a base membrane modified with hydroxyl functional groups;

[0014] b) MOF seed growth

[0015] A seed crystal growth solution is prepared by mixing zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid in a molar ratio of 1:1:500:10:1, and the base film modified with hydroxyl functional groups obtained in step a) is placed in the seed crystal growth solution. The reaction is carried out at 110° C. to 130° C. for 12 to 24 hours. After the reaction is completed, the membrane is taken out, cleaned, and dried to obtain a MOF seed crystal-loaded membrane.

[0016] c) MOF secondary growth

[0017] Zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid are prepared into a secondary growth solution in a molar ratio of (1-2): (1-2): 500:10:1, and the MOF seed-loaded membrane prepared in step b) is placed in the secondary growth solution and reacted at 110°C to 130°C for 20 to 30 hours. After the reaction is completed, the membrane is removed, cleaned, and dried to obtain a MOF-loaded silicon carbide composite membrane, that is, the acid-resistant precious metal ion adsorption membrane.

[0018] In a preferred embodiment, in step a), the silicon carbide substrate is a silicon carbide support or a silicon carbide ceramic membrane.

[0019] In a preferred embodiment, in step a), the oxidation treatment is to place the clean membrane in a muffle furnace and perform oxidation treatment at 900°C to 1200°C for 60 to 150 minutes in air or oxygen atmosphere to obtain the micro-oxidized membrane.

[0020] In one embodiment, in step a), the acid treatment refers to immersing the micro-oxidation membrane in a strong acidic solution for 20 to 30 hours, removing the membrane, washing the membrane with deionized water until neutral, and drying to obtain the base membrane modified with hydroxyl functional groups, wherein the strong acidic solution is a mixed solution of concentrated hydrochloric acid:concentrated nitric acid in a volume ratio of (8 to 12):1.

[0021] In one embodiment, in step b), after the reaction is completed, the membrane is taken out, cleaned with N,N-dimethylformamide solution, and then vacuum dried at 60°C to 100°C to obtain the MOF seed-loaded membrane.

[0022] In one embodiment, in step c), after the reaction is completed, the membrane is taken out and placed in a mixed solution of N,N-dimethylformamide: concentrated hydrochloric acid with a volume ratio of (30-50):1. After soaking at 60°C to 100°C for 8-12 hours, the membrane is taken out and then rinsed with an ethanol solution. Finally, the membrane is vacuum dried at 60°C to 100°C to obtain the MOF-supported silicon carbide composite membrane.

[0023] The present invention also provides an acid-resistant noble metal ion adsorption membrane prepared by the above preparation method. Beneficial effects

[0024] Compared with the prior art, the present invention has the following significant beneficial effects:

[0025] 1. Before loading MOF, the present invention sequentially performs oxidation treatment and acidification treatment on the silicon carbide substrate, so that the silicon carbide surface is modified with a large number of hydroxyl functional groups, which not only provides more nucleation sites for MOF seed growth, but also enhances the bonding stability between MOF and the membrane substrate, thereby achieving a firm bond between MOF and the membrane substrate, improving the stability of MOF loading, and solving the problem of weak bonding between MOF and the membrane substrate;

[0026] 2. The present invention uses UiO-66-NH2 with noble metal adsorption activity as the active adsorption material MOF bonded to the silicon carbide substrate, which has good stability. It can not only achieve efficient and stable recovery of rare and precious metals such as platinum, palladium, and gold in a strong acid environment, but also has a simple preparation method, mild conditions, low cost, high yield, and easy to scale up;

[0027] 3. The present invention adopts a secondary growth method to load MOF on a silicon carbide substrate. The first growth is a seed seeding step. A seed growth liquid is used to load a certain amount of MOF crystals on the silicon carbide substrate and serve as seeds for secondary growth. The second growth is to adjust the loading amount. A secondary growth liquid is used to load more MOF on the silicon carbide substrate. The concentration of the secondary growth liquid is adjustable. By controlling the concentration of the secondary growth liquid, the MOF loading amount on the base film surface can be regulated, and finally the MOF loading amount of the prepared adsorption film is 45.37-67.70 g / m 2 When used for precious metal recovery, the adsorption capacity of precious metal palladium reaches 16.10~22.70 g / m 2 , showing strong recovery ability for precious metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a SEM image of the silicon carbide substrate used in Example 1 of the present invention;

[0029] FIG2 is a SEM image of a MOF seed-supported membrane prepared in Example 1 of the present invention;

[0030] FIG3 is a SEM image of the MOF-supported silicon carbide composite film prepared in Example 1 of the present invention;

[0031] FIG4 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Example 1 of the present invention after ultrasonic treatment for 8 hours;

[0032] FIG5 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Example 1 of the present invention after being immersed in 0.1 M hydrochloric acid for one month;

[0033] FIG6 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Example 1 of the present invention after being immersed in 0.2 M hydrochloric acid for one month;

[0034] FIG7 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Example 1 of the present invention after being immersed in 0.5 M hydrochloric acid for one month;

[0035] FIG8 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Example 1 of the present invention after being immersed in 1M hydrochloric acid for one month;

[0036] FIG9 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Comparative Example 1 of the present invention;

[0037] FIG10 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Comparative Example 2 of the present invention;

[0038] FIG11 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Comparative Example 3 of the present invention;

[0039] FIG12 is a SEM image of the MOF-supported silicon carbide composite membrane prepared in Comparative Example 3 of the present invention after ultrasonic treatment for 8 hours. Best Mode for Carrying Out the Invention

[0040] The technical scheme of the present invention is further described in detail and completely below with reference to the examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally carried out under conventional conditions or as recommended by the manufacturer. Example 1

[0041] a) Basement membrane pretreatment

[0042] The silicon carbide substrate is first cleaned and dried to obtain a clean membrane. The clean membrane is then placed in a muffle furnace and oxidized at 1100°C for 120 minutes in an air atmosphere (to form trace amounts of silica on the substrate surface) to obtain a slightly oxidized membrane. Finally, the slightly oxidized membrane is immersed in a strong acidic solution for 24 hours (to form Si-OH groups on the silica on the substrate surface, providing more bonding sites for the MOF). The membrane is removed, rinsed with deionized water until neutral, and dried to obtain a base membrane modified with hydroxyl functional groups. The strong acidic solution is a mixed solution of concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 10:1.

[0043] b) MOF seed growth

[0044] A seed crystal growth solution was prepared by mixing zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid in a molar ratio of 1:1:500:10:1, and the seed crystal growth solution was added to a reactor. The base membrane modified with hydroxyl functional groups obtained in step a) was placed in the seed crystal growth solution and reacted at 120° C. for 24 hours. After the reaction, the membrane was removed, first cleaned with N,N-dimethylformamide solution, and then dried under vacuum at 80° C. overnight to obtain a MOF seed crystal-loaded membrane.

[0045] c) MOF secondary growth

[0046] A secondary growth solution is prepared by mixing zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid in a molar ratio of 1:1:500:10:1. The secondary growth solution is added to a reactor, and the membrane loaded with the MOF seed crystals obtained in step b) is placed in the secondary growth solution and reacted at 120° C. for 24 hours. After the reaction is completed, the membrane is removed and first placed in a mixed solution of N,N-dimethylformamide: concentrated hydrochloric acid in a volume ratio of 40:1. The membrane is soaked at 80° C. for 10 hours (to clean the oligomers generated during the reaction) and then removed. The membrane is then rinsed with an ethanol solution and finally dried overnight in vacuum at 80° C. to obtain a MOF-loaded silicon carbide composite membrane, i.e., the acid-resistant precious metal ion adsorption membrane.

[0047] FIG1 is a SEM image of the silicon carbide substrate used in this embodiment and the following embodiments. As can be seen from FIG1 , the silicon carbide substrate used in the embodiment has a porous structure.

[0048] FIG2 is a SEM image of the MOF seed-supported membrane prepared in this embodiment. As can be seen from FIG2 , after the reaction treatment with the seed growth solution, a certain amount of MOF crystals are supported on the silicon carbide substrate.

[0049] Figure 3 is an SEM image of the MOF-loaded silicon carbide composite film prepared in this embodiment; it can be seen from Figure 3 that after the secondary growth liquid reaction treatment, a large number of MOF particles are evenly loaded on the silicon carbide base particles. Combined with Figures 2 and 3, it can be seen that the secondary growth reaction can significantly increase the loading amount of MOF on the base film surface.

[0050] The MOF-loaded silicon carbide composite membrane prepared in this example was placed in an ultrasonic instrument for 8 hours, and the surface morphology changes of the MOF-loaded silicon carbide composite membrane were observed to investigate the stability of MOF loading in the MOF-loaded silicon carbide composite membrane.

[0051] Figure 4 is an SEM image of the MOF-loaded silicon carbide composite membrane prepared in this embodiment after 8 hours of ultrasound. Combining Figures 3 and 4, it can be seen that after 8 hours of ultrasound, the surface morphology of the MOF-loaded silicon carbide composite membrane has not changed significantly, indicating that the MOF and the base membrane in the MOF-loaded silicon carbide composite membrane prepared in this embodiment are firmly bonded, and the loaded MOF has good stability.

[0052] The MOF-supported silicon carbide composite membrane prepared in this example was immersed in hydrochloric acid with concentrations of 0.1M, 0.2M, 0.5M, and 1M for one month, and the surface morphology changes of the MOF-supported silicon carbide composite membrane were observed to investigate the acid resistance of the MOF-supported silicon carbide composite membrane.

[0053] Figures 5 to 8 are SEM images of the MOF-loaded silicon carbide composite membrane prepared in this embodiment after being immersed in 0.1M, 0.2M, 0.5M and 1M hydrochloric acid for one month. It can be seen from Figures 5 to 8 that the surface morphology of the MOF-loaded silicon carbide composite membrane does not change significantly after being immersed in high-concentration hydrochloric acid for one month, indicating that the MOF-loaded silicon carbide composite membrane prepared in this embodiment has good acid resistance and can exist stably for a long time under strong acidic conditions. Example 2

[0054] a) Basement membrane pretreatment

[0055] The silicon carbide substrate is first cleaned and dried to obtain a clean membrane. The clean membrane is then placed in a muffle furnace and oxidized at 900°C for 150 minutes in an oxygen atmosphere to obtain a slightly oxidized membrane. Finally, the slightly oxidized membrane is immersed in a strong acidic solution for 20 hours, removed, and washed with deionized water until neutral, and dried to obtain a base membrane modified with hydroxyl functional groups. The strong acidic solution is a mixed solution of concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 12:1.

[0056] b) MOF seed growth

[0057] A seed crystal growth solution was prepared by mixing zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid in a molar ratio of 1:1:500:10:1, and the seed crystal growth solution was added to a reactor. The base membrane modified with hydroxyl functional groups obtained in step a) was placed in the seed crystal growth solution and reacted at 130° C. for 12 hours. After the reaction, the membrane was removed, first cleaned with N,N-dimethylformamide solution, and then dried under vacuum at 60° C. overnight to obtain a MOF seed crystal-loaded membrane.

[0058] c) MOF secondary growth

[0059] Zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid are prepared into a secondary growth solution in a molar ratio of 1.5:1.5:500:10:1, and the secondary growth solution is added to a reactor. The membrane loaded with the MOF seed crystal prepared in step b) is placed in the secondary growth solution and reacted at 110° C. for 30 hours. After the reaction is completed, the membrane is taken out and placed in a mixed solution of N,N-dimethylformamide: concentrated hydrochloric acid with a volume ratio of 50:1. The membrane is soaked at 60° C. for 12 hours and then taken out. The membrane is then rinsed with an ethanol solution and finally dried overnight in vacuum at 100° C. to obtain a MOF-loaded silicon carbide composite membrane, that is, the acid-resistant precious metal ion adsorption membrane.

[0060] The MOF-loaded silicon carbide composite membrane prepared in this example is the same as the MOF-loaded silicon carbide composite membrane prepared in Example 1. After being ultrasonicated for 8 hours and immersed in hydrochloric acid for 1 month, the surface morphology of the MOF-loaded silicon carbide composite membrane did not change significantly, indicating that the MOF-loaded silicon carbide composite membrane prepared in this example has good stability and acid resistance of the MOF loaded therein. Example 3

[0061] a) Basement membrane pretreatment

[0062] The silicon carbide substrate is first cleaned and dried to obtain a clean membrane. The clean membrane is then placed in a muffle furnace and oxidized at 1200°C for 90 minutes in an oxygen atmosphere to obtain a slightly oxidized membrane. Finally, the slightly oxidized membrane is immersed in a strong acidic solution for 30 hours, removed, and washed with deionized water until neutral, and dried to obtain a base membrane modified with hydroxyl functional groups. The strong acidic solution is a mixed solution of concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 8:1.

[0063] b) MOF seed growth

[0064] A seed crystal growth solution was prepared by mixing zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid at a molar ratio of 1:1:500:10:1. The seed crystal growth solution was added to a reactor, and the base membrane modified with hydroxyl functional groups obtained in step a) was placed in the seed crystal growth solution. The reaction was carried out at 110° C. for 18 hours. After the reaction was completed, the membrane was removed, first cleaned with N,N-dimethylformamide solution, and then dried under vacuum at 100° C. overnight to obtain a MOF seed crystal-loaded membrane.

[0065] c) MOF secondary growth

[0066] Zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid are prepared into a secondary growth solution in a molar ratio of 2:2:500:10:1, and the secondary growth solution is added to a reactor. The membrane loaded with the MOF seed crystal obtained in step b) is placed in the secondary growth solution and reacted at 130° C. for 20 hours. After the reaction is completed, the membrane is taken out and placed in a mixed solution of N,N-dimethylformamide: concentrated hydrochloric acid with a volume ratio of 30:1. After soaking at 100° C. for 8 hours, the membrane is taken out and then rinsed with an ethanol solution. Finally, the membrane is dried overnight in vacuum at 60° C. to obtain a MOF-loaded silicon carbide composite membrane, that is, the acid-resistant precious metal ion adsorption membrane.

[0067] The MOF-loaded silicon carbide composite membrane prepared in this example is the same as the MOF-loaded silicon carbide composite membrane prepared in Example 1. After being ultrasonicated for 8 hours and immersed in hydrochloric acid for 1 month, the surface morphology of the MOF-loaded silicon carbide composite membrane did not change significantly, indicating that the MOF-loaded silicon carbide composite membrane prepared in this example has good stability and acid resistance. Comparative Example 1

[0068] The steps of Comparative Example 1 are the same as those of Example 1, except that the silicon carbide substrate is not pretreated.

[0069] FIG9 is a SEM image of the MOF-supported silicon carbide composite film prepared in this comparative example. As can be seen from FIG9 , there is almost no MOF particle support on the surface of the silicon carbide substrate. Comparative Example 2

[0070] The steps of Comparative Example 2 are the same as those of Example 1, except that the silicon carbide substrate is not subjected to acidification treatment.

[0071] FIG10 is an SEM image of the MOF-loaded silicon carbide composite film prepared in this comparative example. As can be seen from FIG10 , the MOF particle loading on the surface of the silicon carbide substrate is sparse, uneven, and falls off. Comparative Example 3

[0072] The steps of Comparative Example 3 are the same as those of Example 1, except that the silicon carbide substrate is not subjected to oxidation treatment.

[0073] FIG11 is a SEM image of the MOF-loaded silicon carbide composite film prepared in this comparative example. As can be seen from FIG11 , a certain amount of MOF particles are loaded on the surface of the silicon carbide substrate.

[0074] The MOF-loaded silicon carbide composite membrane prepared in this comparative example was placed in an ultrasonic instrument for 8 hours, and the surface morphology changes of the MOF-loaded silicon carbide composite membrane were observed to investigate the stability of the MOF loaded in the MOF-loaded silicon carbide composite membrane.

[0075] Figure 12 is an SEM image of the MOF-loaded silicon carbide composite membrane prepared in this comparative example after being ultrasonicated for 8 hours. Combining Figures 11 and 12, it can be seen that the MOF particles loaded on the surface of the silicon carbide substrate are falling off. Combining Figures 12 and 4, it can be seen that compared with the MOF-loaded silicon carbide composite membrane prepared in Example 1, the MOF loaded on the MOF-loaded silicon carbide composite membrane prepared in Example 1 is more stable.

[0076] The MOF loading amounts of the MOF-loaded silicon carbide composite membranes prepared in Examples 1-3 and Comparative Examples 1-3 were tested, and the test results are shown in Table 1.

[0077] Taking palladium, a representative noble metal in the platinum group metals, as an example, the adsorption capacity of noble metals by the MOF-supported silicon carbide composite membranes prepared in Examples 1-3 and Comparative Examples 1-3 was tested. The test results are shown in Table 1. The test method is as follows:

[0078] The same area of ​​MOF-loaded silicon carbide composite membrane was placed in a centrifuge tube, and a certain volume of precious metal ion solution was added. The membrane was kept in a constant temperature oscillator at 25°C for a certain period of time, and the adsorption capacity was calculated based on the change in the precious metal ion concentration in the solution. The precious metal ion concentration was measured using a Thermo Fisher iCAP PRO X inductively coupled plasma emission spectrometer and calculated according to the adsorption capacity formula (1):

[0079] (1);

[0080] Where: Q eq Represents the adsorption capacity of precious metal ions, g / m 2 ; C0 represents the initial concentration of the solution, g / L; C t represents the concentration of the solution at time t, g / L; V f represents the volume of the solution, L; S represents the membrane area, m 2 .

[0081] Table 1 MOF loading and adsorption of noble metals on MOF-loaded silicon carbide composite membranes

[0082]

[0083] From the results shown in Table 1, it can be seen that the MOF-loaded silicon carbide composite membrane prepared by the present invention (i.e., the acid-resistant noble metal ion adsorption membrane) has a high MOF loading capacity and a good adsorption capacity for noble metals, and can be used for rare noble metal recovery.

[0084] Finally, it should be pointed out that the above are only some preferred embodiments of the present invention and should not be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above contents of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing an acid-resistant noble metal ion adsorption membrane, characterized in that: The steps include: a) Base film pretreatment: First, the silicon carbide substrate is cleaned and dried to obtain a clean membrane; then the clean membrane is oxidized in air or oxygen atmosphere to obtain a slightly oxidized membrane; finally, the slightly oxidized membrane is placed in a strong acidic solution for acidification, the membrane is removed, cleaned, and dried to obtain a base membrane modified with hydroxyl functional groups; b) MOF seed growth A seed crystal growth solution is prepared by mixing zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid in a molar ratio of 1:1:500:10:1, and the base film modified with hydroxyl functional groups obtained in step a) is placed in the seed crystal growth solution. The reaction is carried out at 110° C. to 130° C. for 12 to 24 hours. After the reaction is completed, the membrane is taken out, cleaned, and dried to obtain a MOF seed crystal-loaded membrane. c) MOF secondary growth Zirconium chloride: 2-aminoterephthalic acid: N,N-dimethylformamide: water: acetic acid are prepared into a secondary growth solution in a molar ratio of (1-2): (1-2): 500:10:1, and the MOF seed-loaded membrane prepared in step b) is placed in the secondary growth solution and reacted at 110°C to 130°C for 20 to 30 hours. After the reaction is completed, the membrane is removed, cleaned, and dried to obtain a MOF-loaded silicon carbide composite membrane, that is, the acid-resistant precious metal ion adsorption membrane.

2. The preparation method according to claim 1, wherein: In step a), the silicon carbide substrate is a silicon carbide support or a silicon carbide ceramic membrane.

3. The preparation method according to claim 1, wherein: In step a), the oxidation treatment refers to placing the clean membrane in a muffle furnace and performing oxidation treatment at 900° C. to 1200° C. for 60 to 150 minutes in air or oxygen atmosphere to obtain a slightly oxidized membrane.

4. The preparation method according to claim 1, wherein: In step a), the acid treatment refers to immersing the micro-oxidation membrane in a strong acidic solution for 20 to 30 hours, removing the membrane, washing the membrane with deionized water until it is neutral, and drying to obtain a base membrane modified with hydroxyl functional groups, wherein the strong acidic solution is a mixed solution of concentrated hydrochloric acid: concentrated nitric acid in a volume ratio of (8 to 12):

1.

5. The preparation method according to claim 1, wherein: In step b), after the reaction is completed, the membrane is taken out, cleaned with N,N-dimethylformamide solution, and then vacuum dried at 60° C. to 100° C. to obtain a membrane loaded with MOF seed crystals.

6. The preparation method according to claim 1, wherein: In step c), after the reaction is completed, the membrane is taken out and placed in a mixed solution of N,N-dimethylformamide: concentrated hydrochloric acid with a volume ratio of (30-50):

1. The membrane is soaked at 60°C to 100°C for 8-12 hours and then taken out. The membrane is then rinsed with an ethanol solution and finally vacuum dried at 60°C to 100°C to obtain a MOF-supported silicon carbide composite membrane.

7. An acid-resistant noble metal ion adsorption membrane, characterized in that: The preparation method according to any one of claims 1 to 6 is used to prepare the present invention.

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