Bio-based platinum adsorption material and preparation method thereof

Abstract

The invention discloses a bio-based platinum adsorption material and a preparation method thereof, and relates to the technical field of metal adsorbents. The bio-based platinum adsorption material comprises modified nitrogen-doped carbon spheres, persimmon powder coating the outer surfaces of the modified nitrogen-doped carbon spheres, and urea resin for adhering the modified nitrogen-doped carbon spheres and the persimmon powder together, the modified nitrogen-doped carbon spheres are nitrogen-doped carbon spheres modified by glycine; the nitrogen-doped carbon spheres are obtained by taking a biomass material gastrodia elata as a nitrogen source and a carbon source and carrying out hydrothermal treatment, activation and high-temperature carbonization; the prepared bio-based platinum adsorption material is good in platinum adsorption effect.

Description

Technical Field

[0001] The invention relates to the technical field of metal adsorbents, and in particular to a bio-based platinum adsorption material and a preparation method thereof. Background Art

[0002] As environmental issues have received increasing attention, the development of efficient and environmentally friendly adsorbents for the recovery of precious metal ions has become a research hotspot. Although traditional adsorbent materials, such as activated carbon, have excellent adsorption performance, their production process is usually accompanied by high energy consumption and dependence on specific raw materials, which limits their sustainable development capabilities and has an adverse impact on the environment.

[0003] In order to solve the above problems, researchers have begun to turn their attention to renewable biomass resources in order to find greener and lower-cost solutions. This type of biomass comes from a wide range of sources, including agricultural waste, forestry byproducts, and various plant extracts. They can not only provide abundant raw materials, but also reduce carbon footprints during conversion into adsorption materials, thus promoting the development of a circular economy.

[0004] The technicians paid special attention to the unique advantages of Gastrodia elata as a carbon and nitrogen source. As a common Chinese medicinal material, Gastrodia elata is rich in a variety of organic components, which can form nitrogen-doped carbon balls with high specific surface area and rich pore structure during pyrolysis. The introduction of nitrogen makes this material have higher surface chemical activity, thereby significantly enhancing the adsorption capacity of heavy metal ions such as platinum. In addition, the use of Gastrodia elata also avoids the high energy consumption problem that may occur in the preparation of traditional adsorption materials, which is in line with the principles of green chemistry.

[0005] In addition, persimmon powder has also been shown to be one of the ideal choices for preparing high-performance adsorption materials. Persimmons contain a large amount of tannic acid and other polyphenolic compounds, which can be converted into materials with excellent adsorption properties under appropriate conditions. Tannic acid is a natural polymer that has the ability to bind to metal ions, so it has shown great potential in treating heavy metal-containing wastewater. The use of persimmon powder to prepare adsorption materials can not only effectively utilize agricultural waste, but also provide new ideas for solving the problem of poor dispersibility in water.

[0006] However, although Gastrodia elata and persimmon powder each have excellent properties, when used, their dispersibility in water and adsorption effect on platinum ions still have certain limitations. In order to solve this problem, the present invention prepares a bio-based platinum adsorption material. Summary of the invention

[0007] The object of the present invention is to provide a bio-based platinum adsorption material and a preparation method thereof, so as to solve the problems existing in the prior art.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: A bio-based platinum adsorption material comprises modified nitrogen-doped carbon balls, persimmon powder coated on the outer surface of the modified nitrogen-doped carbon balls, and urea-formaldehyde resin adhering the modified nitrogen-doped carbon balls and the persimmon powder together; the modified nitrogen-doped carbon balls are nitrogen-doped carbon balls modified with glycine; the nitrogen-doped carbon balls are obtained by hydrothermal treatment, activation, and high-temperature carbonization of a nitrogen source and a carbon source.

[0009] Furthermore, the free formaldehyde content in the urea-formaldehyde resin is 1-2 wt %.

[0010] Furthermore, the activation is carried out using zinc chloride activation.

[0011] Furthermore, the nitrogen source and carbon source are the biomass material Gastrodia elata.

[0012] The present invention also provides a method for preparing a bio-based platinum adsorption material, characterized in that it comprises the following preparation steps: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) coating the surface of the primary coated nitrogen-doped carbon sphere with a layer of persimmon powder to obtain secondary coated nitrogen-doped carbon spheres; (3) The secondary coated nitrogen-doped carbon spheres were dispersed in distilled water with a solid-liquid ratio of 1:9-11. After adding concentrated hydrochloric acid, the temperature was raised to 40-60 °C and stirred for 100-125 min. After filtration, the mixture was washed with distilled water for 2-4 times and then dried in a forced air drying oven at 50 °C for 24 h to obtain a bio-based platinum adsorption material.

[0013] Furthermore, the preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, and then concentrated sulfuric acid is added, the temperature is raised to 60-70°C, the temperature is kept, the reaction is stirred at 100-200 rpm for 7-9 hours, and then the reaction is allowed to stand for 4 hours, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

[0014] Furthermore, the concentration of the glycine aqueous solution is 2% to 6%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:2 to 10; and the mass of the concentrated sulfuric acid is 0.6 to 0.8 times that of the nitrogen-doped carbon spheres.

[0015] Furthermore, the preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried, and crushed, and then added to a high-pressure reactor with deionized water 80 to 120 times the mass of Gastrodia elata, reacted at a first reaction temperature for 23 to 25 hours, then naturally cooled to room temperature, centrifuged, washed and vacuum dried to obtain a powder, and then the powder is activated with zinc chloride, heated to a carbonization temperature under nitrogen protection and carbonized, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0016] Furthermore, the step of activating the powder with zinc chloride is as follows: adding the powder to a 19-21% zinc chloride solution of 9-11 times the mass of Gastrodia elata and immersing for 23-25 ​​hours.

[0017] Furthermore, the first reaction temperature is 178-182°C; the carbonization temperature is 795-805°C.

[0018] Furthermore, the concentration of the concentrated hydrochloric acid is 36-38%.

[0019] Furthermore, the mass of the concentrated hydrochloric acid is 0.015 to 0.25 times that of the persimmon powder.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are: The bio-based platinum adsorption material prepared by the present invention comprises modified nitrogen-doped carbon balls, persimmon powder coated on the outer surface of the modified nitrogen-doped carbon balls, and urea-formaldehyde resin adhering the modified nitrogen-doped carbon balls and the persimmon powder together; the modified nitrogen-doped carbon balls are nitrogen-doped carbon balls modified with glycine; the nitrogen-doped carbon balls are obtained by hydrothermal, activation and high-temperature carbonization using biomass material Gastrodia elata as nitrogen source and carbon source.

[0021] Firstly, biomass material Gastrodia elata is used as nitrogen source and carbon source, and hydrothermal, activation and high-temperature carbonization are carried out to prepare nitrogen-doped carbon balls, and glycine is used to modify the nitrogen-doped carbon balls. The biomass material Gastrodia elata raw material is abundant, easy to obtain and inexpensive, so it is used as the carbon source and nitrogen source to prepare nitrogen-doped carbon balls. The prepared nitrogen-doped carbon balls are quasi-net-shaped carbon balls, which have many nanopores and good adsorption performance. Then, glycine is used to modify the nitrogen-doped carbon balls, and amino groups and the like are introduced into the carbon balls, which increases the adsorption of platinum by the nitrogen-doped carbon balls and increases the adhesion of the modified nitrogen-doped carbon balls to urea-formaldehyde resin.

[0022] Secondly, urea-formaldehyde resin can be used to firmly bond the modified nitrogen-doped carbon balls and persimmon powder together; persimmon powder is rich in tannins, which have a good adsorption effect on platinum metal ions, and are widely available, environmentally friendly, and have good adsorption effects. When combined with modified nitrogen-doped carbon balls, the bio-based platinum adsorption material prepared has a better platinum adsorption effect.

[0023] Finally, urea-formaldehyde resin and persimmon powder were successively wrapped on the surface of modified nitrogen-doped carbon balls and mixed under concentrated hydrochloric acid conditions. The glycine on the surface of the modified nitrogen-doped carbon balls, the free formaldehyde in the urea-formaldehyde resin and the tannins in the persimmon powder underwent Mannich reaction to form amphoteric tannins. Under acidic conditions, the amphoteric tannins exist in a salt state with excellent solubility, which causes changes in functional groups such as hydroxyl and carboxyl groups on the surface of persimmon phenol. The introduced amino groups, together with the hydroxyl and carboxyl groups, adsorb platinum ions through ion exchange or coordination, further enhancing the platinum adsorption effect of the bio-based platinum adsorption material. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the test methods of various indicators of the bio-based platinum adsorption materials prepared in the following examples are as follows: Platinum adsorption effect: Add 50 parts by mass of bio-based platinum adsorption material to 500 parts by mass of 30 mg / L chloroplatinic acid solution, adjust the pH to 1, oscillate at a constant temperature at 70°C for 12 hours, filter, take the filtrate, and determine the concentration of platinum metal ions in the filtrate with an atomic absorption spectrophotometer. Platinum adsorption rate = (30-concentration of platinum metal ions in the filtrate) * 100% / 30.

[0026] Example 1 A method for preparing a bio-based platinum adsorption material comprises the following preparation steps: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) coating the surface of the primary coated nitrogen-doped carbon sphere with a layer of persimmon powder to obtain secondary coated nitrogen-doped carbon spheres; (3) The secondary wrapped nitrogen-doped carbon balls were dispersed in distilled water with a solid-liquid ratio of 1:9. After adding 36% concentrated hydrochloric acid, the temperature was raised to 40°C and stirred for 100 min. After solid-liquid separation, washing and drying, a bio-based platinum adsorption material was obtained; the mass of concentrated hydrochloric acid was 0.015 times that of persimmon powder.

[0027] The preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, concentrated sulfuric acid is then added, the temperature is raised to 60° C., the temperature is maintained, the reaction is stirred at 100 rpm for 7 hours, and then the mixture is allowed to stand for 4 hours, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

[0028] The concentration of the glycine aqueous solution is 2%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:2; and the mass of the concentrated sulfuric acid is 0.6 times that of the nitrogen-doped carbon spheres.

[0029] The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried at 49° C. to a moisture content of 8%, then crushed into a powder with a particle size of 140 mesh, and then added into a high-pressure reactor with deionized water 80 times the mass of Gastrodia elata, kept reacting at 178° C. for 23 hours, then naturally cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol until the solution is colorless, vacuum dried, then added into a 19% zinc chloride solution 9 times the mass of Gastrodia elata at room temperature and immersed for 23 hours, then heated to 795° C. under nitrogen protection and kept warm, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0030] Example 2 A method for preparing a bio-based platinum adsorption material comprises the following preparation steps: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) coating the surface of the primary coated nitrogen-doped carbon sphere with a layer of persimmon powder to obtain secondary coated nitrogen-doped carbon spheres; (3) The secondary wrapped nitrogen-doped carbon balls were dispersed in distilled water with a solid-liquid ratio of 1:10. After adding 36% concentrated hydrochloric acid, the temperature was raised to 50 °C and stirred for 110 min. After solid-liquid separation, washing and drying, a bio-based platinum adsorption material was obtained. The mass of concentrated hydrochloric acid was 0.02 times that of persimmon powder.

[0031] The preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, concentrated sulfuric acid is then added, the temperature is raised to 65° C., the temperature is maintained, the reaction is stirred at 150 rpm for 8 hours, and then the mixture is allowed to stand for 4 hours, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

[0032] The concentration of the glycine aqueous solution is 4%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:6; and the mass of the concentrated sulfuric acid is 0.7 times that of the nitrogen-doped carbon spheres.

[0033] The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried at 50°C to a moisture content of 10%, then crushed into a powder with a particle size of 150 mesh, and then added into a high-pressure reactor with deionized water 100 times the mass of Gastrodia elata, kept reacting at 180°C for 24 hours, then naturally cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol until the solution is colorless, vacuum dried, then added into a 20% zinc chloride solution 10 times the mass of Gastrodia elata at room temperature and immersed for 24 hours, then heated to 800°C under nitrogen protection and kept warm, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0034] Example 3 A method for preparing a bio-based platinum adsorption material comprises the following preparation steps: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) coating the surface of the primary coated nitrogen-doped carbon sphere with a layer of persimmon powder to obtain secondary coated nitrogen-doped carbon spheres; (3) The secondary wrapped nitrogen-doped carbon spheres were dispersed in distilled water with a solid-liquid ratio of 1:11. After adding 38% concentrated hydrochloric acid, the temperature was raised to 60 °C and stirred for 125 min. After solid-liquid separation, washing and drying, a bio-based platinum adsorption material was obtained. The mass of concentrated hydrochloric acid was 0.025 times that of persimmon powder.

[0035] The preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, concentrated sulfuric acid is then added, the temperature is raised to 70° C., the temperature is maintained, the reaction is stirred at 200 rpm for 9 hours, and then the mixture is allowed to stand for 4 hours, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

[0036] The concentration of the glycine aqueous solution is 6%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:10; and the mass of the concentrated sulfuric acid is 0.8 times that of the nitrogen-doped carbon spheres.

[0037] The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried at 52° C. to a moisture content of 12%, then crushed into a powder with a particle size of 160 mesh, and then added into a high-pressure reactor with deionized water 120 times the mass of Gastrodia elata, kept reacting at 182° C. for 25 hours, then naturally cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol until the solution is colorless, vacuum dried, then added into a 21% zinc chloride solution 11 times the mass of Gastrodia elata at room temperature and immersed for 25 hours, heated to 805° C. under nitrogen protection and kept warm, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0038] Comparative Example 1 A method for preparing a bio-based platinum adsorption material comprises the following preparation steps: (1) coating the outer surface of the nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) coating the surface of the primary coated nitrogen-doped carbon sphere with a layer of persimmon powder to obtain secondary coated nitrogen-doped carbon spheres; (3) The secondary wrapped nitrogen-doped carbon balls were dispersed in distilled water with a solid-liquid ratio of 1:10. After adding 36% concentrated hydrochloric acid, the temperature was raised to 50 °C and stirred for 110 min. After solid-liquid separation, washing and drying, a bio-based platinum adsorption material was obtained. The mass of concentrated hydrochloric acid was 0.02 times that of persimmon powder.

[0039] The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried at 50°C to a moisture content of 10%, then crushed into a powder with a particle size of 150 mesh, and then added into a high-pressure reactor with deionized water 100 times the mass of Gastrodia elata, kept reacting at 180°C for 24 hours, then naturally cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol until the solution is colorless, vacuum dried, then added into a 20% zinc chloride solution 10 times the mass of Gastrodia elata at room temperature and immersed for 24 hours, then heated to 800°C under nitrogen protection and kept warm, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0040] Comparative Example 2 A method for preparing a bio-based platinum adsorption material comprises the following preparation steps: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of persimmon powder to obtain a once-coated nitrogen-doped carbon sphere; (2) The nitrogen-doped carbon balls that had been wrapped once were dispersed in distilled water with a solid-liquid ratio of 1:10. After adding 36% concentrated hydrochloric acid, the temperature was raised to 50 °C and stirred for 110 min. After solid-liquid separation, washing and drying, a bio-based platinum adsorption material was obtained. The mass of concentrated hydrochloric acid was 0.02 times that of persimmon powder.

[0041] The preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, concentrated sulfuric acid is then added, the temperature is raised to 65° C., the temperature is maintained, the reaction is stirred at 150 rpm for 8 hours, and then the mixture is allowed to stand for 4 hours, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

[0042] The concentration of the glycine aqueous solution is 4%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:6; and the mass of the concentrated sulfuric acid is 0.7 times that of the nitrogen-doped carbon spheres.

[0043] The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried at 50°C to a moisture content of 10%, then crushed into a powder with a particle size of 150 mesh, and then added into a high-pressure reactor with deionized water 100 times the mass of Gastrodia elata, kept reacting at 180°C for 24 hours, then naturally cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol until the solution is colorless, vacuum dried, then added into a 20% zinc chloride solution 10 times the mass of Gastrodia elata at room temperature and immersed for 24 hours, then heated to 800°C under nitrogen protection and kept warm, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0044] Comparative Example 3 Nitrogen-doped carbon spheres were used as bio-based platinum adsorption materials.

[0045] Comparative Example 4 The modified nitrogen-doped carbon spheres modified by the same modification method as in Example 1 were used as bio-based platinum adsorption materials.

[0046] Comparative Example 5 Persimmon powder was used as bio-based platinum adsorption material.

[0047] Comparative Example 6 A method for preparing a bio-based platinum adsorption material comprises the following preparation steps: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) A layer of persimmon powder is coated on the surface of the nitrogen-doped carbon spheres to obtain a bio-based platinum adsorption material.

[0048] The preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, concentrated sulfuric acid is then added, the temperature is raised to 65° C., the temperature is maintained, the reaction is stirred at 150 rpm for 8 hours, and then the mixture is allowed to stand for 4 hours, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

[0049] The concentration of the glycine aqueous solution is 4%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:6; and the mass of the concentrated sulfuric acid is 0.7 times that of the nitrogen-doped carbon spheres.

[0050] The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried at 50°C to a moisture content of 10%, then crushed into a powder with a particle size of 150 mesh, and then added into a high-pressure reactor with deionized water 100 times the mass of Gastrodia elata, kept reacting at 180°C for 24 hours, then naturally cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol until the solution is colorless, vacuum dried, then added into a 20% zinc chloride solution 10 times the mass of Gastrodia elata at room temperature and immersed for 24 hours, then heated to 800°C under nitrogen protection and kept warm, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

[0051] Effect example Table 1 below shows the performance analysis results of the bio-based platinum adsorption materials of Examples 1 to 3 of the present invention and Comparative Examples 1 to 6.

[0052] Table 1 From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 6 in Table 1, it can be found that the bio-based platinum adsorption materials prepared in each embodiment have better platinum adsorption effects than the bio-based platinum adsorption materials prepared in each comparative example. After analysis, this is because the nitrogen-doped carbon balls are modified with glycine, and amino groups and the like are introduced into the carbon balls, which not only increases the adsorption of platinum by the nitrogen-doped carbon balls, but also increases the adhesion of the modified nitrogen-doped carbon balls to the urea-formaldehyde resin. The urea-formaldehyde resin can firmly bond the modified nitrogen-doped carbon balls and persimmon powder together, and the free formaldehyde in the urea-formaldehyde resin can react with the glycine on the surface of the modified nitrogen-doped carbon balls and the tannins in the persimmon powder to undergo a Mannich reaction, thereby increasing the dispersion effect of the bio-based platinum adsorption material in water, thereby making the platinum adsorption effect of the bio-based platinum adsorption material better; and by following The urea-formaldehyde resin and persimmon powder are wrapped on the surface of modified nitrogen-doped carbon balls to prepare bio-based platinum adsorption materials, which are then mixed and reacted under concentrated hydrochloric acid conditions to form amphoteric tannins. Under acidic conditions, the amphoteric tannins exist in a salt state with excellent solubility, which increases the dispersion effect of the bio-based platinum adsorption material in water and changes the functional groups such as hydroxyl and carboxyl groups on the surface of the persimmon powder. The introduced amino groups, together with the hydroxyl and carboxyl groups, adsorb platinum ions through ion exchange or coordination, further enhancing the platinum adsorption effect of the bio-based platinum adsorption material. The obtained bio-based platinum adsorption material has a better platinum adsorption effect.

[0053] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A bio-based platinum adsorption material, characterized in that: The invention comprises modified nitrogen-doped carbon balls, persimmon powder coated on the outer surface of the modified nitrogen-doped carbon balls, and urea-formaldehyde resin adhering the modified nitrogen-doped carbon balls and the persimmon powder together; the modified nitrogen-doped carbon balls are nitrogen-doped carbon balls modified with glycine; the nitrogen-doped carbon balls are obtained by subjecting a nitrogen source and a carbon source to hydrothermal treatment, activation, and high-temperature carbonization.

2. The bio-based platinum adsorption material according to claim 1, characterized in that: The free formaldehyde content in the urea-formaldehyde resin is 1-2 wt %.

3. The bio-based platinum adsorption material according to claim 1, characterized in that: The activation is carried out by zinc chloride activation.

4. The bio-based platinum adsorption material according to claim 1, characterized in that: The nitrogen source and carbon source are biomass material Gastrodia elata.

5. A method for preparing the bio-based platinum adsorption material according to any one of claims 1 to 4, characterized in that: The preparation steps include: (1) coating the outer surface of the modified nitrogen-doped carbon sphere with a layer of urea-formaldehyde resin to obtain a nitrogen-doped carbon sphere wrapped once; (2) coating the surface of the primary coated nitrogen-doped carbon sphere with a layer of persimmon powder to obtain secondary coated nitrogen-doped carbon spheres; (3) The secondary wrapped nitrogen-doped carbon spheres are dispersed in distilled water with a solid-liquid ratio of 1:9-11. After adding concentrated hydrochloric acid, the temperature is raised to 40-60 °C and stirred for 100-125 min. After solid-liquid separation, washing and drying, a bio-based platinum adsorption material is obtained.

6. The method for preparing the bio-based platinum adsorption material according to claim 5, characterized in that: The preparation method of the modified nitrogen-doped carbon spheres is as follows: the nitrogen-doped carbon spheres are dispersed in a glycine aqueous solution, concentrated sulfuric acid is then added, the temperature is raised to 60-70° C., the temperature is maintained, the reaction is stirred at 100-200 rpm for 7-9 hours, the reaction is allowed to stand, filtered, repeatedly washed with deionized water until neutral, and dried to obtain modified nitrogen-doped carbon spheres.

7. The method for preparing the bio-based platinum adsorption material according to claim 6, characterized in that: The concentration of the glycine aqueous solution is 2% to 6%; the mass ratio of the nitrogen-doped carbon spheres to glycine is 3:2 to 10; and the mass of the concentrated sulfuric acid is 0.6 to 0.8 times that of the nitrogen-doped carbon spheres.

8. The method for preparing the bio-based platinum adsorption material according to claim 6, characterized in that: The preparation method of the nitrogen-doped carbon spheres is as follows: the biomass material Gastrodia elata is washed with deionized water, dried, and crushed, and then added into a high-pressure reactor with deionized water 80 to 120 times the mass of Gastrodia elata, reacted at a first reaction temperature for 23 to 25 hours, then naturally cooled to room temperature, centrifuged, washed and vacuum dried to obtain powder, and then the powder is activated with zinc chloride, heated to a carbonization temperature under nitrogen protection and carbonized, naturally cooled to room temperature, repeatedly centrifuged and washed with hydrochloric acid and deionized water to remove residual metal impurities, and vacuum dried to obtain nitrogen-doped carbon spheres.

9. The method for preparing the bio-based platinum adsorption material according to claim 8, characterized in that: The step of activating the powder with zinc chloride is as follows: adding the powder to a 19-21% zinc chloride solution with a concentration of 9-11 times the mass of Gastrodia elata and immersing for 23-25 ​​hours.

10. The method for preparing the bio-based platinum adsorption material according to claim 6, characterized in that: The first reaction temperature is 178-182°C; the carbonization temperature is 795-805°C.

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