Preparation of flavonoid graded porous carbon material and application of flavonoid graded porous carbon material in adsorption of highly toxic heavy metal Tl (I) in water

Abstract

The invention discloses preparation of a flavonoid graded porous carbon material and application of the flavonoid graded porous carbon material in adsorption of highly toxic heavy metals Tl (I) in water. The flavonoid graded porous carbon material prepared by taking flavonoid biomass as a carbon source and potassium hydroxide as an activating agent has excellent structural characteristics such as a developed porous structure, a relatively high specific surface area and rich functional groups, and shows efficient Tl (I) adsorption performance in an aqueous solution. The novel flavonoid graded porous carbon material disclosed by the invention realizes green, efficient and convenient removal of Tl (I) in an aqueous solution, and has a wide application prospect in the field of Tl (I) pollution treatment in an aquatic environment.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a heavy metal adsorbent, and in particular to the preparation of a flavonoid graded porous carbon material and its application in adsorbing the highly toxic heavy metal Tl(I) in water. Background Art

[0002] Thallium (Tl), a highly toxic heavy metal, poses a greater risk than mercury, cadmium, and lead. Ingesting just 5.0 mg of Tl per kilogram of body weight can be fatal, posing a significant risk. Therefore, Tl has been designated a highly toxic and hazardous environmental pollutant requiring priority control. In aquatic environments, Tl primarily exists in two oxidation states: Tl(I) and Tl(III). Because Tl(I) compounds are highly water-soluble, they often migrate in the Tl(I) form within water. This high mobility directly inhibits the growth and reproduction of aquatic organisms, resulting in long-term negative impacts on aquatic ecosystems. Therefore, there is an urgent need to develop efficient technologies for removing Tl(I) contamination from industrial wastewater. Currently reported technologies include adsorption, membrane separation, chemical precipitation, biological treatment, solvent extraction, ion exchange, and electrochemical oxidation.

[0003] Among these technologies, adsorption offers unique advantages in treating Tl(I)-containing wastewater, including economical, simple, efficient, widely adaptable, and low risk of secondary pollution. It primarily relies on the interaction between active sites on the adsorbent surface and Tl(I) ions to achieve Tl(I) separation. However, metal oxides and metal-organic frameworks (MOFs) often suffer from limited adsorption capacity, poor selectivity, and slow adsorption kinetics when removing Tl(I). Therefore, there is an urgent need to develop new, high-performance adsorbents to treat the increasing amount of Tl(I)-contaminated wastewater.

[0004] Hierarchical porous carbon possesses interconnected micropores, mesopores, and macropores, providing rapid mass transfer pathways and effectively improving adsorption efficiency. Furthermore, due to its unique physicochemical properties, such as high specific surface area, good chemical stability, and abundant surface functional groups, it is considered a highly promising Tl(I) adsorbent.

[0005] In the preparation process of hierarchical porous carbon, additional functional groups are usually grafted, but this may lead to increased production costs and cumbersome operation procedures. Flavonoid biomass, as a natural, widely available substance rich in carbon and multiple functional groups, can make full use of its own structure to make the hierarchical porous carbon skeleton rich in more functional groups. The preparation of hierarchical porous carbon from flavonoid biomass can not only achieve high-value utilization of biomass resources, which is in line with the concept of sustainable development, but also provide a new and economically feasible way to prepare high-performance porous carbon materials. Summary of the Invention

[0006] In view of the many limitations of current adsorbents, such as limited adsorption capacity, poor selectivity, and slow adsorption kinetics, the purpose of the present invention is to provide a method for preparing a flavonoid hierarchical porous carbon material and its application in adsorbing highly toxic heavy metal Tl(I) in aqueous solution. The flavonoid hierarchical porous carbon material not only contains a developed porous structure but also can provide abundant adsorption active sites, showing efficient Tl(I) adsorption performance in aqueous solution.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] Step 1: Take a certain amount of flavonoid biomass and potassium hydroxide, and prepare a mixed precursor through impregnation and drying in sequence.

[0009] Step 2: Subject the activation product obtained in Step 1 to carbonization, washing, and drying in sequence to prepare a flavonoid hierarchical porous carbon material. 2. The method for preparing a flavonoid hierarchical porous carbon material according to claim 1, wherein the mass ratio of the flavonoid biomass to potassium hydroxide in Step 1 is 1:1 to 1:20.

[0010] The mass ratio of the flavonoid biomass in Step 1 to the volume of the mixed solution of water and ethanol is 1.0 g:50.0 mL, and the impregnation time is 12.0 h to 24.0 h.

[0011] The drying temperature in Step 1 is 100°C, and the drying time is 12.0 h to 24.0 h.

[0012] The carbonization process in Step 2 is carried out under a nitrogen atmosphere, heating from room temperature to 900°C at a heating rate of 10°C / min and maintaining at 900°C for 2.0 h to 4.0 h.

[0013] The washing process in Step 2 specifically includes repeatedly rinsing with distilled water until the pH value of the filtrate is neutral.

[0014] The drying temperature in Step 2 is 100°C, and the drying time is 12.0 h to 24.0 h.

[0015] The present invention also provides the application of the flavonoid hierarchical porous carbon material in adsorbing highly toxic heavy metal Tl(I) in aqueous solution. The specific process is as follows: Add different amounts of the flavonoid hierarchical porous carbon material adsorbent (0.005 - 0.05 g) to 100.0 mL of different initial Tl(I) concentrations (40.0 mg·L -1 -100mg·L -1)(in an aqueous solution with a solution pH value of 2.0 - 12.0). Subsequently, the mixed solution was transferred to a thermostatic air bath shaker and shaken thoroughly at a rate of 200 rpm for a period of time (0 - 4.0 h). Finally, the adsorption solution was filtered using a Büchner funnel, and the mass concentration of residual Tl(I) in the filtrate was determined by ICP - OES.

[0016] Compared with the prior art, the present invention has the following advantages and effects: The flavonoid - based hierarchically porous carbon material prepared by the present invention has excellent structural characteristics such as a developed porous structure, a high specific surface area, and abundant functional groups, and exhibits efficient Tl(I) adsorption performance in aqueous solution. The novel flavonoid - based hierarchically porous carbon material disclosed by the present invention realizes the green, efficient, and convenient removal of Tl(I) in aqueous solution and has broad application prospects in the field of treating Tl(I) pollution in the aquatic environment. Description of the Drawings

[0017] Figure 1 Infrared spectrum of the flavonoid - based hierarchically porous carbon material obtained in Example 1.

[0018] Figure 2 Scanning electron microscope image of the flavonoid - based hierarchically porous carbon material obtained in Example 1.

[0019] Figure 3 Nitrogen adsorption - desorption isotherm and pore size distribution diagram of the flavonoid - based hierarchically porous carbon material obtained in Example 1.

[0020] Figure 4 Relationship diagram between the adsorption amount of highly toxic heavy metal Tl(I) and the adsorbent dosage in the effect example.

[0021] Figure 5 Relationship diagram between the adsorption amount of highly toxic heavy metal Tl(I) and the reaction pH value in the effect example.

[0022] Figure 6 Relationship diagram between the adsorption amount of highly toxic heavy metal Tl(I) and the reaction time in the effect example. Detailed Description of the Invention

[0023] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the following specific embodiments are used to describe the specific implementation manners of the present invention in detail. Many specific details are set forth in the following description to fully understand the present invention. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0024] Example 1

[0025] This embodiment provides a method for preparing a flavonoid graded porous carbon material.

[0026] Baicalin and potassium hydroxide were weighed in a mass ratio of 1:1 to 1:20, added to a mixed solution of 50 mL of water and ethanol, stirred for 12.0 h to 24.0 h, and then dried in an oven at 100 ° C for 12.0 h to 24.0 h. Then carbonized in a tube furnace under N2 atmosphere. The temperature was raised from room temperature to 900 ° C at a heating rate of 10 ° C / min, and maintained at 900 ° C for 2.0 h to 4.0 h. The hierarchical porous carbon material was prepared by repeatedly rinsing with distilled water until the pH value in the filtrate was neutral, and dried at 100 ° C for 12.0 h to 24.0 h. Figure 1 As shown in Figure 2, the material has rich functional groups; Figure 2 As shown in , the material presents an irregular, rough, and porous surface structure; Figure 3 As shown, there are a certain proportion of micropores and mesopores in the material structure.

[0027] Effect Example

[0028] This embodiment is the application of flavonoid graded porous carbon materials in the adsorption of highly toxic heavy metal Tl(I).

[0029] 0.005 g to 0.05 g of the hierarchical porous carbon material obtained in Example 1 and 100.0 mL of a 40.0 mg·L -1 The Tl(I)-containing aqueous solution was added to a 250.0 mL conical flask, and the pH value was adjusted to pH = 4.0. The reaction mixture was shaken in a constant temperature air bath at 35°C for 30.0 min. Finally, the adsorption solution was filtered using a Büchner funnel, and the mass concentration of residual Tl(I) in the filtrate was determined by ICP-OES. Figure 4 As shown in the figure, when the adsorbent dosage is 0.005 g, the adsorption amount is the highest.

[0030] 0.2 g of the hierarchical porous carbon material obtained in Example 1 and 100.0 mL of a 40.0 mg·L -1 The Tl(I)-containing aqueous solution was added to a 250.0 mL conical flask, and the pH value was adjusted to pH = 2.0-12.0. The reaction mixture was shaken in a constant temperature air bath at 35°C for 30.0 min. Finally, the adsorption solution was filtered using a Büchner funnel, and the mass concentration of residual Tl(I) in the filtrate was determined by ICP-OES. Figure 5 As shown in the figure, the adsorption amount is the highest when the reaction pH is 12.0.

[0031] 0.005 g of the hierarchical porous carbon material obtained in Example 1 and 100.0 mL of an aqueous solution containing Tl(I) with a concentration of 40.0 mg·L -1 were added to a 250.0 mL conical flask. After adjusting the pH value to pH = 2.0 - 12.0, the reaction mixture was reacted in a constant-temperature air bath shaker at 35 °C for 30.0 min. Finally, the adsorption solution was filtered using a Büchner funnel, and the mass concentration of residual Tl(I) in the filtrate was determined by ICP-OES. As Figure 6 shown, the adsorption capacity was the highest when the reaction time value was 4.0 h.

[0032] This material has excellent structural characteristics such as a hierarchical porous structure, a high specific surface area, and rich functional groups. In addition, this material is easy to recycle and exhibits efficient Tl(I) adsorption performance in aqueous solution as an environmentally friendly highly toxic heavy metal Tl(I) adsorbent. The flavonoid hierarchical porous carbon material disclosed in the present invention realizes the green, efficient, and convenient removal of Tl(I) in aqueous solution and has broad application prospects in the field of treating Tl(I) pollution in the aquatic environment.

[0033] Finally, it should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a flavonoid hierarchical porous carbon material, characterized in that, The following steps are involved: Step 1: Take a certain amount of flavonoid biomass and potassium hydroxide, soak them in sequence, and dry them to prepare a mixture.

2. Step 2: The mixed precursor obtained in step 1 is carbonized, washed, and dried in sequence to prepare a flavonoid graded porous carbon material.

3. The method for preparing the flavonoid hierarchical porous carbon material according to claim 1, wherein: The mass ratio of the flavonoid biomass to potassium hydroxide in the step 1 is 1:1 to 1:

20.

4. The preparation method of the flavonoid hierarchical porous carbon material according to claim 1, wherein, In the step 1, the volume ratio of the mass of the flavonoid biomass to the mixed solution of water and ethanol is 1.0 g:50.0 mL, and the immersion time is 12.0 h to 24.0 h.

5. The preparation method of the flavonoid hierarchical porous carbon material according to claim 1, wherein The drying temperature in step 1 is 100° C., and the drying time is 12.0 h to 24.0 h.

6. The method for preparing the flavonoid hierarchical porous carbon material according to claim 1, wherein: The carbonization process in the second step is carried out under a nitrogen atmosphere, with the temperature being increased from room temperature to 900° C. at a heating rate of 10° C. / min, and maintained at 900° C. for 2.0 h to 4.0 h.

7. The preparation method of the flavonoid hierarchical porous carbon material according to claim 1, characterized in that, The washing process in step 2 specifically includes repeatedly washing with distilled water until the pH value of the filtrate is neutral.

8. The preparation method of the flavonoid hierarchical porous carbon material according to claim 1, characterized in that, The drying temperature in step 2 is 100° C., and the drying time is 12.0 h to 24.0 h.

9. Use of the flavonoid graded porous carbon material obtained by the preparation method according to claim 1 for adsorbing the highly toxic heavy metal Tl(I) in aqueous solution, characterized in that: Add flavonoid-based hierarchically porous carbon adsorbents in different dosages (0.005 - 0.05 g) to 100.0 mL of aqueous solutions with different initial Tl(I) concentrations (40.0 mg·L -1 and solution pH values (2.0 - 12.0). Subsequently, transfer the mixed solution to a thermostatic air-bath shaker and shake it vigorously at a rate of 200 rpm for a certain period of time (0 - 4.0 h). Finally, filter the adsorption solution using a Büchner funnel and determine the mass concentration of residual Tl(I) in the filtrate by ICP-OES.

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