A method for preparing iron-manganese Prussian blue nanomaterials with tunable pore structure and its application

Abstract

This invention discloses a method for preparing pore-structure-tunable iron-manganese Prussian blue nanomaterials and their applications. Potassium ferrocyanide is used as the iron source. Polyvinylpyrrolidone is added and mixed with hydrochloric acid until fully dissolved. Then, potassium permanganate powder is added and stirred again until dissolved. The mixture is transferred to a high-temperature reactor, where it is reacted completely under different hydrothermal conditions and then naturally cooled to room temperature. The resulting product is centrifuged, washed, and dried in a vacuum drying oven to obtain a series of porous iron-manganese Prussian blue nanomaterials. The porous iron-manganese Prussian blue nanomaterials prepared by this invention can activate PMS and exhibit degradation properties to 10 ppm methylene blue solution. This invention uses a hydrothermal method to prepare pore-structure-tunable iron-manganese Prussian blue nanomaterials. This invention features high economic efficiency, a simple preparation process, and the potential for large-scale industrial production, demonstrating good economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to a method for preparing iron-manganese Prussian blue nanomaterials with tunable pore structure and their applications. Background Technology

[0002] In recent years, with the development of environmental functional materials, porous Prussian blue-like materials have become a research hotspot in catalytic materials. Compared with continuous media materials, porous materials generally have advantages such as low relative density, high specific strength, high specific surface area, light weight, sound insulation, heat insulation, and good permeability. Furthermore, due to their specific pore topology and abundant active sites, the performance of the final material is optimized. Prussian blue-like compounds, due to their low biotoxicity, controllable size, and ease of modification, have also been widely studied and applied.

[0003] Since the preparation of porous materials relies on the action of pore-forming agents, the process of adding these agents in industrial production or scientific research still involves cumbersome steps. Furthermore, some pore-forming agents are toxic and can impact the environment, thus limiting production and research. To address this bottleneck, a simple method for synthesizing porous materials without pore-forming agents was designed. The method allows for the adjustment of parameters such as pore size by modifying the synthesis conditions, enabling the preparation of porous iron-manganese Prussian blue nanomaterials using potassium ferrocyanide as a raw material. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a highly efficient and rapid method for preparing iron-manganese Prussian blue nanomaterials with tunable pore structures that degrade methylene blue. This invention uses potassium ferrocyanide as the iron source. Potassium ferrocyanide and polyvinylpyrrolidone are dissolved in hydrochloric acid solution, and ground potassium permanganate powder is added. A hydrothermal reaction is then carried out to obtain porous iron-manganese Prussian blue nanomaterials. First, appropriate amounts of potassium ferrocyanide and polyvinylpyrrolidone are weighed and thoroughly stirred and dissolved in hydrochloric acid solution. Then, ground potassium permanganate powder is added to the acid solution. After thorough stirring, the mixture is transferred to a high-temperature reactor for a hydrothermal reaction. By adjusting different hydrothermal reaction conditions, iron-manganese Prussian blue nanomaterials with different pore structures are ultimately formed. This invention provides a simple, versatile, and applicable green synthesis method for preparing iron-manganese Prussian blue nanomaterials whose pore structure can be modified by changing the conditions. Moreover, the obtained iron-manganese Prussian blue nanomaterials with tunable pore structure exhibit extremely high catalytic activity in the degradation of methylene blue. The method is simple, low-cost, and has good economic and environmental benefits.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing iron-manganese Prussian blue nanomaterials with tunable pore structure and its application, comprising the following raw materials: potassium ferrocyanide (K4Fe(CN)6·3H2O) and polyvinylpyrrolidone ((C6H9NO)). n Potassium permanganate (KMnO4) and hydrochloric acid (HCl).

[0007] A method for preparing iron-manganese Prussian blue nanomaterials with tunable pore structure and its application:

[0008] Using potassium ferrocyanide as the iron source, potassium ferrocyanide, polyvinylpyrrolidone, and hydrochloric acid solution were stirred at room temperature until the solution became clear. Then, ground potassium permanganate was added and stirred until dissolved. The mixed solution was then transferred to a reaction vessel and reacted under different hydrothermal conditions. After natural cooling to room temperature, a series of Prussian blue-like compounds were obtained by stirring, centrifugation, washing, and drying.

[0009] The pore structure of the iron-manganese Prussian blue nanomaterial can be tuned, specifically including the following steps:

[0010] (1) Weigh a certain mass of potassium ferrocyanide and polyvinylpyrrolidone, place them in hydrochloric acid solution and stir thoroughly until the solution is clear;

[0011] (2) Weigh a certain mass of solid potassium permanganate and grind it into powder;

[0012] (3) Add potassium permanganate powder to the mixed solution obtained in step (1) and stir thoroughly;

[0013] (4) Transfer the stirred solution to a high-temperature reaction vessel, place it in an oven to react, and allow it to cool naturally to room temperature;

[0014] (5) The solution after the reaction was taken out, centrifuged, washed and dried to obtain porous iron-manganese Prussian blue nanomaterials;

[0015] Further, the mass of potassium ferrocyanide and polyvinylpyrrolidone in step (1) is: potassium ferrocyanide: 0.12g, polyvinylpyrrolidone: 3.8g.

[0016] Further, the hydrochloric acid solution mentioned in step (1) is: 50 ml of hydrochloric acid with a concentration of 0.1 mmol / L;

[0017] Furthermore, the stirring in step (1) is: magnetic stirring; stirring speed is 500-1000 rpm; stirring time is 20-40 min;

[0018] Further, the mass of potassium permanganate mentioned in step (2) is 0.02244 g.

[0019] Further, the stirring in step (3) is: magnetic stirring; stirring speed is 500-1000 rpm; stirring time is 20-40 min.

[0020] Furthermore, the high-temperature reactor in step (4) specifically has an inner liner capacity of 100 ml;

[0021] Further, the hydrothermal reaction in step (4) is as follows: initial temperature: 30℃, heating rate: 5℃ / min, holding temperature: 120℃-130℃, holding time: 12h-18h and naturally cooled to room temperature.

[0022] Further, the centrifugation in step (5) specifically involves centrifuging with a centrifuge at a speed of 8000 rpm for a time of 3-5 min.

[0023] Further, the washing in step (5) specifically involves washing with ethanol three times and then washing with deionized water three times.

[0024] Further, the drying in step (5) specifically involves drying in a vacuum drying oven at 60°C for 12 hours.

[0025] Application: The pore structure of the described iron-manganese Prussian blue nanomaterials can be regulated for use in the efficient degradation of methylene blue.

[0026] The beneficial effects of this invention are as follows:

[0027] (1) This invention uses a hydrothermal method with potassium ferrocyanide as the iron source and adds polyvinylpyrrolidone, potassium permanganate and hydrochloric acid to prepare porous iron-manganese Prussian blue nanomaterials. This provides a new method for synthesizing porous iron-manganese Prussian blue nanomaterials and offers new ideas for the preparation of porous transition metal nanomaterials and the synthesis of Prussian blue-like compounds.

[0028] (2) The preparation method of the present invention does not require the addition of a pore-forming agent. Porous iron-manganese Prussian blue nanomaterials are prepared by a one-step hydrothermal method, and nanomaterials with different pore sizes can be formed by changing the hydrothermal conditions.

[0029] (3) The raw materials and equipment required for the preparation method of the present invention are simple and readily available, the process is simple, easy to operate and safe, the cost is relatively low, and it can be mass-produced industrially. By changing different hydrothermal conditions, iron-manganese Prussian blue compounds with the same phase but different pore size and number can be obtained. Compared with the products prepared by other traditional methods, this nanomaterial shows good degradation ability for methylene blue. It is an environmentally friendly new material with good promotion and application value and application prospects. Attached Figure Description

[0030] Figure 1 These are X-ray diffraction (XRD) patterns of the porous Prussian blue nanomaterials (MnFePBA@16h) prepared in Example 1, the porous Prussian blue nanomaterials (MnFePBA@18h) prepared in Example 2, the porous Prussian blue nanomaterials (MnFePBA@130°C) prepared in Example 3, and the Prussian blue nanomaterials (MnFePBA@12h) prepared in Comparative Example 1.

[0031] Figure 2 This is a graph showing the degradation rate of methylene blue by the porous Prussian blue-like nanomaterial (MnFePBA@16h) prepared in Example 1, the porous Prussian blue-like nanomaterial (MnFePBA@18h) prepared in Example 2, the porous Prussian blue-like nanomaterial (MnFePBA@130°C) prepared in Example 3, and the Prussian blue-like nanomaterial (MnFePBA@12h) prepared in Comparative Example 1.

[0032] Figure 3 This is a performance graph of the porous Prussian blue nanomaterial (MnFePBA@16h) prepared in Example 1 of this invention, after undergoing a cyclic experiment.

[0033] Figure 4 This is a scanning electron microscope (SEM) image of the porous Prussian blue nanomaterial (MnFePBA@16h) prepared in Example 1 of this invention.

[0034] Figure 5 This is a scanning electron microscope (SEM) image of the porous Prussian blue nanomaterial (MnFePBA@18h) prepared in Example 2 of the present invention.

[0035] Figure 6 This is a scanning electron microscope (SEM) image of the porous Prussian blue nanomaterial (MnFePBA@130℃) prepared in Example 3 of the present invention.

[0036] Figure 7 This is a scanning electron microscope (SEM) image of the porous Prussian blue nanomaterial (MnFePBA@12h) prepared in Comparative Example 1 of this invention.

[0037] Figure 8 The dimensions are those of the porous Prussian blue nanomaterial (MnFePBA@16h) prepared in Example 1, the porous Prussian blue nanomaterial (MnFePBA@18h) prepared in Example 2, the porous Prussian blue nanomaterial (MnFePBA@130°C) prepared in Example 3, and the Prussian blue nanomaterial (MnFePBA@12h) prepared in Comparative Example 1.

[0038] Figure 9 Images (a)-(c) are transmission electron microscope (TEM) images, electron diffraction (EDS) images of porous Prussian blue nanomaterials (MnFePBA@16h) prepared in Example 1, (e)-(g) of porous Prussian blue nanomaterials (MnFePBA@18h) prepared in Example 2, and (h)-(j) of porous Prussian blue nanomaterials (MnFePBA@130°C) prepared in Example 3. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined as long as they do not conflict with each other.

[0040] Example 1

[0041] Preparation of porous iron-manganese Prussian blue nanomaterials:

[0042] (1) Weigh 0.12g of potassium ferrocyanide and 3.8g of polyvinylpyrrolidone into a beaker using an electronic balance, and add 50ml of 0.5mmol / L hydrochloric acid into the beaker using a graduated cylinder.

[0043] (2) Stir the mixture under magnetic stirring for 30 minutes until the solution is clear;

[0044] (3) Weigh 0.02244 g of potassium permanganate solid using an electronic balance, grind it into powder using a mortar and pestle, add the powder to the mixture that has been stirred until clear, and continue to stir magnetically for 30 min.

[0045] (4) Transfer the mixture to a high-temperature reactor and place it in an oven for hydrothermal reaction. The hydrothermal conditions are set as follows: heating rate 5℃ / min, holding temperature 120℃, holding time 16h, and then naturally cool to room temperature.

[0046] (5) The solution after the reaction was centrifuged to obtain the precipitate, washed 3 times with ethanol and 3 times with deionized water, and vacuum dried for 12h to obtain porous iron-manganese Prussian blue nanomaterial, denoted as MnFePBA@16h.

[0047] Example 2

[0048] Preparation of porous iron-manganese Prussian blue nanomaterials:

[0049] (1) Weigh 0.12g of potassium ferrocyanide and 3.8g of polyvinylpyrrolidone into a beaker using an electronic balance, and add 50ml of 0.5mmol / L hydrochloric acid into the beaker using a graduated cylinder.

[0050] (2) Stir the mixture under magnetic stirring for 30 minutes until the solution is clear;

[0051] (3) Weigh 0.02244 g of potassium permanganate solid using an electronic balance, grind it into powder using a mortar and pestle, add the powder to the mixture that has been stirred until clear, and continue to stir magnetically for 30 min.

[0052] (4) Transfer the mixture to a high-temperature reactor and place it in an oven for hydrothermal reaction. The hydrothermal conditions are set as follows: heating rate 5℃ / min, holding temperature 120℃, holding time 18h, and then naturally cool to room temperature.

[0053] (5) The solution after the reaction was centrifuged to obtain the precipitate, washed 3 times with ethanol and 3 times with deionized water, and vacuum dried for 12h to obtain porous iron-manganese Prussian blue nanomaterial, denoted as MnFePBA@18h.

[0054] Example 3

[0055] Preparation of porous iron-manganese Prussian blue nanomaterials:

[0056] (1) Weigh 0.12g of potassium ferrocyanide and 3.8g of polyvinylpyrrolidone into a beaker using an electronic balance, and add 50ml of 0.5mmol / L hydrochloric acid into the beaker using a graduated cylinder.

[0057] (2) Stir the mixture under magnetic stirring for 30 minutes until the solution is clear;

[0058] (3) Weigh 0.02244 g of potassium permanganate solid using an electronic balance, grind it into powder using a mortar and pestle, add the powder to the mixture that has been stirred until clear, and continue to stir magnetically for 30 min.

[0059] (4) Transfer the mixture to a high-temperature reactor and place it in an oven for hydrothermal reaction. The hydrothermal conditions are set as follows: heating rate 5℃ / min, holding temperature 130℃, holding time 12h, and then naturally cool to room temperature.

[0060] (5) The solution after the reaction was centrifuged to obtain the precipitate, washed 3 times with ethanol and 3 times with deionized water, and vacuum dried for 12 h to obtain porous iron-manganese Prussian blue nanomaterial, denoted as MnFePBA@130°C.

[0061] Comparative Example 1

[0062] Preparation of iron-manganese Prussian blue nanomaterials:

[0063] (1) Weigh 0.12g of potassium ferrocyanide and 3.8g of polyvinylpyrrolidone into a beaker using an electronic balance, and add 50ml of 0.5mmol / L hydrochloric acid into the beaker using a graduated cylinder.

[0064] (2) Stir the mixture under magnetic stirring for 30 minutes until the solution is clear;

[0065] (3) Weigh 0.02244 g of potassium permanganate solid using an electronic balance, grind it into powder using a mortar and pestle, add the powder to the mixture that has been stirred until clear, and continue to stir magnetically for 30 min.

[0066] (4) Transfer the mixture to a high-temperature reactor and place it in an oven for hydrothermal reaction. The hydrothermal conditions are set as follows: heating rate 5℃ / min, holding temperature 120℃, holding time 12h, and then naturally cool to room temperature.

[0067] (5) The solution after the reaction was centrifuged to obtain the precipitate, washed 3 times with ethanol and 3 times with deionized water, and vacuum dried for 12h to obtain porous iron-manganese Prussian blue nanomaterial, denoted as MnFePBA@12h.

[0068] Organic matter degradation experiment

[0069] Application Example 1

[0070] The porous iron-manganese Prussian blue nanomaterials obtained in Example 1 were used to degrade organic matter. The specific steps are as follows:

[0071] (1) Prepare a 10 ppm methylene blue solution and a 5 M H2O2 solution;

[0072] (2) Weigh 50 ml of methylene blue solution using a graduated cylinder;

[0073] (3) Take 10 mg of porous iron-manganese Prussian blue nanomaterial and put it into the solution of step (2), and sonicate for 5 min;

[0074] (4) Take 25 μl of 5 M H2O2 solution and add it to the solution in step (3);

[0075] (5) After different time periods, the ultraviolet absorbance of methylene blue in water was measured with an ultraviolet-visible spectrophotometer, and the removal rate of methylene blue was calculated.

[0076] Application Example 2

[0077] The porous iron-manganese Prussian blue nanomaterials obtained in Example 2 were used to degrade organic matter. The specific steps are as follows:

[0078] (1) Prepare a 10 ppm methylene blue solution and a 5 M H2O2 solution;

[0079] (2) Weigh 50 ml of methylene blue solution using a graduated cylinder;

[0080] (3) Take 10 mg of porous iron-manganese Prussian blue nanomaterial and put it into the solution of step (2), and sonicate for 5 min;

[0081] (4) Take 25 μl of 5 M H2O2 solution and add it to the solution in step (3);

[0082] (5) After different time periods, the ultraviolet absorbance of methylene blue in water was measured with an ultraviolet-visible spectrophotometer, and the removal rate of methylene blue was calculated.

[0083] Application Example 3

[0084] The porous iron-manganese Prussian blue nanomaterials obtained in Example 3 were used to degrade organic matter. The specific steps are as follows:

[0085] (1) Prepare a 10 ppm methylene blue solution and a 5 M H2O2 solution;

[0086] (2) Weigh 50 ml of methylene blue solution using a graduated cylinder;

[0087] (3) Take 10 mg of porous iron-manganese Prussian blue nanomaterial and put it into the solution of step (2), and sonicate for 5 min;

[0088] (4) Take 25 μl of 5 M H2O2 solution and add it to the solution in step (3);

[0089] (5) After different time periods, the ultraviolet absorbance of methylene blue in water was measured with an ultraviolet-visible spectrophotometer, and the removal rate of methylene blue was calculated.

[0090] Application Example 4

[0091] The iron-manganese Prussian blue nanomaterials obtained in Comparative Example 1 were used to degrade organic matter. The specific steps are as follows:

[0092] (1) Prepare a 10 ppm methylene blue solution and a 5 M H2O2 solution;

[0093] (2) Weigh 50 ml of methylene blue solution using a graduated cylinder;

[0094] (3) Take 10 mg of iron-manganese Prussian blue nanomaterial and put it into the solution of step (2), and sonicate for 5 min;

[0095] (4) Take 25 μl of 5 M H2O2 solution and add it to the solution in step (3).

[0096] (5) After different time periods, the ultraviolet absorbance of methylene blue in water was measured with an ultraviolet-visible spectrophotometer, and the removal rate of methylene blue was calculated.

[0097] Figure 2 This diagram illustrates the degradation of methylene blue solution by the porous Prussian blue-like nanomaterials (MnFePBA@16h) prepared in Example 1, Example 2, Example 3 (MnFePBA@130°C), and Comparative Example 1 (MnFePBA@12h). The diagrams show that the porous Prussian blue-like nanomaterials exhibit good degradation activity towards methylene blue. It can be seen that the degradation performance of iron-manganese Prussian blue nanomaterials with different pore sizes is different for methylene blue. Among them, the porous Prussian blue nanomaterial prepared in Example 1 (MnFePBA@16h) has the best performance, followed by the Prussian blue nanomaterial prepared in Comparative Example 1 (MnFePBA@12h), the porous Prussian blue nanomaterial prepared in Example 2 (MnFePBA@18h), and the porous Prussian blue nanomaterial prepared in Example 3 (MnFePBA@130°C).

[0098] Figure 3 This is a schematic diagram of the degradation performance of the porous Prussian blue nanomaterial prepared in Example 1 of the present invention during cyclic reaction. After 4 cycles, the performance of the porous Prussian blue nanomaterial does not decrease significantly.

[0099] Figure 4 , Figure 5 , Figure 6 , Figure 7 The images show SEM images of porous Prussian blue nanomaterials: MnFePBA@16h, MnFePBA@18h, MnFePBA@130°C, and MnFePBA@12h. As can be seen from the images, the number and size of pores in the porous Prussian blue nanomaterials can be changed by altering the hydrothermal conditions of the reaction.

[0100] Figure 8 The sizes of four porous iron-manganese Prussian blue nanomaterials are as follows: Figure 8 In (a) compared to the MnFePBA@12h nanomaterial, the original iron-manganese Prussian blue nanomaterial has a size of 374.52636 nm, and its surface is smooth with indistinct pore structure. Figure 8In (b), the MnFePBA@16h nanomaterial, after being incubated at 120℃ for 16h, has a size of 246.48564 nm, and a porous structure can be seen on its surface, but the pore size is small and the distribution is dense. Figure 8 As shown in (c), after being kept at 120℃ for 18h, the size of the MnFePBA@18h nanomaterial further decreased to 157.2324nm, with an increase in the number and size of pores on the surface. And as... Figure 8 The MnFePBA@130°C nanomaterials obtained by further heat treatment at 130°C for 12 hours (d) have a size of 276.75604 nm, with obvious surface pore structure, large pore size and dense pore distribution.

[0101] In addition, through Figure 9 TEM images were used to analyze the pore size of porous iron-manganese Prussian blue nanomaterials formed under four different hydrothermal conditions. The results are shown in Table 1. It can be seen that the pore size of the porous iron-manganese Prussian blue nanomaterials increases with the increase of hydrothermal reaction time or temperature. Figure 9 EDS analysis also showed that the synthesized porous iron-manganese Prussian blue nanomaterials had a uniform elemental distribution.

[0102] Table 1. Pore sizes of various porous iron-manganese Prussian blue nanomaterials

[0103]

[0104] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of a pore structure-tunable iron-manganese Prussian blue nanomaterial in the efficient degradation of methylene blue, characterized in that: The method for preparing the iron-manganese Prussian blue nanomaterial with tunable pore structure includes the following steps: (1) Add potassium ferrocyanide and polyvinylpyrrolidone to a reactor containing an acid solution and stir thoroughly to prepare a reaction precursor solution; (2) Add potassium permanganate to the reaction precursor solution, stir to dissolve, and then transfer the mixed solution to a high-temperature reactor for hydrothermal reaction to prepare heterogeneous solution A; (3) The heterogeneous solution A is centrifuged, washed, and dried until the water is completely evaporated to obtain iron-manganese Prussian blue nanomaterials with tunable pore structure. By adjusting different hydrothermal reaction conditions, iron-manganese Prussian blue nanomaterials with different pore structures can be formed. The specific hydrothermal reaction conditions are: initial temperature: 30℃, heating rate: 5℃ / min, holding temperature: 120℃-130℃, holding time: 12h-18h and natural cooling to room temperature.

2. The application according to claim 1, characterized in that: The amount of potassium ferrocyanide used is 0.12g, and the amount of polyvinylpyrrolidone used is 3.8g.

3. The application according to claim 1, characterized in that: The acid solution mentioned is specifically hydrochloric acid.

4. The application according to claim 1, characterized in that: The amount of potassium permanganate used is 0.02244g.

5. The application according to claim 1, characterized in that: The centrifugation in step (3) specifically refers to centrifuging at a speed of 9000 rpm for 3 minutes.

6. The application according to claim 1, characterized in that: The washing process in step (3) specifically involves washing with ethanol three times and then washing with deionized water three times.

7. The application according to claim 1, characterized in that: The drying process described in step (3) specifically involves placing the item in a vacuum drying oven at 60°C for 12 hours.

Images