Preparation method of a biochar loaded iron-manganese composite oxide material, the material and application of the material

Abstract

The application relates to the technical field of nano-powder preparation, and particularly discloses a preparation method of a biochar-loaded iron-manganese composite oxide material, the material and an application of the material. In the preparation method, mainly comprising the following steps: S1. grinding and fully mixing an iron source, a manganese source and biomass in a carrier according to a proportion to obtain a first mixture; S2. reacting the first mixture in a protective gas atmosphere at a temperature in the range of 700-800 DEG C for 2-3 hours, and then cooling to room temperature to obtain a second mixture; and S3. washing and vacuum drying the second mixture to obtain the required composite material, wherein the iron source is ferrous acetate. According to the preparation method, the main steps only include grinding, mixing, heating reaction, washing and drying, and the operations of the steps are relatively simple. Meanwhile, the raw materials used are all solid, and no laboratory waste with complex components and difficult treatment methods such as waste liquid is generated, so that the preparation method is relatively high in environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of nanopowder preparation technology, specifically to a method for preparing biochar-supported iron-manganese composite oxide materials, the materials themselves, and their applications. Background Technology

[0002] Trichloroethylene (TCE) is a typical organic halogenated pollutant in wastewater. It is highly toxic, has an anesthetic effect on the human central nervous system, and can also cause damage to the liver, kidneys, heart, and trigeminal nerve. Methylene blue (MB) is a typical alkaline organic dye pollutant in wastewater. Microorganisms in the natural environment have difficulty effectively degrading it, thus it easily accumulates in the environment, posing a potential toxic effect on aquatic ecosystems. Long-term exposure to methylene blue may increase the risk of cancer in humans. Both TCE and MB may be present in wastewater from dyeing and printing combined with chemical processing, laboratory waste, and wastewater from integrated industrial zones.

[0003] Iron-manganese composite oxides are a class of compounds composed of iron, manganese, and oxygen. Due to their large specific surface area, high adsorption capacity, and reactivity, they have been widely used in water and soil pollution control in recent years. Particularly in water pollution control, iron-manganese composite oxides can simultaneously remove multiple environmental pollutants, including the aforementioned TCE and MB. However, in practical applications, iron-manganese composite oxides suffer from problems such as easy aggregation, which significantly affects their adsorption performance and the removal efficiency of pollutants.

[0004] In existing technologies, loading iron-manganese composite oxides onto biochar is a mainstream approach to address the aforementioned drawbacks of iron-manganese composite oxides. Patent CN109847698A discloses a method for preparing mulberry stalk biochar / iron-manganese oxide composite adsorbent. The method involves adding crushed and dried mulberry stalk powder to a ZnCl2 solution, stirring, and heating in a water bath with vibration; naturally cooling, filtering, drying, carbonizing, grinding, sieving, washing, and drying to obtain mulberry stalk biochar; placing the mulberry stalk biochar material in ultrapure water, ultrasonically treating, adding KMnO4 solution under magnetic stirring, heating in a water bath with stirring; adding NH4HCO3 solution and stirring; adding FeSO4 solution dropwise, adjusting the pH of the mixture to 6.0-8.0 with NaOH solution, heating in a water bath with stirring; naturally cooling, filtering, washing, and drying to obtain the mulberry stalk biochar / iron-manganese oxide composite adsorbent. The preparation method is quite complicated and inconvenient to produce. It also involves a large number of reagents, which can easily cause problems with the safety and reaction efficiency of the preparation process. Furthermore, the use of multiple reagents will produce more complex waste liquid components, making waste liquid treatment more difficult. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing biochar-supported iron-manganese composite oxide materials, which has fewer synthesis steps and is more convenient to operate. At the same time, the number of reagents involved in the overall process is also smaller, making the preparation method more environmentally friendly.

[0006] This invention is achieved through the following technical solution.

[0007] A method for preparing a biochar-supported iron-manganese composite oxide material, characterized by comprising the following steps: S1. Grinding and fully mixing an iron source, a manganese source, and biomass in a carrier in a certain proportion to obtain a first mixture; S2. Reacting the first mixture under a protective atmosphere at a temperature range of 700-800°C for 2-3 hours, and then cooling to room temperature to obtain a second mixture; S3. Washing and vacuum drying the second mixture to obtain the composite material, wherein the iron source is ferrous acetate.

[0008] This preparation method mainly involves only grinding, mixing, heating reaction, washing, and drying to obtain the target material, and the entire operation is relatively simple. Furthermore, the raw materials used in the preparation method are all solids, and no complex laboratory waste such as waste liquids or wastewater requiring complex treatment methods is generated, making the preparation method highly environmentally friendly.

[0009] In step S2 of this preparation method, when the reaction temperature is below 700℃, the prepared material contains a relatively large number of phases, including Fe. 0.099 Mn 0.901 O, Fe 19 Mn, Fe4N, etc., but only Fe 0.099 Mn 0.901 O is the primary target for synthesis, but the presence of numerous byproducts will reduce the utilization rate of the raw materials; simultaneously, when the reaction temperature exceeds 800℃, the Fe content in the prepared material will decrease. 0.099 Mn 0.901 The reduced O content decreases the material's ability to remove pollutants.

[0010] Furthermore, this preparation method requires the use of ferrous acetate as the iron source. Using other iron sources may result in pure Fe... 0.099 Mn 0.901 O could not be synthesized, and the iron source was used to generate Fe. 19 Non-target phases such as Mn and Fe lead to the failure of the synthesis of biochar-supported iron-manganese composite oxide materials, making it difficult to achieve efficient removal of TCE and MB.

[0011] As a further improvement of the present invention, the method for preparing the biomass in S1 includes: washing, drying, and crushing at least one of waste tea leaves, cyanobacteria, and clover to obtain the biomass. The biomass source used in the present invention has low cost and involves waste tea leaves, etc., which can achieve the effect of reusing waste.

[0012] As a further improvement of the present invention, the drying is carried out at a temperature range of 60~80°C for 5~10 hours.

[0013] As a further improvement of the present invention, the mass ratio of the iron source to the manganese source is (4~1):1, the metal source includes the iron source and the manganese source, and the mass ratio of the metal source to the biomass is 1:1.

[0014] As a further improvement of the present invention, the manganese salt is potassium permanganate.

[0015] As a further improvement of the present invention, in step S2, a heating rate of 9~10 °C / min is used to reach the temperature range.

[0016] As a further improvement of the present invention, nitrogen is used to provide a protective atmosphere in step S2.

[0017] As a further improvement of the present invention, in step S3, the second mixture is washed with deionized water 2 to 3 times and vacuum dried at a temperature of 75 to 85°C for 8 to 10 hours.

[0018] Secondly, the present invention provides a biochar-supported iron-manganese composite oxide material, which is prepared by any of the preparation methods described above.

[0019] Thirdly, the present invention provides an application of the above-mentioned biochar-supported iron-manganese composite oxide material, which can remove trichloroethylene and methylene blue without the need for deoxygenation treatment.

[0020] The beneficial effects of this invention include:

[0021] (1) The preparation method has relatively simple operation steps, a short overall process, fewer types and quantities of equipment used in the preparation process, and low cost of raw materials, thus it has good prospects for industrial production.

[0022] (2) The preparation method uses waste resources, including waste tea leaves, in the biomass preparation process; at the same time, the reagents used in the preparation method do not involve the use of strong acids / bases and other chemical substances, so the process as a whole has good environmental friendliness.

[0023] (3) The biochar-supported iron-manganese composite oxide material prepared by this preparation method can remove pollutants such as TCE and MB quickly and efficiently without the need for deoxygenation treatment, and has good commercial prospects. Attached Figure Description

[0024] The accompanying drawings are provided below to illustrate the preferred embodiments of the invention and to aid in understanding the objectives and advantages of the invention, wherein:

[0025] Figure 1 The image shows the XRD pattern of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 1.

[0026] Figure 2 The image shows the FT-IR spectrum of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 1.

[0027] Figure 3 SEM image of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 1;

[0028] Figure 4 EDS image of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 1;

[0029] Figure 5 The image shows the XRD pattern of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 2.

[0030] Figure 6 The image shows the XRD pattern of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 3.

[0031] Figure 7 The XRD pattern of the composite material prepared in Comparative Example 1 is shown.

[0032] Figure 8 The XRD pattern of the composite material prepared in Comparative Example 2 is shown.

[0033] Figure 9 This is the standard curve for MB;

[0034] Figure 10 The graph shows the removal performance of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 1 for TCE at a concentration of 20 mg / L.

[0035] Figure 11 The graph shows the removal performance of the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared in Example 1 for MB at a concentration of 100 mg / L. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0038] Example 1:

[0039] S1. After washing the cyanobacteria and waste tea leaves, dry them at 60℃ for 8 h and then pulverize them to obtain the corresponding biomass. Weigh potassium permanganate, ferrous acetate, cyanobacteria and waste tea powder in a mass ratio of 1:1:1:1 and grind them in a mortar for 20 min to fully mix the four substances and obtain the first mixture. Transfer the mixture to a porcelain boat.

[0040] S2. Move the ceramic boat carrying the first mixture into the tube furnace, and introduce nitrogen into the tube furnace to form a protective atmosphere; set the temperature of the tube furnace to rise at a programmed temperature rise rate of 9 ℃ / min until it reaches 700 ℃, and react within this temperature range for 2 h. After the tube furnace cools to room temperature, remove the material to obtain the second mixture.

[0041] S3. The second mixture was washed three times with deionized water and then placed in a drying oven and vacuum dried at 80 °C for 8 h to obtain nitrogen-doped biochar-supported iron-manganese composite oxide material.

[0042] The X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS or XEDS) results of the materials prepared by the method in this embodiment are as follows: Figures 1-4 As shown.

[0043] Example 2:

[0044] S1. After washing the clover and waste tea leaves, dry them at 70°C for 7 h and then pulverize them to obtain the corresponding biomass. In this embodiment, compared with Example 1, the mass ratio of metal source to biomass is kept at 1:1, but the mass ratio of potassium permanganate and ferrous acetate is adjusted to 2:1. Weigh the corresponding mass of the above raw materials, put them in a mortar and grind them for 30 min to fully mix the four substances to obtain the first mixture, and transfer it to a porcelain boat.

[0045] S2. Move the ceramic boat carrying the first mixture into the tube furnace, and introduce nitrogen into the tube furnace to form a protective atmosphere; set the temperature of the tube furnace to rise at a programmed heating rate of 9 ℃ / min until it reaches 750 ℃, and react within this temperature range for 2 h. After the tube furnace cools to room temperature, remove the material to obtain the second mixture.

[0046] S3. After washing the second mixture three times with deionized water, place it in a drying oven and vacuum dry it at 80 °C for 8 h to obtain nitrogen-doped biochar-supported iron-manganese composite oxide material.

[0047] The XRD test results of the material prepared by the method in this embodiment are as follows: Figure 5 As shown.

[0048] Example 3:

[0049] S1. After washing the blue algae and waste tea leaves, dry them at 60°C for 9 h and then pulverize them to obtain the corresponding biomass. In this embodiment, compared with Example 1, the mass ratio of metal source to biomass is kept at 1:1, but the mass ratio of potassium permanganate and ferrous acetate is adjusted to 4:1. Weigh the corresponding mass of the above raw materials, put them in a mortar and grind them for 40 min to fully mix the four substances to obtain the first mixture, and transfer it to a porcelain boat.

[0050] S2. Move the ceramic boat carrying the first mixture into the tube furnace, and introduce nitrogen into the tube furnace to form a protective atmosphere; set the temperature of the tube furnace to rise at a programmed temperature rise rate of 10 ℃ / min until it reaches 800 ℃, and react within this temperature range for 1 h. After the tube furnace cools to room temperature, remove the material to obtain the second mixture.

[0051] S3. After washing the second mixture three times with deionized water, place it in a drying oven and vacuum dry it at 80 °C for 8 h to obtain nitrogen-doped biochar-supported iron-manganese composite oxide material.

[0052] The XRD test results of the material prepared by the method in this embodiment are as follows: Figure 6 As shown.

[0053] Comparative Example 1:

[0054] The difference between this comparative example and Example 1 is that the reaction temperature in S2 is adjusted to 650°C.

[0055] The XRD test results of the materials prepared by the method in this comparative example are as follows: Figure 7 As shown.

[0056] Comparative Example 2:

[0057] The difference between this comparative example and Example 1 is that the iron source is replaced with ferric chloride.

[0058] The XRD test results of the materials prepared by the method in this comparative example are as follows: Figure 8 As shown.

[0059] Material removal effect testing method:

[0060] In this embodiment, the removal effect and removal rate of TCE and MB by the nitrogen-doped biochar-supported iron-manganese composite oxide material prepared by the method in Example 1 were tested. The relevant testing steps for the removal effect and removal rate of TCE by the corresponding material are as follows:

[0061] (1) At room temperature, add 20 mL of TCE solution with an initial concentration of 20 mg / L to a brown sample vial with a headspace cap (no deoxygenation treatment required), and record the concentration of TCE solution at this time as C0.

[0062] (2) Weigh 20 mg of the corresponding material and add it to the bottle, then place it on a shaker at room temperature and pressure for reaction;

[0063] (3) At time points of 10 min, 30 min, 60 min and 120 min after the start of the reaction, 2 mL of liquid sample was taken from the bottle and filtered through a filter with a pore size of 0.22 μm to obtain the test solution.

[0064] (4) The test solution is added to the headspace vial, and the concentration of TCE in the test solution is measured by headspace gas chromatography-mass spectrometry and recorded as C1, C2, C3 and C4 respectively.

[0065] (5) C n Using the ratio of / C0 (n=1~4 integers) as the vertical axis and the reaction time as the horizontal axis, plot the reaction curve of the corresponding material.

[0066] The relevant testing steps for the removal effect and removal rate of MB by the corresponding materials are as follows:

[0067] 1. Plot the MB standard curve:

[0068] (1) Prepare a standard MB solution with a concentration of 100 mg / L;

[0069] (2) Take 0.5 ml, 1 ml, 2 ml, 3 ml, 4 ml and 5 ml of MB standard solution into 50 ml volumetric flasks and dilute to volume to obtain MB solutions with concentrations of 1 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L and 10 mg / L respectively;

[0070] (3) The absorbance of MB solutions of different concentrations was measured once from low to high using an ultraviolet spectrophotometer. The corresponding concentration of MB solution was added to a 10 mm cuvette, and the absorbance was measured at a wavelength of 664 nm using water as a reference.

[0071] (4) Plot the results as follows: with the concentration of MB solution on the x-axis and absorbance on the y-axis. Figure 9 The standard curve shown.

[0072] 2. Tests on the effectiveness and rate of MB removal:

[0073] (1) At room temperature, add 20 mL of MB solution with an initial concentration of 100 mg / L to a beaker (no deoxygenation treatment required), and record the concentration of MB solution at this time as C0;

[0074] (2) Weigh 20 mg of the corresponding material and add it to the above beaker. Insert a magnetic stir bar into the inner beaker and move the beaker to the magnetic stirrer. Turn on the magnetic stirrer at room temperature and pressure to stir the mixture in the beaker.

[0075] (3) At 2 min, 5 min, 8 min and 10 min after the start of the stirring reaction, 3 mL of liquid sample was taken from the beaker and filtered through a filter with a pore size of 0.22 μm to obtain the test solution. The test solution was transferred to a 10 mm cuvette and the absorbance of the corresponding test solution was measured at 664 nm with water as a reference using an ultraviolet spectrophotometer. The concentration value of MB in the sample obtained at the corresponding reaction time was obtained by converting the standard curve and recorded as C1, C2, C3 and C4 respectively.

[0076] (4) Place C n Using the ratio of / C0 (n=1~4 integers) as the vertical axis and the reaction time as the horizontal axis, plot the reaction curve of the corresponding material.

[0077] Analysis of test results:

[0078] 1. Regarding the results of material preparation:

[0079] First, from the appendix Figure 1 , 5The test results of 6 show that the material prepared by this method contains the target phase Fe. 0.099 Mn 0.901 O, and from the appendix Figure 2 The test results show that the prepared material contains C=C, CO, and CN functional groups, proving the successful loading of iron-manganese composite oxides onto biochar. This indicates that the preparation method can produce the desired nitrogen-doped biochar-loaded iron-manganese composite oxide material. Additionally, [further details are missing]. Figure 2 The test results showed that the biochar contained a certain amount of nitrogen doping, and nitrogen-doped biochar had better adsorption and catalytic properties, which further improved the removal effect of the final material on pollutants.

[0080] From the appendix Figure 3 The test results show that the nitrogen-doped biochar-supported iron-manganese composite oxide material has a highly wrinkled surface and abundant porous structure. At the same time, the iron-manganese composite oxide particles are relatively uniform in size, solving the problem of agglomeration when used as monomers, which is beneficial to improving the adsorption effect of the core material, the iron-manganese composite oxide, on pollutants.

[0081] From the appendix Figure 4 The test results show that the nitrogen-doped biochar-supported iron-manganese composite oxide material is mainly composed of elements such as Fe, Mn, C, O and N, and the distribution of each element is very uniform.

[0082] Secondly, by comparing the appendix Figure 1 and appendix Figures 7-8 The test results show that the preparation of nitrogen-doped biochar-supported iron-manganese composite oxide materials requires suitable reaction conditions.

[0083] Suitable reaction conditions specifically include reaction temperature. When the mass ratio of biomass to metal source remains constant, and the selection of manganese and iron sources remains unchanged, and the reaction temperature is below 700 °C, through the adsorption... Figure 7 The test results show that the prepared material contains multiple phases, including the target phase Fe. 0.099 Mn 0.901 O and other phases such as Fe 19 Mn and Fe4N, etc.; at the same time, the proportion of other phases is relatively large, which makes the utilization rate of raw materials low under these reaction conditions. In contrast, the attached... Figure 5 and attached Figure 6 The detection results show that as the reaction temperature increases, the generated target phase Fe... 0.099 Mn 0.901 The total amount of O decreases, so excessively high reaction temperatures are also detrimental to the preparation of materials.

[0084] Suitable reaction conditions also include the selection of raw materials, through the addition of... Figure 8The test results show that when the iron source is replaced with anhydrous ferric chloride, it becomes difficult to synthesize the corresponding target material. Therefore, to ensure the successful preparation of nitrogen-doped biochar-supported iron-manganese composite oxide materials, it is necessary to select a suitable iron source.

[0085] 2. Regarding the material's effectiveness in removing pollutants:

[0086] Combined with appendix Figures 10-11 It can be seen that nitrogen-doped biochar-supported iron-manganese composite oxide materials exhibit better removal performance for TCE and MB. (From the attached...) Figure 10 As can be seen, this material achieves a 90% removal rate of TCE within 10 minutes of the reaction; from the attached... Figure 11 As can be seen, this material achieves a 100% removal rate of MB within 5 minutes of the reaction. (Combined with the attached...) Figures 1-4 Based on the test results, the inventors speculate that this is because the loading of biochar effectively solved the agglomeration phenomenon of the iron-manganese composite oxide material particles. At the same time, the redox potential difference between iron and manganese elements also promoted electron transfer during the reaction process, thereby improving the reactivity and adsorption performance of the material, resulting in good performance in the removal of TCE and MB.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a biochar-supported iron-manganese composite oxide material, characterized in that, Includes the following steps: S1. Iron source, manganese source and biomass are placed in a carrier in a certain proportion, ground and mixed thoroughly to obtain a first mixture, wherein the mass ratio of the iron source to the manganese source is (4~1):1, the metal source includes the iron source and the manganese source, and the mass ratio of the metal source to the biomass is 1:1; S2. The first mixture is reacted under a protective atmosphere at a temperature range of 700~800℃ for 2~3 hours, and then cooled to room temperature to obtain the second mixture; S3. The second mixture is washed and vacuum dried to obtain biochar-supported iron-manganese composite oxide material; The iron source is ferrous acetate, and the manganese source is potassium permanganate.

2. The method for preparing a biochar-supported iron-manganese composite oxide material according to claim 1, characterized in that, The biomass preparation method described in S1 includes: The biomass is obtained by washing, drying, and crushing at least one of waste tea leaves, blue-green algae, and clover.

3. The method for preparing a biochar-supported iron-manganese composite oxide material according to claim 2, characterized in that, In the biomass preparation method, the drying conditions are maintained at a temperature range of 60~80℃ for 5~10 h.

4. The method for preparing a biochar-supported iron-manganese composite oxide material according to claim 1, characterized in that, In step S2, the temperature range is reached by using a heating rate of 9~10 ℃ / min.

5. The method for preparing a biochar-supported iron-manganese composite oxide material according to claim 1, characterized in that, In step S2, a protective atmosphere is provided by filling with nitrogen.

6. The method for preparing a biochar-supported iron-manganese composite oxide material according to claim 1, characterized in that, In step S3, the second mixture is washed 2-3 times with deionized water and then vacuum dried at a temperature of 75-85°C for 8-10 hours.

7. A biochar-supported iron-manganese composite oxide material, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 6.

8. The application of the biochar-supported iron-manganese composite oxide material according to claim 7, characterized in that, Without deoxygenation treatment, the biochar-supported iron-manganese composite oxide material removes trichloroethylene and methylene blue.

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