A preparation method and application of nitrogen-doped biochar material

Abstract

The present application provides a preparation method and application of nitrogen-doped biochar material, which belongs to the field of catalytic material manufacturing. The preparation method of nitrogen-doped biochar material comprises the following steps: immersing collagen fibers in a solvent to obtain a first reaction precursor, wherein the pH of the solvent is ≤7; mixing the first reaction precursor with a second reaction precursor containing a nitrogen source and heating the mixture to obtain a reaction intermediate; performing solid-liquid separation on the reaction intermediate to obtain a solid-phase reaction intermediate; heating and carbonizing the solid-phase reaction intermediate to obtain a nitrogen-doped biochar material. The preparation method of the nitrogen-doped biochar material can improve the problems of complex preparation process and high preparation cost in the preparation method of the nitrogen-doped biochar material to a certain extent.

Description

Technical Field

[0001] The present application relates to the field of catalytic material manufacturing, and specifically, to a preparation method of nitrogen-doped biochar material and its application. Background Art

[0002] In the prior art, activated persulfate is usually used to treat organic pollutants. Among them, a commonly used activator is nitrogen-doped biochar. However, the current preparation method of this type of activator has the problems of complex preparation process and high preparation cost. Summary of the invention

[0003] The purpose of the present application is to provide a method for preparing nitrogen-doped biochar materials and applications thereof, which can to a certain extent improve the problems of complex preparation process and high preparation cost in the method for preparing nitrogen-doped biochar materials.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, the present invention provides a method for preparing a nitrogen-doped biochar material, comprising the following steps:

[0006] The collagen fibers are immersed in a solvent to obtain a first reaction precursor, wherein the pH of the solvent is ≤7; the first reaction precursor is mixed with a second reaction precursor containing a nitrogen source and then heated to react to obtain a reaction intermediate; the reaction intermediate is subjected to solid-liquid separation to obtain a solid-phase reaction intermediate; the solid-phase reaction intermediate is heated and carbonized to obtain a nitrogen-doped biochar material.

[0007] In the above technical solution, collagen fibers are directly used as the reaction raw material, and the reaction solvent does not need to be adjusted to acidity in advance. Compared with the conventional preparation method (which requires an acidity adjustment step in advance), the preparation process can be simplified and the preparation cost can be reduced.

[0008] In some optional embodiments, the mass ratio of the collagen fibers to the nitrogen source in the second reaction precursor is 1:(1-3).

[0009] In the above technical solution, the mass ratio of collagen fibers to nitrogen source is limited within a specific range, so that the two have a suitable usage ratio, so that the nitrogen source can be better doped into the internal pores of the collagen fibers.

[0010] In some optional embodiments, the nitrogen source in the second reaction precursor includes at least one of polyethyleneimine, dopamine and amino acid.

[0011] The technical solution provided in the examples of the present application is applicable to the above-mentioned various nitrogen source systems and can provide more feasible implementation plans, thereby facilitating the promotion and application of the technical solution provided in the examples of the present application.

[0012] In some optional embodiments, after obtaining the first reaction precursor and before performing the heating reaction step, the first reaction precursor is activated by using an aldehyde solution;

[0013] Optionally, the aldehyde solution includes at least one of glutaraldehyde, formaldehyde and acetaldehyde;

[0014] Optionally, the mass volume ratio of the first reaction precursor to the aldehyde solution is 1 g: (3-5) mL;

[0015] Optionally, the activation treatment time is 10 to 20 minutes.

[0016] In the above technical solution, the first reaction precursor is activated before the heating reaction step, which can increase the reaction activity of the collagen fibers, so that the reaction intermediates can be more easily obtained when the collagen fibers react with the nitrogen source, thereby improving the reaction efficiency.

[0017] Furthermore, the technical solution provided in the embodiments of the present application is applicable to a variety of aldehyde solutions and can provide more feasible implementation plans, thereby facilitating the promotion and application of the technical solution of the present application.

[0018] Furthermore, by limiting the mass volume ratio of the first reaction precursor to the aldehyde solution and the activation treatment time within a specific range, the two can have an appropriate dosage ratio, thereby activating the collagen fibers better.

[0019] In some optional embodiments, the step of heating and carbonizing includes firstly performing a first stage of carbonization and then raising the temperature to perform a second stage of carbonization.

[0020] In the above technical solution, the two-stage carbonization method is adopted, which can increase the carbonization rate of the material and thus improve the activation performance of the material compared to the one-stage carbonization method.

[0021] In some optional embodiments, during the first stage carbonization, the treatment temperature is 200-400°C and the treatment time is 2-5 hours; and / or, during the second stage carbonization, the treatment temperature is 400-800°C and the treatment time is 2-5 hours.

[0022] In the above technical solution, the temperature and time in the two carbonization processes are limited to specific ranges respectively, so that the two carbonization processes can be carried out under more suitable conditions. Compared with not being within the specific range, the carbonization effect of the material can be improved.

[0023] In some optional embodiments, during the second stage carbonization, the treatment temperature is 500-800°C;

[0024] Optionally, the processing temperature is 600-800°C;

[0025] Optionally, the processing temperature is 700-800°C.

[0026] In the above technical scheme, the treatment temperature is limited to a specific range. On the one hand, effective carbonization of the material can be achieved; on the other hand, by limiting the treatment temperature of the second stage carbonization to a specific range, the nitrogen-doped biochar material having only a free radical active path can have a free radical activation path and a non-free radical activation path or only a non-free radical activation path, thereby making the prepared nitrogen-doped biochar material more suitable for the degradation of electron-rich organic pollutants.

[0027] Furthermore, gradually increasing the treatment temperature can, on the one hand, make the carbonization efficiency higher; on the other hand, it can further convert the free radical activation pathway of the nitrogen-doped biochar material into a non-free radical activation pathway, and may even achieve a complete conversion into a non-free radical activation pathway, thereby further increasing the degradation ability of the prepared nitrogen-doped biochar material for electron-rich organic pollutants.

[0028] In a second aspect, an embodiment of the present application provides an application of a nitrogen-doped biochar material in degrading organic pollutants, and the nitrogen-doped biochar material is prepared by the preparation method of the nitrogen-doped biochar material provided in the embodiment of the first aspect.

[0029] In some optional embodiments, the following steps are included:

[0030] Activating persulfate with nitrogen-doped biochar materials, and then using the activated persulfate to degrade organic pollutants;

[0031] Optionally, in the activation solution system for activating persulfate by nitrogen-doped biochar material, the concentration ratio of nitrogen-doped biochar material to persulfate is (0.05-0.15) g / L: (1-3) mM;

[0032] Optionally, during the process of degrading organic pollutants, the treatment time is 40 to 60 minutes.

[0033] In the above technical solution, persulfate activated by nitrogen-doped biochar is used to degrade organic pollutants, which has the advantages of being green and efficient.

[0034] Furthermore, in the activation solution system for activating persulfate by nitrogen-doped biochar, limiting the concentration ratio of nitrogen-doped biochar to persulfate within a specific range can make the two have an appropriate dosage ratio, thereby being able to better activate persulfate.

[0035] Furthermore, in the process of degrading organic pollutants, the treatment time is limited to a specific range. On the one hand, it can effectively avoid the failure to effectively remove organic pollutants due to a short treatment time, and on the other hand, it can effectively avoid the waste of time due to too long treatment time (after reaching the degradation saturation, continuing to extend the time will not significantly improve the degradation effect, but will only cause a waste of time).

[0036] In some alternative embodiments, the organic contaminant comprises an electron-rich organic contaminant.

[0037] In the above technical solutions, the nitrogen-doped biochar material provided in the first aspect of the embodiment is particularly suitable for degrading electron-rich organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A process flow chart of a method for preparing a nitrogen-doped biochar material provided in an embodiment of the present application;

[0040] Figure 2 The activation performance test results of nitrogen-doped biochar materials at different carbonization temperatures provided in the examples of the present application;

[0041] Figure 3 to Figure 7 The activation performance test results of a series of transition metal catalysts provided in the examples of this application under the action of different quenchers;

[0042] Figure 8 A statistical diagram of activation paths of nitrogen-doped biochar materials at different carbonization temperatures provided in the embodiments of the present application;

[0043] Fig. 9 The test results of the degradation performance of sodium persulfate on electron-rich organic pollutants after being activated by nitrogen-doped biochar materials at different carbonization temperatures provided in the examples of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0045] It should be noted that “and / or” in this application, such as “Feature 1 and / or Feature 2”, refers to the three situations of “Feature 1” alone, “Feature 2” alone, or “Feature 1” plus “Feature 2”.

[0046] In addition, in the description of the present application, unless otherwise specified, the meaning of "multiple" in "one or more" refers to two or more; the range of "value a ~ value b" includes the two end values ​​"a" and "b", and the "unit" in "value a ~ value b + unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0047] At present, the preparation method of nitrogen-doped biochar materials usually requires a preliminary acid adjustment step and corresponding post-treatment steps (such as subsequent cleaning and acid removal processes), which leads to a more complicated preparation process and higher preparation cost.

[0048] Through creative research, the researchers of this application found that by optimizing the types of reaction raw materials, the problems of complex preparation process and high preparation cost in the preparation method of nitrogen-doped biochar materials can be improved to a certain extent.

[0049] The following is a detailed description of a method for preparing a nitrogen-doped biochar material and its application in an embodiment of the present application.

[0050] In a first aspect, the present invention provides a method for preparing a nitrogen-doped biochar material, comprising the following steps:

[0051] The collagen fibers are immersed in a solvent to obtain a first reaction precursor, wherein the pH of the solvent is ≤7; the first reaction precursor is mixed with a second reaction precursor containing a nitrogen source and then heated to react to obtain a reaction intermediate; the reaction intermediate is subjected to solid-liquid separation to obtain a solid-phase reaction intermediate; the solid-phase reaction intermediate is heated and carbonized to obtain a nitrogen-doped biochar material.

[0052] In the present application, collagen fibers are directly used as the reaction raw material, and there is no need to adjust the reaction solvent to be acidic in advance. Compared with the conventional preparation method (which requires an acid adjustment step in advance), the preparation process can be simplified and the preparation cost can be reduced.

[0053] It should be noted that collagen fibers have a triple helix structure and contain many highly active functional groups, such as hydroxyl, carboxyl and amine groups, which can react with a large amount of organic matter through tanning. In addition, the steric hindrance of its specific triple helix structure can also improve the structural stability of the prepared product for subsequent applications.

[0054] It should be noted that, considering the binding effect of collagen fibers and nitrogen elements, relevant parameters in the immersion process (such as immersion time, mass ratio of collagen fibers and solvent, etc.) can be adjusted.

[0055] As an example, in the step of immersing the collagen fibers in the solvent, the mass ratio of the collagen fibers to the solvent is 1:(25-35); and / or the immersion time is 8-12 hours.

[0056] In this embodiment, during the soaking process, the mass ratio of collagen fibers to solvent and the soaking time are respectively limited within specific ranges, so that the collagen fibers have appropriate structural looseness after being soaked, thereby better combining with nitrogen elements.

[0057] It should be noted that, considering the combining effect of collagen fibers and nitrogen elements, the dosage ratio of the two can be adjusted.

[0058] As an example, the mass ratio of the collagen fibers to the nitrogen source in the second reaction precursor is 1:(1-3), such as but not limited to any one of 1:1, 1:2 and 1:3 or a range between any two of the mass ratios.

[0059] In this embodiment, the mass ratio of the collagen fibers to the nitrogen source is limited within a specific range, so that the two have a suitable usage ratio, so that the nitrogen source can be better doped into the internal pores of the collagen fibers.

[0060] It should be noted that the parameters during the heating reaction can be adjusted considering the binding effect between collagen fibers and nitrogen.

[0061] As an example, in the step of heating the reaction, the treatment temperature is 35 to 45° C. and the treatment time is 5 to 7 hours.

[0062] In this embodiment, the processing temperature and time in the heating reaction step are limited to specific ranges, respectively, so that the heating reaction can be carried out at a suitable temperature and duration, so that the nitrogen source can be better doped into the internal pores of the collagen fibers.

[0063] It should be noted that the type of nitrogen source is not limited and can be set according to routine selection in the art.

[0064] As an example, the nitrogen source in the second reaction precursor includes at least one of polyethyleneimine, dopamine and amino acid.

[0065] In this embodiment, the technical solution provided in the embodiment of the present application is applicable to the above-mentioned various nitrogen source systems, and can provide more feasible implementation plans, thereby facilitating the promotion and application of the technical solution provided in the embodiment of the present application.

[0066] It should be noted that for different types of nitrogen sources, the mixing process of the two can be adjusted in consideration of the binding effect between the nitrogen source and the collagen fibers.

[0067] Illustratively, when the nitrogen source is liquid (such as polyethyleneimine), it can be directly used as the second reaction precursor and mixed with the first reaction precursor; when the nitrogen source is solid (such as dopamine), dopamine is first dissolved in a solvent to prepare a liquid to obtain the second reaction precursor, and then mixed with the first reaction precursor.

[0068] In this embodiment, different types of nitrogen sources are mixed with collagen fibers in a specific form, so that the two can have a better mixing uniformity, so that the nitrogen element can be better doped into the collagen fibers.

[0069] It should be noted that the preparation process can be optimized considering the ease of preparation of the reaction intermediates and the efficiency of this reaction stage.

[0070] As an example, after obtaining the first reaction precursor and before performing the heating reaction step, the first reaction precursor is activated by using an aldehyde solution.

[0071] Optionally, the aldehyde solution includes at least one of glutaraldehyde, formaldehyde and acetaldehyde.

[0072] Optionally, the mass volume ratio of the first reaction precursor to the aldehyde solution is 1g:(3-5)mL, for example but not limited to a mass volume ratio of at least one of 1g:3mL, 1g:4mL and 1g:5mL or a range value between any two thereof.

[0073] Optionally, the activation treatment time is 10 to 20 minutes, for example but not limited to a range of at least one of 10 minutes, 15 minutes and 20 minutes, or any two thereof.

[0074] In this embodiment, the first reaction precursor is activated before the heating reaction step, which can increase the reactivity of the collagen fibers, so that the reaction intermediates can be more easily obtained when the collagen fibers react with the nitrogen source, thereby improving the reaction efficiency.

[0075] Furthermore, the technical solution provided in the embodiments of the present application is applicable to a variety of aldehyde solutions and can provide more feasible implementation plans, thereby facilitating the promotion and application of the technical solution of the present application.

[0076] Furthermore, by limiting the mass volume ratio of the first reaction precursor to the aldehyde solution and the activation treatment time within a specific range, the two can have an appropriate dosage ratio, thereby activating the collagen fibers better.

[0077] It should be noted that the process of carbonization can be adjusted considering the carbonization effect of the material.

[0078] As an example, in the step of heating carbonization, a first stage carbonization is performed first, and then the temperature is increased to perform a second stage carbonization.

[0079] In this embodiment, a two-stage carbonization method is adopted, which can increase the carbonization rate of the material and thus improve the activation performance of the material compared to a one-stage carbonization method.

[0080] It is understandable that the treatment temperature and treatment time in the two-stage carbonization process can be adjusted in consideration of the carbonization effect.

[0081] As an example, during the first stage carbonization, the treatment temperature is 200-400°C and the treatment time is 2-5 hours; and / or, during the second stage carbonization, the treatment temperature is 400-800°C and the treatment time is 2-5 hours.

[0082] In this embodiment, the temperature and time in the two carbonization processes are respectively limited to specific ranges, so that the two carbonization processes can be carried out under more suitable conditions, which can improve the carbonization effect of the material compared to when the temperature and time are not within the specific range.

[0083] As an example, during the second stage carbonization, the treatment temperature is 500-800°C, for example but not limited to any one of 500°C, 600°C, 700°C and 800°C or a range between any two of them.

[0084] Optionally, the processing temperature is 600-800° C., for example but not limited to, any one of 600° C., 650° C., 700° C., 750° C. and 800° C. or a range between any two of the temperatures.

[0085] Optionally, the processing temperature is 700-800° C., for example but not limited to, any one of 700° C., 750° C. and 800° C. or a range between any two of them.

[0086] In this embodiment, the treatment temperature is limited to a specific range. On the one hand, effective carbonization of the material can be achieved; on the other hand, by limiting the treatment temperature of the second stage carbonization to a specific range, the nitrogen-doped biochar material having only a free radical active pathway can have a free radical activation pathway and a non-free radical activation pathway or only a non-free radical activation pathway, thereby making the prepared nitrogen-doped biochar material more suitable for degrading electron-rich organic pollutants.

[0087] Furthermore, gradually increasing the treatment temperature can, on the one hand, make the carbonization efficiency higher; on the other hand, it can further convert the free radical activation pathway of the nitrogen-doped biochar material into a non-free radical activation pathway, and may even achieve a complete conversion into a non-free radical activation pathway, thereby further increasing the degradation ability of the prepared nitrogen-doped biochar material for electron-rich organic pollutants.

[0088] As an example, between the first stage carbonization and the second stage carbonization, an activation treatment is further included using an alkaline solution to the solid phase reaction intermediate after the first stage carbonization treatment.

[0089] In this embodiment, an activation treatment is added between the first stage carbonization and the second stage carbonization, which can promote the formation of pores inside the material and increase the specific surface area of ​​the material, thereby providing more catalytic sites.

[0090] It should be noted that the type of alkaline solution is not limited and can be selected according to routine practice in the art.

[0091] As an example, the alkaline solution includes at least one of potassium hydroxide, potassium carbonate and potassium bicarbonate.

[0092] It is understood that the ratio of the alkaline solution to the solid phase reaction intermediate and the time of the activation treatment can be adjusted in consideration of the activation effect.

[0093] As an example, the mass ratio of the alkaline solution to the solid phase reaction intermediate is (3-5):1.

[0094] As an example, the activation treatment time is 2 to 4 hours.

[0095] In this embodiment, the mass ratio of the alkaline solution to the solid phase reaction intermediate and the activation time are limited within a specific range, so that the two can have a suitable dosage ratio, thereby being able to better activate the solid phase reaction intermediate.

[0096] It should be noted that, in the preparation process of nitrogen-doped biochar materials, any steps not specifically described or limited may be arranged according to conventional selections in the art.

[0097] As an example, after obtaining the solid phase reaction intermediate and before heating and carbonization, the method further includes the steps of alternately washing and drying the solid phase reaction intermediate with ethanol and deionized water.

[0098] As an example, the heating carbonization process is performed under an inert atmosphere.

[0099] As an example, the process flow chart of a method for preparing a nitrogen-doped biochar material provided in an embodiment of the present application is exemplarily as follows: Figure 1 shown.

[0100] In a second aspect, an embodiment of the present application provides an application of a nitrogen-doped biochar material in degrading organic pollutants, and the nitrogen-doped biochar material is prepared by the preparation method of the nitrogen-doped biochar material provided in the embodiment of the first aspect.

[0101] As an example, the following steps are included: activating persulfate with nitrogen-doped biochar material, and then using the activated persulfate to degrade organic pollutants.

[0102] In this embodiment, persulfate activated by nitrogen-doped biochar is used to degrade organic pollutants, which has the advantages of being green and efficient.

[0103] It should be noted that the concentration ratio of nitrogen-doped biochar material to persulfate can be adjusted considering the activation effect.

[0104] As an example, in the activation solution system of nitrogen-doped biochar material to activate persulfate, the concentration ratio of nitrogen-doped biochar material to persulfate is (0.05-0.15) g / L: (1-3) mM, for example but not limited to the concentration ratio of 0.05 g / L: 1 mM, 0.05 g / L: 3 mM, 0.1 g / L: 1 mM, 0.1 g / L: 3 mM, 0.15 / L: 1 mM and 0.15 / L: 3 mM, any one of the point values ​​or the range value between any two of them.

[0105] In this embodiment, in the activation solution system for activating persulfate by nitrogen-doped biochar, the concentration ratio of nitrogen-doped biochar to persulfate is limited to a specific range, so that the two can have a suitable dosage ratio, thereby being able to better activate persulfate.

[0106] It should be noted that the treatment time can be adjusted considering the degradation effect of organic pollutants.

[0107] As an example, in the process of degrading organic pollutants, the treatment time is 40 to 60 minutes, for example but not limited to any one of 40 minutes, 50 minutes and 60 minutes, or a range between any two of them.

[0108] In this embodiment, during the process of degrading organic pollutants, the treatment time is limited to a specific range. On the one hand, it can effectively avoid the failure to effectively remove organic pollutants due to short treatment time, and on the other hand, it can effectively avoid the waste of time due to too long treatment time (after reaching the degradation saturation, continuing to extend the time will not significantly improve the degradation effect, but will only cause a waste of time).

[0109] As an example, the organic pollutants include electron-rich organic pollutants.

[0110] In this embodiment, the nitrogen-doped biochar material provided in the first aspect of the embodiment is particularly suitable for degrading electron-rich organic pollutants.

[0111] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0112] Example 1

[0113] The present invention provides a method for preparing a nitrogen-doped biochar material, comprising the following steps:

[0114] The washed and dried collagen fibers are immersed in deionized water to obtain a first reaction precursor; wherein the mass ratio of the collagen fibers to the deionized water is 1:30 and the reaction time is 12 hours.

[0115] The first reaction precursor is activated by using a glutaraldehyde (25 wt %) solution to obtain an activated first reaction precursor; wherein the mass volume ratio of the first reaction precursor to the glutaraldehyde solution is 1 g:4 mL, and the activation treatment time is 15 min.

[0116] Polyethyleneimine is used as the second reaction precursor and mixed with the activated first reaction precursor and then heated to react to obtain a reaction intermediate. Then, the reaction intermediate is subjected to solid-liquid separation to obtain a solid-phase reaction intermediate; wherein the mass ratio of polyethyleneimine to collagen fiber is 1:3, the treatment temperature is 38°C, and the treatment time is 6h.

[0117] The solid-phase reaction intermediate is subjected to the first-stage carbonization, activation treatment and the second-stage carbonization in sequence to obtain a transition metal catalyst; wherein, the treatment temperature of the first-stage carbonization is 300°C, and the treatment time is 3 hours; the alkaline solution of the activation treatment is 3 mol / L potassium hydroxide, the mass ratio of the activation solution to the solid-phase reaction intermediate is 3:1, and the activation treatment time is 3 hours; the treatment temperature of the second-stage carbonization is 400°C, and the treatment time is 2 hours.

[0118] Example 2

[0119] The embodiment of the present application provides a method for preparing a nitrogen-doped biochar material, which differs from Embodiment 1 only in that the treatment temperature of the second stage carbonization is 500° C. and the treatment time is 2 h.

[0120] Example 3

[0121] The embodiment of the present application provides a method for preparing a nitrogen-doped biochar material, which differs from Embodiment 1 only in that the treatment temperature of the second stage carbonization is 600° C. and the treatment time is 2 h.

[0122] Example 4

[0123] The embodiment of the present application provides a method for preparing a nitrogen-doped biochar material, which differs from Embodiment 1 only in that the treatment temperature of the second stage carbonization is 700° C. and the treatment time is 2 h.

[0124] Example 5

[0125] The embodiment of the present application provides a method for preparing a nitrogen-doped biochar material, which differs from Embodiment 1 only in that the treatment temperature of the second stage carbonization is 800° C. and the treatment time is 2 h.

[0126] Test Example 1

[0127] Activation performance test of nitrogen-doped biochar materials

[0128] Test method:

[0129] The nitrogen-doped biochar materials prepared according to the preparation method of Examples 1 to 5 were numbered respectively, and then, the nitrogen-doped biochar materials with different numbers were activated with sodium persulfate according to the same dosage standard, and then, the activated sodium persulfate was used to degrade tetracycline, and the residual concentration of tetracycline changing with time was recorded respectively; at the same time, sodium persulfate alone and biochar materials not doped with nitrogen were used as the first control example and the second control example respectively; wherein, in the activation solution system, the concentration of the nitrogen-doped biochar material was 0.1 g / L, the concentration of sodium persulfate was 2 mM, and the concentration of tetracycline was 20 mg / L.

[0130] It should be noted that PDS is the first control example, BC / PDS is the second control example, and the other five correspond to the nitrogen-doped biochar materials prepared at different carbonization temperatures in Examples 1 to 5.

[0131] See also Figure 2 It can be seen that the nitrogen-doped biochar materials prepared in Examples 1 to 5 can effectively activate sodium persulfate to degrade tetracycline, and the more suitable degradation time is 40 to 60 minutes; at the same time, from the test results of Examples 1 to 5 and the second control example, it can be seen that after nitrogen doping, the activation performance of the biochar material is significantly improved.

[0132] Test Example 2

[0133] Study on the activation mechanism of nitrogen-doped biochar materials at different carbonization temperatures

[0134] Test method:

[0135] The nitrogen-doped biochar materials prepared according to the preparation methods of Examples 1 to 5 were numbered respectively, and then, the nitrogen-doped biochar materials of each number were activated with sodium persulfate according to the same dosage standard, and then, the activated sodium persulfate was used to degrade tetracycline containing different quenchers, and the residual concentration of tetracycline changing with time was recorded respectively; at the same time, the one without adding quencher was used as a control example; wherein, in the activation solution system, the concentration of the transition metal catalyst was 0.05 g / L, the concentration of sodium persulfate was 2 mM, and the concentration of tetracycline was 20 mg / L; the quenchers included 5 kinds, namely: quenching OH and SO 4 ·- Me-OH can quench OH TBA can quench O 2 -· p-BQ can quench 1 O 2 L-histidine and KI that can quench the electron transfer pathway.

[0136] It should be noted that None is a control example, and N / BC-400 / PDS is the nitrogen-doped biochar material prepared in Example 1 (corresponding to Figure 3 ), N / BC-500 / PDS is the nitrogen-doped biochar material prepared in Example 2 (corresponding to Figure 4 ), N / BC-600 / PDS is the nitrogen-doped biochar material prepared in Example 3 (corresponding to Figure 5 ), N / BC-700 / PDS is the nitrogen-doped biochar material prepared in Example 4 (corresponding to Figure 6 ), N / BC-800 / PDS is the nitrogen-doped biochar material prepared in Example 5 (corresponding to Figure 7 ).

[0137] See also Figure 3 to Figure 8 It can be seen that with the increase of the preparation temperature of nitrogen-doped biochar material (N / BC), the proportion of non-radical pathway of persulfate becomes larger and larger, until it reaches 100% at 800 degrees Celsius, indicating that the radical / non-radical activation pathway of persulfate can be effectively regulated by controlling the carbonization temperature of nitrogen-rich biochar.

[0138] Test Example 3

[0139] The nitrogen-doped biochar materials prepared according to the preparation method of Examples 1 to 5 were numbered respectively, and then the nitrogen-doped biochar materials with different numbers were activated with sodium persulfate according to the same dosage standard. Then, the activated sodium persulfate was used to degrade phenol (a typical electron-rich organic pollutant), and the residual concentration of phenol changing with time was recorded respectively, and then a statistical graph of the removal efficiency was drawn.

[0140] See also Figure 8 and Fig. 9It can be seen that the higher the proportion of non-radical activation pathways in the nitrogen-doped biochar material, the better its degradation effect on phenol. When the nitrogen-doped biochar material only has non-radical activation pathways, its degradation effect on phenol reaches a peak, indicating that the nitrogen-doped biochar material provided in the embodiment of the present application is particularly suitable for degrading electron-rich organic pollutants.

[0141] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

Claims

1. A method for preparing nitrogen-doped biochar material, characterized in that: The following steps are involved: Soaking collagen fibers in a solvent to obtain a first reaction precursor, wherein the pH of the solvent is ≤7; The first reaction precursor is mixed with the second reaction precursor containing a nitrogen source and then heated to react to obtain a reaction intermediate; Performing solid-liquid separation on the reaction intermediate to obtain a solid-phase reaction intermediate; heating and carbonizing the solid phase reaction intermediate to obtain a nitrogen-doped biochar material; After obtaining the first reaction precursor and before carrying out the heating reaction step, the method further includes activating the first reaction precursor with an aldehyde solution; The aldehyde solution includes at least one of glutaraldehyde, formaldehyde and acetaldehyde; The mass volume ratio of the first reaction precursor to the aldehyde solution is 1 g: (3-5) mL; The activation treatment time is 10 to 20 minutes.

2. The method for preparing nitrogen-doped biochar material according to claim 1, characterized in that: The mass ratio of the collagen fibers to the nitrogen source in the second reaction precursor is 1:(1-3).

3. The method for preparing nitrogen-doped biochar material according to claim 2, characterized in that: The nitrogen source in the second reaction precursor includes at least one of polyethyleneimine, dopamine and amino acid.

4. The method for preparing the nitrogen-doped biochar material according to any one of claims 1 to 3, characterized in that: The heating carbonization step includes firstly performing a first stage carbonization and then raising the temperature to perform a second stage carbonization.

5. The method for preparing nitrogen-doped biochar material according to claim 4, characterized in that: During the first stage carbonization, the treatment temperature is 200-400°C and the treatment time is 2-5h; and / or, during the second stage carbonization, the treatment temperature is 400-800°C and the treatment time is 2-5h.

6. The method for preparing nitrogen-doped biochar material according to claim 5, characterized in that: During the second stage carbonization, the treatment temperature is 500-800°C.

7. The method for preparing nitrogen-doped biochar material according to claim 6, characterized in that: The processing temperature is 600-800°C.

8. The method for preparing nitrogen-doped biochar material according to claim 7, characterized in that: The processing temperature is 700-800°C.

9. Application of nitrogen-doped biochar material in degrading organic pollutants, characterized in that: The nitrogen-doped biochar material is prepared by the method for preparing the nitrogen-doped biochar material according to any one of claims 1 to 8.

10. The use according to claim 9, characterized in that: The following steps are involved: The nitrogen-doped biochar material is used to activate persulfate, and the activated persulfate is then used to degrade organic pollutants.

11. The use according to claim 10, characterized in that: In the activation solution system for activating the persulfate with the nitrogen-doped biochar material, the concentration ratio of the nitrogen-doped biochar material to the persulfate is (0.05-0.15) g / L: (1-3) mM.

12. The use according to claim 10, characterized in that: In the process of degrading organic pollutants, the treatment time is 40 to 60 minutes.

13. The use according to any one of claims 9 to 12, characterized in that: The organic pollutants include electron-rich organic pollutants.

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