Amino-grafted biochar and its preparation method and application

Abstract

The present invention relates to the field of biomass energy, and specifically provides an amino-grafted biochar and a preparation method and application thereof. The preparation method of the amino-grafted biochar comprises the following steps: using polyphosphoric acid and phosphorus pentoxide as reaction media, and using L-phenylalanine to perform amination treatment on the biochar to obtain amino-grafted biochar. The present invention uses polyphosphoric acid (PPA) / phosphorus pentoxide (P2O5) as a medium, and through Friedel-Crafts acylation, environmentally friendly and biocompatible L-phenylalanine is attached to the edge of the biochar, thereby obtaining amino-grafted biochar with excellent photocatalytic effect, which provides a new idea for the rational design and development of more efficient biochar photocatalytic materials, and is expected to expand its application in environmental remediation.

Description

Technical Field

[0001] The present invention relates to the field of biomass energy, and specifically provides an amino-grafted biochar and a preparation method and application thereof. Background Art

[0002] The statements herein merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] Photocatalytic degradation of organic pollutants is a green environmental remediation technology that does not require additional energy other than light. However, the degradation efficiency of organic pollutants is very low by light radiation alone, and the addition of catalysts can improve the oxidative properties of photocatalysis. Biochar is produced by pyrolysis of waste biomass (such as agricultural residues and wood powder) under anaerobic conditions. It is a new type of carbonaceous material with relatively low cost and sustainability. If it can be used as an economical catalyst, it will have significant advantages.

[0004] However, studies have found that biochar has poor photocatalytic activity and visible light reaction, and the functional structure of biochar leads to its semiconductor-like ability. In current research, it is more used as a semiconductor carrier rather than a photocatalyst. Therefore, providing a biochar-based photocatalyst using biochar as raw material will have broad application prospects. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides an amino-grafted biochar and a preparation method and application thereof. The amino-grafted biochar (AGPC) is prepared by attaching environmentally friendly and biocompatible L-phenylalanine to the edge (CH, C-OH) of the biochar using polyphosphoric acid (PPA) / phosphorus pentoxide (P2O5) as a medium through Friedel-Crafts acylation. The present invention provides a new idea for the rational design and development of more efficient biochar photocatalytic materials, and is expected to expand its application in environmental remediation.

[0006] The first aspect of the present invention provides a method for preparing amino-grafted biochar, comprising: using polyphosphoric acid and phosphorus pentoxide as reaction media, and using L-phenylalanine to perform amination treatment on biochar to obtain amino-grafted biochar.

[0007] A second aspect of the present invention provides an amino-grafted biochar prepared by the above method.

[0008] A third aspect of the present invention provides the use of the above-mentioned amino-grafted biochar in the photocatalytic degradation of organic pollutants.

[0009] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0010] 1. The present invention treats garlic peel biochar by Friedel-Crafts chemical acylation to obtain an amino-grafted biochar, and the grafting of amino groups can effectively improve the photocatalytic degradation ability of biochar. Experimental results show that the photodegradation efficiency of amino-grafted biochar on rhodamine B can reach 81%, which has a good photocatalytic effect.

[0011] 2. The preparation method of amino-grafted biochar provided by the present invention is simple and environmentally friendly, and improves the utilization value of biochar in a renewable and low-cost manner. It uses agricultural waste as raw material, turning waste into treasure, effectively reducing environmental pollution caused by arbitrary discarding of agricultural waste, and realizing high added value utilization of agricultural waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0013] Figure 1 The present invention is a flow chart of the preparation process of amino-grafted biochar.

[0014] Figure 2 The photodegradation effect diagram (left) and photodegradation kinetic diagram (right) of Rhodamine B by amino-grafted biochar in Example 1.

[0015] Figure 3 The photodegradation effect diagram (left) and photodegradation kinetic diagram (right) of Rhodamine B by amino-grafted biochar in Example 2.

[0016] Figure 4 The photodegradation effect diagram (left) and photodegradation kinetic diagram (right) of Rhodamine B by amino-grafted biochar in Example 3.

[0017] Figure 5 The photodegradation effect diagram (left) and photodegradation kinetic diagram (right) of Rhodamine B by amino-grafted biochar in Example 4.

[0018] Figure 6 The photodegradation effect diagram of biochar on Rhodamine B in the comparative example (left) and the photodegradation kinetic diagram (right). DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] In view of the problem that biochar is more often used as a semiconductor carrier rather than a photocatalyst in the prior art, and the relatively low cost and sustainability of biochar cannot be utilized to effectively achieve photocatalytic degradation of organic pollutants, the present invention provides an amino-grafted biochar and a preparation method and application thereof.

[0022] A typical embodiment of the present invention provides a method for preparing amino-grafted biochar, which specifically includes: using polyphosphoric acid and phosphorus pentoxide as reaction media, using L-phenylalanine to aminize biochar to obtain amino-grafted biochar.

[0023] Among them, using polyphosphoric acid and phosphorus pentoxide as reaction media and Friedel-Crafts chemical acylation reaction, L-phenylalanine can be attached to the edge of biochar to obtain amino-grafted biochar with excellent photocatalytic effect.

[0024] In some embodiments, the biochar preparation method is: sintering garlic peels in a tube furnace under an inert atmosphere, cooling to room temperature, and then taking out and grinding to obtain biochar.

[0025] In some embodiments, the biochar is ground to 100-120 mesh.

[0026] In some embodiments, the sintering temperature is 400-800° C., and the sintering time is 1-3 hours.

[0027] In some embodiments, the mass ratio of the biochar, polyphosphoric acid, phosphorus pentoxide, and L-phenylalanine is 1:50:10:1.

[0028] In some embodiments, the amination treatment is performed under stirring, the stirring temperature is 120-150° C., and the stirring time is 60-76 hours. The process is performed under heating conditions, mainly because the mixture of biochar, polyphosphoric acid, phosphorus pentoxide, and L-phenylalanine is composed of solid and colloidal substances at room temperature, and heating and stirring can make these substances fully mixed and contacted.

[0029] In some embodiments, after stirring, ultrapure water is added to dilute the mixture when the mixture is cooled to 50-60°C.

[0030] In some embodiments, after dilution with ultrapure water, the precipitate is collected by centrifugation, washed with ultrapure water and methanol for one day respectively under stirring, and then filtered, washed, dried, and ground to obtain amino-grafted biochar.

[0031] In some embodiments, the drying temperature is 55-65° C., the drying time is 12-24 hours, and the amino-grafted biochar is ground to a particle size of 120-140 mesh.

[0032] Another embodiment of the present invention provides amino-grafted biochar obtained by the above preparation method.

[0033] A third embodiment of the present invention provides the use of the above-mentioned amino-grafted biochar in the photocatalytic degradation of organic pollutants.

[0034] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0035] Example 1

[0036] This embodiment provides a method for preparing amino-grafted biochar, and the specific steps are as follows:

[0037] (1) 10 g of garlic peel was placed in a tubular furnace, N2 was introduced at a flow rate of 200 mL / min, and the temperature was raised to 400 °C at a heating rate of 5 °C / min and maintained for 2 h to prepare garlic peel biochar, which was then cooled to room temperature and ground into 120 mesh;

[0038] (2) Friedel-Crafts chemical acylation of garlic peel biochar: 1g garlic peel biochar, 50g PPA, 10g P2O5, 1g L-phenylalanine were mixed and stirred at 130℃ for 72h, then diluted with ultrapure water when cooled to 55℃. The precipitate was collected by centrifugation at 3000rpm for 10min, washed with ultrapure water for one day under stirring to remove the residual reaction mixture, and then washed with methanol for one day to remove low molar mass impurities. The final sample was filtered, washed, and dried in a blast furnace at 60℃ for 12h before grinding to 140 mesh.

[0039] Example 2

[0040] This embodiment provides a method for preparing amino-grafted biochar, and the specific steps are as follows:

[0041] (1) 8 g of garlic peel was placed in a tubular furnace, N2 was introduced at a flow rate of 180 mL / min, and the temperature was raised to 800 °C at a heating rate of 4 °C / min and maintained for 2 h to prepare garlic peel biochar, which was then cooled to room temperature and ground into 100 mesh;

[0042] (2) Friedel-Crafts chemical acylation was used to treat garlic peel biochar. 1 g garlic peel biochar, 50 g PPA, 10 g P2O5, and 1 g L-phenylalanine were mixed and stirred at 120 °C for 76 h, and then diluted with ultrapure water when cooled to 60 °C. The precipitate was collected by centrifugation at 3500 rpm for 20 min, washed with ultrapure water for one day under stirring to remove the residual reaction mixture, and then washed with methanol for one day to remove low molar mass impurities. The final sample was filtered, washed, and dried in a blast furnace at 55 °C for 20 h before grinding to 130 mesh.

[0043] Example 3

[0044] This embodiment provides a method for preparing amino-grafted biochar, and the specific steps are as follows:

[0045] (1) 12 g of garlic peel was placed in a tubular furnace, N2 was introduced at a flow rate of 220 mL / min, and the temperature was raised to 600 °C at a heating rate of 6 °C / min and maintained for 2 h to prepare garlic peel biochar, which was then cooled to room temperature and ground into 110 mesh;

[0046] (2) Garlic peel biochar was treated by Friedel-Crafts chemical acylation. 1 g garlic peel biochar, 50 g PPA, 10 g P2O5, and 1 g L-phenylalanine were mixed and stirred at 140 °C for 68 h, and then diluted with ultrapure water when cooled to 50 °C. The precipitate was collected by centrifugation at 4000 rpm for 15 min, washed with ultrapure water for one day under stirring to remove the residual reaction mixture, and then washed with methanol for one day to remove low molar mass impurities. The final sample was filtered, washed, and dried in a blast furnace at 65 °C for 12 h before grinding to 120 mesh.

[0047] Example 4

[0048] This embodiment provides a method for preparing amino-grafted biochar, and the specific steps are as follows:

[0049] (1) 20 g of garlic peel was placed in a tubular furnace, N2 was introduced at a flow rate of 100 mL / min, and the temperature was raised to 800 °C at a heating rate of 10 °C / min and maintained for 2 h to prepare garlic peel biochar, which was then cooled to room temperature and ground into 100 mesh;

[0050] (2) Garlic peel biochar was treated with Friedel-Crafts chemical acylation. 1 g garlic peel biochar, 50 g PPA, 10 g P2O5, and 1 g L-phenylalanine were stirred at 150 °C for 60 h, and then diluted with ultrapure water when cooled to 50 °C. The precipitate was collected by centrifugation at 10,000 rpm for 5 min, washed with ultrapure water for one day under stirring to remove the residual reaction mixture, and then washed with methanol for one day to remove low molar mass impurities. The final sample was filtered, washed, and dried in a blast furnace at 60 °C for 12 h before grinding to 120 mesh.

[0051] Comparative Example

[0052] This comparative example provides a method for preparing biochar, and the specific steps are as follows:

[0053] 10 g of garlic peel was placed in a tubular furnace, N2 was introduced at a flow rate of 200 mL / min, and the temperature was raised to 400 °C at a heating rate of 5 °C / min and maintained for 2 h to prepare garlic peel biochar, which was then cooled to room temperature and ground into 120 mesh;

[0054] Performance Testing:

[0055] The photocatalytic degradation effect of the amino-grafted biochar in the comparative example and Examples 1 to 4 on organic pollutants was tested, and the specific test scheme is as follows:

[0056] 12 mg of amino-grafted biochar was added to 48 mL of an aqueous solution of the Rhodamine B (RhB) model pollutant (200 mg / L), and the mixture was then magnetically stirred in the dark for 24 h to establish adsorption-desorption equilibrium. Subsequently, the reaction mixture was irradiated using a 500 W xenon lamp with a UV cutoff filter (λ>420 nm), and every 2 h, 1.5 mL of the suspension was taken out and mixed with 1.5 mL of ultrapure water and filtered through a filter membrane (0.22 μm). Subsequently, the concentration of RhB was measured using a double-beam spectrophotometer at a maximum absorbance of 553 nm.

[0057] The photocatalytic activity for RhB degradation was evaluated by the following formula:

[0058]

[0059] RhB degradation conforms to the first-order kinetic formula:

[0060]

[0061] Among them, C0 and C are the initial concentration of RhB before irradiation and the concentration at a certain time point after irradiation, respectively.

[0062] The test results of photodegradation of Rhodamine B in Examples 1 to 4 and the comparative example are shown in Table 1 and Figure 2-6 (Among them, R 2 is the fitting degree, k is the reaction rate constant) as shown:

[0063] Table 1

[0064] Catalyst samples Photodegradation efficiency (%) Reaction rate constant k Example 1 81 0.144 Example 2 76 0.096 Example 3 68 0.060 Example 4 66 0.065 Comparative Example 37 0.014

[0065] According to the test results, it can be found that in the dark process, due to the presence of a large number of oxygen-containing functional groups at a lower pyrolysis temperature, the adsorption capacity of the amino-grafted biochar (Example 1) sintered at 400°C is better than that of the amino-grafted biochar (Examples 2, 3, and 4) sintered at 600°C and 800°C. After irradiation with visible light, the oxygen functional groups of the low-temperature pyrolysis biochar can form an electron exchange system with the amino group, so the amino-grafted biochar (Example 1) sintered at 400°C shows a better photodegradation effect.

[0066] Compared with the comparative example, the amino-grafted biochars of Examples 1-4 showed good photodegradation effects of Rhodamine B after amino functionalization, indicating that under the same photodegradation conditions, the amino-grafted biochars had significantly improved photocatalytic ability.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An application of amino-grafted biochar in photocatalytic degradation of organic pollutants, characterized in that: The preparation method of amino-grafted biochar comprises the following steps: using polyphosphoric acid and phosphorus pentoxide as reaction media, and using L-phenylalanine to perform amination treatment on biochar to obtain amino-grafted biochar.

2. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 1, characterized in that: The biochar preparation method comprises the following steps: sintering garlic peel in a tube furnace under an inert atmosphere, cooling the garlic peel to room temperature, taking the garlic peel out and grinding the garlic peel to obtain the biochar.

3. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 2, characterized in that: The sintering temperature is 400-800° C., and the sintering time is 1-3 hours.

4. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 1, characterized in that: The mass ratio of the biochar, polyphosphoric acid, phosphorus pentoxide and L-phenylalanine is 1:50:10:

1.

5. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 1, characterized in that: The amination treatment is completed under stirring, the stirring temperature is 120-150° C., and the stirring time is 60-76 h.

6. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 5, characterized in that: After stirring, cool to 50-60°C and dilute with ultrapure water.

7. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 6, characterized in that: After dilution with ultrapure water, the precipitate was collected by centrifugation, washed with ultrapure water and methanol for one day respectively under stirring, and then filtered, washed, dried and ground to obtain amino-grafted biochar.

8. The use of amino-grafted biochar in photocatalytic degradation of organic pollutants as claimed in claim 7, characterized in that: The drying temperature is 55-65° C., the drying time is 12-24 h, and the amino-grafted biochar is ground to a particle size of 120-140 mesh.

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