Self-doped N-regulatable sophora flavescens biochar as well as preparation method and application thereof

Abstract

The invention discloses self-doped adjustable N sophora flavescens biochar as well as a preparation method and application thereof, and belongs to the technical field of advanced oxidation catalysts. The invention relates to self-doped N-adjustable sophora flavescens biochar, which is biochar with a plurality of functional groups on the surface. The functional groups comprise oxygen-containing functional groups and nitrogen-containing functional groups; wherein the oxygen-containing groups comprise C = O, and the content of C = O accounts for more than 18% of the content of the oxygen-containing functional groups; the nitrogen-containing functional group comprises pyrrole N, and the pyrrole N accounts for more than 40% of the nitrogen-containing functional group. According to the method, multiple functional groups such as C = O, pyrrole, carboxyl and graphite nitrogen are constructed on the surface of the sophora flavescens residue biochar through calcination regulation and control, so that the Cl <-> interference resistance of biochar activated PMS to degrade antibiotics is improved, the practicability is higher, and the activation efficiency and the degradation efficiency are improved. Besides, the lightyellow sophora root dregs can influence the environment when being randomly treated as biomass wastes, so that the invention not only provides an ideal traditional Chinese medicine residue biomass resource utilization method, but also achieves the effect of treating wastes with wastes in treating organic wastes in water by utilizing an adsorption-catalysis bifunctional material prepared from the biomass wastes.

Description

Technical Field

[0001] The present invention relates to self-doped and controllable N-sophora flavescens biochar and a preparation method and application thereof, belonging to the technical field of advanced oxidation catalysts. Background Art

[0002] In recent years, water pollution has become increasingly serious. Emerging pollutants, particularly those from antibiotics and other pharmaceuticals, have attracted significant attention due to their potential persistence and bioaccumulation. Persulfate-based advanced oxidation processes (PS-AOPs) are considered promising for the removal of emerging pollutants in water due to their strong oxidative capacity, rapid reaction speed, and wide pH range.

[0003] Persulfate (PMS, PDS) is usually unable to directly react with pollutants to oxidize them and requires effective activation. Common activation methods include thermal activation, photoactivation, ultrasonic activation, and catalyst activation. Among them, catalyst activation has attracted attention because it does not require additional energy input. Although metal catalysts (such as Fe, Co, and Mn) can quickly activate PMS to degrade pollutants, there is a risk of metal leaching causing secondary pollution. In addition, most metal catalysts degrade pollutants by promoting PMS to produce free radicals, resulting in the common anion Cl in their actual application in natural water bodies. - The degradation effect is severely inhibited when it exists.

[0004] At present, there are few studies on the use of Chinese medicine waste residue as a raw material for biochar preparation and then its application in activating PMS to degrade pollutants. The continuous expansion of the pharmaceutical industry has led to an increase in the scale of Chinese herbal medicine cultivation. The large-scale cultivation of traditional Chinese medicine results in a large amount of by-products, such as Chinese medicine waste residue, produced every year. The treatment methods for these by-products include incineration, landfill and composting. Further research on how to rationally utilize this substance is imperative. Chinese medicine waste residue contains a variety of bioactive components, including flavonoids, alkaloids and polysaccharides. During the pyrolysis process, these biomass components may be converted into catalytically active functional groups, which can improve the catalytic performance of biochar. However, the presence of anions in actual water bodies will still interfere with the above-mentioned biochar activation of PMS to degrade antibiotics. An article in the journal Process Safety and Environmental Protection disclosed the use of peanut shell-derived biochar for antibiotic degradation. Although the degradation rate can reach 97%, the addition of Cl - The degradation effect was reduced from about 97% to about 85%, and the anti-interference ability was poor. The journal Applied Catalysis B: Environmental published a study on the use of cow dung-derived biochar in a 10mM Cl - The degradation rate of carbamazepine in solution was also inhibited. Summary of the Invention

[0005] In order to solve or partially solve the problems existing in the related art, the present invention provides a self-doped and controllable N-Sophora flavescens biochar and its preparation method and application.

[0006] The present invention provides a self-doped and controllable N-sophora flavescens biochar, which is a biochar containing multiple functional groups on the surface; the functional groups include oxygen-containing functional groups and nitrogen-containing functional groups; the oxygen-containing groups include C=O, and the amount of C=O accounts for more than 18% of the amount of the oxygen-containing functional groups; the nitrogen-containing functional groups include pyrrole N, and the amount of pyrrole N accounts for more than 40% of the amount of the nitrogen-containing functional groups.

[0007] The oxygen-containing functional groups in the present invention include C=O, lattice oxygen (O L ), CO and adsorbed H2O. Nitrogen-containing functional groups include pyrrolic nitrogen, pyridinic nitrogen and graphitic nitrogen. Among them, self-doping can regulate the N-Sophora flavescens biomass, and according to the oxygen fine spectrum, the C=O content (the number of C=O functional groups in the total number of oxygen-containing functional groups) is increased to more than 18%, O L Content (O L According to the N fine spectrum, when the pyrrole N content (the number of pyrrole N accounts for the total number of nitrogen-containing functional groups) increases to more than 40%, these functional groups begin to act as active sites, thus giving the material Cl - Anti-interference ability.

[0008] The present invention also claims a method for preparing the self-doped and controllable N-Sophora flavescens biochar, comprising:

[0009] (1) drying and grinding the Sophora flavescens residues into powder to obtain the residue powder;

[0010] (2) The medicinal residue powder was calcined under nitrogen, then washed with hydrochloric acid solution, washed with water, and dried to obtain self-doped and controllable N-Sophora flavescens biochar.

[0011] Preferably, the calcination temperature is 900° C., the calcination time is 2.5-3 h, and the heating rate is 10° C. / min.

[0012] The present invention also claims to protect the use of the self-doped and controllable N-Sophora flavescens biochar in activating PMS to catalyze the degradation of antibiotics.

[0013] Preferably, the antibiotic is carbamazepine.

[0014] The technical solution provided by the present invention can have the following beneficial effects:

[0015] (1) The self-doped N-Sophora flavescens biochar synthesized by a simple one-step pyrolysis method can effectively adsorb the pollutant CBZ while effectively activating PMS to degrade CBZ. It has application potential in water pollution control as a bifunctional catalyst for adsorption and catalysis.

[0016] (2) The present invention constructs a variety of functional groups on the surface of Sophora flavescens residue biochar by calcination regulation, such as C=O, pyrrole, carboxyl, graphite nitrogen, etc., which improves the anti-Cl2 resistance of biochar activated PMS to degrade antibiotics. - The interference ability is stronger, the practicality is stronger, and the activation efficiency and degradation efficiency are improved.

[0017] (3) The arbitrarily disposal of Sophora flavescens residue as biomass waste will have an impact on the environment. The present invention not only provides an ideal method for the resource utilization of Chinese medicinal residue biomass, but also achieves the effect of "treating waste with waste" by using biomass waste to prepare adsorption-catalysis dual-functional materials for the treatment of organic waste in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0019] Figure 1 This is a comparison chart of the removal effect of carbamazepine by adsorption of biochar prepared from Sophora flavescens residue in Example 1 and Comparative Examples 1-3.

[0020] Figure 2 This is a comparison chart of the removal effects of carbamazepine by biochar adsorption synergistic degradation using Sophora flavescens residues prepared in Example 1 and Comparative Examples 1-3.

[0021] Figure 3 These are X-ray photoelectron spectroscopy (XPS) graphs of the Sophora flavescens residue biochar prepared at different temperatures according to the present invention, wherein (a), (b), and (c) are the C1S, O 1S, and N 1S fine spectra of the Sophora flavescens biochar prepared in Comparative Example 2, respectively; (d), (e), and (f) are the C1S, O 1S, and N 1S fine spectra of the Sophora flavescens biochar prepared in Comparative Example 1; (g), (h), and (i) are the C1S, O 1S, and N 1S fine spectra of the Sophora flavescens biochar prepared in Example 1; and (j), (k), and (l) are the C1S, O 1S, and N 1S fine spectra of the Sophora flavescens biochar prepared in Example 1 after degradation performance test.

[0022] Figure 4 The biochar prepared in Example 1 was prepared from Sophora flavescens residue under different Cl - The removal effect diagram of carbamazepine by adsorption synergistic degradation in carbamazepine solution, where the control is the carbamazepine solution without adding Cl- . DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0024] Example 1

[0025] A method for preparing self-doped and controllable N-Sophora flavescens biochar, comprising:

[0026] (1) Sophora flavescens dregs are the dregs obtained after Sophora flavescens is extracted with alcohol.

[0027] (2) After the Sophora flavescens residue is recovered, it is dried at 60°C. An appropriate amount of the dried Sophora flavescens residue is weighed and placed in a ball mill. After ball milling at a frequency of 25 Hz for 35 minutes, the powder is passed through an 80-mesh sieve and collected for later use to obtain the residue powder.

[0028] (3) The dregs powder was placed in a tubular furnace and heated to 900 °C at a rate of 10 °C / min under a nitrogen atmosphere and maintained for 3 h.

[0029] (4) After the tubular furnace cools down naturally, the material is taken out and added with 30 mL of 1 mmol / L HCl to soak for 12 h to remove the ash produced on the surface of the biochar during the calcination process. After that, the HCl is washed off by filtration and deionized water. The biochar is placed in an oven and dried at 60 °C for 12 h. The ground Sophora flavescens residue biochar is taken out.

[0030] Comparative Example 1

[0031] The only difference between the preparation method of the self-doped and controllable N-Sophora flavescens biochar described in this comparative example and that in Example 1 is:

[0032] In the step (3), the calcination temperature is 800° C., maintained for 2.5 hours, and the heating rate is 5° C. / min.

[0033] Comparative Example 2

[0034] The only difference between the preparation method of the self-doped and controllable N-Sophora flavescens biochar described in this comparative example and that in Example 1 is:

[0035] In the step (3), the calcination temperature is 700° C., maintained for 2 h, and the heating rate is 5° C. / min.

[0036] Comparative Example 3

[0037] The only difference between the preparation method of the self-doped and controllable N-Sophora flavescens biochar described in this comparative example and that in Example 1 is:

[0038] In the step (3), the calcination temperature is 600° C., maintained for 2 h, and the heating rate is 5° C. / min.

[0039] Comparative Example 4

[0040] The only difference between the preparation method of the self-doped and controllable N-Sophora flavescens biochar described in this comparative example and that in Example 1 is:

[0041] Replace the Sophora flavescens residue with the same mass of Polygonatum sibiricum residue.

[0042] Comparative Example 5

[0043] The only difference between the preparation method of the self-doped and controllable N-Sophora flavescens biochar described in this comparative example and that in Example 1 is:

[0044] Replace the Sophora flavescens residue with tobacco stems of the same mass.

[0045] Effect Example 1

[0046] Test samples: biochar prepared in Example 1 and Comparative Examples 1-5.

[0047] Adsorption performance test method: 0.6 g / L of different test samples were added to 5 mg / L carbamazepine solution (initial pH of the solution = 5.8), and the reaction was started under natural light and room temperature. 0.5 mL of experimental samples were taken at 5 min, 10 min, 15 min, 20 min, 30 min, 40 min, and 60 min, respectively, and the concentration of CBZ solution was detected by liquid chromatography to calculate the adsorption removal rate. The results are shown in Figure 1 And Table 1. Adsorption removal rate = (C0-C t ) / C0; C0 is the initial concentration of carbamazepine solution, C t is the carbamazepine concentration in the carbamazepine solution at the time of adsorption t min.

[0048] Degradation performance test method: 0.6 g / L of different test samples were added to 5 mg / L carbamazepine solution (initial pH of the solution = 5.8), the reaction was started under natural light and room temperature, and 2.5 mmol / L peroxymonosulfate PMS was added after adsorption for 5 minutes to reach the dynamic equilibrium of adsorption and desorption. Thereafter, 0.5 mL of experimental samples were taken at 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 40 minutes, and 60 minutes respectively, and the concentration of CBZ solution was detected by liquid chromatography to calculate the degradation rate. The results are shown in the table. Figure 2 And Table 1. Degradation rate = (C e -C t ) / C0; C0 is the initial concentration of carbamazepine solution, C e The concentration at adsorption equilibrium, C t is the carbamazepine concentration in the carbamazepine solution at degradation t min.

[0049] Table 1

[0050]

[0051] from Figure 1 As can be seen from Table 1, the biochar prepared in the examples and comparative examples can reach adsorption-desorption equilibrium in 5 minutes. The adsorption removal rate of carbamazepine in Example 1 is 37.1%, while the adsorption removal rates of carbamazepine in Comparative Examples 1-5 are 15.3%, 8.1%, 4.5%, 0%, and 74.3%, respectively.

[0052] from Figure 2 As can be seen from Table 1, the removal efficiency of carbamazepine by adsorption and catalysis of PMS in Example 1 is 95.3%, while that of Comparative Examples 1-5 are 40.9%, 7.3%, 6%, 0% and 74.3% respectively.

[0053] according to Figure 3 The XPS spectra show that as the preparation temperature increases from 700°C to 900°C, the C=O content significantly increases from 2.76% at 700°C to 16.81% at 800°C, further increasing to 22.74% at 900°C before decreasing to 2.11% after degradation testing, indicating that the C=O functional group functions as an active site. The N 1S spectra reveal that at 700°C, the nitrogen species are primarily graphitic nitrogen and pyrrolic nitrogen. At 800°C, these two species transform into pyridinic nitrogen. However, at 900°C, pyridinic nitrogen disappears, while pyrrolic nitrogen reappears. The pyrrolic nitrogen content decreases after degradation testing, indicating that pyrrolic nitrogen functions as a key active site in the material. At 700°C, the material's inherently poor adsorption properties prevent the nitrogen species from participating in subsequent degradation. However, the degradation performance at 800°C suggests that the C=O functional group functions as an active site. The further improvement in degradation at 900°C with only a slight increase in C=O can be attributed to pyrrolic N. The calcination conditions defined in the present invention increase the C=O functional group content of the material and regulate the proportion of N species, making it conducive to activating PMS for CBZ degradation.

[0054] Effect Example 2

[0055] Test samples: biochar prepared in Example 1 and Comparative Examples 1-5.

[0056] Anti-interference performance test method: add 0.6g / L of different test samples to the solution containing 5mmol / L, 10mmol / L and 10mmol / L of -The reaction was started in a 5 mg / L carbamazepine solution under natural light and room temperature. After adsorption for 5 minutes to reach the dynamic equilibrium of adsorption and desorption, 2.5 mmol / L peroxymonosulfate PMS was added. Thereafter, 0.5 mL of experimental samples were taken at 10 minutes, 15 minutes, 20 minutes, 25 minutes, 35 minutes, 45 minutes, and 65 minutes respectively. The concentration of CBZ solution was detected by liquid chromatography to calculate the removal rate. The results are shown in Table 1 and Figure 4 . Removal rate = (C0-C t ) / C0; C0 is the initial concentration of carbamazepine solution, C t is the concentration of carbamazepine in the carbamazepine solution at reaction time t min.

[0057] from Figure 4 It can be seen that within 60 minutes after adsorption equilibrium, the Cl - Although the adsorption performance of the CBZ solution was inhibited in the adsorption stage, it slightly promoted the catalytic effect in the activation of PMS to remove CBZ, so that CBZ was completely removed within 1 hour. This was due to the fact that pyrrole N and C=O as active sites promoted the production of PMS with 1 O2-based non-free radical degradation pathway.

[0058] Comparative Example 1 lacks pyrrole N as an active site, which may generate more free radical pathways. - The degradation effect was inhibited to a certain extent. Comparative Example 5 lacked the ability to degrade CBZ. Cl was added during the adsorption stage. - Then inhibition occurred due to the adsorption competition effect.

[0059] While various embodiments of the present invention have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A self-doping and controllable N-Sophora flavescens biochar, characterized by: The biochar has multiple functional groups on its surface; the functional groups include oxygen-containing functional groups and nitrogen-containing functional groups; the oxygen-containing groups include C=O, and the amount of C=O accounts for more than 18% of the amount of oxygen-containing functional groups; the nitrogen-containing functional groups include pyrrole N, and the amount of pyrrole N accounts for more than 40% of the amount of nitrogen-containing functional groups.

2. The method for preparing the self-doped and controllable N-Sophora flavescens biochar according to claim 1, characterized in that: include: (1) drying and grinding the Sophora flavescens residues into powder to obtain the residue powder; (2) The medicinal residue powder was calcined under nitrogen, then washed with hydrochloric acid solution, washed with water, and dried to obtain self-doped and controllable N-Sophora flavescens biochar.

3. The method for preparing the self-doped and controllable N-Sophora flavescens biochar according to claim 2, characterized in that: The calcination temperature is 900° C., the calcination time is 2.5-3 hours, and the heating rate is 10° C. / min.

4. Use of the self-doped and controllable N-Sophora flavescens biochar according to claim 1 in activating PMS to catalyze the degradation of antibiotics.

5. The application according to claim 4, characterized in that: The antibiotic is carbamazepine.

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