Preparation method of modified sunflower seed shell biochar adsorbent, adsorbent and application thereof

Abstract

The application discloses a preparation method of a modified sunflower seed shell biochar adsorbent, the adsorbent and application thereof, and belongs to the technical field of environmental functional materials. The modified biochar adsorbent doped with nitrogen and sulfur is prepared by mixing sunflower seed shells as agricultural and forestry waste with thiourea, ball milling and high-temperature calcination under a nitrogen atmosphere at 900-950 DEG C. The sunflower seed shells have the characteristics of low ash content, so the defects of needing acid pickling pretreatment of traditional raw materials such as rice hulls and straws are avoided. The mechanical chemical action of ball milling promotes the uniform dispersion of thiourea, and the synergistic effect of nitrogen and sulfur doping is generated, so that the adsorption performance is significantly improved. The raw material source is wide, the process is simple, the adsorption efficiency is high, and the modified sunflower seed shell biochar adsorbent has a wide application prospect in the field of antibiotic wastewater treatment.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically a method for preparing modified sunflower seed shell biochar adsorbent, the adsorbent itself, and its application. Background Technology

[0002] Sulfamethoxazole (SMX), a broad-spectrum antibacterial agent, is widely used in human medicine, animal husbandry, and aquaculture. Due to its stable chemical structure, SMX is difficult to remove effectively using conventional wastewater treatment technologies. Therefore, developing efficient and environmentally friendly technologies for the effective removal of SMX is of significant practical importance.

[0003] Currently, the main methods for removing sulfamethoxazole include adsorption, oxidation, and biodegradation. Among these, adsorption has become one of the most promising removal technologies due to its advantages such as simple operation, no toxic byproducts, and good economic efficiency. Therefore, developing efficient and environmentally friendly adsorption materials has become a key research focus.

[0004] Biochar is a type of carbon material prepared by the pyrolysis of biomass raw materials under oxygen-limited conditions. It has advantages such as large specific surface area, excellent surface properties, strong stability, and low cost, and combines the dual benefits of carbon sequestration and resource utilization of biomass waste, making it an ideal pollutant adsorption material. However, unmodified raw biochar usually has limited adsorption capacity and weak anti-interference ability, making it difficult to meet the actual needs of antibiotic wastewater treatment.

[0005] On the other hand, existing technologies often use raw materials such as rice husks and straw for biochar preparation. However, the inherent high ash content of rice husks and straw limits the performance of biochar. Taking rice husks as an example, their silica content is as high as 15-20%. These inorganic components melt and clog pores during pyrolysis, significantly reducing the effective specific surface area and consuming some doping reagents, resulting in low doping efficiency. To overcome this problem, raw materials such as rice husks usually require complex acid leaching and desilication pretreatment, which significantly increases process costs and environmental risks. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention uses sunflower seed shells, an agricultural and forestry waste, as raw material. Through nitrogen and sulfur co-doping modification, a modified biochar adsorbent is prepared and applied to the efficient removal of sulfamethoxazole from water bodies, as detailed below: A method for preparing a modified sunflower seed shell biochar adsorbent includes the following steps: Step 1: Wash, dry, crush and sieve the sunflower seed shell raw material to obtain sunflower seed shell powder; Step 2: Mix the sunflower seed shell powder with thiourea until homogeneous to obtain a mixture; Step 3: The mixture is ball-milled to obtain a ball-milling precursor; Step 4: The ball-milled precursor is calcined at high temperature under an inert gas atmosphere to obtain nitrogen and sulfur co-doped modified sunflower seed shell biochar adsorbent; the inert gas is nitrogen. The modified sunflower seed shell biochar adsorbent is used to remove sulfamethoxazole from water; the modified sunflower seed shell biochar adsorbent has recyclability, stability, and regeneration properties.

[0007] Furthermore, in step 1, the drying temperature is 60-80℃, the drying time is 20-28 hours, and the sieve mesh size is 60 mesh.

[0008] Further, in step 2, the mass ratio of sunflower seed shell powder to thiourea is (4-8):(0.5-1.2).

[0009] Furthermore, in step 3, the ball milling speed is 300-500 rpm and the ball milling time is 30-50 minutes.

[0010] Furthermore, in step 4, the high-temperature calcination temperature is 900-950℃ (preferably 900℃), the calcination time is 1-3 hours, and the heating rate is 5-15℃ / min.

[0011] On the other hand, the present invention discloses a modified sunflower seed shell biochar adsorbent, which is prepared using the above-mentioned preparation method.

[0012] Furthermore, the modified sunflower seed shell biochar adsorbent has a specific surface area of ​​3639.8 m². 2 / g, with an average pore size of 3.4nm.

[0013] Thirdly, the present invention discloses the application of the modified sunflower seed shell biochar adsorbent in the removal of sulfamethoxazole from water.

[0014] Furthermore, the modified sunflower seed shell biochar adsorbent is added to water containing sulfamethoxazole at a dosage of 0.5-1.2 g / L and an adsorption time of 20-120 seconds.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses sunflower seed shells, agricultural and forestry waste, as raw material, realizing the resource utilization of biomass waste and avoiding the complex process and high environmental cost of acid washing pretreatment required for traditional raw materials (such as rice husks and straw) due to their high ash content. 2. This invention achieves uniform co-doping of nitrogen and sulfur elements in the biochar framework by mixing sunflower seed shell powder with thiourea, followed by ball milling and high-temperature pyrolysis. The prepared adsorbent material N,S-BBC has an adsorption efficiency of 99.6% for SMX and an adsorption capacity of 49.8 mg / g, which is far superior to unmodified biochar BC and ball-milled BBC, and also superior to N,S-MBC doped without ball milling. This indicates that the mechanochemical effect of ball milling and thiourea doping produce a significant synergistic effect. 3. The modified sunflower seed shell biochar adsorbent prepared by this invention has a specific surface area of ​​up to 3639.8 m². 2 / g, with an average pore size of 3.4nm, which is significantly improved compared to unmodified BC, and the micropore volume is significantly increased, providing abundant active sites for adsorption; 4. The adsorbent prepared by this invention can achieve almost complete removal of SMX within 20 seconds, and the adsorption rate of SMX is significantly better than that of other pollutants such as methylene blue, methyl orange, chloramphenicol and cresol red, showing excellent selective recognition ability. 5. The dynamic fitting results show that the R-values ​​of the quasi-second-order dynamic model and the Elovich model are... 2 All values ​​are greater than 0.99, indicating that the adsorption process is mainly chemisorption, occurs in a heterogeneous reaction system, and the adsorption is stable and more selective. 6. The recycling experiment shows that the adsorbent prepared by this invention maintains stable adsorption efficiency after being reused three times, and its adsorption performance can be restored by calcination at 900℃ after it becomes ineffective, thus exhibiting good stability and regeneration performance. 7. In the preparation method of the present invention, the calcination temperature can be flexibly adjusted within the range of 900-950℃, ball milling speed of 300-500rpm, and ball milling time of 30-50 minutes, and an SMX removal rate of over 99% can be obtained. The process conditions are mild and controllable, which is convenient for large-scale production. Attached Figure Description

[0016] Figure 1 For BC and N, S-BBC 900 SEM images and element distributions, where a is the SEM image of BC and b is the SEM image of N, S-BBC. 900 SEM image, c is N, S-BBC 900 SEM secondary electron substrate image, d is N, S-BBC 900 EDS element surface distribution diagram; Figure 2 For BC and N, S-BBC 900 XRD patterns; Figure 3 For BC and N, S-BBC 900 Nitrogen adsorption-desorption curves; Figure 4 For N, S-BBC 900 Effect curve of dosage on SMX adsorption efficiency and adsorption capacity; Figure 5 For N, S-BBC 900 Results of cyclical performance tests; Figure 6 For N, S-BBC 900 Comparison of removal efficiencies for pollutants MB, MO, CAP, CR and SMX; Figure 7 S-BBC after acid washing 700、 S-BBC 800 Adsorption curves for SMX; Figure 8 The adsorption curve of SMX on the polyethersulfone (PES) filter membrane is shown. Figure 9 For N, S-BBC 900 UV-Vis absorption spectrum of adsorbed SMX; Figure 10 The UV-Vis absorption spectrum of SMX adsorbed by N,S-MBC is shown. Detailed Implementation

[0017] Example 1 A method for preparing a modified sunflower seed shell biochar adsorbent includes the following steps: Step 1: Using sunflower seed shells as raw material, after washing with deionized water, dry at 60℃ for 20 hours. Then, crush the dried sample and pass it through a 60-mesh sieve. Step 2: Weigh 4g of sunflower seed shell powder and mix it evenly with 0.5g of thiourea; Step 3: Place the mixture in a ball mill and ball mill at 300 rpm for 30 minutes. Then, heat-treat the milled precursor under a nitrogen atmosphere by calcining at 920℃ for 1 hour at a heating rate of 5℃ / min to obtain nitrogen- and sulfur-co-doped modified sunflower seed shell biochar adsorbent, denoted as N,S-BBC. 920 .

[0018] Example 2 A method for preparing a modified sunflower seed shell biochar adsorbent includes the following steps: Step 1: Using sunflower seed shells as raw material, after washing with deionized water, dry at 80℃ for 24 hours. Then, crush the dried sample and pass it through a 60-mesh sieve. Step 2: Weigh 8g of sunflower seed shell powder and mix it evenly with 1.2g of thiourea; Step 3: Place the mixture in a ball mill and ball mill at 500 rpm for 50 minutes. Then, heat-treat the milled precursor under a nitrogen atmosphere by calcining at 950℃ for 3 hours at a heating rate of 15℃ / min to obtain nitrogen- and sulfur-co-doped modified sunflower seed shell biochar adsorbent, denoted as N,S-BBC. 950 .

[0019] Example 3 A method for preparing a modified sunflower seed shell biochar adsorbent includes the following steps: Step 1: Using sunflower seed shells as raw material, after washing with deionized water, dry at 70℃ for 28 hours. Then, crush the dried sample and pass it through a 60-mesh sieve. Step 2: Weigh 5g of sunflower seed shell powder and mix it evenly with 0.8g of thiourea; Step 3: Place the mixture in a ball mill and ball mill at 400 rpm for 40 minutes. Then, heat-treat the milled precursor under a nitrogen atmosphere by calcining at 900℃ for 2 hours at a heating rate of 10℃ / min to obtain nitrogen- and sulfur-co-doped modified sunflower seed shell biochar adsorbent, denoted as N,S-BBC. 900 .

[0020] Comparative Example 1 The difference from Example 3 is that the calcination temperature in step 3 is 700℃. That is, calcination at 700℃ for 2 hours yields the N,S-BBC material. 700 .

[0021] Comparative Example 2 The difference from Example 1 is that the calcination temperature in step 3 is 800℃. That is, calcination at 800℃ for 2 hours yields the N,S-BBC material. 800 .

[0022] Comparative Example 3 The difference from Example 3 is that thiourea is not added in step 2 and ball milling is not performed in step 3, resulting in unmodified biochar material (BC).

[0023] Comparative Example 4 The difference from Example 3 is that thiourea is not added in step 2, resulting in ball-milled biochar material (BBC).

[0024] Comparative Example 5 The only difference from Example 3 is that ball milling is not performed in step 3; instead, manual grinding and mixing are carried out. The resulting material is N,S-MBC.

[0025] Experimental Section Experiment 1 The adsorbents prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to SMX adsorption tests. The specific steps are as follows: 30 mg of adsorbent was weighed and placed in 30 mL of SMX solution with a concentration of 50 mg / L. The solution was stirred and adsorbed at 350 r / min. 2.5 mL of the solution was taken at 20 s intervals and filtered through a 0.22 μm aqueous filter membrane. The absorbance value was measured at 270 nm using a UV-Vis spectrophotometer, and the SMX concentration was calculated. At the same time, the adsorption performance of Comparative Examples 1-6 was tested as a control using the same steps. The adsorption capacity (1) and adsorption efficiency (2) were calculated using the following formulas: ; Where C0 represents the initial concentration of the pollutant, in mg / L; C t The concentration of pollutant at time t is expressed in mg / L; V represents the volume of pollutant in L; and m represents the mass of adsorbent in g. The adsorption efficiency and adsorption capacity results are shown in Table 1.

[0026] Table 1 Adsorption efficiency and adsorption capacity results

[0027] As shown in Table 1, the pyrolysis temperature has a decisive influence on the performance of the adsorbent in removing SMX. At temperatures of 700-800℃, Comparative Examples 1 and 2 showed no adsorption effect on SMX, with an adsorption efficiency of 0%, at calcination temperatures of 700℃ and 800℃. This is because the carbonization of the material is insufficient at lower temperatures, resulting in incomplete development of the specific surface area and pore structure, leading to a lack of surface active sites. When the temperature is 900-950℃, Examples 1-3 all showed a removal rate of over 99%. Among them, 900℃ (Example 3) achieved peak performance (99.6%, 49.8 mg / g), showing the best effect.

[0028] Comparing the results of Comparative Example 3 (BC, unmodified) and Comparative Example 4 (BBC, ball-milled only), it can be seen that ball milling alone has a very limited effect on improving adsorption performance. The SMX removal rate of BC was only 10.5%, while the removal rate of BBC after ball milling only increased to 17.1%, with adsorption capacities of 5.2 mg / g and 8.5 mg / g, respectively. This indicates that while mechanical ball milling can physically refine the particles to some extent and increase the exposed area, it cannot fundamentally change the surface chemical properties of biochar, and its effect on improving adsorption performance is extremely limited.

[0029] Comparing Comparative Examples 3 and 5, it can be seen that N and S doping significantly contribute to the adsorption performance. By simply mixing sunflower seed shell powder with thiourea and then pyrolyzing it, without ball milling, the SMX removal rate of N,S-MBC reached 77.0%, and the adsorption capacity reached 38.5 mg / g, a significant improvement compared to the BC group. This indicates that the nitrogen- and sulfur-containing functional groups introduced by heteroatom doping are the dominant factors in improving adsorption performance, and N and S co-doping can effectively regulate the surface electron density and active site density of biochar.

[0030] It should be emphasized that the actual removal rate of Example 3 reached 99.6%, which is much higher than that of Comparative Example 4, Comparative Example 5 and their superposition. This proves that the mechanochemical effect of ball milling promotes the uniform dispersion and embedding of thiourea in sunflower seed shell powder, and enables N and S heteroatoms to be more effectively incorporated into the carbon skeleton, forming richer active sites and a more stable co-doped structure. The two achieve a synergistic effect.

[0031] To investigate the materials obtained in Comparative Examples 1 and 2 (N, S-BBC) 700 、N、S-BBC 800 The reason why SMX has no adsorption effect can be explained by taking N and S-BBC samples respectively. 700 、N、S-BBC 800 Biochar samples were placed in beakers, and 1 mol / L HCl solution was added. The samples were ultrasonically washed at room temperature for 30 min, followed by repeated soaking and washing with deionized water until the pH of the filtrate was neutral. After drying, SMX adsorption kinetics were tested under the same adsorption conditions (30 mg adsorbent, 30 mL 50 mg / L SMX solution, stirring at 350 r / min, sampling at 0-120 s intervals), and adsorption curves were plotted simultaneously. Figure 7 Biochar N,S-BBC prepared by acid washing to remove ash and water washing to neutrality at 700℃ and 800℃ 700 、N、S-BBC 800 The biochar showed almost no adsorption of SMX throughout the 0-120s time period, with a removal rate approaching zero. This demonstrates that the complete failure of the adsorption performance of N,S co-doped biochar prepared by calcination at 700℃ and 800℃ was not caused by the ash from the raw materials clogging the pores, but rather by intrinsic structural defects in the material, such as insufficient carbonization of the biochar under low-temperature calcination conditions, incomplete development of the carbon skeleton, extremely low heteroatom doping insertion efficiency, and inherent lack of pore structure. Only when the calcination temperature is increased to 900-950℃, with full graphitization of the carbon skeleton, the formation of a large number of pore structures, and stable incorporation of N / S heteroatoms into the carbon skeleton, can the material possess excellent adsorption performance.

[0032] Figure 9 and Figure 10 N and S-BBC were shown respectively. 900The UV-Vis adsorption spectra of SMX with N,S-MBC are shown in the figure. As the contact time increases, the absorbance at each wavelength decreases significantly and synchronously, but the overall spectral profile and characteristic peak position (λmax) remain stable, and no obvious red shift / blue shift or new characteristic peaks are observed. In addition, the entire adsorption process reaches equilibrium within a very short time (2 min), and the significant decrease in characteristic peak intensity is consistent with the rapid kinetics of adsorption, thus ruling out a slow oxidative degradation mechanism.

[0033] In summary, N,S-BBC 900 The removal mechanism of SMX by N,S-MBC is mainly surface adsorption, with a relatively small contribution from degradation.

[0034] Experiment 2 To further reveal the structural reasons for the differences in adsorption performance, biochar (BC), which had the worst adsorption performance, and N,S-BBC, which had the best adsorption performance, were selected. 900 (Example 3) Morphology, crystal structure and pore structure were characterized.

[0035] Figure 1 For BC and N, S-BBC 900 SEM images and element distributions: a) SEM image of BC, showing a relatively flat surface with a regular circular pore structure; b) SEM image of N, S-BBC. 900 The SEM images show that, compared to BC, the surface is significantly rougher, with numerous wrinkles and lamellar stacking structures. This is due to the etching of the carbon skeleton by nitrogen- and sulfur-containing gases released during the pyrolysis of thiourea, resulting in a rich hierarchical porous structure; c represents N,S-BBC. 900 The SEM secondary electron substrate image clearly shows the overall morphology of the material's rough and wrinkled structure; d is the EDS elemental distribution map of N, S-BBC, which shows that C, O, N, and S elements are uniformly distributed on the material surface, confirming that N and S elements were successfully co-doped into the biochar framework.

[0036] Figure 2 For BC and N, S-BBC 900 The XRD patterns of both materials show two broadened diffraction peaks near 2θ≈22° and 43°, corresponding to the (002) crystal plane of amorphous carbon and the (100) crystal plane of graphitic carbon, respectively, indicating that the materials are generally amorphous carbon structures. Compared with BC, N,S-BBC 900 The (002) peak shifts to a higher diffraction angle and the peak intensity increases, indicating that after N and S co-doping modification, the interlayer spacing of carbon materials decreases and the structural order and graphitization degree are improved.

[0037] Figure 3 The diagram shows BC and N, S-BBC. 900The nitrogen adsorption-desorption curves were obtained. According to the IUPAC classification standard, the adsorption-desorption isotherms of both materials belong to type IV and exhibit a type H3 hysteresis loop, indicating that their pore structure is predominantly mesoporous. Figure 3 The calculated BET specific surface area and pore structure parameters show that the specific surface area of ​​BC is 2709.1 m². 2 / g, with an average pore size of 3.9nm; while N,S-BBC 900 The specific surface area increased to 3639.8 m². 2 / g, with an average pore size of 3.4 nm. Furthermore, micropore distribution comparison indicates N,S-BBC 900 The pore volume in the microporous region is significantly higher than that in BC. These results indicate that nitrogen and sulfur co-doping can synergistically increase the specific surface area of ​​biochar and enrich its microporous structure, thereby increasing adsorption active sites and enhancing the adsorption performance of the material.

[0038] Experiment 3 With N, S-BBC 900 Using [a specific adsorbent] as the target adsorbent, the effect of adsorbent dosage on the adsorption efficiency of SMX was investigated. The adsorbent dosages were 0.2 g / L, 0.5 g / L, 0.7 g / L, 1.0 g / L, and 1.2 g / L. Figure 4 It can be seen that as the adsorbent concentration increases, the adsorption efficiency gradually increases. The effects are good at 0.5 g / L, 0.7 g / L, 1.0 g / L and 1.2 g / L, and tend to the maximum value at 1.0 g / L. Therefore, the optimal adsorbent dosage is determined to be 1.0 g / L.

[0039] To further analyze the adsorption mechanism, the above experimental data were fitted using a pseudo-first-order kinetic model, a pseudo-second-order kinetic model, and an Elovich model. The model equations and related parameters are shown in Table 2.

[0040] Table 2 Model Equations and Related Parameters

[0041] The data fitting results are shown in Table 3.

[0042] Table 3 Data Fitting Results

[0043] Table 3 shows that the correlation coefficient R between the pseudo-second-order dynamics model and the Elovich model is... 2All values ​​were higher than those of the pseudo-first-order kinetic model and greater than 0.99 under different adsorbent dosages. This indicates that the adsorption process of SMX by the N,S-BBC prepared in this invention is not a simple physical adhesion, but rather a chemical adsorption-dominant process. Strong binding is achieved through chemical bonding forces such as hydrogen bonds, π-π conjugation, and functional group complexation. Furthermore, this process occurs in a heterogeneous reaction system with uneven energy distribution of surface active sites. Compared to simple physical adsorption, the chemical adsorption-dominant mechanism endows the material with more stable adsorption performance and stronger selective recognition ability. This conclusion is consistent with the surface wrinkles, rich microporous structure, and successful doping of nitrogen and sulfur heteroatoms observed in the material characterization, confirming that this invention effectively constructs a heterogeneous surface structure rich in chemically active sites through nitrogen and sulfur co-doping and ball milling synergistic modification, thereby significantly improving the adsorption performance of biochar for SMX.

[0044] Experiment 4 To examine the regeneration performance of the material, the used N,S-BBC was collected after each adsorption reaction. 900 The adsorbent was washed twice alternately with deionized water and anhydrous ethanol, centrifuged (8000 r / min), and dried at 65℃ for 3 hours before being used in the next adsorption reaction. The results of the recycling performance test are as follows: Figure 5 As shown, the results indicate that after three repeated uses, N,S-BBC 900 The adsorption efficiency remained stable; after the fourth and fifth cycles, the adsorption efficiency decreased to 87.9% and 59.8%, respectively. Under a nitrogen atmosphere, the sample after the fifth cycle was calcined at 900℃ for 2 hours (heating rate 10℃ / min), and the adsorption performance was restored. These results indicate that the material has good recyclability, stability, and regeneration performance.

[0045] Experiment 5 Given the presence of various recalcitrant pollutants in actual wastewater, this study investigates the N,S-BBC (Nitrogen, Sodium, and Biologically Oxygen) profile. 900 The adsorption advantages of the adsorbent for SMX, using N,S-BBC 900 As the adsorbent material, methylene blue (MB), methyl orange (MO), chloramphenicol (CAP), and cresol red (CR) at the same concentration were selected as control pollutants. Adsorption kinetics were tested in a single solute system. Samples were taken and measured at time points of 0, 20, 40, 60, 80, 100, and 120 s. The results are as follows: Figure 6 As shown, N,S-BBC 900It exhibits certain adsorption activity for SMX, MB, MO, CAP, and CR. Among them, the adsorption rate for SMX is significantly better than that for other pollutants, achieving almost complete adsorption and removal within 20 seconds. This can be attributed to the high degree of matching between the pore size structure of N,S-BBC and the kinetic size of SMX molecules, as well as the hydrogen bonding and π-π conjugation effects formed between the nitrogen-containing heterocycles and sulfonamide groups in SMX molecules and the functional groups on the adsorbent surface, which jointly enhance the adsorption performance.

[0046] Experiment 6 To eliminate data interference caused by SMX adsorption on the filter membrane and to verify N, S-BBC 900 The adsorption performance originates from the material itself. A blank control experiment was set up: without adding any adsorbent, 30 mL of a 50 mg / L SMX blank solution was prepared. The mixture was stirred at 350 r / min, and samples were taken at 0-120 s intervals. After filtration through a polyethersulfone (PES) aqueous filter membrane, the SMX concentration was measured. The results are as follows: Figure 8 As shown. By Figure 8 It can be seen that within the 120s test period, the concentration of the SMX solution remained essentially constant, and the adsorption and removal rate of SMX by the PES filter membrane was negligible. This demonstrates the N,S-BBC... 900 The SMX adsorption performance is due to the sunflower seed shell biochar itself, which is modified by nitrogen and sulfur co-doping, rather than the retention or adsorption effect of the filter membrane during the experiment.

Claims

1. The application of a modified sunflower seed shell biochar adsorbent in the removal of sulfamethoxazole from water, characterized in that, The modified sunflower seed shell biochar adsorbent is prepared by the following method: Step 1: Wash, dry, crush and sieve the sunflower seed shell raw material to obtain sunflower seed shell powder; Step 2: Mix the sunflower seed shell powder with thiourea evenly to obtain a mixture; the mass ratio of the sunflower seed shell powder to thiourea is (4-8):(0.5-1.2); Step 3: The mixture is ball-milled to obtain a ball-milling precursor; Step 4: The ball milling precursor is calcined at 900-950℃ in an inert gas atmosphere to obtain nitrogen and sulfur co-doped modified sunflower seed shell biochar adsorbent; the inert gas is nitrogen. The modified sunflower seed shell biochar adsorbent has recyclability, stability, and regeneration properties.

2. The application according to claim 1, characterized in that, In step 1, the drying temperature is 60-80℃, the drying time is 20-28 hours, and the sieve mesh size is 60 mesh.

3. The application according to claim 1, characterized in that, In step 3, the ball milling speed is 300-500 rpm and the ball milling time is 30-50 minutes.

4. The application according to claim 1, characterized in that, In step 4, the high-temperature calcination temperature is 900℃, the calcination time is 1-3 hours, and the heating rate is 5-15℃ / min.

5. The application according to claim 1, characterized in that, The modified sunflower seed shell biochar adsorbent was added to water containing sulfamethoxazole at a dosage of 0.5-1.2 g / L and an adsorption time of 20-120 seconds.

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