Preparation method and application of selenium and carbon double bond enriched torreya grandis shell biochar

Abstract

The application discloses a preparation method of selenium and carbon double bond rich modified torreya grandis shell biochar, which comprises the following steps of S1, raw material pretreatment and torreya grandis shell biochar preparation: after torreya grandis shells are pretreated by washing, drying and smashing, the torreya grandis shells are pyrolyzed and carbonized under an inert atmosphere at 500-700 DEG C, and after cooling, the torreya grandis shells are washed, dried, smashed, and torreya grandis shell biochar is obtained; and S2, nano selenium solution preparation: after a selenite solution and a surfactant solution are mixed and stirred, a reducing agent solution is added to perform a reduction reaction, and the reaction product is purified by dialysis to obtain a nano selenium dispersion solution.The application has the beneficial effects that: torreya grandis shell biochar is prepared by pyrolysis of agricultural and forestry waste torreya grandis shells, nano selenium is prepared by taking sodium dodecyl sulfate as a dispersion stabilizer, the obtained torreya grandis shell biochar and nano selenium solution are mixed and treated by magnetic stirring, selenium and carbon double bond rich modified torreya grandis shell biochar is prepared, and the selenium and carbon double bond rich modified torreya grandis shell biochar is applied to control and prevent the atrazine poisoning of pea seedlings.

Description

Technical Field

[0001] This invention relates to the field of agricultural and forestry waste resource utilization technology, specifically to a method for preparing and applying selenium- and carbon double bond-modified Torreya grandis shell biochar. Background Technology

[0002] Atrazine is a widely used triazine herbicide with high weed control efficiency. However, this substance has a long half-life and strong migration ability in the soil, and long-term application can easily cause soil residual pollution. Atrazine residues in the soil can induce oxidative stress in crops, hindering normal crop growth. At the same time, atrazine can be absorbed by crops and enter the food chain, posing a potential threat to human health. Therefore, the development of green and efficient atrazine toxicity control technology has become a research focus in the field of agricultural environment.

[0003] Biochar, with its large specific surface area, well-developed pore structure, and abundant surface functional groups, is widely used in the field of soil organic pollutant control. However, unmodified primary biochar relies solely on physical pore retention and weak polar interactions to fix pollutants, resulting in limited adsorption capacity. Moreover, the adsorption process is mostly a reversible reaction. Under complex environmental disturbances such as temperature fluctuations, rainwater leaching, and soil ion competition, the adsorbed pollutants are easily re-desorbed and released, causing harm. Modifying biochar can effectively improve its adsorption and fixation performance for pollutants.

[0004] Existing carbon-based selenium nanomaterials generally rely solely on physical methods such as van der Waals forces, electrostatic interactions, and pore trapping to load selenium nanoparticles. Stable covalent bonds are not formed between selenium and the biochar substrate, making the selenium nanoparticles easily oxidized by soil moisture, releasing selenium ions. Furthermore, from a mechanism perspective, these materials have two limitations: firstly, relying solely on pore physical trapping to fix pollutants lacks irreversible fixation capacity, and adsorbed pollutants are easily released again; secondly, material performance depends on the slow release of free selenium ions from the selenium nanoparticles. The method of this invention constructs a large number of stable selenium-carbon double bonds on biochar. These selenium-carbon double bonds possess strong electron-donating capabilities, acting as strong π-electron donors. Atrazine contains highly electronegative nitrogen atoms, which can act as π-electron acceptors. Electron transfer occurs between the two, resulting in π-π stacking interactions and forming a stable conjugated stacked structure, achieving irreversible adsorption of atrazine. Existing research has not reported on the construction of a large number of stable selenium-carbon double bonds on selenium nanoparticle-modified biochar, nor on its application in controlling the toxicity of plant organic pollutants. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a method for preparing and applying selenium-carbon double bond-modified Torreya grandis shell biochar, so as to solve the problems mentioned in the background art.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar, comprising:

[0008] S1. Raw material pretreatment and preparation of Torreya grandis shell biochar: Torreya grandis shells are pretreated by washing, drying and crushing, and then pyrolyzed and carbonized at 500~700℃ under an inert atmosphere. After cooling, they are washed, dried and crushed to obtain Torreya grandis shell biochar.

[0009] S2. Preparation of nano-selenium solution: After mixing and stirring the selenite solution and the surfactant solution, a reducing agent solution is added to carry out a reduction reaction. The reaction product is purified by dialysis to obtain a nano-selenium dispersion.

[0010] S3. Preparation of nano-selenium modified Torreya grandis shell biochar: The Torreya grandis shell biochar obtained in S1 and the nano-selenium dispersion obtained in S2 were mixed and stirred in an aqueous system at room temperature to form selenium-carbon double bonds with the carbon sites on the surface of the biochar. After solid-liquid separation, the mixture was washed and dried to obtain Torreya grandis shell biochar rich in selenium-carbon double bonds.

[0011] In some embodiments, step S1 includes rinsing the torreya nut shells three times with deionized water, drying them at 105 °C for 8 hours, then pulverizing them with a pulverizer and passing them through a 20-mesh nylon sieve, and finally placing the torreya nut shells in a muffle furnace at a 0.1 m... 3 Nitrogen gas was introduced into the furnace at a rate of 1 h, and the heating rate was controlled at 5 ℃ / min. After heating to 600℃, the sample was calcined at a constant temperature for 2 h. After the sample cooled naturally, the black solid was collected, rinsed repeatedly with deionized water, and then dried in an 80℃ oven. The dried solid was pulverized and passed through a 100-mesh nylon sieve to obtain Torreya grandis shell biochar.

[0012] In some embodiments, S2 includes mixing 20 ml of 0.04 mol / L sodium selenite solution with 50 ml of 0.8 g / L sodium dodecyl sulfate solution, stirring magnetically at 180 r / min for 8 h, adding 30 ml of 0.1 mol / L ascorbic acid solution after stirring, reacting for 0.5 h, and then placing the resulting solution into a MW 3500 Da dialysis bag. The dialysis bag is then placed in a 3 L beaker filled with deionized water and stirred magnetically at 800 r / min for dialysis. After dialysis for 48 h, a nano-selenium solution is obtained.

[0013] In some embodiments, step S3 includes taking 100g of Torreya grandis shell biochar obtained in step one, soaking it in a mixture of 2 ml of nano-selenium solution prepared in step two and 500 ml of deionized water, and magnetically stirring at 400 r / min for 2 h at room temperature. After stirring, the solid is filtered to obtain a solid, which is then washed with deionized water. The washed solid is then placed in an 80°C oven and dried to constant weight to obtain selenium-carbon double bond modified Torreya grandis shell biochar.

[0014] In some embodiments, during S1, nitrogen is continuously introduced into the muffle furnace to isolate the air throughout the roasting process, thereby preventing the high-temperature oxidation of the Torreya grandis shell from damaging the aromatic carbon structure and ensuring the number of carbon sites on the surface of the biochar that can participate in the formation of selenium-carbon double bonds.

[0015] In some embodiments, during S2, the entire process of raw material mixing, chemical reaction, and dialysis is carried out in a light-proof and sealed environment to prevent the nano-selenium particles from agglomerating and failing, and to ensure that the nano-selenium particles have uniform particle size and good dispersion. During the dialysis process, deionized water is continuously replaced to remove residual inorganic ions and reaction byproducts in the solution, thereby improving the purity of the nano-selenium solution and avoiding impurities from interfering with subsequent bonding reactions.

[0016] In some embodiments, the magnetic stirring speed is constantly controlled at 400 r / min in S3. By stirring at a uniform speed and in a stable manner, the nano-selenium is uniformly modified onto the biochar, thereby improving the overall uniformity of the modified material's properties.

[0017] In some embodiments, unpolluted farmland soil is selected, and atrazine is added to 150g of soil at a ratio of 0.8 mg / kg. Then, nano-selenium-modified Torreya grandis shell biochar prepared according to claim 1 is added at a ratio of 2% of the soil mass. After thorough mixing, the mixture is placed in a cultivation pot with an inlet diameter of 8.8cm and a height of 7.6cm for later use.

[0018] In some embodiments, the method also includes pea seedling sowing and transplanting steps: select plump, uniformly sized, fast-growing, hairless pea seedlings, soak them in water at room temperature for 8 hours to promote germination; after the seedlings have grown their second true leaves, transplant 3 pea seedlings per pot in an equilateral triangle arrangement with sides of 6cm.

[0019] In some embodiments, the cultivation management steps are also included: placing the transplanted cultivation pots in a light cultivation room for cultivation, with the ambient temperature set to a stable 25°C, adopting a 16-hour light and 8-hour dark cycle light regime, and performing routine water management daily, and cultivating continuously for 14 days to complete the cultivation of pea seedlings and the control of atrazine poisoning in the soil.

[0020] Compared with existing technologies, this invention provides a method for preparing selenium-carbon double-bond modified Torreya grandis shell biochar. This method utilizes nano-selenium-modified Torreya grandis shell biochar to construct a large number of stable selenium-carbon double bonds on the biochar. These selenium-carbon double bonds possess strong electron-donating capabilities, acting as strong π-electron donors. Atrazine contains highly electronegative nitrogen atoms, which can act as π-electron acceptors. Electron transfer occurs between the two, resulting in π-π stacking interactions and forming a stable conjugated stacked structure, thus achieving the desired effect on atrazine. Reversible adsorption; the selenium-rich carbon double bond-modified Torreya grandis shell biochar prepared by this invention can significantly reduce the content of desorbable (highly active) atrazine in the soil, increase the proportion of non-desorbable (low-risk) atrazine, and reduce the absorption and accumulation of atrazine by pea seedlings; at the same time, it can significantly alleviate the plant hydrogen peroxide accumulation and membrane lipid peroxidation damage caused by atrazine stress, eliminate the inhibitory effect of atrazine on pea seedling growth, and increase crop yield. The control effect is significantly better than that of unmodified Torreya grandis shell biochar. Attached Figure Description

[0021] Figure 1 These are scanning electron microscope images of Torreya grandis shell biochar (TSB) and nano-selenium modified Torreya grandis shell biochar (SeNPs@TSB) provided in the embodiments of the present invention, wherein a is a microscopic morphology image of TSB and b is a microscopic morphology image of SeNPs@TSB.

[0022] Figure 2 The X-ray photoelectron spectra of TSB and SeNPs@TSB provided in this embodiment of the invention are as follows: A is the high-resolution C1s spectrum of TSB, B is the high-resolution Se3d spectrum of TSB, C is the high-resolution C1s spectrum of SeNPs@TSB, and D is the high-resolution Se3d spectrum of SeNPs@TSB.

[0023] Figure 3 These are the Fourier transform infrared spectra of TSB and SeNPs@TSB provided in the embodiments of the present invention;

[0024] Figure 4 This is a comparison diagram of the adsorption characteristics of atrazine on soil, TSB-soil and SeNPs@TSB-soil provided in the embodiments of the present invention, where A is the adsorption kinetic curve of atrazine, B is the equilibrium unit adsorption capacity, and C is the desorption rate of atrazine.

[0025] Figure 5 These are phenotypic photos of pea seedlings from different treatment groups provided in the embodiments of the present invention;

[0026] Figure 6 This is a comparison chart of the growth indicators of pea seedlings in different treatment groups provided in the embodiments of the present invention, where A is plant height, B is aboveground fresh weight, C is root fresh weight, and D is total fresh weight.

[0027] Figure 7This is a comparison chart of atrazine content in pea seedlings from different treatment groups provided in this embodiment of the invention;

[0028] Figure 8 This is a comparison chart of oxidative damage indices of pea seedlings in different treatment groups provided in the embodiments of the present invention, where A represents hydrogen peroxide content and B represents malondialdehyde content;

[0029] Figure 9 This is a comparison chart of the content of different forms of atrazine in soil under different treatment groups provided in the embodiments of the present invention, where A is the content of desorbable atrazine in the soil, B is the content of non-desorbable atrazine in the soil, and C is the total atrazine content in the soil. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] Example 1: Preparation of Selenium-Rich Carbon Double Bond Modified Torreya grandis Shell Biochar

[0032] Step 1: Raw material pretreatment and preparation of Torreya grandis shell biochar. The Torreya grandis shells were rinsed three times with deionized water, dried at 105℃ for 8 hours, then pulverized using a pulverizer and passed through a 20-mesh nylon sieve. The Torreya grandis shells were then placed in a muffle furnace at a 0.1 m... 3 Nitrogen gas was introduced into the furnace at a rate of 1 h, and the heating rate was controlled at 5 °C / min. After heating to 600 °C, the sample was calcined at a constant temperature for 2 h. After the sample cooled naturally, the black solid was collected, rinsed repeatedly with deionized water, and then dried in an 80 °C oven. The dried solid was pulverized and passed through a 100-mesh nylon sieve to obtain Torreya grandis shell biochar (TSB).

[0033] Step 2: Preparation of nano-selenium solution. 20 ml of 0.04 mol / L sodium selenite solution was mixed with 50 ml of 0.8 g / L sodium dodecyl sulfate solution and magnetically stirred at 180 r / min for 8 h. After stirring, 30 ml of 0.1 mol / L ascorbic acid solution was added, and the reaction was allowed to proceed for 0.5 h. The resulting solution was then placed in a 3L dialysis bag (MW 3500Da), and the bag was placed in a 3L beaker filled with deionized water and magnetically stirred at 800 r / min for dialysis. After dialysis for 48 h, the nano-selenium solution was obtained. The particle size of the prepared nano-selenium was characterized using a Baxter nanoparticle size analysis system. The results showed that the Z-average particle size of the obtained nano-selenium was 73.22 ± 0.39 nm, which is within the typical nanoscale range and conforms to the particle size characteristics of nanoparticles.

[0034] Step 3: Preparation of nano-selenium modified Torreya grandis shell biochar. Take 100 g of Torreya grandis shell biochar obtained in Step 1 and soak it in a mixture of 2 ml of nano-selenium solution prepared in Step 2 and 500 ml of deionized water. Stir magnetically at 400 r / min for 2 h at room temperature. After stirring, filter to obtain solid. Wash the solid with deionized water and dry it in an 80℃ oven to constant weight to obtain selenium-carbon double bond modified Torreya grandis shell biochar (SeNPs@TSB).

[0035] Example 2: Atrazine-contaminated soil improvement and pea seedling cultivation (ATZ-SeNPs@TSB group)

[0036] Soil treatment steps: Select unpolluted farmland soil, add atrazine to 150 g of soil at a ratio of 0.8 mg / kg, and then add nano-selenium modified Torreya grandis shell biochar prepared in Example 1 at a ratio of 2% of soil mass. After thorough mixing, put it into a cultivation pot with an inlet diameter of 8.8 cm and a height of 7.6 cm for later use.

[0037] Pea sprout sowing and transplanting steps: Select plump, uniformly sized, fast-growing, hairless pea sprout seeds and soak them in clean water at room temperature for 8 hours to promote germination; after the seedlings have grown their second true leaves, transplant 3 pea sprouts per pot in an equilateral triangle arrangement with sides of 6cm.

[0038] Cultivation and management steps: Place the transplanted pots in a light-incubation room and keep the ambient temperature stable at 25℃. Use a 16-hour light and 8-hour dark cycle light regime and routine water management. Cultivate continuously for 14 days to complete pea seedling cultivation and control of atrazine and toxicity in the soil.

[0039] Comparative Example 1: Unmodified Torreya grandis shell biochar group (ATZ-TSB group)

[0040] The sowing, transplanting, and cultivation management steps of pea seedlings in this comparative example are completely consistent with those in Example 2. The only difference is that the soil treatment step involves selecting unpolluted farmland soil, adding atrazine to 150 g of soil at a ratio of 0.8 mg / kg, and then adding the Torreya grandis shell biochar prepared in Example 1 at a ratio of 2% of the soil mass. After thorough mixing, the mixture is placed in a cultivation pot with an opening diameter of 8.8 cm and a height of 7.6 cm for later use.

[0041] Comparative Example 2: Blank Stress Group (ATZ Group)

[0042] The sowing, transplanting, and cultivation management steps of pea seedlings in this comparative example are completely consistent with those in Example 2. The only difference is that the soil treatment step involves selecting unpolluted farmland soil, adding atrazine to 150 g of soil at a ratio of 0.8 mg / kg, mixing thoroughly, and then filling a cultivation pot with an inlet diameter of 8.8 cm and a height of 7.6 cm for later use.

[0043] Comparative Example 3: Blank Control Group (CK Group)

[0044] The sowing, transplanting, and cultivation management steps of pea seedlings in this comparative example are completely consistent with those in Example 2. The only difference is that the soil treatment step involves selecting unpolluted farmland soil, thoroughly mixing it, and then filling it into a cultivation pot with an inlet diameter of 8.8 cm and a height of 7.6 cm for later use.

[0045] Test Example 1

[0046] The surface morphology and pore structure of biochar and modified biochar were observed using scanning electron microscopy (SEM); the elemental composition and mass fraction of the materials were analyzed using an elemental analyzer; the surface functional groups of the materials were identified by Fourier transform infrared spectroscopy (FTIR); and the proportion of Se=C chemical bonds was analyzed by X-ray photoelectron spectroscopy (XPS).

[0047]

[0048] Table 1 Physicochemical properties of biochar

[0049] As shown in Table 1, the physicochemical properties of biochar show that compared with TSB, the C and H contents of SeNPs@TSB are reduced, while the O content is increased, indicating that the aromatization degree of SeNPs@TSB is improved and more oxygen-containing functional groups are introduced. At the same time, the selenium content of the material is increased from 1.08 mg / kg to 41.89 mg / kg, proving that nano-selenium is successfully loaded on the surface of biochar.

[0050] Figure 1 Scanning electron microscopy (SEM) results showed that TSB has a regular porous structure with clear macropores and smooth, intact pore walls; nanoscale white particles are uniformly distributed on the surface of SeNPs@TSB, proving that the nano-selenium particles are uniformly and stably modified onto biochar.

[0051] Figure 2 X-ray photoelectron spectroscopy (XPS) analysis showed that the proportion of Se=C bonds in the original TSB was only 7.25%, and the selenium element was mostly in a weakly bound state. After modification with nano-selenium, the proportion of Se=C bonds in SeNPs@TSB increased significantly to 24.50%, proving that nano-selenium and biochar substrate formed a large number of stable selenium-carbon double bonds.

[0052] Figure 3 Fourier transform infrared (FTIR) spectroscopy analysis showed that TSB and SeNPs@TSB were at 3400 cm⁻¹ -1 2900cm -1 1600cm -1 1100cm -1Characteristic absorption peaks appeared at all locations, corresponding to the stretching vibrations of -OH, aliphatic CH, aromatic C=O, and CO, respectively; compared with TSB, the modified SeNPs@TSB showed a higher absorption peak at 680 cm⁻¹. -1 The presence of a new Se-OC characteristic absorption peak indicates that nano-selenium forms a chemical bond with biochar.

[0053] Test Example 2

[0054] Biochar adsorption and desorption experiments of nano-selenium-modified Torreya grandis shell biochar in soil:

[0055] Adsorption experiment: 5.00 g of soil, 5.00 g of soil with 2% (mass ratio) TSB, and 5.00 g of soil with 2% (mass ratio) SeNPs@TSB were weighed and added to 50 mL centrifuge tubes. 25 mL of atrazine solution with a background of 0.01 mol / L calcium chloride and a concentration of 1.6 mg / L was added. The tubes were sealed and placed in a constant-temperature shaking incubator at 25℃ and 180 rpm in the dark. The centrifuge tubes were removed at 4h, 12h, 24h, and 36h, and centrifuged at 4000 r / min for 10 min. The supernatant was filtered through a 0.22 μm organic filter membrane. The atrazine content was determined by high-performance liquid chromatography (HPLC). The mobile phase was a methanol-water mixture (70:30, v / v), the flow rate was 0.8 mL / min, the temperature was 40℃, and the detection wavelength was 225 nm.

[0056] Desorption experiment: The supernatant in the centrifuge tube corresponding to 36h was poured out, and 25 mL of 0.01 mol / L calcium chloride solution was added. After sealing, the tube was placed in a constant temperature shaking shaker and shaken continuously at 25℃ and 180 rpm in the dark for 36h. After centrifugation at 4000 r / min for 10min, the supernatant was filtered through a 0.22μm organic filter membrane, and the atrazine content was determined by high performance liquid chromatography (HPLC).

[0057] Figure 4Adsorption kinetics curves showed that both types of biochar-treated soil exhibited an adsorption characteristic of "rapid adsorption to slow equilibrium" for atrazine. The equilibrium adsorption capacity of atrazine showed that the equilibrium adsorption capacity of the three soil groups was SeNPs@TSB-soil > TSB-soil > soil, with significant differences between groups. The desorption test results showed that the desorption rate of atrazine in soil was in the order of soil > TSB-soil > SeNPs@TSB-soil. There was a significant difference between the desorption rates of TSB-soil and SeNPs@TSB-soil. The core mechanism is that after the Torreya grandis shell biochar was modified with nano-selenium, a large number of stable selenium-carbon double bonds were constructed on the biochar. The selenium-carbon double bonds have a strong electron-donating capacity and can act as strong π electron donors. Atrazine contains highly electronegative nitrogen atoms, which can act as π electron acceptors. Electron transfer occurs between the two, resulting in π-π stacking interaction and forming a stable conjugated stacked structure, which realizes the irreversible adsorption of atrazine.

[0058] Test Example 3

[0059] Plant height was measured using a ruler, and fresh weight was weighed using an electronic analytical balance.

[0060] Hydrogen peroxide (H2O2) content was detected using the Beijing Solarbio Hydrogen Peroxide Content Detection Kit, and malondialdehyde (MDA) content was determined using the thiobarbituric acid (TBA) colorimetric method: 0.2 g of fresh leaves were taken, 4 mL of 10% trichloroacetic acid was added, and the mixture was thoroughly ground. The mixture was centrifuged at 4000 r / min for 10 min to obtain the supernatant. 2 mL of the supernatant was mixed with 2 mL of 0.6% TBA solution, boiled in a water bath for 10 min, and then rapidly cooled. The mixture was centrifuged again at 1800 r / min for 8 min. Using distilled water as a blank control, the absorbance values ​​of the supernatant at 450 nm and 532 nm were measured, and the results were expressed using the formula C = 6.45 × OD. 532 -0.56×OD 450 The MDA concentration of the extract was calculated, and finally, the MDA content per unit fresh weight of leaves was calculated by combining the extract volume and the fresh weight of the sample.

[0061] Atrazine content determination in plants: 0.5 g of plant sample was weighed and placed in a 50 mL centrifuge tube. 5 mL of n-hexane-acetone mixed solution (volume ratio 1:1) was added. The mixture was ultrasonically extracted for 30 min. The extract was centrifuged at 10,000 rpm for 15 min. The supernatant and plant residue were separated. The supernatant was filtered through a 0.22 μm organic filter membrane. The atrazine content was determined by high performance liquid chromatography (HPLC).

[0062] Determination of desorbable (water-soluble) atrazine in soil: Weigh 8.00 g of air-dried soil, place it in a 50 mL centrifuge tube, add 10 mL of ultrapure water, and shake at 25℃ and 180 rpm for 4 h. After shaking, centrifuge, and filter the supernatant through a 0.22 μm organic filter membrane. Determine the content of desorbable atrazine using high performance liquid chromatography (HPLC). Determination of non-desorbable (organically extractable) atrazine in soil: Air-dry the soil sample from which desorbable atrazine has been extracted, add 10 mL of acetonitrile solution, and incubate at 25℃ and 180 rpm for 4 h. Shake at rpm for 4 hours, centrifuge after shaking, and filter the supernatant through a 0.22 μm organic filter membrane. Determine the content of non-desorbable atrazine by high performance liquid chromatography (HPLC). Calculation of total atrazine content in soil: The total atrazine content in soil is the sum of the content of desorbable atrazine and the content of non-desorbable atrazine.

[0063] from Figure 5 The plant phenotypic photos show that, compared to the CK group, the addition of atrazine to the ATZ group inhibited the growth of pea seedlings. The ATZ-TSB and ATZ-SeNPs@TSB groups grew better than the ATZ group. Among them, the growth status of the ATZ-SeNPs@TSB group recovered to the level of the CK group. Therefore, it is preliminarily inferred that both TSB and ATZ-SeNPs@TSB can effectively alleviate the growth inhibition effect of atrazine on pea seedlings, and the alleviating effect of nano-selenium modified Torreya grandis shell biochar is more prominent.

[0064] from Figure 6 It can be seen that under atrazine stress, the plant height, aboveground fresh weight, and total fresh weight of pea seedlings in the ATZ group decreased significantly, while the root fresh weight had no significant effect. The TSB treatment resulted in pea seedling height that was significantly higher than that in the ATZ group but significantly lower than that in the CK group. The aboveground fresh weight was not significantly different from that in the CK group, and the total fresh weight could be restored to the same level as that in the CK group, confirming that TSB can alleviate the inhibitory effect of atrazine on pea seedling growth to a certain extent. The plant height of the SeNPs@TSB group was restored to the level of the CK group, and the aboveground fresh weight and total fresh weight were significantly higher than those in the CK group, indicating that nano-selenium modification can significantly enhance the inhibitory effect of biochar on atrazine toxicity and can further promote the accumulation of pea seedling biomass.

[0065] from Figure 7 It can be seen that the ATZ group had the highest atrazine accumulation in pea seedlings, posing a significant food safety risk; TSB treatment could reduce the absorption and accumulation of atrazine by crops to a certain extent; the SeNPs@TSB treatment group had the lowest atrazine content in pea seedlings, with the best effect in controlling pollutant accumulation, which could effectively ensure the safe production of pea seedlings.

[0066] from Figure 8It can be seen that, compared with the CK group, the H2O2 and MDA contents in the ATZ group were significantly increased, indicating that atrazine stress induced a large accumulation of hydrogen peroxide in the plants, exacerbating cell membrane lipid peroxidation damage. After applying ATZ-TSB, the H2O2 and MDA contents decreased significantly compared with the ATZ group, but were still significantly higher than those in the CK group, indicating that TSB can alleviate atrazine-induced oxidative stress damage to some extent. Furthermore, ATZ-SeNPs@TSB treatment can further significantly downregulate the H2O2 and MDA contents, restoring both indicators to levels that are not significantly different from those in the CK group, proving that nano-selenium modification can significantly enhance the mitigation efficacy of Torreya grandis shell biochar against atrazine-induced oxidative damage.

[0067] from Figure 9 It can be seen that both biochar treatments significantly reduced the content of atrazine in the soil, with the ATZ-SeNPs@TSB group showing the most significant reduction. This indicates that SeNPs@TSB has the best risk reduction effect. SeNPs@TSB can significantly increase the proportion of non-desorbable atrazine in the soil, and strengthens the irreversible retention of atrazine in the soil through physical adsorption and chemical combination, thereby reducing the risk of secondary release. Biochar does not reduce the total atrazine residue in the soil, but rather achieves the transformation of atrazine from a highly bioavailable form to a low-risk form by regulating the pollutant form.

[0068] In summary, after modification with nano-selenium, Torreya grandis shell biochar exhibits a large number of stable selenium-carbon double bonds. These double bonds possess strong electron-donating capabilities, acting as strong π-electron donors. Atrazine contains highly electronegative nitrogen atoms, which can act as π-electron acceptors. Electron transfer occurs between the two, resulting in π-π stacking interactions and forming a stable conjugated stacked structure, achieving irreversible adsorption of atrazine. Applying this modified biochar to atrazine-contaminated soil significantly reduces the content of available atrazine in the soil, decreasing the absorption and accumulation of atrazine by crops. Simultaneously, it significantly alleviates the hydrogen peroxide accumulation and membrane lipid peroxidation damage caused by atrazine stress, eliminates the inhibitory effect of atrazine on pea seedling growth, and increases crop yield. The control effect is significantly better than that of unmodified Torreya grandis shell biochar.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0070] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar, characterized in that, include: S1. Raw material pretreatment and preparation of Torreya grandis shell biochar: Torreya grandis shells are pretreated by washing, drying and crushing, and then pyrolyzed and carbonized at 500~700℃ under an inert atmosphere. After cooling, they are washed, dried and crushed to obtain Torreya grandis shell biochar. S2. Preparation of nano-selenium solution: After mixing and stirring the selenite solution and the surfactant solution, a reducing agent solution is added to carry out a reduction reaction. The reaction product is purified by dialysis to obtain a nano-selenium dispersion. S3. Preparation of nano-selenium modified Torreya grandis shell biochar: The Torreya grandis shell biochar obtained in S1 and the nano-selenium dispersion obtained in S2 were mixed and stirred in an aqueous system at room temperature to form selenium-carbon double bonds with the carbon sites on the surface of the biochar. After solid-liquid separation, the mixture was washed and dried to obtain Torreya grandis shell biochar rich in selenium-carbon double bonds.

2. The method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar according to claim 1, characterized in that: S1 includes rinsing the torreya nut shells three times with deionized water, drying them at 105 °C for 8 hours, then pulverizing them with a pulverizer and passing them through a 20-mesh nylon sieve. The torreya nut shells are then placed in a muffle furnace and heated at 0.1 m... 3 Nitrogen gas was introduced into the furnace at a rate of 1 h, and the heating rate was controlled at 5 ℃ / min. After heating to 600 ℃, the sample was calcined at a constant temperature for 2 h. After the sample cooled naturally, the black solid was collected, rinsed repeatedly with deionized water, and then dried in an 80 ℃ oven. The dried solid was pulverized and passed through a 100-mesh nylon sieve to obtain Torreya grandis shell biochar.

3. The method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar according to claim 2, characterized in that: S2 involves mixing 20 ml of 0.04 mol / L sodium selenite solution with 50 ml of 0.8 g / L sodium dodecyl sulfate solution, stirring magnetically at 180 r / min for 8 h, adding 30 ml of 0.1 mol / L ascorbic acid solution after stirring, reacting for 0.5 h, and then placing the resulting solution into a MW 3500Da dialysis bag. The dialysis bag is then placed in a 3L beaker filled with deionized water and stirred magnetically at 800 r / min for dialysis. After dialysis for 48 h, a nano-selenium solution is obtained.

4. The method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar according to claim 3, characterized in that: S3 involves taking 100g of Torreya grandis shell biochar obtained in step one, soaking it in a mixture of 2 ml of nano-selenium solution prepared in step two and 500 ml of deionized water, and magnetically stirring at 400 r / min for 2 hours at room temperature. After stirring, the solid is filtered to obtain a solid, which is then washed with deionized water. The washed solid is then placed in an 80℃ oven and dried to constant weight to obtain selenium-carbon double bond modified Torreya grandis shell biochar.

5. The method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar according to claim 4, characterized in that: In S1, nitrogen is continuously introduced into the muffle furnace during the entire roasting process to isolate the air, thereby preventing the high-temperature oxidation of the Torreya grandis shell from damaging the aromatic carbon structure and ensuring the number of carbon sites on the surface of the biochar that can participate in the formation of selenium-carbon double bonds.

6. The method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar according to claim 5, characterized in that: In S2, the entire process of raw material mixing, chemical reaction, and dialysis is carried out in a light-proof and sealed environment to prevent the nano-selenium particles from agglomerating and failing, and to ensure that the nano-selenium particles have uniform particle size and good dispersion. During the dialysis process, deionized water is continuously replaced to remove residual inorganic ions and reaction byproducts in the solution, improve the purity of the nano-selenium solution, and avoid impurities interfering with subsequent bonding reactions.

7. The method for preparing selenium-rich carbon double bond modified Torreya grandis shell biochar according to claim 6, characterized in that: In step S3, the magnetic stirring speed is constantly controlled at 400 r / min. Through uniform and stable stirring, the nano-selenium is uniformly modified onto the biochar, thereby improving the overall uniformity of the modified material's properties.

8. The application of selenium-rich carbon double bond-modified Torreya grandis shell biochar prepared by the method according to any one of claims 1-7 in controlling atrazine poisoning in pea seedlings, characterized in that: The process includes a soil treatment step, in which uncontaminated farmland soil is selected, atrazine is added to 150 g of soil at a ratio of 0.8 mg / kg, and nano-selenium-modified Torreya grandis shell biochar prepared according to claim 1 is added at a ratio of 2% of the soil mass. After thorough mixing, the mixture is placed in a cultivation pot with an opening diameter of 8.8 cm and a height of 7.6 cm for later use.

9. The application of selenium-rich carbon double bond-modified Torreya grandis shell biochar according to claim 8 in controlling atrazine toxicity in pea seedlings, characterized in that: It also includes the steps of sowing and transplanting pea seedlings. Select plump, uniformly sized, fast-growing, hairless pea seedlings and soak them in water at room temperature for 8 hours to promote germination. After the seedlings have grown their second true leaves, transplant 3 pea seedlings per pot in an equilateral triangle arrangement with sides of 6cm.

10. The application of selenium-rich carbon double bond-modified Torreya grandis shell biochar according to claim 9 in controlling atrazine toxicity in pea seedlings, characterized in that: It also includes cultivation management steps, placing the transplanted cultivation pots in a light cultivation room, setting the ambient temperature to a stable 25 ℃, adopting a 16-hour light and 8-hour dark cycle light and dark system, and carrying out routine water management. After 14 days of continuous cultivation, the pea seedlings are cultivated and the soil atrazine poisoning is controlled.

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