Composite material for repairing antimony-polluted soil and increasing rice yield as well as preparation method and application of composite material

Abstract

The invention discloses a composite material for repairing antimony-polluted soil and increasing rice yield and a preparation method and application thereof, and belongs to the technical field of polluted soil repairing. The biochar is applied to the antimony-polluted soil and the zinc oxide nanoparticles are sprayed on the leaf surfaces of the rice, so that the toxicity of antimony can be relieved in multiple ways, the effectiveness of antimony in the soil is remarkably reduced, the absorption and accumulation of antimony by the rice are reduced, meanwhile, a plant antioxidant defense system is activated, the activity of antioxidant enzyme is improved, and the expression of related genes is regulated and controlled; the method has the advantages that the antimony-contaminated soil can be effectively degraded, oxidative damage can be relieved, soil microenvironment can be improved, nutrient effectiveness and enzyme activity can be enhanced, photosynthesis and root development of the rice can be promoted, yield increase can be ultimately realized, the synergistic strategy is efficient and environment-friendly, limitation of application of single materials can be broken through, and an innovative method is provided for remediation of the antimony-contaminated soil and agricultural sustainable development.

Description

Technical Field

[0001] This invention relates to the field of contaminated soil remediation technology, and in particular to composite materials for remediating antimony-contaminated soil and increasing rice yield, as well as their preparation methods and applications. Background Technology

[0002] Rice is the staple food of nearly half the world's population. However, because rice is grown in flooded, anaerobic environments, it easily accumulates antimony. Rice is one of the main sources of antimony ingested by humans, posing a significant threat to human health. Therefore, remediating antimony-contaminated soil is a formidable challenge, and there is an urgent need to develop effective measures to mitigate antimony toxicity and ensure safe and sustainable crop production. Currently, there are numerous reports on the role of biochar in mitigating antimony toxicity, but the role of nanoparticles in mitigating antimony toxicity remains poorly understood. Only one study has explored the effects of selenium nanoparticles on mitigating antimony stress. Furthermore, no research has yet focused on the combined use of biochar and zinc oxide nanoparticles in mitigating antimony toxicity.

[0003] Based on existing technologies, traditional antimony-contaminated soil remediation techniques mainly rely on single amendments such as biochar or nanoparticles, but these have significant drawbacks: while biochar can partially adsorb antimony, its remediation efficiency is limited and inhibited by soil acidity; nanoparticles are costly, may pose secondary environmental risks, and their single application cannot comprehensively regulate plant physiological responses. Existing methods lack multi-target synergistic mechanisms, making it difficult to simultaneously optimize soil physicochemical properties and plant stress resistance, resulting in incomplete antimony toxicity mitigation and insufficient crop yield improvement. In particular, research on the combined application of biochar and zinc oxide nanoparticles is lacking, limiting the comprehensiveness of remediation effects. Therefore, this invention proposes a composite material for remediating antimony-contaminated soil and increasing rice yield, along with its preparation method and application, to address the problems existing in current technologies. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to propose a composite material for remediating antimony-contaminated soil and increasing rice yield, along with its preparation method and application. Utilizing the synergistic effect of biochar and zinc oxide nanoparticles, this invention promotes chlorophyll synthesis, enhances antioxidant enzyme activity, increases the synthesis of hormones and osmotic regulators, and promotes root iron film formation. Simultaneously, it reduces oxidative damage, decreases soil antimony availability and plant antimony accumulation, thereby mitigating the adverse effects of antimony and increasing rice yield.

[0005] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a composite material for remediating antimony-contaminated soil and increasing rice yield, comprising biochar and zinc oxide nanoparticles, wherein the biochar and zinc oxide nanoparticles are in independent physical forms before application and are applied separately during use.

[0006] A further improvement is that the biochar is prepared from rice straw under oxygen-limited conditions at a pyrolysis temperature of 450–550℃, with a pH value of 9.0–11.0 and a cation exchange capacity of not less than 10 cmol / kg. The biochar has a porous structure, and its surface functional groups include hydroxyl and carboxyl groups. Scanning electron microscopy characterizes it as having a densely distributed pore structure. Figure 1 The microstructure and functional groups of biochar are directly displayed, which can be embedded to provide supporting evidence.

[0007] A further improvement is that the average particle size of the zinc oxide nanoparticles is 20-100 nm, and the application form is an aqueous dispersion with a concentration of 50-150 mg / L, and 0.01-0.1% Tween 20 is added as a dispersant.

[0008] A further improvement is that the amount of biochar applied is 1.5 to 2.5% of the antimony-contaminated soil mass, and the amount of the aqueous dispersion of zinc oxide nanoparticles sprayed is 5 to 20 mL per plant.

[0009] A method for preparing a composite material for remediating antimony-contaminated soil and increasing rice yield includes the following steps:

[0010] Step 1: Wash, dry, and crush the rice straw, then place it in a pyrolysis furnace. Under limited oxygen conditions, heat the straw to 450-550°C at a heating rate of 4-6°C / min, and maintain the temperature for 2-4 hours. After cooling, sieve the straw to obtain the biochar.

[0011] Step 2: Mix zinc oxide nanoparticle powder with deionized water, and add Tween 20 at a concentration of 0.01-0.1% as a dispersant. Disperse the mixture fully by ultrasonic vibration to obtain a zinc oxide nanoparticle dispersion with a concentration of 50-150 mg / L.

[0012] A further improvement is that: after the rice straw is pyrolyzed and cooled in the pyrolysis furnace, it is sieved through a 100-mesh sieve, and the ultrasonic vibration time is 30-50 minutes.

[0013] Application of a composite material for remediating antimony-contaminated soil and increasing rice yield, wherein the composite material is used to remediate antimony-contaminated soil and increase rice yield in antimony-contaminated soil.

[0014] Further improvements are made in the following aspects: the mechanism for remediating antimony-contaminated soil includes: reducing the content of available antimony in the soil, increasing the soil pH value, improving the availability of nitrogen, phosphorus and potassium nutrients in the soil, and enhancing the activity of soil urease and catalase.

[0015] The mechanisms for increasing rice yield include:

[0016] Reduce the accumulation of antimony in the roots and aboveground parts of rice plants;

[0017] Increase the content of chlorophyll a, chlorophyll b and anthocyanins in rice leaves;

[0018] Reduce the content of hydrogen peroxide and malondialdehyde in rice leaves and reduce electrolyte leakage rate;

[0019] The expression of antioxidant-related genes OsAPx6, OsCAT, OsPOD and OsSOD in rice leaves was upregulated, while the expression of antimony absorption-related genes OsSMP and OsMTP1 was downregulated.

[0020] It promotes the formation of iron film in rice roots, increases the iron content in the iron film, and reduces the antimony content fixed in it.

[0021] The beneficial effects of this invention are as follows: By applying biochar to antimony-contaminated soil and spraying zinc oxide nanoparticles on rice leaves, this invention can alleviate antimony toxicity through multiple pathways, significantly reduce the availability of antimony in the soil, reduce the absorption and accumulation of antimony by rice, activate the plant's antioxidant defense system, increase the activity of antioxidant enzymes and regulate the expression of related genes, thereby reducing oxidative damage. It can also improve the soil microenvironment, enhance nutrient availability and enzyme activity, promote rice photosynthesis and root development, and ultimately increase yield. The above synergistic strategy is not only highly efficient and environmentally friendly, but also breaks through the limitations of single material application, providing an innovative method for the remediation of antimony-contaminated soil and sustainable agricultural development. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the surface morphology and properties of the biochar of the present invention;

[0023] Figure 2 This is a schematic diagram showing the effects of biochar and zinc nanoparticles of the present invention on the content of chlorophyll a, chlorophyll b, carotenoids and anthocyanins in rice in antimony-contaminated soil.

[0024] Figure 3 This is a schematic diagram illustrating the effects of biochar and zinc nanoparticles of the present invention on the activities of ascorbic acid peroxidase, catalase, peroxidase and superoxide dismutase in rice in antimony-contaminated soil.

[0025] Figure 4 This is a schematic diagram illustrating the effects of biochar and zinc nanoparticles of the present invention on the activities of methylglyoxal, glyoxalase-I, and glyoxalase-II in rice in antimony-contaminated soil.

[0026] Figure 5 This is a schematic diagram illustrating the effects of biochar and zinc nanoparticles of the present invention on the expression of antioxidant-related genes (ad) and antimony absorption-related genes (ef) in rice in antimony-contaminated soil.

[0027] Figure 6 This is a schematic diagram illustrating the effects of biochar and zinc nanoparticles of the present invention on the antimony and iron content in the ascorbic acid-citrate-acetic acid extract of rice roots. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that technical means not described in detail in the embodiments of the present invention can be implemented by conventional means and are not the key points of the invention, and will not be elaborated upon.

[0029] Antimony inhibits the growth and yield of rice, specifically by increasing hydrogen peroxide (H2O2) content by 142.48%, exacerbating electrolyte leakage (EL), increasing the availability of antimony in the soil, and increasing the accumulation of antimony in plant tissues by 48.12% and 65.73%, respectively. Simultaneously, it leads to a 51.10–103% reduction in plant hormone synthesis and a 63.45%, 71.51%, and 38.99% decrease in the availability of nitrogen (N), phosphorus (P), and potassium (K) nutrients in the soil, respectively.

[0030] The combined use of biochar and zinc oxide nanoparticles can significantly increase rice yield. The mechanism of action is as follows: it reduces H2O2 synthesis by 26.06%, EL production by 25.68%, and the availability of antimony in the soil by 41.80%, while increasing the availability of nitrogen, phosphorus, and potassium in the soil by 31.72%, 45.99%, and 27.91%, respectively. In addition, it can also increase the activity of antioxidant enzymes, including glyoxalase-I (Gly-I) activity by 23.80% and glyoxalase-II (Gly-II) activity by 33.33%, and promote the formation of iron film in rice roots (by 63.60%).

[0031] The BC+ZnO-NPs combination can also upregulate the expression of antioxidant-related genes such as OsAPx6, OsCAT, OsPOD and OsSOD, and downregulate the expression levels of genes related to antimony absorption (OsSMP and OsMTP1), thereby helping rice resist antimony toxicity.

[0032] Example 1

[0033] This embodiment provides a composite material for remediating antimony-contaminated soil and increasing rice yield. The composite material includes biochar and zinc oxide nanoparticles, wherein the biochar and zinc oxide nanoparticles are in independent physical forms before application and are applied separately during use.

[0034] The biochar of this embodiment is prepared from rice straw under oxygen-limited conditions at a pyrolysis temperature of 450–550°C (500°C in this embodiment). Its pH value is 9.0–11.0 (pH value 10.78 in this embodiment), and its cation exchange capacity is not less than 10 cmol / kg. The biochar has a porous structure, and its surface functional groups include hydroxyl and carboxyl groups. It is characterized by a dense pore distribution by scanning electron microscopy.

[0035] The average particle size of the zinc oxide nanoparticles in this embodiment is 20-100 nm (20 nm in this embodiment). The application form is an aqueous dispersion with a concentration of 50-150 mg / L (100 mg / L in this embodiment). Tween 20 at a concentration of 0.01-0.1% is added as a dispersant (0.05% Tween 20 in this embodiment).

[0036] In this embodiment, the amount of biochar applied is 1.5-2.5% of the mass of antimony-contaminated soil (2% is used in this embodiment), and the amount of water dispersion made of zinc oxide nanoparticles sprayed is 5-20 mL per plant (10 mL is used in this embodiment).

[0037] See Figure 1 This embodiment also provides a method for preparing a composite material for remediating antimony-contaminated soil and increasing rice yield, including the following steps:

[0038] Step 1: Preparation of biochar

[0039] Rice straw is taken, rinsed with tap water to remove surface dust, and then dried in an 80℃ oven to constant weight. The dried rice straw is then crushed using a plant crusher. The crushed rice straw is then placed in a tubular pyrolysis furnace and heated to 500℃ at a rate of 5℃ / min under pure nitrogen protection (oxygen-limited conditions). The temperature is then kept constant at this temperature for 2 hours. After the pyrolysis is completed, the straw is naturally cooled to room temperature under a nitrogen atmosphere. Finally, the solid product is taken out and sieved through a 100-mesh sieve to obtain the biochar product used as a composite material.

[0040] The biochar was characterized by the following physicochemical properties: pH value 10.78 (water-to-soil ratio 1:5), cation exchange capacity (CEC) 11.58 cmol / kg, and carbon content 575 g / kg. Figure 1 As shown ( Figure 1 In the image, Part A shows a scanning electron microscope (SEM) image of the biochar, Part B shows a transmission electron microscope (TEM) image, Part C shows a Fourier transform infrared (FTIR) spectrum, Part D shows an elemental distribution map, and Part E shows an X-ray energy dispersive spectroscopy (EDS) analysis. SEM observation reveals a rich porous structure on the surface of the biochar (see [link to image]). Figure 1Part A of the data was analyzed by Fourier transform infrared spectroscopy (FTIR), revealing that its surface contains abundant functional groups such as hydroxyl and carboxyl groups (see Part A). Figure 1 (Part C in the text);

[0041] Step 2: Preparation of zinc oxide nanoparticle dispersion

[0042] Commercial zinc oxide nanoparticles with an average particle size of 20 nm (purchased from Meiji Biomedical Technology Co., Ltd.) were purchased. An appropriate amount of zinc oxide nanoparticle powder was weighed and added to deionized water to prepare an initial mixture with a concentration of 100 mg / L. Subsequently, 0.05% (v / v) of Tween 20 was added to the initial mixture as a dispersant to obtain a mixture. The mixture was then placed in an ultrasonic cell disruptor and ultrasonically vibrated for 30 min under ice-water bath conditions to ensure that the nanoparticles were fully and uniformly dispersed in water to form a stable aqueous dispersion of zinc oxide nanoparticles.

[0043] Example 2

[0044] This embodiment applies the composite material prepared in Example 1 to the remediation of antimony-contaminated soil and the improvement of rice yield. The application experiment was conducted in the nethouse of Hunan University of Humanities and Technology. The test soil was the topsoil (0-20cm) of farmland, and its basic physicochemical properties were: pH 5.55, total nitrogen (TN) 1.74 g / kg, available phosphorus (AP) 26.22 mg / kg, and available potassium (AK) 119.56 mg / kg. The specific steps were as follows:

[0045] (1) Construction and stabilization of antimony-contaminated soil:

[0046] Potassium antimony tartrate was added to the test soil to make the antimony concentration in the soil reach 250 mg / kg. The prepared soil was thoroughly mixed and then placed in a plastic basin. It was placed in a dark environment and kept at 70% field capacity for two months to stabilize.

[0047] (2) Experimental Design and Treatment:

[0048] This embodiment includes 8 processes:

[0049] T1: Control group (uncontaminated, no amendment applied)

[0050] T2: Biochar group (BC, application rate of 2% of soil mass)

[0051] T3: Zinc oxide nanoparticles (ZnO-NPs, foliar spray 100 mg / L)

[0052] T4: Biochar + Zinc Oxide Nanoparticles (BC + ZnO-NPs)

[0053] T5: Antimony stress group (Sb, 250 mg / kg)

[0054] T6: Antimony stress + biochar group (Sb+BC)

[0055] T7: Antimony stress + zinc oxide nanoparticle group (Sb+ZnO-NPs)

[0056] T8: Antimony stress + biochar + zinc oxide nanoparticle group (Sb+BC+ZnO-NPs)

[0057] Each treatment was repeated three times in a completely randomized block design. Biochar was mixed with soil and applied before rice transplanting. Zinc oxide nanoparticle dispersion was sprayed on the leaves 15 days after rice transplanting and sprayed continuously for 5 days. A small sprayer was used to ensure even coverage on both sides of the leaves, and the spraying amount was about 50 mL per pot.

[0058] (3) Rice cultivation and management:

[0059] After the soil in the plastic pot has stabilized, add water to the plastic pot to maintain a water layer of 2-3 cm. Select 25-day-old rice seedlings with uniform growth and transplant 5 seedlings into each pot. Maintain the water layer throughout the entire growth period and keep other field management measures consistent.

[0060] Example 3

[0061] This embodiment verifies the application effect of the composite material in Example 2. Leaf samples were collected 40 days after rice transplanting in Example 2 for physiological and biochemical analysis. Yield was measured after maturity, and soil properties were analyzed. The specific steps are as follows:

[0062] (1) Effects on promoting rice growth and yield:

[0063] As shown in Table 1, antimony stress (T5) severely inhibited rice growth. Compared with the control group (T1), root length (RL), root fresh weight (RFW), and root dry weight (RDW) decreased by 59.89%, 43.73%, and 40.26%, respectively; grain yield (GY) and biomass (BY) decreased by 37.52% and 51.43%, respectively.

[0064] Both biochar (T6) and zinc oxide nanoparticles (T7) can alleviate antimony toxicity to some extent when applied alone, but the combined application of the composite material (T8) has the most significant effect. Compared with the antimony stress group (T5), the T8 treatment increased root length, root fresh weight, and root dry weight by 37.12%, 46.86%, and 32.25%, respectively; and significantly increased grain yield and biomass by 22.54% and 34.68%, respectively. This indicates that the composite material of the present invention can effectively reverse the inhibition of antimony on rice growth and greatly improve yield.

[0065] (2) Its effect on improving the physiological metabolism of rice:

[0066] Photosynthesis and water status: The composite material (T8) significantly increased the photosynthetic pigment content in rice leaves under antimony stress (e.g., ... Figure 2 As shown in Table 2), chlorophyll a and chlorophyll b increased by 68.44% and 94.60% respectively compared with the antimony stress group (T5), while the relative water content (RWC) of leaves increased by 11.88% (as shown in Table 2).

[0067] Oxidative stress relief: The composite material (T8) effectively removed reactive oxygen species in the body, reducing the hydrogen peroxide (H2O2) content by 26.06%, alleviating membrane lipid peroxidation, and reducing malondialdehyde (MDA) content and electrolyte leakage rate (EL) by 15.46% and 25.68%, respectively (as shown in Table 2).

[0068] Antioxidant system activation: The composite material (T8) significantly improved the activity of antioxidant enzymes (such as... Figure 3 As shown in the figure, the activities of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) increased by 27.38%, 25.87%, 23.78%, and 35.66%, respectively. Simultaneously, it significantly activated the glyoxalase system, increasing the activities of glyoxalase-I (Gly-I) and glyoxalase-II (Gly-II) by 23.80% and 33.33%, respectively, thereby effectively clearing toxic methylglyoxal (MG) (as shown in the figure). Figure 4 (as shown);

[0069] Hormonal balance regulation: The composite material (T8) reversed the hormonal imbalance caused by antimony stress, promoted the synthesis of growth-promoting hormones gibberellin (GA), auxin (IAA) and jasmonic acid (JA), and significantly reduced the content of the stress hormone abscisic acid (ABA) by 32.53%.

[0070] (3) Regulation of molecular level and root morphology:

[0071] Gene expression regulation: qRT-PCR analysis showed (e.g.) Figure 5 As shown, the composite material (T8) can significantly upregulate the expression of antioxidant-related genes (OsAPx6, OsCAT, OsPOD, OsSOD) and downregulate the expression of antimony absorption-related genes (OsSMP, OsMTP1), by 53.01% and 51.35%, respectively. This explains the mechanism by which it reduces antimony absorption and enhances antioxidant capacity at the molecular level.

[0072] Root iron film promotion: discovered by ACA extraction method ( Figure 6The iron content in the iron film of rice roots treated with the composite material (T8) increased by 29.87%, while the antimony content fixed in the iron film decreased significantly by 63.60%. This indicates that the composite material promotes the formation of a thicker and "cleaner" iron film, effectively blocking antimony from entering the roots.

[0073] (4) Remediation effect on soil environment:

[0074] Reduced antimony availability: The composite material (T8) reduced the content of available antimony in the soil by 41.80%, which was far better than applying it alone (as shown in Table 3);

[0075] Improving soil fertility: The composite material (T8) significantly increased soil pH and improved the availability of total nitrogen (TN), available phosphorus (AP), and available potassium (AK) by 31.72%, 45.99%, and 27.91%, respectively (as shown in Table 4).

[0076] Activation of soil enzyme activity: The composite material (T8) restored the antimony-inhibited activities of soil urease and catalase by 73.37% and 40.74%, respectively (as shown in Table 4);

[0077] (5) Effects on plant nutrients and antimony accumulation:

[0078] As shown in Table 3, the composite material (T8) significantly promoted the absorption of nitrogen, phosphorus and potassium nutrients by rice. More importantly, as shown in Table 4, it significantly reduced the accumulation of antimony in the roots and aboveground parts of rice, with reductions of 48.12% and 65.73% respectively, greatly reducing the risk of antimony transmission through the food chain.

[0079] Table 1. Effects of biochar and zinc nanoparticles on rice morphology and yield traits in antimony-contaminated soil.

[0080]

[0081] Data in the table are the mean ± standard deviation (±SD) of three replicates. Different letters after the data in the same column indicate significant differences between treatments (Tukey test, p<0.05). RL: root length; RFW: root fresh weight; RDW: root dry weight; PH: plant height; TPP: number of tillers per pot; TGW: thousand-grain weight; BY: biomass; GY: grain yield; HI: harvest index.

[0082] Table 2. Effects of biochar and zinc nanoparticles on water content, oxidation parameters, and synthesis of osmotic regulators in rice leaves.

[0083]

[0084] The data in the table are the mean ± standard deviation (±SD) of three replicates. Different letters after the data in the same column indicate significant differences between treatments (Tukey test, p<0.05). RWC: relative water content; EL: electrolyte leakage rate; MDA: malondialdehyde; H2O2: hydrogen peroxide; TSP: total soluble protein; FAA: free amino acids.

[0085] Table 3. Effects of biochar and zinc nanoparticles on nitrogen, phosphorus, and potassium content in rice seedlings in antimony-contaminated soil.

[0086]

[0087] The data given in the table are the mean (± standard deviation) of three repeated trials. Different letters indicate that there are significant differences between the treatment groups after Tukey test (p<0.05).

[0088] Table 4. Effects of biochar and zinc nanoparticles on antimony accumulation in plant organs, soil antimony content, soil nutrient availability, and soil enzyme activity after rice harvest.

[0089]

[0090] The data presented in the table are the mean (± standard deviation) of three replicates. Different letters indicate significant differences between treatment groups after Tukey's test (p<0.05). TN: Total nitrogen; AP: Available phosphorus; AK: Available potassium.

[0091] The above embodiments fully demonstrate that the composite material made of biochar and zinc oxide nanoparticles provided by the present invention can produce excellent synergistic remediation and yield-increasing effects in antimony-contaminated soil-rice systems through a simple method of separate application. Its mechanism of action is comprehensive, including: fixing antimony in the soil, promoting the formation of root iron film, regulating gene expression, activating the endogenous antioxidant defense system, improving hormone balance, and enhancing soil fertility and biological activity.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite material for remediating antimony-contaminated soil and increasing rice yield, comprising biochar and zinc oxide nanoparticles, characterized in that: The biochar and the zinc oxide nanoparticles are independent physical forms before application, and are applied separately when used.

2. The composite material for remediation of antimony contaminated soil and for increasing the yield of rice according to claim 1, characterized in that: The biochar is prepared from rice straw under oxygen-limited conditions at a pyrolysis temperature of 450-550 DEG C, has a pH value of 9.0-11.0, a cation exchange capacity of not less than 10 cmol / kg, and a porous structure, and its surface functional groups include hydroxyl and carboxyl groups, and the pore distribution is dense as characterized by scanning electron microscopy, and the microstructure and functional groups of the biochar are directly shown in Figure 1, which can be embedded for evidence.

3. The composite material for remediation of antimony contaminated soil and for increasing the yield of rice according to claim 1, characterized in that: The average particle size of the zinc oxide nanoparticles is 20-100 nm, the application form is an aqueous dispersion, the concentration of the aqueous dispersion is 50-150 mg / L, and 0.01-0.1% Tween 20 is added as a dispersant.

4. The composite material for remediation of antimony contaminated soil and for increasing the yield of rice according to claim 1, characterized in that: The application amount of the biochar is 1.5-2.5% of the mass of the antimony-contaminated soil, and the spraying amount of the zinc oxide nanoparticle aqueous dispersion is 5-20 mL per plant.

5. A method for preparing the composite material for remediation of antimony contaminated soil and increasing rice yield according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: Step 1: After washing, drying and crushing, the rice straw is placed in a pyrolysis furnace, heated to 450-550 DEG C at a heating rate of 4-6 DEG C / min under oxygen-limited conditions, and kept at a constant temperature for 2-4 hours, and then sieved after cooling to obtain the biochar; Step 2: The zinc oxide nanoparticle powder is mixed with deionized water, and 0.01-0.1% Tween 20 is added as a dispersant, and the mixture is fully dispersed by ultrasonic oscillation to obtain a zinc oxide nanoparticle dispersion with a concentration of 50-150 mg / L.

6. The method for preparing the composite material for remediation of antimony contaminated soil and increasing rice yield according to claim 5, characterized in that: The rice straw is sieved with a 100-mesh sieve after pyrolysis and cooling in the pyrolysis furnace, and the ultrasonic oscillation time is 30-50 min.

7. Use of a composite material for remediation of antimony-contaminated soil and for increasing rice yield, characterized in that: The composite material for repairing antimony-contaminated soil and improving rice yield is applied to repairing antimony-contaminated soil and improving rice yield in antimony-contaminated soil.

8. The use of the composite material for remediation of antimony contaminated soil and for increasing the yield of rice according to claim 7, characterized in that: The repairing mechanism of the antimony-contaminated soil includes reducing the content of available antimony in the soil, increasing the pH value of the soil, improving the availability of nitrogen, phosphorus and potassium nutrients in the soil, and enhancing the activities of soil urease and catalase; The mechanism for improving rice yield includes: Reducing the accumulation of antimony in the roots and aboveground parts of rice plants; Increasing the contents of chlorophyll a, chlorophyll b and anthocyanin in rice leaves; Reducing the contents of hydrogen peroxide and malondialdehyde in rice leaves and the electrolyte leakage rate; Up-regulating the expression of antioxidant-related genes OsAPx6, OsCAT, OsPOD and OsSOD in rice leaves, and down-regulating the expression of antimony absorption-related genes OsSMP and OsMTP1; Promoting the formation of iron membrane in rice roots, increasing the iron content in the iron membrane and reducing the fixed antimony content in the iron membrane.

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