Iron-doped nano material and preparation method thereof

Abstract

The invention discloses an iron-doped nano material and a preparation method thereof, and the preparation method comprises the following steps: dissolving calcium chloride in deionized water to form a solution A, juicing lemons, and filtering to obtain a solution B; mixing and stirring the solution A and the solution B at room temperature, standing, and taking supernate to obtain a solution C; dissolving dipotassium phosphate in deionized water to obtain a dipotassium phosphate solution, and adjusting the pH value of the dipotassium phosphate solution to 11-12 by adopting alkali to obtain a solution D; mixing and stirring the solution C and the solution D at room temperature to obtain a solution E; dissolving ferrous chloride in deionized water to form a ferrous chloride solution, and adding a sulfuric acid solution to obtain a solution F; mixing and stirring the solution E and the solution F at room temperature to obtain an iron-doped nano material solution; and carrying out centrifugal washing on the iron-doped nano material solution at 4-6 DEG C, and taking solids to obtain the iron-doped nano material. The raw materials adopted by the invention are green and pollution-free, the preparation process is simple and quick, and the arsenic absorption of rice can be effectively reduced and the rice growth can be promoted.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nanomaterial preparation, and in particular to an iron-doped nanomaterial and a preparation method thereof. BACKGROUND

[0002] As a large country in rice planting and consumption, the situation of soil arsenic pollution in China is particularly serious. According to the survey, the area of arable land contaminated by arsenic in China has exceeded 10 million mu, of which 30% is paddy field. Due to its special flooded growth environment, arsenic in the soil is easily converted into highly toxic forms (such as trivalent arsenic and dimethyl arsenic) under anaerobic conditions by microorganisms, and is absorbed into the plant through the root system, and finally accumulates in the grain. The arsenic enrichment capacity of rice is significantly higher than that of other crops, and the arsenic content in polished rice can be more than 10 times that of other crops. Long-term intake of arsenic rice can cause serious consequences such as cancer, cardiovascular disease, diabetes and nervous system damage. Therefore, how to effectively regulate the absorption and transport of arsenic in rice and reduce the arsenic content in rice has become a core problem to protect food security and human health.

[0003] At present, the main methods for treating arsenic pollution in rice are phytoremediation, microbial remediation and chemical remediation. Phytoremediation mainly utilizes the absorption and transformation ability of plants to arsenic to repair, and converts toxic arsenic into non-toxic or low-toxic arsenic. Microbial remediation mainly relies on the absorption, accumulation and transformation of microorganisms to arsenic to alleviate the toxicity of arsenic to rice growth. The chemical remediation method mainly changes the soil pH condition by using chemical reagents, or uses materials such as biochar and iron to adsorb arsenic in the soil, thereby reducing its migration to rice crops.

[0004] Nanomaterials are a new type of functional material that has received widespread attention in recent years. They have unique physical and chemical properties (shape, surface area, chemical properties and surface charge), which are significantly different from other materials of the same composition, and can improve the sustainability of the material. Compared with chemical reducing agents or chelating agents, nanomaterials have lower environmental risk. In recent years, more and more people have begun to study the adsorption and fixation of new nanomaterials to arsenic, thereby developing a series of farmland soil pollution remediation products: for example, using sodium carboxymethyl cellulose and starch as dispersants to synthesize nanomaterials of ferrihydrite, which can adsorb arsenic in the soil and reduce the effective content of arsenic in the soil. However, there may be pollutant emissions in the production process, and the related materials are expensive and difficult to obtain; using eucalyptus leaf extract and ferric sulfate heptahydrate as raw materials to prepare Fe0-iron oxide core-shell structure with polyphenol as stabilizer, which has good arsenic adsorption capacity and effectively reduces the absorption of arsenic by crops, but the preparation process is complex and difficult to mass-produce, and the practicability is low.

[0005] The prior art mainly reduces the toxicity of arsenic by changing the form of arsenic in the soil or adsorbing arsenic in the solution. However, during the rice planting process, the form of arsenic changes greatly due to the flooding and drainage process, and the fixation effect of a single material on arsenic is uncertain. At the same time, the existing products mainly aim at the adsorption and passivation of arsenic in the soil, thereby reducing the absorption of arsenic by rice, improving the growth environment of rice by reducing the stress of arsenic on rice, and improving the yield and quality of rice. The effect on promoting the growth of rice is relatively insufficient, and it is difficult to effectively combine the reduction of arsenic stress and the promotion of growth.

[0006] Therefore, it is urgent to develop a new type of low-cost green nanomaterial to solve the problems existing in the prior art. SUMMARY

[0007] The purpose of the present application is to provide a kind of iron-doped nanomaterial and its preparation method, the raw material of the iron-doped nanomaterial is green, pollution-free, easy to obtain and low in cost, the mixing reaction between raw materials is carried out at room temperature, the preparation process is simple, fast, and the use effect is good, which can effectively reduce the absorption of arsenic by rice and promote the growth of rice when applied to the treatment of arsenic pollution in rice.

[0008] To achieve the above purpose, the present application provides a preparation method of iron-doped nanomaterial, comprising the following steps: (1) dissolve calcium chloride in deionized water to form solution A, squeeze the juice of lemon and filter to obtain solution B; (2) mix and stir solution A and solution B at room temperature, then stand, take the supernatant to obtain solution C; (3) dissolve dipotassium hydrogen phosphate in deionized water to obtain a dipotassium hydrogen phosphate solution, adjust the pH of the dipotassium hydrogen phosphate solution to 11-12 with alkali to obtain solution D; (4) mix and stir solution C and solution D at room temperature to obtain solution E; (5) dissolve ferrous chloride in deionized water to form a ferrous chloride solution, then add sulfuric acid solution to obtain solution F; (6) mix and stir solution E and solution F at room temperature to obtain an iron-doped nanomaterial solution; (7) centrifugal wash the iron-doped nanomaterial solution at 4-6℃, and take the solid to obtain the iron-doped nanomaterial.

[0009] Compared with the prior art, the preparation raw material of the iron-doped nanometer material includes calcium chloride, dipotassium hydrogen phosphate, lemon juice and ferrous chloride, and the lemon juice is rich in citric acid, vitamin B, vitamin C, iron, phosphorus, potassium and other substances. The calcium chloride solution is stirred and mixed with the lemon juice, citric acid in the lemon juice is combined with calcium ions to generate calcium citrate, the calcium citrate is unstable, after being mixed with the potassium dihydrogen phosphate, calcium can be combined with phosphoric acid to form calcium phosphate, citric acid belongs to tricarboxylic acid, and can be coordinated with potassium ions under the condition that the pH is 11-12, so that the calcium phosphate can be effectively dispersed, and the calcium phosphate is prevented from being accumulated intensively, so that the calcium phosphate nanometer material is formed. The ferrous chloride solution is further added with the sulfuric acid solution, so that the ferrous chloride can be effectively prevented from being oxidized into ferric chloride. The calcium phosphate nanometer material is stirred and mixed with the ferrous chloride solution, so that the ferrous ions are adsorbed on the surface of the calcium phosphate, so that the iron-doped nanometer material is formed, and under the protection of the organic molecules such as vitamin C and vitamin B, the ferrous ions in the iron-doped nanometer material can be further effectively prevented from being oxidized into ferric ions, so that the use effect is better. In the centrifugal washing, the temperature of the centrifugation is controlled to be 4-6℃, so that the iron-doped nanometer material can be effectively prevented from reacting and accumulating under the temperature condition, and the stability of the iron-doped nanometer material can be effectively improved. The raw material used in the iron-doped nanometer material is green, pollution-free, easy to obtain and low in cost, in the preparation process, the mixing reaction between the raw materials is carried out at room temperature, without high-temperature heating, so that the preparation process is simple and fast. As a preferred technical scheme, in step (1), the concentration of solution A is 0.2±0.05 mol / L.

[0010] As a preferred technical scheme, in step (2), the volume ratio of solution A to solution B is 1:2-3.

[0011] As a preferred technical scheme, in step (2), the mixing and stirring time is 5-10 min.

[0012] As a preferred technical scheme, in step (2), the standing time is 10-30 min.

[0013] As a preferred technical scheme, in step (3), the concentration of the dipotassium hydrogen phosphate solution is 0.12±0.02 mol / L.

[0014] As a preferred technical scheme, in step (3), the base is selected from potassium hydroxide.

[0015] As a preferred technical scheme, in step (4), the volume ratio of solution C to solution D is 1:1-1.5.

[0016] As a preferred technical scheme, in step (4), the mixing and stirring time is 5-10 min.

[0017] As a preferred technical solution, in step (5), the concentration of the ferrous chloride solution is 0.04±0.01 mol / L.

[0018] As a preferred technical solution, in step (5), the concentration of the sulfuric acid solution is 0.001 mol / L-0.002 mol / L.

[0019] As a preferred technical solution, in step (5), the volume ratio of the ferrous chloride solution and the sulfuric acid solution is 1:0.005-0.01.

[0020] As a preferred technical solution, in step (6), the volume ratio of the solution E and the solution F is 1.5-2:1.

[0021] As a preferred technical solution, in step (7), the centrifugal washing is repeated 1-5 times, the centrifugal speed is 4500 rpm-6500 rpm, and the centrifugal time is 10 min-20 min.

[0022] The second aspect of the present application provides a ferro-doped nanomaterial, which is prepared by the above-mentioned method for preparing a ferro-doped nanomaterial.

[0023] The third aspect of the present application provides an application of a ferro-doped nanomaterial in arsenic pollution treatment of rice, wherein the ferro-doped nanomaterial is the above-mentioned ferro-doped nanomaterial.

[0024] Due to the absorption of phosphorus by plants, mainly in the form of phosphate, after the phosphate is applied to the soil, part of it may be combined with arsenic in the soil to fix arsenic in the soil, avoiding the absorption and utilization of arsenic by plants. Another part may activate arsenic in the soil, making arsenic more easily absorbed by plants, thereby increasing the accumulation of arsenic in plants. The ferro-doped nanomaterial of the present application is specifically a ferro-doped calcium phosphate nanomaterial, which is applied to arsenic pollution treatment of rice, effectively solving the problem that phosphate may increase the activation of arsenic in the soil, thereby increasing the accumulation of arsenic in rice, and at the same time, the adsorption of arsenic by the root surface iron film formed by ferrous ions reduces the stress of arsenic on rice. The ferro-doped nanomaterial of the present application can effectively reduce the absorption of arsenic by rice and promote the growth of rice. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM spectrum of the ferro-doped nanomaterial prepared in Example 1 of the present application; Figure 2 SEM-EDS spectrum of the ferro-doped nanomaterial prepared in Example 1 of the present application; Figure 3 XRD spectrum of the ferro-doped nanomaterial prepared in Example 1 of the present application; Figure 4 Rice growth situation diagram of each experimental group in Example 2 of the present application; Figure 5 The arsenic content distribution diagram of the subcellular components of the rice plants in each experimental group of the embodiment 2 of the present application; Figure 6 The Fe, As, P, Ca element content diagram in the iron membrane on the root surface of the rice in each experimental group in the embodiment 2 of the present application. DETAILED DESCRIPTION

[0026] The iron-doped nanomaterial of the present application is specifically iron-doped calcium phosphate nanomaterial, which is applied to the arsenic pollution treatment of rice, effectively solves the problem that phosphate may increase the activation of soil arsenic, thereby increasing the accumulation of arsenic in rice, and at the same time, iron elements can form an iron membrane in the soil, which can adsorb arsenic in the soil, reduce the activity of arsenic, effectively avoid the absorption of arsenic by plants, reduce the stress of arsenic on rice, and the product effect is better than that of single use of phosphate and / or nanometer iron composite material.

[0027] The preparation method of the iron-doped nanomaterial of the present application comprises the following steps: (1) Dissolve calcium chloride in deionized water to form solution A, and squeeze the lemon to obtain solution B; (2) Mix and stir solution A and solution B at room temperature, and then stand, take the supernatant to obtain solution C; (3) Dissolve dipotassium hydrogen phosphate in deionized water to obtain a dipotassium hydrogen phosphate solution, and adjust the pH of the dipotassium hydrogen phosphate solution to 11-12 with alkali to obtain solution D; (4) Mix and stir solution C and solution D at room temperature to obtain solution E; (5) Dissolve ferrous chloride in deionized water to form a ferrous chloride solution, and then add sulfuric acid solution to obtain solution F; (6) Mix and stir solution E and solution F at room temperature to obtain an iron-doped nanomaterial solution; (7) Centrifugal wash the iron-doped nanomaterial solution at 4-6℃, and take the solid to obtain the iron-doped nanomaterial.

[0028] In step (1), the concentration of solution A is 0.2±0.05 mol / L. As an example, the concentration of solution A can be but is not limited to 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, 0.2 mol / L, 0.21 mol / L, 0.22 mol / L, 0.23 mol / L, 0.24 mol / L, 0.25 mol / L. The squeezing and filtering of the lemon specifically includes selecting fresh lemons with complete skin, no mildew and appropriate maturity, washing and then placing in a juicer to squeeze the lemon juice, and filtering the lemon juice to remove solid lemon residue to obtain lemon juice, that is, solution B. The lemon juice contains citric acid, vitamin B, vitamin C, iron, phosphorus, potassium and other substances.

[0029] In step (2), the volume ratio of solution A and solution B is 1:2-3. For example, the volume ratio of solution A and solution B can be, but is not limited to, 1:2, 1:3. The mixing and stirring time is 5-10 min. For example, the mixing and stirring time can be, but is not limited to, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min. The standing time is 10-30 min. For example, the standing time can be, but is not limited to, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min. In this step, the calcium chloride solution and the lemon juice are stirred and reacted at room temperature. The citric acid in the lemon juice reacts with the calcium ions in the calcium chloride to form calcium citrate.

[0030] In step (3), the concentration of the dipotassium hydrogen phosphate solution is 0.12±0.02 mol / L. For example, the concentration of the dipotassium hydrogen phosphate solution can be, but is not limited to, 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L. The base is selected from potassium hydroxide. The pH of the dipotassium hydrogen phosphate solution is adjusted to 11-12 using the base, which is beneficial to improving the dispersion effect of the material in the subsequent reaction.

[0031] In step (4), the volume ratio of solution C and solution D is 1:1-1.5. For example, the volume ratio of solution C and solution D can be, but is not limited to, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5. The mixing and stirring time is 5-10 min. For example, the mixing and stirring time can be, but is not limited to, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min. In this step, calcium citrate is unstable. After mixing with potassium dihydrogen phosphate, calcium can combine with phosphoric acid to form calcium phosphate. Meanwhile, citric acid belongs to tricarboxylic acid, which can effectively disperse calcium phosphate under the condition of pH 11-12 and potassium ion coordination, thereby avoiding the severe accumulation of calcium phosphate and forming calcium phosphate nanomaterials.

[0032] In step (5), the concentration of the ferrous chloride solution is 0.04±0.01 mol / L, and as an example, the concentration of the ferrous chloride solution can be but is not limited to 0.03 mol / L, 0.04 mol / L, 0.05 mol / L. The concentration of the sulfuric acid solution is 0.001 mol / L-0.002 mol / L, and as an example, the concentration of the sulfuric acid solution can be but is not limited to 0.001 mol / L, 0.002 mol / L. The volume ratio of the ferrous chloride solution to the sulfuric acid solution is 1:0.005-0.01, and as an example, the volume ratio of the ferrous chloride solution to the sulfuric acid solution can be but is not limited to 1:0.005, 1:0.006, 1:0.007, 1:0.008, 1:0.009, 1:0.01. In this step, a certain amount of the sulfuric acid solution is added to the ferrous chloride solution, which can effectively avoid the oxidation of the ferrous chloride to ferric chloride, and is conducive to the formation of the root surface iron film when the iron-doped nanometer material is used.

[0033] In step (6), the volume ratio of the solution E to the solution F is 1.5-2:1, and as an example, the volume ratio of the solution E to the solution F can be but is not limited to 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1. In this step, the ferrous ions in the ferrous chloride solution are adsorbed on the surface of the calcium phosphate nanometer material, and the vitamin B and vitamin C contained in the solution E can further avoid the oxidation of the ferrous ions to trivalent iron ions, thereby ensuring the use performance of the iron-doped nanometer material.

[0034] In step (7), the centrifugal washing is repeated 1-5 times. The solvent used for the centrifugal washing is pure water or deionized water. The rotation speed of the centrifugation is 4500 rpm-6500 rpm, and as an example, the rotation speed of the centrifugation can be but is not limited to 4500 rpm, 4800 rpm, 5000 rpm, 5200 rpm, 5400 rpm, 5600 rpm, 5800 rpm, 6000 rpm, 6200 rpm, 6400 rpm, 6500 rpm. If the rotation speed of the centrifugation is too low, the iron-doped nanometer material is difficult to precipitate, and if the rotation speed of the centrifugation is too high, the iron-doped nanometer material is difficult to take out. The centrifugation time is 10 min-20 min, and as an example, the centrifugation time can be but is not limited to 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min. In this step, the iron-doped nanometer material solution is centrifugally washed at 4°C-6°C, and under this temperature condition, the reaction of the iron-doped nanometer material can be effectively avoided to accumulate, thereby improving the stability thereof.

[0035] To better illustrate the purpose, technical solution, and beneficial effects of this invention, the invention will be further described below with reference to specific embodiments. It should be noted that the methods described below are further explanations of this invention and should not be construed as limiting it.

[0036] Example 1 This embodiment provides a method for preparing iron-doped nanomaterials, including the following steps: (1) Dissolve calcium chloride in deionized water to form a solution A with a concentration of 0.2 mol / L. Juice the lemon and filter to obtain solution B. (2) Mix solution A and solution B at a volume ratio of 1:2 at room temperature, stir, and let stand for 20 minutes. Take the supernatant to obtain solution C. (3) Dissolve dipotassium hydrogen phosphate in deionized water to form a dipotassium hydrogen phosphate solution with a concentration of 0.12 mol / L. Adjust the pH of the dipotassium hydrogen phosphate solution to 12 using potassium hydroxide to obtain solution D; (4) Mix solutions C and D at a volume ratio of 1:1 at room temperature and stir for 8 minutes to obtain solution E; (5) Dissolve ferrous chloride in deionized water to form a ferrous chloride solution with a concentration of 0.04 mol / L, and then add 5 mL of sulfuric acid solution with a concentration of 0.001 mol / L to each liter of ferrous chloride solution to obtain solution F; (6) Mix and stir solutions E and F at a volume ratio of 2:1 at room temperature to obtain an iron-doped nanomaterial solution; (7) Centrifuge the iron-doped nanomaterial solution at 5000 rpm for 15 min at 5°C, discard the supernatant, rinse the solid with pure water, and centrifuge again at 5000 rpm for 15 min at 5°C. Repeat this step twice and take the solid to obtain the iron-doped nanomaterial.

[0037] The morphology of the prepared iron-doped nanomaterials was characterized by scanning electron microscopy (SEM), and the SEM images are shown below. Figure 1 As shown, in Figure 1 In the middle, from left to right are: Figure 1 (a) SEM images of iron-doped nanomaterials at 2 μm magnification Figure 1 (b) is Figure 1 (a) shows the SEM image of the iron-doped nanomaterial at 100 nm magnification in the boxed area. The image shows that the iron-doped nanomaterial of this invention exhibits a typical granular distribution on its surface. Further analysis reveals… Figure 1 (b) Uniformly distributed spherical particles can be observed in the high-magnification image, with particle sizes concentrated in the range of 0~100nm.

[0038] Further analysis of the main elements of the iron-doped nanomaterials of this invention using an energy dispersive spectroscopy (EDS) analyzer yielded the following SEM-EDS spectra:Figure 2 As shown in Figure 2 It can be seen that the main elements of the iron-doped nanomaterial are Fe, Ca, P and O.

[0039] The iron-doped nanomaterial is detected and analyzed by X-ray diffraction (XRD), and the XRD spectrum is as shown in Figure 3 As shown in Figure 3 It can be seen that there are obvious characteristic diffraction peaks at positions of 2θ = 30°, and the peak positions are highly consistent with the crystal face diffraction peak of Ca3(PO4)2 phase in the standard PDF card PDF#48-0488. The XRD analysis result confirms that the sample successfully prepares the Ca3(PO4)2 phase material with high crystallinity, and the crystal structure is consistent with the expected design. Meanwhile, a characteristic diffraction peak appears at a position of 2θ = 44.5°, which coincides with the diffraction peak position of Fe, proving that there is Fe element in the material.

[0040] Example 2 This embodiment is the application of the iron-doped nanomaterial (hereinafter referred to as Fe-CaP NPs) in the treatment of arsenic pollution of rice.

[0041] Uniformly growing rice of the same batch and quality is selected, and is cultured in pure water for 3 days, and then is transferred into a culture solution containing the same concentration of nutrient solution. First, three experimental groups are set to study the growth promoting effect of the material on rice, which are CK group, Fe1 group and Fe2 group, wherein the CK group is used as a blank control group; the Fe1 group adds 50 mg / L of Fe-CaP NPs prepared in Example 1; and the Fe2 group adds 200 mg / L of Fe-CaP NPs prepared in Example 1. Secondly, As pollution is simulated by adding NaAsO2 solution, and the As concentration is 2 µmol / L. Three experimental groups are set, which are As group, As+Fe1 group and As+Fe2 group. The As group adds As with a concentration of 2 µmol / L; the As+Fe1 group adds 50 mg / L of Fe-CaP NPs prepared in Example 1 on the basis of the As group; and the As+Fe2 group adds 200 mg / L of Fe-CaP NPs prepared in Example 1 on the basis of the As group. Five parallel experiments are set for each experimental group. After the rice is treated for 12 days, the rice samples are collected, and relevant parameters are measured. The specific experimental group implementation conditions are shown in Table 1.

[0042] Table 1 Implementation conditions of each experimental group

[0043] After the cultivation, the rice biomass of each experimental group was measured, including the rice plant height, the rice root fresh weight, the rice aboveground fresh weight, etc.; the differential centrifugation method was used to study the distribution of As in the subcellular components of the rice roots and the rice aboveground; the root surface iron film was extracted by DCB, and the contents of Fe, As, P and Ca elements in the DCB extraction solution were determined by an inductively coupled plasma optical emission spectrometer (ICP-OES), and the test results are shown in Figure 4~Figure 6 .

[0044] Figure 4 The rice growth conditions of each experimental group in this embodiment are shown from left to right and from top to bottom as follows: Figure 4 (A) is the solid figure of the rice of each experimental group, Figure 4 (B) is the rice plant height of each experimental group, Figure 4 (C) is the rice root fresh weight of each experimental group, Figure 4 (D) is the rice aboveground fresh weight of each experimental group. Specifically, as shown in Figure 4 (B), compared with the CK group, the rice plant height of the Fe1 group and the Fe2 group was increased by 21.36% and 14.71% respectively. The rice plant height of the As group was reduced by 15.53% compared with the CK group. Compared with the As treatment group, the rice plant height of the As+Fe1 group and the As+Fe2 group was increased by 45.98% and 42.53% respectively. Further as shown in Figure 4 (C) and Figure 4 (D), compared with the CK group, the rice root fresh weight of the Fe1 group and the Fe2 group was increased by 12.53% and 27.09% respectively, and the rice aboveground fresh weight was increased by 7.79% and 22.24% respectively. Compared with the CK group, the rice root fresh weight of the As group was reduced by 5.93%, and the rice aboveground fresh weight was reduced by 25.00%. Compared with the As group, the rice root fresh weight of the As+Fe1 group and the As+Fe2 group was increased by 19.04% and 21.32% respectively, and the rice aboveground fresh weight was increased by 29.54% and 47.85% respectively. It can be seen that the addition of the Fe-CaP NPs of the present application can effectively promote the growth of rice.

[0045] The As content distribution in each component of the rice plant cells is shown in Figure 5 , from top to bottom and from left to right as follows: Figure 5 (a) the arsenic content in the subcellular cell wall component of the rice roots (in the figure, the cell wall component is represented by F1), Figure 5 (b) the arsenic content in the subcellular organelle component of the rice roots (in the figure, the organelle component is represented by F2), Figure 5 (c) the arsenic content in the subcellular soluble component of the rice roots (in the figure, the soluble component is represented by F3), Figure 5 (d) the arsenic content in the subcellular cell wall component of the rice aboveground, Figure 5(e) arsenic content in subcellular organelle components of rice aboveground parts, Figure 5 (f) arsenic content in subcellular soluble components of rice aboveground parts. Specifically, as shown in Figure 5 (a)~ Figure 5 (c) As+Fe1 group and As+Fe2 group of rice root F1 (cell wall components) As concentration reduced by 15.11% and 46.62% respectively compared with As group; As+Fe1 group and As+Fe2 group of rice root F2 (organelle components) As concentration reduced by 60.67% and 89.33% respectively; As+Fe1 group and As+Fe2 group of rice root F3 (soluble components) As concentration reduced by 64.62% and 77.72% respectively. Further as shown in Figure 5 (d)~ Figure 6 (f) As+Fe1 group and As+Fe2 group of rice aboveground parts F1 (cell wall components) reduced by 20.80% and 60.80% respectively compared with As group; As+Fe1 group and As+Fe2 group of rice aboveground parts F2 (organelle components) reduced by 7.96% and 54.87% respectively; As+Fe1 group and As+Fe2 group of rice aboveground parts F3 (soluble components) reduced by 37.78% and 80.00% respectively. It can be seen that the iron-doped nanomaterials of the application can effectively reduce the absorption of arsenic by rice.

[0046] Figure 6 For the element content of Fe, As, P and Ca in the iron film on the root surface of rice in each experimental group, from left to right and from top to bottom are as follows: Figure 6 (A) is the Fe element content in the iron film on the root surface of rice, Figure 6 (B) is the As element content in the iron film on the root surface of rice, Figure 6 (C) is the P element content in the iron film on the root surface of rice, Figure 6 (D) is the Ca element content in the iron film on the root surface of rice. Specifically, as shown in Figure 6 (A), compared with the CK group, the Fe element content in the iron film on the root surface of rice in the Fe1 group and the Fe2 group increased by 7 times and 9 times respectively. Compared with the As group, the Fe element content in the iron film on the root surface of rice in the As+Fe1 group and the As+Fe2 group increased by 6 times and 10 times respectively. As shown in Figure 6 (B), compared with the CK group, the As element content in the iron film on the root surface of rice in the Fe1 group and the Fe2 group increased by 111.66% and 96.33% respectively. The As element content in the iron film on the root surface of rice in the As group increased by 4 times compared with the CK treatment group. Compared with the As group, the As element content in the iron film on the root surface of rice in the As+Fe1 group reduced by 49.84%, and the As+Fe2 group increased by 49.45%. As shown in Figure 6(C) shows that compared with the CK group, the P element content of the root surface iron film of the Fe1 group and the Fe2 group increased by 1 times and 3 times, respectively. Compared with the As group, the P element content of the root surface iron film of the As+Fe1 group and the As+Fe2 group increased by 2 times and 5 times, respectively. As shown in ​ (D) shows that compared with the CK group, the Ca element content of the root surface iron film of the Fe1 group and the Fe2 group increased by 124.85% and 99.31%, respectively. The Ca element content of the root surface iron film of the As group decreased by 38.64% compared with the CK treatment group. Compared with the As group, the Ca element content of the root surface iron film of the As+Fe1 group and the As+Fe2 group increased by 37.99% and 185.77%, respectively. From the above analysis, in this study, after adding As stress, the As content in the root surface iron film of the As group increased significantly, and after adding different concentrations of Fe-CaP NPs, the As content in the root surface iron film of the As+Fe1 group decreased significantly, while that of the As+Fe2 group increased, which indicates that when the concentration of Fe-CaP NPs is low, due to the relatively small amount of iron, the root surface iron film formed under hydroponic conditions cannot completely cover the new root tip area, and the new rice roots have a certain absorption of As. The concentration of Fe-CaP NPs in the As+Fe2 group is high, the coverage area of the iron film formed is large, and its adsorption capacity for As is strong, which blocks the absorption of As by rice roots. At the same time, the treatment of Fe-CaP NPs significantly improves the content of P and Ca elements. It shows that Fe-CaP NPs with appropriate concentration can promote the alleviation of root surface iron film to As stress, and at the same time, enhance the uptake of essential elements such as Fe, P and Ca, so as to improve the stress resistance and growth ability of rice in heavy metal pollution or low oxygen environment.

[0047] The above data results show that the iron-doped nanomaterials of the application can alleviate the toxicity of As to rice and promote the growth of rice under As stress. The iron-doped nanomaterials of the application can effectively promote the adsorption and fixation of As by the root surface iron film of rice, thereby inhibiting the absorption of As by rice roots. The iron-doped nanomaterials of the application can significantly improve the adsorption of As by the cell walls of various parts of rice, thereby alleviating the stress of As on rice.

[0048] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the application and not to limit the protection scope of the application. Although the application has been described in detail with reference to the preferred embodiments, it is not limited to the examples listed in the embodiments. Those skilled in the art should understand that the technical solutions of the application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the application.

Claims

1. A method for preparing iron-doped nanomaterials, characterized in that, Including the following steps: (1) Dissolve calcium chloride in deionized water to form solution A, and juice lemons and filter to obtain solution B; (2) Mix and stir the solution A and the solution B at room temperature, let stand, and take the supernatant to obtain solution C; (3) Dissolve dipotassium hydrogen phosphate in deionized water to form a dipotassium hydrogen phosphate solution, and adjust the pH of the dipotassium hydrogen phosphate solution to 11-12 using an alkali to obtain solution D; (4) Mix and stir the solution C and the solution D at room temperature to obtain solution E; (5) Dissolve ferrous chloride in deionized water to form a ferrous chloride solution, and then add sulfuric acid solution to obtain solution F; (6) Mix and stir the solution E and the solution F at room temperature to obtain an iron-doped nanomaterial solution; (7) The iron-doped nanomaterial solution is centrifuged and washed at 4℃~6℃, and the solid is taken to obtain the iron-doped nanomaterial.

2. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (1), the concentration of solution A is 0.2 ± 0.05 mol / L.

3. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (2), the volume ratio of solution A to solution B is 1:2~3, the mixing and stirring time is 5min~10min, and the standing time is 10min~30min.

4. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (3), the concentration of the dipotassium hydrogen phosphate solution is 0.12 ± 0.02 mol / L, and the alkali is selected from potassium hydroxide.

5. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (4), the volume ratio of solution C to solution D is 1:1 to 1.5, and the mixing time is 5 min to 10 min.

6. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (5), the concentration of the ferrous chloride solution is 0.04±0.01mol / L, the concentration of the sulfuric acid solution is 0.001mol / L~0.002mol / L, and the volume ratio of the ferrous chloride solution to the sulfuric acid solution is 1:0.005~0.

01.

7. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (6), the volume ratio of solution E to solution F is 1.5 to 2:

1.

8. The method for preparing iron-doped nanomaterials according to claim 1, characterized in that, In step (7), the centrifugal washing is repeated 1 to 5 times, the centrifugation speed is 4500 rpm to 6500 rpm, and the centrifugation time is 10 min to 20 min.

9. An iron-doped nanomaterial, characterized in that, The iron-doped nanomaterials were prepared using the preparation method described in any one of claims 1 to 8.

10. The application of an iron-doped nanomaterial in the remediation of arsenic pollution in rice, characterized in that, The iron-doped nanomaterial is the iron-doped nanomaterial as described in claim 9.

Images