Nano material for improving saline-alkaline tolerance of soybeans as well as preparation and application of nano material

Abstract

The invention discloses a nano material for improving saline-alkaline tolerance of soybeans as well as preparation and application of the nano material, and belongs to the technical field of nano agriculture. The preparation method of the nano material comprises the following steps: preparing a sol system by using hexadecyl trimethyl ammonium bromide, triethanolamine and tetraethyl orthosilicate as raw materials, then adding 3-aminopropyltriethoxysilane to carry out sol solution modification, aging, carrying out low-temperature vacuum drying on a precipitate, and grinding, so as to obtain the nano material for improving the saline-alkaline tolerance of soybeans. The nanometer material for improving the saline-alkaline tolerance of the soybeans is obtained. The stable micelle is obtained by optimizing the dosage ratio of the silicon source to the surfactant. Furthermore, an amino silane in-situ grafting surface modification process is adopted, so that the density of surface functional groups is increased by 86% compared with that of a traditional post-treatment method. The low-temperature vacuum drying process adopted by the invention ensures that the pore integrity rate of the nano material is greater than or equal to 98%. According to the nano material provided by the invention, multiple stress relief mechanisms are established through particle size control and surface chemical property optimization.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanoagriculture, and particularly relates to a nanomaterial for improving the saline-alkali tolerance of soybeans, and its preparation and application. Background Art

[0002] Due to its unique surface effect and size effect, nanosilicon materials exhibit great application potential in the field of agricultural stress resistance regulation. Especially for the difficult problem of saline-alkali soil treatment, nanosilicon, with its high specific surface area and surface modifiable characteristics, can alleviate the stress effect of salts on crops through multiple mechanisms such as ion adsorption and physical barriers.

[0003] Currently, the existing technology prepares nanosilicon at low temperature by the sol-gel method, including basic processes such as the hydrolysis and polycondensation of tetraethyl orthosilicate and the guidance of surfactant templates. However, this method still has defects:

[0004] First, the imbalance in the ratio of silicon source to surfactant in the precursor mixing stage (traditional mass ratio 10:0.5) will lead to insufficient stability of the micelle structure, and the lack of dynamic regulation in the hydrolysis reaction process will result in insufficient porosity of the product (the porosity of the traditional method is about 65%), affecting its adsorption capacity for Na + ; Second, high-temperature drying is used in the gelation stage, and the prepared nanomaterial has the problem of particle agglomeration. In the gel drying stage, the volume shrinkage rate caused by local stress concentration is as high as 15%, resulting in the collapse of the mesoporous structure; Third, the surface modification process is separated from the synthesis process, and the addition time of the surface modifier is lagged (introduced in the post-treatment stage), resulting in the modifier being unable to participate in the construction of the sol network, limited grafting rate of functional groups, and low loading density of functional groups (traditional amino group density ≤ 1.5 mmol / g), restricting the chelation efficiency with saline-alkali ions.

[0005] The existing technology attempts to improve the pore structure by introducing CO2 supercritical drying, but it requires supporting high-pressure equipment (operating pressure > 7.3 MPa), greatly increasing the production cost. Therefore, there is an urgent need to develop an integrated sol-gel preparation process that can achieve precise regulation of pore structure and efficient grafting of functional groups under normal pressure conditions. Summary of the Invention

[0006] The purpose of the present invention is to provide a nanomaterial for improving the saline-alkali tolerance of soybeans, and its preparation and application. By controlling the dosage of raw materials, the density of the film is increased and the volume shrinkage is reduced. At the same time, an appropriate amount of 3-aminopropyltriethoxysilane is added during the gel process for surface modification and functionalization, improving the quality and performance of the material. The mild and controllable preparation of nanosilicon materials is realized, and the prepared nanosilicon materials have a size of 20 - 50 nm.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention: Provide a preparation method of a nanomaterial for improving the saline-alkali tolerance of soybeans, including the following steps:

[0009] Dissolve cetyltrimethylammonium bromide and triethanolamine in a solvent, add tetraethyl orthosilicate to prepare a sol solution, then add 3-aminopropyltriethoxysilane, stir to obtain a modified sol solution, age, separate the precipitate, vacuum dry at 75-85 °C and then grind to obtain the nanomaterial (i.e., nano-silicon) for improving the saline-alkali tolerance of soybeans.

[0010] Preferably, the dosage ratio of cetyltrimethylammonium bromide, tetraethyl orthosilicate and triethanolamine is 0.8 g: 7.5-8.5 mL: 160-180 μL.

[0011] Preferably, the addition amount of 3-aminopropyltriethoxysilane is 1.1%-1.3% of the mass of the sol solution.

[0012] Preferably, the temperature of the solution system when adding tetraethyl orthosilicate is 78-82 °C, and stir for 1.5-2.5 h after adding tetraethyl orthosilicate.

[0013] The pH value range of the sol solution prepared according to the raw material ratio of the present invention is 6.8-7.2.

[0014] Preferably, the temperature of the sol system when adding 3-aminopropyltriethoxysilane is 80±2 °C, and stir for 1.5-2.5 h after adding 3-aminopropyltriethoxysilane.

[0015] Preferably, the temperature for aging is 23-27 °C and the time is 6 h.

[0016] Preferably, the way to separate the precipitate is centrifugation.

[0017] More preferably, the centrifugation is carried out under the protection of an inert gas, and the material of the centrifuge tube is polypropylene.

[0018] Two of the technical solutions of the present invention: Provide a nanomaterial for improving the saline-alkali tolerance of soybeans prepared by the above preparation method for the nanomaterial for improving the saline-alkali tolerance of soybeans.

[0019] Three of the technical solutions of the present invention: Provide an application of the above nanomaterial for improving the saline-alkali tolerance of soybeans in planting soybeans in saline-alkali land.

[0020] The beneficial technical effects of the present invention are as follows:

[0021] By optimizing the dosage ratio of the silicon source and the surfactant, the present invention solves the problem of discrete pore size distribution caused by insufficient stability of the micelle structure in traditional preparation.

[0022] Furthermore, an in-situ grafting surface modification process with amino silane is adopted, which increases the surface functional group density by 86% compared with the traditional post-treatment method.

[0023] The low-temperature vacuum drying process adopted in the present invention ensures that the pore integrity rate of the nanomaterials is ≥98%.

[0024] The nanomaterials provided by the present invention establish a multiple stress mitigation mechanism through particle size control and surface chemical property optimization. Description of the Drawings

[0025] Figure 1 TEM image of the nano-silicon prepared in Example 1.

[0026] Figure 2 TEM image of the nano-silicon prepared in Example 2.

[0027] Figure 3 TEM image of the commercially available nano-silicon.

[0028] Figure 4 Plant height, stem diameter and number of nodes of soybean plants treated with the nano-silicon prepared in Example 1 under saline-alkali stress.

[0029] Figure 5 Biomass accumulation diagram of soybean pods treated with the nano-silicon prepared in Example 1 under saline-alkali stress.

[0030] Figure 6 Plant height, stem diameter and number of nodes of soybean plants treated with the nano-silicon prepared in Example 2 under saline-alkali stress.

[0031] Figure 7 Biomass accumulation diagram of soybean pods treated with the nano-silicon prepared in Example 2 under saline-alkali stress.

[0032] Figure 8 Plant height, stem diameter and number of nodes of soybean plants treated with the commercially available nano-silicon under saline-alkali stress.

[0033] Figure 9 Biomass accumulation diagram of soybean pods treated with the commercially available nano-silicon under saline-alkali stress.

[0034] Figure 10 Infrared spectrum diagram of the nano-silicon prepared in Example 1.

[0035] Figure 11 XRD pattern of the nano-silicon prepared in Example 1.

[0036] Figure 12 Zeta potential diagram of the nano-silicon prepared in Example 1.

[0037] Figure 13Particle size distribution diagram of the nanosilicon prepared in Example 1. Detailed implementation mode

[0038] Now, various exemplary implementation modes of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention. It should be understood that the terms described in the present invention are only used to describe specific implementation modes and are not used to limit the present invention.

[0039] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention.

[0041] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0042] Example 1

[0043] Preparation of nanosilicon by sol-gel method:

[0044] S1: Dissolve 0.8 g of cetyltrimethylammonium bromide in 50 mL of deionized water and completely dissolve it under the condition of a 35°C water bath.

[0045] S2: Add 170 μL of triethanolamine to the solution of S1, place it in a magnetic stirrer, and continuously stir at a speed of 350 rpm at 80°C for 30 min.

[0046] S3: Slowly add 8 mL of tetraethyl orthosilicate under stirring conditions, maintain the temperature at 80°C and continuously stir for 2 h to form a stable sol system, and the pH of the sol system is 7.2.

[0047] S4: Add 0.5 mL of 3-aminopropyltriethoxysilane as an adhesion promoter (accounting for 1.2% of the mass of the sol system of S3) to the sol system of S3, and continue to stir at 80°C for 2 h to complete chemical modification.

[0048] S5: After naturally cooling the modified sol system to 25 °C, age it for 6 h, and centrifuge it at a rate of 9000 rpm for 30 min under the protection of inert gas to separate the precipitate. The centrifuge tube is made of polypropylene;

[0049] S6: Wash the precipitate 3 times alternately with deionized water and absolute ethanol, then dry it in a vacuum oven at 80 °C for 6 h, and obtain the nanosilicon material after grinding with a planetary ball mill (the grinding medium is a mixture of zirconia balls and agate balls with a ratio of 1:3).

[0050] Example 2

[0051] Preparation of nanosilicon by sol-gel method:

[0052] S1: Dissolve 0.8 g of cetyltrimethylammonium bromide in 50 mL of deionized water and completely dissolve it under the water bath condition of 35 °C;

[0053] S2: Add 170 μL of triethanolamine to the S1 solution, place it in a magnetic stirrer and continuously stir at a speed of 350 rpm at 80 °C for 30 min;

[0054] S3: Slowly add 8 mL of tetraethyl orthosilicate under stirring conditions, and maintain the temperature at 80 °C and continuously stir for 2 h to form a stable sol system;

[0055] S4: After naturally cooling the stable sol system to 25 °C, age it for 6 h, and centrifuge it at a rate of 9000 rpm for 30 min under the protection of inert gas to separate the precipitate. The centrifuge tube is made of polypropylene;

[0056] S5: Wash the precipitate 3 times alternately with deionized water and absolute ethanol, then dry it in a vacuum oven at 80 °C for 6 h, and obtain the nanosilicon material after grinding with a planetary ball mill (the grinding medium is a mixture of zirconia balls and agate balls with a ratio of 1:3).

[0057] It was measured that the particle sizes of the nanosilicon materials prepared in Examples 1-2 were all 20-50 nm.

[0058] The TEM image of the nanosilicon prepared in Example 1 is shown in Figure 1 ;

[0059] The TEM image of the nanosilicon prepared in Example 2 is shown in Figure 2 .

[0060] As Figure 1 shown, the nanosilicon material prepared in Example 1 by the in-situ APTES modification process exhibits a uniform spherical morphology, and the particle size is distributed in the range of 20-50 nm. The pore structure between particles is clearly visible, the pore diameter is concentrated in 2-5 nm, and rough textures formed by the grafting of amino silanes can be seen on the surface, indicating that the active groups are successfully anchored on the material surface.

[0061] Comparison Figure 2 It can be seen that the nano-silicon particles without APTES modification show local agglomeration, and the average particle size increases to 30 - 80 nm. The pore size distribution is discrete, showing irregular collapse. The surface is smooth without modification features. Compared with Example 1, it confirms the key role of in-situ grafting of functional groups in regulating the material morphology.

[0062] Commercially available nano-silicon, the purchased nano-silicon is prepared by the fluidized bed method (FBR), and the reaction process is carried out under high temperature (>120 °C) conditions. Its TEM image is shown in Figure 3 .

[0063] From Figure 3 it can be seen that the size of commercially available nano-silicon particles is relatively large, concentrated in 50 - 100 nm. It is significantly larger than 20 - 50 nm in Example 1 of the present invention. It can be expected that its adsorption capacity for saline-alkali ions is poor, and there is obvious agglomeration of particles and poor dispersibility ( Figure 3 aggregated block structures can be seen in Figure 1 ), while Figure 3 the particles are uniformly and independently dispersed, indicating that the precursor ratio and gradient drying process of the present invention effectively inhibit agglomeration. The fluidized bed method requires a reaction at >120 °C, which destroys the micelle self-assembly ability (Example 1 realizes controllable self-assembly through 80 °C solubilization + 25 °C gelation). The fluidized bed method does not optimize surface modification: adding additives in post-treatment cannot penetrate into the pores of the material (

[0064] Example 3

[0065] Investigate the effects of the nano-silicon materials prepared in Examples 1 - 2 and commercially available nano-silicon on growing soybeans in saline-alkali soil:

[0066] (1) Select salt-tolerant Hefeng 50 (HF50) and conventional Henong 95 (HN95) soybean varieties with a germination rate ≥90% and 100-seed weight of 18 - 22 g;

[0067] (2) Sieve the saline-alkali soil matrix through a 2 mm sieve and autoclave it at 121 °C for 30 min. Simulate the saline-alkali stress condition as a compound system of NaCl:Na2SO4:NaCO3:NaHCO3 = 1:9:1:9, and control the salt content to be 0.6 wt% and the pH value to be 9.0;

[0068] (3) Use a breathable cultivation container with a diameter of 30 cm and a height of 37 cm, and fill 20 ± 0.5 kg of saline-alkali soil in each container;

[0069] (4) Apply the nano-silicon material aqueous preparation (surfactant - Tween 20 at 0.02 wt%) at the stage of true leaf unfolding in soybeans, and the treatment concentration gradients are 0 mg / L (Sa-MsNs0), 20 mg / L (Sa-MsNs 20 ), 50 mg / L (Sa-MsNs 50 ), and 100 mg / L (Sa-MsNs 100 );

[0070] (5) Continuously perform precise foliar spraying for 3 days until the front and back sides are completely wetted without liquid droplets dripping, and the spraying operation is carried out when the light intensity < 1000 lx;

[0071] (6) Sample and detect the plant biomass index at the beginning of podding stage, and detect the pod biomass index after harvest.

[0072] The plant height, stem diameter and number of nodes of soybean plants treated with the nano-silicon prepared in Example 1 under saline-alkali stress are shown in Figure 4 .

[0073] The biomass accumulation diagram of soybean pods treated with the nano-silicon prepared in Example 1 under saline-alkali stress is shown in Figure 5 .

[0074] The plant height, stem diameter and number of nodes of soybean plants treated with the nano-silicon prepared in Example 2 under saline-alkali stress are shown in Figure 6 .

[0075] The biomass accumulation diagram of soybean pods treated with the nano-silicon prepared in Example 2 under saline-alkali stress is shown in Figure 7 .

[0076] The plant height, stem diameter and number of nodes of soybean plants treated with commercially available nano-silicon under saline-alkali stress are shown in Figure 8 .

[0077] The biomass accumulation diagram of soybean pods treated with commercially available nano-silicon under saline-alkali stress is shown in Figure 9 .

[0078] Example 1 ( Figure 4-5 )

[0079] Plant biomass accumulation ( Figure 4 ) : In the treatment group, the biomass of soybeans increased by 34.9% compared with the control group, and showed a dose-dependence (significant differences in the 20 / 50 / 100 mg / L gradients), indicating that the pore size optimization and amino modification of nano-silicon significantly improved the adsorption capacity for saline-alkali ions.

[0080] Pod biomass ( Figure 5 ) : The dry weight of soybean grains in the treatment group reached 19.7 ± 1.3 g / plant, which was significantly higher than 14.5 ± 1.1 g in the control group, indicating that the material improved root H+ -ATPase activity (2.4-fold increase) optimized nutrient absorption.

[0081] Example 2 ( Figure 6-7 )

[0082] Biomass accumulation ( Figure 6 ): The biomass increase of nano-silicon without APTES surface modification was only 18.2% under the same 100 mg / L treatment, which was only 52.1% of that in Example 1.

[0083] Pod yield ( Figure 7 ): The dry weight of bean grains was 16.1 ± 0.9 g / plant, with only an 11% increase compared to the control group. This indicates that due to insufficient amino density (1.5 mmol / g) of unmodified nano-silicon, the chelation rate of Na + was low (adsorption amount was only 120 meq / 100 g).

[0084] Commercially available nano-silicon ( Figure 8-9 )

[0085] Biomass performance ( Figure 8 ): After treatment with nano-silicon prepared by the FBR method, the biomass increase was 9.8%, and growth inhibition occurred in the high-concentration treatment group (100 mg / L) (-3.2% compared to the control group).

[0086] Pod impact ( Figure 9 ): The dry weight of bean grains was 14.9 ± 1.2 g / plant, and the actual yield increase was negligible. The main reason is that the nano-silicon particles prepared by the fluidized bed method are relatively large in size (50 - 100 nm), with a specific surface area of only 280 m 2 / g (450 m 2 / g in Example 1), resulting in insufficient effective adsorption sites. The high-temperature reaction caused pore collapse (porosity of 65% compared to 85% in Example 1), and the material structure failed.

[0087] The infrared spectrum of the nano-silicon prepared in Example 1 is shown in Figure 10 , its XRD pattern is shown in Figure 11 , its zeta potential diagram is shown in Figure 12 , and its particle size distribution diagram is shown in Figure 13 .

[0088] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a nanomaterial for improving the saline-alkali tolerance of soybeans, characterized in that, It includes the following steps: Dissolve cetyltrimethylammonium bromide and triethanolamine in a solvent, add tetraethyl orthosilicate to prepare a sol solution, then add 3-aminopropyltriethoxysilane, stir to obtain a modified sol solution, age, separate the precipitate, grind after vacuum drying at 75-85 °C to obtain the nanomaterial for improving the saline-alkali tolerance of soybeans.

2. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 1, characterized in that, The dosage ratio of the cetyltrimethylammonium bromide, the tetraethyl orthosilicate and the triethanolamine is 0.8 g: 7.5-8.5 mL: 160-180 μL.

3. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 1, characterized in that, The addition amount of the 3-aminopropyltriethoxysilane is 1.1%-1.3% of the mass of the sol solution.

4. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 1, characterized in that, The temperature of the solution system when adding the tetraethyl orthosilicate is 80±2 °C, and stir for 1.5-2.5 h after adding the tetraethyl orthosilicate.

5. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 1, characterized in that, The temperature of the sol system when adding the 3-aminopropyltriethoxysilane is 78-82 °C, and stir for 1.5-2.5 h after adding the 3-aminopropyltriethoxysilane.

6. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 1, characterized in that, The temperature for aging is 23-27 °C and the time is 6 h.

7. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 1, characterized in that, The way to separate the precipitate is centrifugation.

8. The preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 7, characterized in that, The centrifugation is carried out under the protection of an inert gas, and the material of the centrifuge tube is polypropylene.

9. A nanomaterial for improving the saline-alkali tolerance of soybeans prepared by the preparation method of the nanomaterial for improving the saline-alkali tolerance of soybeans according to any one of claims 1-8.

10. Application of the nanomaterial for improving the saline-alkali tolerance of soybeans according to claim 9 in planting soybeans in saline-alkali land.

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