A silicon calcium potassium magnesium type soil conditioner and a preparation method thereof

Abstract

The application belongs to the technical field of soil improver, and particularly relates to a silicon-calcium-potassium-magnesium type soil improver and a preparation method thereof. The preparation method comprises the following steps: S1, adding quicklime into a sodium silicate solution to perform a reaction, separating, and drying to obtain calcium silicate with a water content of 0-80%; S2, uniformly mixing the calcium silicate, a magnesium salt / molecular sieve / modified cellulose, and a potassium salt / modified chitosan to obtain a mixture; and S3, spraying an alcohol solution containing alkyl quaternary ammonium salt modified palygorskite on the mixture, stirring, and drying to obtain the silicon-calcium-potassium-magnesium type soil improver. The silicon-calcium-potassium-magnesium type soil improver can meet the index requirements of the national standard GB / T 36207-2018 'Silicon-calcium-potassium-magnesium type fertilizer', and has good slow-release effect, storage stability, can improve the pH of acidic soil, and can increase the organic matter content of soil.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soil improver, and particularly relates to a silicon-calcium-potassium-magnesium type soil improver and a preparation method thereof. BACKGROUND

[0002] Soil acidification is one of the important factors restricting the green and high-quality development of agriculture. Soil acidification can lead to a decrease in soil pH, exacerbate the imbalance of calcium and magnesium nutrients in soil, increase the activity of heavy metals, and increase the incidence of soil-borne diseases.

[0003] At present, the silicon-calcium-potassium-magnesium type soil improver is mainly an alkaline soil improver prepared by high-temperature calcination of phosphorus tailings, phosphogypsum, potassium feldspar and the like, which contains calcium, magnesium, silicon and other nutrients. It can not only adjust the acidic pH value, but also significantly increase the content of available nutrients in soil. At the same time, it has little impact on the soil and ecological environment, and can effectively overcome the problem of soil compaction caused by lime and other substances when adjusting the pH value of acidic soil.

[0004] The method for preparing the silicon-calcium-potassium-magnesium type soil improver in the prior art mainly includes high-temperature calcination and hydrothermal method. For example, a Chinese patent with publication number CN113620724A discloses a method for producing silicon-calcium-potassium-magnesium fertilizer from dolomitic limestone. The dolomitic limestone, potassium feldspar, phosphogypsum and the like are mixed with additives I and II in a certain proportion, and then subjected to processes such as molding, drying, calcination, cooling, ball milling and granulation to prepare a mineral fertilizer produced from dolomitic limestone. The effective components of the silicon-calcium-potassium-magnesium fertilizer obtained by the technical scheme are not less than 85%, among which the effective calcium oxide is greater than 30%, the effective silicon dioxide is greater than 21%, the effective magnesium oxide is greater than 7%, and the effective potassium oxide is greater than 5%. The fertilizer contains various trace elements and has weak alkalinity (pH=8-12), and can be used to adjust the physicochemical properties of soil and comprehensively improve the level of trace elements in soil. However, the preparation process is relatively complex, and high-temperature calcination results in high cost.

[0005] A Chinese patent with publication number CN110078538A discloses a kind of comprehensive utilization tailings preparation silicon calcium potassium magnesium slow-release fertilizer and its preparation method, including the following steps: (1) each component raw material is according to the following mass ratio: low-grade magnesite: carnallite tailings: high-silicon iron tailings: boron mud: quicklime = 3-4:4-6:3-4:6-7:3-4 batching, fully mixed by vertical turbulent stirrer, to obtain homogeneous mixture; (2) the mixture of step (1) is mixed with water to form a uniform slurry; (3) the uniform slurry of step (2) is fed into a high-pressure magnetic stirring reaction kettle through a slurry pump to decompose and synthesize the substances, to obtain the reaction material; (4) the reaction material of step (3) is dried in a drying furnace, then ground by a Raymond mill, and classified by a vibrating screen, to obtain the silicon calcium potassium magnesium slow-release fertilizer. Although the product obtained by the technical solution meets the national standards in terms of the contents of effective K2O, CaO, MgO and SiO2, there are still a series of problems such as excessive use of additives, harsh reaction conditions, high production cost and no consideration of the leaching of heavy metal elements in tailings. SUMMARY

[0006] The present application provides a kind of silicon calcium potassium magnesium type soil conditioner and its preparation method, the silicon calcium potassium magnesium type soil conditioner of the present application can meet the index requirements of national standard GB / T 36207-2018 "silicon calcium potassium magnesium type fertilizer", and has good slow-release effect, storage stability, improves the pH of acidic soil and increases the organic matter content of soil.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] The present application provides a kind of silicon calcium potassium magnesium type soil conditioner and its preparation method, the silicon calcium potassium magnesium type soil conditioner of the present application can meet the index requirements of national standard GB / T 36207-2018 "silicon calcium potassium magnesium type fertilizer", and has good slow-release effect, storage stability, improves the pH of acidic soil and increases the organic matter content of soil.

[0009] S1, adding quicklime to sodium silicate solution for reaction, separation and drying to obtain calcium silicate with water content of 0-80%;

[0010] S2, uniformly mixing calcium silicate, magnesium salt / molecular sieve / modified cellulose and potassium salt / modified chitosan to obtain a mixture;

[0011] S3, spraying alcohol solution containing alkyl quaternary ammonium salt modified palygorskite on the mixture, stirring and drying to obtain the product.

[0012] The mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is 100: (110-130): (8-10): (3-6).

[0013] The source of the sodium silicate solution in the present application includes but is not limited to self-made or sodium silicate solution generated during the comprehensive utilization of fly ash or high-silicon bauxite.

[0014] Preferably, the sodium silicate solution in step S1 is derived from a sodium silicate solution produced in the comprehensive utilization of fly ash or high-silicon bauxite.

[0015] Preferably, the mass ratio of the active calcium oxide in the quicklime to the mass of silicon dioxide in the sodium silicate solution in step S1 is (0.6-2):1, preferably (0.8-1.2):1.

[0016] Preferably, the reaction temperature in step S1 is 20-150°C, preferably 70-90°C, and the reaction time is 0.2-10h, preferably 1-1.5h.

[0017] Preferably, the preparation method of the magnesium salt / molecular sieve / modified cellulose in step S2 comprises the following steps:

[0018] Step 1: disperse the molecular sieve in the aqueous magnesium salt solution to perform an exchange reaction to obtain a magnesium-exchanged molecular sieve;

[0019] Step 2: dissolve the cellulose in a solvent, and under nitrogen protection, add a dimethylacetamide solution containing lauric acid, 4-toluenesulfonyl chloride and triethylene glycol mono-p-toluenesulfonate, and pyridine to perform a modification reaction. After the reaction is completed, perform vacuum distillation, water recrystallization, and drying to obtain the modified cellulose;

[0020] Step 3: add the magnesium-exchanged molecular sieve and the modified cellulose into water to perform a stirring reaction. After the reaction is completed, perform filtration and drying to obtain the magnesium salt / molecular sieve / modified cellulose.

[0021] Preferably, the molecular sieve in step 1 is a FAU-type Y zeolite molecular sieve with a silicon-aluminum molar ratio of 60-90 and a specific surface area of 650-750 m 2 / g.

[0022] Further preferably, the molecular sieve in step 1 is a FAU-type Y zeolite molecular sieve with a silicon-aluminum molar ratio of 81 and a specific surface area of 710 m 2 / g.

[0023] Preferably, the concentration of the aqueous magnesium salt solution in step 1 is 4-6 mol / L, and the aqueous magnesium salt solution is at least one selected from the group consisting of an aqueous magnesium chloride solution and an aqueous magnesium sulfate solution.

[0024] Preferably, the ratio of the molecular sieve to the aqueous magnesium salt solution in step 1 is 1g:100-200mL.

[0025] Preferably, the temperature of the exchange reaction in step 1 is 25-30°C, and the time of the exchange reaction is 8-12h.

[0026] Preferably, the solvent in step 2 is a mixture of lithium chloride and dimethylacetamide, and the mass ratio of the two is (8-10):(90-92).

[0027] Preferably, the mass ratio of the cellulose, the solvent, the dimethylacetamide solution and the pyridine in step 2 is 1:(10-15):(15-25):(2-3).

[0028] Preferably, the dimethylacetamide solution in step 2 is a mixture of lauric acid, 4-toluenesulfonyl chloride, triethylene glycol monop-toluenesulfonate and dimethylacetamide; and the mass ratio of the lauric acid, 4-toluenesulfonyl chloride, triethylene glycol monop-toluenesulfonate and dimethylacetamide is 1:(1.1-1.3):(1.5-2.5):(6-8).

[0029] Preferably, the temperature of the modification reaction in step 2 is 80-90℃, and the time is 18-22h.

[0030] Preferably, the mass ratio of the magnesium-exchanged nanomolecular sieve, the modified cellulose and water in step 3 is (1-3):(3-5):(20-30).

[0031] Preferably, the stirring speed of the reaction in step 3 is 300-500rpm, and the time is 6-10h.

[0032] Preferably, the preparation method of the potassium salt / modified chitosan in step S2 comprises the following steps:

[0033] (1) After the zinc oxide reacts with the chitosan solution, dry the zinc oxide / chitosan to obtain the modified chitosan with a porous structure;

[0034] (2) After the zinc oxide / chitosan is added to the stearic acid solution for impregnation and then taken out and dried, the modified chitosan with a porous structure is obtained;

[0035] (3) The modified chitosan and the potassium salt are added to the ethanol aqueous solution for stirring reaction, and after the stirring reaction is completed, the potassium salt / modified chitosan is obtained by filtration and drying.

[0036] The present inventors add quicklime to the sodium silicate solution generated in the comprehensive utilization of fly ash or high-silicon bauxite, and the synthesized calcium silicate can be used as one of the raw materials of the silicon-calcium-potassium-magnesium type soil conditioner, and the silicon-calcium-potassium-magnesium type soil conditioner obtained by mixing the potassium salt and the magnesium salt is more convenient, but the potassium salt and the magnesium salt are prone to be lost due to the influence of rainwater, in order to solve the technical problem, the present inventors creatively modify the potassium salt and the magnesium salt in different ways, wherein the modification of the magnesium salt is to prepare a magnesium-exchanged molecular sieve first, and the magnesium ions can be fixed inside or on the surface of the molecular sieve; then a comb-shaped modified cellulose is prepared from lauric acid and triethylene glycol mono-p-toluenesulfonate, and finally the comb-shaped modified cellulose is coated on the surface of the magnesium-exchanged molecular sieve, the hydrophobicity and network structure of the modified cellulose can effectively slow down the speed of water molecules entering the inside of the molecular sieve, so as to control the release speed of the magnesium ions; the modification of the potassium salt is to graft chitosan on the surface of zinc oxide first, and then immerse in a stearic acid solution, the stearic acid can be adsorbed on the surface of the chitosan, and when drying, the ethanol aqueous solution will volatilize, and then a modified chitosan with a porous structure is formed, finally the modified chitosan is mixed with the potassium salt, the potassium salt is adsorbed in the porous structure of the modified chitosan at the same time, and the hydrophobic layer of the stearic acid forms a barrier to slow down the penetration speed of water molecules, so as to control the release rate of the potassium salt; the release rates of the potassium salt and the magnesium salt are controlled, and the local pH surge of the soil fertilization point can be avoided to cause the soil to be fixed in the phosphate ion; at the same time, the present inventors find that the different modification methods for the potassium salt and the magnesium salt avoid the caking or adhesion phenomenon of the calcium silicate with a water content of 20-40% when mixed with the potassium salt and the magnesium salt; and the porosity, bulk density, water content and organic matter content of the soil can be improved.

[0037] Preferably, the ratio of the zinc oxide and the chitosan solution in step (1) is 1g: (10-30) mL; the chitosan solution is a mixture of chitosan and acetic acid, and the concentration of the chitosan is 0.05g / mL.

[0038] Preferably, the temperature of the reaction in step (1) is 70-90℃, and the time is 2-4h.

[0039] Preferably, the ratio of the zinc oxide / chitosan and the stearic acid solution in step (2) is 1g: (20-30) mL; the stearic acid solution is a mixture of stearic acid and ethanol, and the concentration of the stearic acid is 10g / mL.

[0040] Preferably, the temperature of the immersion in step (2) is 50-70℃, and the time is 1-2h.

[0041] Preferably, the ratio of the modified chitosan, the potassium salt and the ethanol aqueous solution in step (3) is 1g: (1-2) g: (10-20) mL.

[0042] Preferably, the aqueous ethanol solution is a mixture of ethanol and water with a mass ratio of (70-90):1.

[0043] Preferably, the potassium salt is selected from at least one of potassium chloride and potassium sulfate.

[0044] Preferably, the stirring speed in step (3) is 300-500 rpm, and the stirring time is 3-5 h.

[0045] Preferably, the water content of the calcium silicate is 20-40%.

[0046] Preferably, the alcohol solution of the alkyl quaternary ammonium salt modified palygorskite in step S3 is a mixture of alkyl quaternary ammonium salt modified palygorskite and ethanol, and the ratio of the two is 1 g:(20-30) mL.

[0047] Preferably, the preparation method of the alkyl quaternary ammonium salt modified palygorskite is as follows: taking palygorskite and ethanol, adding alkyl quaternary ammonium salt at 80-100℃ for reflux reaction for 6-10 h, and then washing and drying the product after the reaction is completed.

[0048] Preferably, the ratio of the palygorskite, ethanol and alkyl quaternary ammonium salt is 1 g:(10-30) mL:(0.4-0.6) mL.

[0049] Preferably, the alkyl quaternary ammonium salt is cetyltrimethylammonium bromide.

[0050] In order to avoid a large amount of dust generated by the self-made calcium silicate and ensure its fluidity, the water content of the calcium silicate is controlled to be 20-40% in the present application. However, calcium silicate with high water content is prone to caking or sticking during the mixing process and storage process with potassium salt and magnesium salt. The present inventors found that although the use of modified potassium salt and magnesium salt can avoid caking or sticking during the mixing process with calcium silicate, caking or sticking still occurs during high-temperature and high-humidity storage. To solve this technical problem, the present inventors creatively prepared alkyl quaternary ammonium salt modified palygorskite, which was sprayed on the mixture to avoid caking or sticking of the calcium silicate-potassium-magnesium type soil conditioner. The present inventors further found that when palygorskite was replaced by montmorillonite, the effect was not good. The present inventors speculated that this was because the special chain structure of palygorskite could provide more physical support than the layered structure of montmorillonite, thereby avoiding the sticking or caking of the calcium silicate-potassium-magnesium type soil conditioner.

[0051] In addition, the present inventors also found that the mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite needs to be controlled to be 100:(110-130):(8-10):(3-6), otherwise the effect of the calcium silicate-potassium-magnesium type soil conditioner on adjusting the pH of the soil and increasing the organic matter content will be poor.

[0052] As another implementation, the magnesium salt / molecular sieve / modified cellulose can also be replaced by a magnesium salt; and the potassium salt / modified chitosan can also be replaced by a potassium salt.

[0053] The second aspect of the present application provides a silicon-calcium-potassium-magnesium type soil conditioner prepared by the method described above.

[0054] Compared with the prior art, the present application has the following beneficial effects:

[0055] 1. The present application realizes the full use of the sodium silicate solution produced in the comprehensive utilization of fly ash or high-silicon bauxite, and the synthesized calcium silicate can be used as one of the raw materials of the silicon-calcium-potassium-magnesium type soil conditioner, which is more convenient to mix with potassium salt and magnesium salt to obtain the silicon-calcium-potassium-magnesium type soil conditioner.

[0056] 2. The present application creatively modifies the magnesium salt: first, a magnesium-exchanged molecular sieve is prepared, and the magnesium ions can be fixed inside or on the surface of the molecular sieve; then a comb-shaped modified cellulose is prepared by using lauric acid and triethylene glycol mono-p-toluenesulfonate; and finally, the comb-shaped modified cellulose is coated on the surface of the magnesium-exchanged molecular sieve, and the hydrophobicity and network structure of the modified cellulose can effectively slow down the speed of water molecules entering the inside of the molecular sieve, thereby controlling the release speed of the magnesium ions.

[0057] 3. The present application creatively modifies the potassium salt: first, chitosan is grafted on the surface of zinc oxide, and then immersed in a stearic acid solution, and the stearic acid can be adsorbed on the surface of the chitosan; when dried, the ethanol aqueous solution will volatilize, and a porous modified chitosan is formed; finally, the modified chitosan is mixed with the potassium salt, and the potassium salt is adsorbed in the porous structure of the modified chitosan, while the hydrophobic layer of the stearic acid forms a barrier to slow down the penetration speed of water molecules, thereby controlling the release rate of the potassium salt.

[0058] 4. The release rate of the potassium salt and the magnesium salt in the present application is controlled, and the local pH surge of the soil fertilization point can also be avoided to cause the soil to be fixed in phosphate ions; at the same time, different modification methods are adopted for the potassium salt and the magnesium salt, which avoids the caking or sticking phenomenon of the calcium silicate with a water content of 20-40% when mixed with the potassium salt and the magnesium salt; and the porosity, bulk density, water content and organic matter content of the soil can be improved.

[0059] 5、The present application creatively prepares alkyl ammonium salt modified palygorskite, which is sprayed on the mixture, which can avoid the caking or sticking of the silicon calcium potassium magnesium type soil modifier, control the mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite to be 100:(110-130):(8-10):(3-6), and avoid the effect of the silicon calcium potassium magnesium type soil modifier on adjusting the soil pH and increasing the organic matter content. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 SEM image of the calcium silicate prepared in Basic Example 1. DETAILED DESCRIPTION

[0061] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments will be described in detail.

[0062] The present application will be further described below in conjunction with examples, but the present application is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific use, and the implementation conditions indicated are the conventional conditions in the industry. The technical features involved in each embodiment of the present application can be combined with each other as long as there is no conflict.

[0063] In the following examples and comparative examples, the raw materials used are all from commercial sources or prepared by conventional methods in the art, unless otherwise specified.

[0064] Basic Example 1

[0065] To the sodium silicate solution derived from the silicon dioxide concentration of 102.3 g / L generated in the comprehensive utilization of fly ash, add the quicklime with the effective calcium oxide content of 85.5%, and the mass ratio of the effective calcium oxide in the quicklime to the silicon dioxide in the sodium silicate solution is 1.2, the reaction temperature is 90℃, the reaction time is 1h, and the separated calcium silicate is obtained without drying. The indexes of the calcium silicate are shown in Table 1:

[0066] Table 1

[0067]

[0068] Basic Example 2

[0069] To the sodium silicate solution derived from the silicon dioxide concentration of 30.02 g / L generated in the comprehensive utilization of fly ash, add the quicklime with the effective calcium oxide concentration of 105.6 g / L, and the mass ratio of the effective calcium oxide in the quicklime to the silicon dioxide in the sodium silicate solution is 1, the reaction temperature is 80℃, the reaction time is 1.2h, and the separated calcium silicate is obtained without drying. The indexes of the calcium silicate are shown in Table 2:

[0070] Table 2

[0071]

[0072] Example 1 A silicon calcium potassium magnesium type soil conditioner, the preparation method is:

[0073] S1, drying the calcium silicate which is not dried in the basic example 1 to the moisture content of 38.24%;

[0074] S2, uniformly mixing the calcium silicate, magnesium salt / molecular sieve / modified cellulose and potassium salt / modified chitosan to obtain a mixture;

[0075] S3, spraying the alcohol solution containing alkyl quaternary ammonium salt modified palygorskite on the mixture, stirring, drying to obtain the product.

[0076] The mass ratio of the calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is 100:120:9:5.

[0077] The preparation method of the magnesium salt / molecular sieve / modified cellulose in step S2 is:

[0078] Step 1, dispersing the molecular sieve in the aqueous magnesium salt solution to carry out exchange reaction to obtain magnesium exchanged molecular sieve;

[0079] Step 2, dissolving the cellulose in the solvent, under the protection of nitrogen, adding the dimethylacetamide solution containing lauric acid, 4-toluenesulfonyl chloride and triethylene glycol mono-p-toluenesulfonate, pyridine to carry out modification reaction, after the reaction, carrying out vacuum distillation, water recrystallization and drying to obtain the modified cellulose;

[0080] Step 3: adding the magnesium exchanged molecular sieve and the modified cellulose into water to carry out stirring reaction, after the reaction, carrying out filtration and drying to obtain the product.

[0081] The molecular sieve in step 1 is FAU type Y zeolite molecular sieve, the molar ratio of silicon and aluminum is 81, the specific surface area is 710m 2 / g, purchased from Tianjin Nanhua Catalyst Co., Ltd., model NKF-7-5-80.

[0082] The concentration of the aqueous magnesium salt solution in step 1 is 5mol / L, and the aqueous magnesium salt solution is magnesium sulfate aqueous solution.

[0083] The ratio of the molecular sieve and the aqueous magnesium salt solution in step 1 is 1g:200mL.

[0084] The temperature of the exchange reaction in step 1 is 25℃, and the time of the exchange reaction is 10h.

[0085] The solvent in step 2 is a mixture of lithium chloride and dimethylacetamide, and the mass ratio of the two is 9:91.

[0086] The mass ratio of the cellulose, the solvent, the dimethylacetamide solution and the pyridine in step 2 is 1:12:20:2.5; the dimethylacetamide solution is a mixture of lauric acid, 4-toluenesulfonyl chloride, triethylene glycol monop-toluenesulfonate and dimethylacetamide; and the mass ratio of the lauric acid, 4-toluenesulfonyl chloride, triethylene glycol monop-toluenesulfonate and dimethylacetamide is 1:1.2:2:7.

[0087] The temperature of the modification reaction in step 2 is 85℃, and the time is 20h.

[0088] The mass ratio of the magnesium-exchanged nanoscale molecular sieve, the modified cellulose and water in step 3 is 2:4:25.

[0089] The stirring speed of the stirring reaction in step 3 is 400rpm, and the time is 8h.

[0090] The preparation method of the potassium salt / modified chitosan in step S2 is as follows:

[0091] (1) After the zinc oxide and the chitosan solution are reacted, the zinc oxide / chitosan is dried to obtain the zinc oxide / chitosan;

[0092] (2) The zinc oxide / chitosan is added into a stearic acid solution for impregnation, taken out and dried to obtain the modified chitosan with a porous structure;

[0093] (3) The modified chitosan and the potassium salt are added into an ethanol aqueous solution for stirring reaction, and after the stirring reaction, the potassium salt / modified chitosan is obtained through filtration and drying.

[0094] The ratio of the zinc oxide and the chitosan solution in step (1) is 1g:20mL; the chitosan solution is a mixture of chitosan and acetic acid, and the concentration of the chitosan is 0.05g / mL.

[0095] The zinc oxide is purchased from Shijiazhuang Honghong Chemical Co., Ltd., and the chitosan is an agricultural grade and is purchased from Shandong Haiyiwa Biological Technology Co., Ltd.

[0096] The temperature of the reaction in step (1) is 80℃, and the time is 3h.

[0097] The ratio of the zinc oxide / chitosan and the stearic acid solution in step (2) is 1g:25mL; the stearic acid solution is a mixture of stearic acid and ethanol, and the concentration of the stearic acid is 10g / mL.

[0098] The temperature of the impregnation in step (2) is 60℃, and the time is 1.5h.

[0099] The ratio of modified chitosan, potassium salt and ethanol aqueous solution in step (3) is 1 g: 1.5 g: 15 mL.

[0100] The ethanol aqueous solution is a mixture of ethanol and water with a mass ratio of 80:1; and the potassium salt is potassium sulfate.

[0101] The stirring speed in step (3) is 400 rpm, and the stirring time is 4 h.

[0102] The alcohol solution of the alkyl quaternary ammonium salt modified palygorskite in step S3 is a mixture of alkyl quaternary ammonium salt modified palygorskite and ethanol, and the ratio of the two is 1 g: 25 mL.

[0103] The preparation method of the alkyl quaternary ammonium salt modified palygorskite is as follows: taking palygorskite and ethanol, adding alkyl quaternary ammonium salt at 90°C for reflux reaction for 8 h, and then washing and drying the product after the reaction is completed.

[0104] The palygorskite is purchased from Shunze Mineral Product Processing Factory in Lingshou County.

[0105] The ratio of the palygorskite, ethanol and alkyl quaternary ammonium salt is 1 g: 20 mL: 0.5 mL.

[0106] The alkyl quaternary ammonium salt is cetyltrimethylammonium bromide.

[0107] Example 2

[0108] The difference from Example 1 is that the mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is 100:110:8:3; and the rest is the same.

[0109] Example 3

[0110] The difference from Example 1 is that the mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is 100:130:10:6; and the rest is the same.

[0111] Comparative Example 1

[0112] The difference from Example 1 is that the magnesium salt / molecular sieve / modified cellulose is replaced by the same mass of magnesium salt / modified chitosan, and the preparation method of the magnesium salt / modified chitosan is the same as that of the potassium salt / modified chitosan; and the rest is the same.

[0113] Comparative Example 2

[0114] The difference from Example 1 is that the potassium salt / modified chitosan is replaced by a mixture of potassium salt and chitosan with a mass ratio of 1.5:1; and the rest is the same.

[0115] Comparative Example 3

[0116] The difference from Example 1 is that the preparation method of the potassium salt / modified chitosan is:

[0117] (1) zinc oxide / chitosan is obtained by drying after the reaction of zinc oxide and chitosan solution;

[0118] (2) zinc oxide / chitosan and potassium salt are added into the aqueous ethanol solution for stirring reaction, and after the stirring reaction, the product is obtained by filtration and drying, and the ratio of zinc oxide / chitosan, potassium salt and aqueous ethanol solution is 1g:1.5g:15mL; the rest is the same.

[0119] Comparative Example 4

[0120] The difference from Example 1 is that the magnesium salt / molecular sieve / modified cellulose is replaced by a mixture of magnesium salt, molecular sieve and modified cellulose, and the mass ratio of the three is 1:1:4; the rest is the same.

[0121] Comparative Example 5

[0122] The difference from Example 1 is that the magnesium salt / molecular sieve / modified cellulose is replaced by the same mass of magnesium salt / molecular sieve, and the preparation method of the magnesium salt / molecular sieve is: molecular sieve is dispersed in the aqueous magnesium salt solution for exchange reaction to obtain magnesium salt / molecular sieve; the rest is the same.

[0123] Comparative Example 6

[0124] The difference from Example 1 is that the modified cellulose is replaced by the same mass of cellulose, i.e. the magnesium salt / molecular sieve / modified cellulose is replaced by the same mass of magnesium salt / molecular sieve / cellulose; the rest is the same.

[0125] Comparative Example 7

[0126] The difference from Example 1 is that the palygorskite is replaced by the same mass of montmorillonite, which is purchased from the Lingshou County Shunze Mineral Product Processing Factory; the rest is the same.

[0127] Comparative Example 8

[0128] The difference from Example 1 is that the mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is 80:140:11:3; the rest is the same.

[0129] Performance test:

[0130] 1. The calcium silicate potassium magnesium type soil conditioner of Examples 1-3 is tested according to GB / T 36207-2018 indicators, and the results are shown in Table 3;

[0131] 2. Slow-release performance: The release rate was tested according to the standard GB / T23348-2009, and the test temperature was 25℃. The results are shown in Table 4.

[0132] 3. Storage stability: The silicon-calcium-potassium-magnesium type soil conditioner was placed in an environment with a temperature of 40℃ and a humidity of 65% for 6 months, and whether there was adhesion or caking phenomenon was observed. The results are shown in Table 5.

[0133] 4. Pot experiment: The soil used was acidic red soil with a pH of 5.0 and an organic matter content of 13.52g / kg. The amount of silicon-calcium-potassium-magnesium type soil conditioner added to each pot was 100kg / acre. After 6 months, the soil pH (standard HJ962-2018), soil porosity and bulk density (standard NY / T 1121.4-2006), soil moisture content (standard NY / T 1121.3-2006) and organic matter content (standard NY / T 1121.6-2006) were tested. The results are shown in Table 6.

[0134] Table 3

[0135]

[0136] As can be seen from Table 3, the silicon-calcium-potassium-magnesium type soil conditioner prepared by Examples 1-3 of the present application can meet the requirements of the national standard GB / T 36207-2018 "Silicon-calcium-potassium-magnesium type fertilizer".

[0137] Table 4

[0138]

[0139] As can be seen from Table 4, the silicon-calcium-potassium-magnesium type soil conditioner of Examples 1-3 has good slow-release performance.

[0140] In Comparative Example 1, the magnesium salt / molecular sieve / modified cellulose was replaced by the same amount of magnesium salt / modified chitosan, and the slow-release performance of the obtained silicon-calcium-potassium-magnesium type soil conditioner decreased, indicating that using different modification methods for magnesium salt and potassium salt can achieve better slow-release performance.

[0141] In Comparative Example 2, the potassium salt / modified chitosan was replaced by a mixture of potassium salt and chitosan; and in Comparative Example 3, the preparation method of potassium salt / modified chitosan did not use stearic acid for modification, and the slow-release performance of the obtained silicon-calcium-potassium-magnesium type soil conditioner decreased; indicating that modification of potassium salt can improve the slow-release performance, but only when the modification method of Examples 1-3 of the present application is used, the effect is the best.

[0142] Comparative Example 4, because the magnesium salt / molecular sieve / modified cellulose is replaced by a mixture of magnesium salt, molecular sieve and modified cellulose; Comparative Example 5, because the magnesium salt / molecular sieve / modified cellulose is replaced by the same mass of magnesium salt / molecular sieve; Comparative Example 6, because the modified cellulose is replaced by the same mass of cellulose; the release performance of the resulting silicon-calcium-potassium-magnesium type soil conditioner is reduced; it is shown that modification of the magnesium salt can improve the release performance, but only when the modification method of Examples 1-3 of the present application is used, the effect is the best;

[0143] Comparative Examples 7-8 have little difference in release performance from Example 1.

[0144] Table 5

[0145]

[0146] As can be seen from Table 5, the silicon-calcium-potassium-magnesium type soil conditioners of Examples 1-3 have good storage stability under high temperature and high humidity; Comparative Examples 1-8, although no sticking or caking phenomenon occurs at 1d, the stability is poor after 3 months or 6 months of storage, and sticking or caking phenomenon occurs.

[0147] Table 6

[0148]

[0149] As can be seen from Table 6, the silicon-calcium-potassium-magnesium type soil conditioners of Examples 1-3 can improve the pH of the acidic soil, and the improved soil has higher porosity, lower bulk density, higher water content and higher organic matter content;

[0150] Comparative Examples 1-7 can also improve the organic matter content of the acidic soil, but the porosity of the improved soil decreases, the bulk density increases, the water content decreases, and the organic matter content decreases;

[0151] Comparative Example 8, the mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is not in the preferred range, and the silicon-calcium-potassium-magnesium type soil conditioner obtained has higher porosity, lower bulk density, and higher water content, but the improvement of the pH of the acidic soil is not good, and the organic matter content is low.

[0152] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a silicon calcium potassium magnesium type soil conditioner, characterized by, It comprises the following steps: S1, adding quicklime into sodium silicate solution to react, separate and dry to obtain calcium silicate with water content of 20-40%; S2, uniformly mixing calcium silicate, magnesium salt / molecular sieve / modified cellulose and potassium salt / modified chitosan to obtain a mixture; S3, spraying alcohol solution containing alkyl quaternary ammonium salt modified palygorskite on the mixture, stirring and drying to obtain the product; The mass ratio of calcium silicate, magnesium salt / molecular sieve / modified cellulose, potassium salt / modified chitosan and alkyl quaternary ammonium salt modified palygorskite is 100:(110-130):(8-10):(3-6); The preparation method of the magnesium salt / molecular sieve / modified cellulose comprises the following steps: Step 1, dispersing molecular sieve in aqueous magnesium salt solution to exchange to obtain magnesium exchanged molecular sieve; Step 2, dissolving cellulose in solvent, adding dimethylacetamide solution containing lauric acid, 4-toluenesulfonyl chloride and triethylene glycol monoparaisotoluenesulfonate, pyridine under nitrogen protection to modify, distilling under reduced pressure after reaction, water recrystallization and drying to obtain modified cellulose; Step 3, adding magnesium exchanged molecular sieve and modified cellulose into water to stir, filtering and drying after reaction to obtain the product; The preparation method of the potassium salt / modified chitosan comprises the following steps: (1) reacting zinc oxide with chitosan solution and drying to obtain zinc oxide / chitosan; (2) immersing zinc oxide / chitosan in stearic acid solution, taking out and drying to obtain modified chitosan with porous structure; (3) adding modified chitosan and potassium salt into ethanol aqueous solution to stir, filtering and drying after reaction to obtain the product; The preparation method of the alkyl quaternary ammonium salt modified palygorskite is as follows: taking palygorskite and ethanol, adding alkyl quaternary ammonium salt under the condition of 80-100℃ to reflux for 6-10h, washing and drying the product after reaction to obtain the product.

2. The method of preparing a silicon-calcium-potassium-magnesium type soil conditioner according to claim 1, characterized in that, The molecular sieve described in step 1 is a Y zeolite molecular sieve of FAU type, with a molar silica / alumina of 60-90 and a specific surface area of 650-750 m 2 / g.

3. The method for preparing the silicon-calcium-potassium-magnesium type soil conditioner according to claim 2, characterized in that, The dimethylacetamide solution in step 2 is a mixture of lauric acid, 4-toluenesulfonyl chloride, triethylene glycol monoparaisotoluenesulfonate and dimethylacetamide; the mass ratio of lauric acid, 4-toluenesulfonyl chloride, triethylene glycol monoparaisotoluenesulfonate and dimethylacetamide is 1:(1.1-1.3):(1.5-2.5):(6-8).

4. The method of claim 3, wherein the silty clay loam soil amendment is prepared by the steps of: a) mixing the clay loam soil amendment of claim 1 with the silty soil amendment of claim 2; and b) mixing the mixture of step a) with the silty clay loam soil amendment of claim 3. The mass ratio of magnesium exchanged nanometer molecular sieve, modified cellulose and water in step 3 is (1-3):(3-5):(20-30).

5. The method for preparing the silicon-calcium-potassium-magnesium type soil conditioner according to claim 4, characterized in that, The ratio of modified chitosan, potassium salt and ethanol aqueous solution in step (3) is 1g:(1-2)g:(10-20)mL.

6. The method of claim 5, wherein the silty clay loam soil amendment is prepared by the steps of: a) mixing the clay loam soil amendment of claim 1 with the silty clay loam soil amendment of claim 2; and b) mixing the mixture of step a) with the silty clay loam soil amendment of claim 3. The ratio of palygorskite, ethanol and alkyl quaternary ammonium salt is 1g:(10-30)mL:(0.4-0.6)mL.

7. The silicon calcium potassium magnesium type soil conditioner prepared by the method of any one of claims 1-6.

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