Saline-alkali soil modifier and preparation method thereof

Abstract

The invention relates to the technical field of saline-alkali soil improvement, and discloses a saline-alkali soil improver and a preparation method thereof. The saline-alkali soil improver is obtained by uniformly stirring and mixing calcium chloride, desulfurized gypsum, wood vinegar, modified cellulose hydrogel, bacillus subtilis and brown nitrogen-fixing bacteria and then granulating. A pyrrole group, a piperazine group and a pyridine group in the cellulose hydrogel and nitrogen atoms in a Mannich base structure enhance the hydrogen-bond interaction and improve the water retention capacity of the improver; si-O-Si in a modified organic silicon monomer structure has a strong adsorption effect on soil microparticles to promote soil to form a stable aggregate structure, the salinization degree of a plough layer is reduced, in addition, oxygen atoms of Si-O bonds have adsorption and complexation effects on positive salt-based ions, hydrophilic sites of cellulose are further increased on the hydrophilic surface of the modified organic silicon monomer, and therefore the surface hydrophilicity of the soil is improved. The water absorption rate is improved; the potassium element and the phosphorus element synergistically optimize the physical and chemical properties of the soil and relieve saline-alkali stress, and the improvement effect of the improver is enhanced.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land improvement technology, specifically to a saline-alkali land conditioner and its preparation method. Background Technology

[0002] Saline-alkali land suffers from soil compaction, poor permeability, and weak water and fertilizer retention capacity due to the accumulation of soluble salts and excessive sodium ion content, severely restricting crop growth. Traditional saline-alkali land amendments often use materials such as gypsum, humic acid, or chemical desulfurization byproducts to improve soil aggregate structure through ion exchange or organic matter addition. However, while conventional amendments can adjust the pH and ionic composition of saline-alkali soils, their ability to improve water retention is limited, especially in arid and semi-arid regions where rapid soil moisture evaporation makes the improvement effect unsustainable. Patent CN117865755B discloses a saline-alkali land amendment and its preparation method, which is prepared by mixing, grinding, and sieving desulfurized gypsum, coconut coir, and sugarcane bagasse, then adding a compound biological agent, oyster shell matrix, ammonium dihydrogen phosphate, and potassium humate. This improves the effect and efficiency of saline-alkali land remediation, but its water absorption and retention capacity still needs improvement. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a saline-alkali land conditioner and its preparation method. The saline-alkali land conditioner prepared by this invention exhibits excellent improvement and water absorption / retention effects on saline-alkali land.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a saline-alkali land conditioner, comprising the following weight components: 8-12 parts by weight of calcium chloride, 32-40 parts by weight of desulfurized gypsum, 4-8 parts by weight of wood acetate, 18-22 parts by weight of modified cellulose hydrogel, 1.5-2 parts by weight of Bacillus subtilis, and 2-2.8 parts by weight of brown nitrogen-fixing bacteria.

[0007] Preferably, the method for preparing the modified cellulose hydrogel includes the following steps:

[0008] (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 20-30 min to remove oxygen, heat to 92-98℃, add 1-(2-chloroethyl)piperazine dropwise, heat to 132-140℃ and react for 4-6 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate.

[0009] (2) Under a nitrogen atmosphere, add 6.4-7.2 g of potassium bisulfite to 40-50 mL of deionized water, heat and stir until dissolved, and when the temperature is raised to 66-78℃, add 5.7-6 g of 3-(ethylene oxide-2-yl)pyridine, and continue to heat to 80-90℃ for 2.5-4.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate;

[0010] (3) Add 12.6-13.4g of Mannich base intermediate, 8.2-8.8g of potassium 2,7-pyridylsulfonate intermediate, and 0.05-0.08g of potassium hydroxide catalyst to 90-120mL of N,N-dimethylformamide solvent, stir and mix, heat to the reaction temperature and react for 3-4h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer;

[0011] (4) Mix 20-40 mL of anhydrous ethanol and 6-14 mL of deionized water as a solvent, add 5.4-8.6 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 30-50 min, add 2.4%-2.8% hydrochloric acid solution to adjust the pH value, add 1.2-1.7 g of nano silica, sonicate for 45-60 min, heat to 72-84℃ and reflux for 3.5-5.5 h. After the reaction is completed, wash with anhydrous ethanol, filter and dry to obtain secondary amino nano silica;

[0012] (5) Under a nitrogen atmosphere, add 3.2-3.7g of secondary amine nano silica and 5.4-5.8g of phosphorous acid to 60-80mL of anhydrous ethanol solvent, stir and mix, cool in an ice bath to 0-5℃, add 5.5-6.5mL of formaldehyde solution dropwise, after the addition is complete, add 0.02-0.06g of glacial acetic acid catalyst, heat to 70-80℃ and react for 5-8h. After the reaction is complete, add 4.5%-5% sodium hydroxide solution to adjust the pH to neutral, remove the ethanol solvent by rotary evaporation, wash and dry to obtain the modified organosilicon monomer;

[0013] (6) Add 1.6-2g of carboxymethyl cellulose to 100-150mL of deionized water, sonicate for 10-20min, add 4.1-4.5g of acrylic acid, 2.2-2.4g of modified Mannich base monomer, 2.6-2.8g of modified organosilicon monomer, and 0.1-0.16g of crosslinking agent, stir and mix, purge with nitrogen for 15-25min to remove oxygen, heat to 58-68℃, add 0.03-0.07g of ammonium persulfate initiator, react for 3-7h, after the reaction is complete, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel.

[0014] Preferably, in step (1), the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 5.5-6:1.13-1.17:0.8-1.12:0.05-0.06:1.

[0015] Preferably, the reaction temperature in step (3) is 55-62℃.

[0016] Preferably, the pH value in step (4) is 4.5-5.

[0017] Preferably, the formaldehyde solution in step (5) has a mass fraction of 37%-39%.

[0018] Preferably, the crosslinking agent in step (6) is N,N'-methylenebisacrylamide.

[0019] Preferably, the preparation method of the saline-alkali land conditioner is as follows: calcium chloride, desulfurized gypsum, wood acetate, modified cellulose hydrogel, Bacillus subtilis, and brown nitrogen-fixing bacteria are added to a high-speed mixer, and after being stirred and mixed evenly at 30-35℃ and 100-150 rpm, the mixture is granulated at 80 mesh in a granulator to obtain the saline-alkali land conditioner.

[0020] (III) Beneficial Technical Effects

[0021] This invention obtains a saline-alkali land conditioner by mixing calcium chloride, desulfurized gypsum, wood acetate, modified cellulose hydrogel, Bacillus subtilis, and brown nitrogen-fixing bacteria evenly and then granulating the mixture in a granulator.

[0022] Cellulose hydrogels, added as water-retaining agents to saline-alkali soil conditioners, can improve soil properties and reduce water shortages for plant growth. The pyrrole, piperazine, and pyridine groups introduced into the modified Mannich base monomer, along with the nitrogen atom in the Mannich base structure, act as hydrogen bond acceptors, enhancing hydrogen bonding with the hydroxyl groups on the cellulose molecular chain. This forms a stable physical cross-linked network structure, helping to maintain the structural stability of the cellulose hydrogel in high-salt environments and improving the water-retaining performance of the conditioner. The sulfonic acid groups in potassium sulfonate are strong hydrophilic groups, which can improve the water absorption and retention of the cellulose hydrogel. The multiple Si-O-Si groups in the modified organosilicon monomer structure provide multiple adsorption sites, and the strong adsorption of soil microparticles promotes the formation of stable soil aggregates and enhances soil capillary action. The improved structure blocks the rise of underground salts, reduces the degree of salinization in the topsoil, and facilitates surface water infiltration, leaching away the salts in the topsoil. In addition, the oxygen atoms of the Si-O bond have adsorption and complexation effects on positive base ions, reducing the activity of salt ions. The hydrophilic surface of the modified organosilicon monomer also increases the hydrophilic sites of cellulose, improving the water absorption rate. Its network structure can delay water evaporation, thereby enhancing the improvement effect and water absorption and retention effect of the soil conditioner. The potassium element in the cellulose hydrogel reduces salt damage by replacing sodium ions, improving soil structure, and enhancing plant stress resistance. The phosphorus element enhances nutrient availability by activating fixed phosphorus, neutralizing alkalinity, and promoting microbial activity. The two elements work synergistically to optimize the soil physicochemical properties and alleviate salt and alkali stress, thus enhancing the improvement effect of the soil conditioner. Attached Figure Description

[0023] Figure 1 It is the synthetic reaction formula for modified Mannich base monomers.

[0024] Figure 2 It is the synthesis reaction formula for modified organosilicon monomers. Detailed Implementation

[0025] Example 1

[0026] (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 20 min to remove oxygen, heat to 92℃, and add 1-(2-chloroethyl)piperazine dropwise, wherein the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 5.5:1.13:0.8:0.05:1, heat to 132℃ and react for 4 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate;

[0027] (2) Under a nitrogen atmosphere, add 6.4 g of potassium bisulfite to 40 mL of deionized water, heat and stir until dissolved, raise the temperature to 66 °C, add 5.7 g of 3-(ethylene oxide-2-yl)pyridine, continue to raise the temperature to 80 °C and react for 2.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate;

[0028] (3) Add 12.6 g of Mannich base intermediate, 8.2 g of potassium 2,7-pyridylsulfonate intermediate, and 0.05 g of potassium hydroxide catalyst to 90 mL of N,N-dimethylformamide solvent, stir and mix, heat to 55 °C and react for 3 h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer.

[0029] (4) Mix 20 mL of anhydrous ethanol and 6 mL of deionized water as a solvent, add 5.4 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 30 min, add 2.4% hydrochloric acid solution to adjust the pH to 4.5, add 1.2 g of nano silica, sonicate for 45 min, heat to 72 °C and reflux for 3.5 h. After the reaction is complete, wash with anhydrous ethanol, filter and dry to obtain secondary amino nano silica;

[0030] (5) Under a nitrogen atmosphere, 3.2 g of secondary amine nano silica and 5.4 g of phosphorous acid were added to 60 mL of anhydrous ethanol solvent and stirred. The mixture was cooled to 0 °C in an ice bath. 5.5 mL of 37% formaldehyde solution was added dropwise. After the addition was complete, 0.02 g of glacial acetic acid catalyst was added and the temperature was raised to 70 °C for 5 h. After the reaction was completed, 4.5% sodium hydroxide solution was added to adjust the pH to neutral. The ethanol solvent was removed by rotary evaporation, and the mixture was washed and dried to obtain the modified organosilicon monomer.

[0031] (6) Add 1.6g of carboxymethyl cellulose to 100mL of deionized water, sonicate for 10min, add 4.1g of acrylic acid, 2.2g of modified Mannich base monomer, 2.6g of modified organosilicon monomer, and 0.1g of N,N'-methylenebisacrylamide crosslinking agent, stir and mix, purge with nitrogen for 15min to remove oxygen, heat to 58℃, add 0.03g of ammonium persulfate initiator, react for 3h, after the reaction is completed, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel;

[0032] (7) Add 8 parts by weight of calcium chloride, 32 parts by weight of desulfurized gypsum, 4 parts by weight of wood acetate, 18 parts by weight of modified cellulose hydrogel, 1.5 parts by weight of Bacillus subtilis and 2 parts by weight of brown nitrogen-fixing bacteria to a high-speed mixer. After stirring and mixing evenly at 30°C and 100 rpm, granulate the mixture in a granulator at 80 mesh to obtain a saline-alkali land conditioner.

[0033] Example 2

[0034] (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 30 min to remove oxygen, heat to 98℃, and add 1-(2-chloroethyl)piperazine dropwise, wherein the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 6:1.17:1.12:0.06:1, heat to 140℃ and react for 6 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate;

[0035] (2) Under a nitrogen atmosphere, add 7.2 g of potassium bisulfite to 50 mL of deionized water, heat and stir until dissolved, raise the temperature to 78 °C, add 6 g of 3-(ethylene oxide-2-yl)pyridine, continue to raise the temperature to 90 °C and react for 4.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate;

[0036] (3) Add 13.4 g of Mannich base intermediate, 8.8 g of potassium 2,7-pyridylsulfonate intermediate and 0.08 g of potassium hydroxide catalyst to 120 mL of N,N-dimethylformamide solvent, stir and mix, heat to 62 °C and react for 4 h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer.

[0037] (4) Mix 40 mL of anhydrous ethanol and 14 mL of deionized water as a solvent, add 8.6 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 50 min, add 2.8% hydrochloric acid solution to adjust the pH to 5, add 1.7 g of nano silica, sonicate for 60 min, heat to 84 °C and reflux for 5.5 h. After the reaction is complete, wash with anhydrous ethanol, filter and dry to obtain secondary amine nano silica;

[0038] (5) Under a nitrogen atmosphere, 3.7 g of secondary amine nano silica and 5.8 g of phosphorous acid were added to 80 mL of anhydrous ethanol solvent, stirred and mixed, cooled to 5 °C in an ice bath, and 6.5 mL of 39% formaldehyde solution was added dropwise. After the addition was complete, 0.06 g of glacial acetic acid catalyst was added, and the temperature was raised to 80 °C and reacted for 8 h. After the reaction was completed, 5% sodium hydroxide solution was added to adjust the pH to neutral, the ethanol solvent was removed by rotary evaporation, and the product was washed and dried to obtain the modified organosilicon monomer.

[0039] (6) Add 2g of carboxymethyl cellulose to 150mL of deionized water, sonicate for 20min, add 4.5g of acrylic acid, 2.4g of modified Mannich base monomer, 2.8g of modified organosilicon monomer, and 0.16g of N,N'-methylenebisacrylamide crosslinking agent, stir and mix, purge with nitrogen for 25min to remove oxygen, heat to 68℃, add 0.07g of ammonium persulfate initiator, react for 7h, after the reaction is completed, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel;

[0040] (7) Add 12 parts by weight of calcium chloride, 40 parts by weight of desulfurized gypsum, 8 parts by weight of wood acetate, 22 parts by weight of modified cellulose hydrogel, 2 parts by weight of Bacillus subtilis and 2.8 parts by weight of brown nitrogen-fixing bacteria to a high-speed mixer. After stirring and mixing evenly at 35°C and 150 rpm, granulate the mixture in a granulator at 80 mesh to obtain a saline-alkali land conditioner.

[0041] Example 3

[0042] (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 25 min to remove oxygen, heat to 95℃, and add 1-(2-chloroethyl)piperazine dropwise, wherein the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 5.7:1.15:0.96:0.055:1, heat to 136℃ and react for 5 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate;

[0043] (2) Under a nitrogen atmosphere, add 6.8 g of potassium bisulfite to 45 mL of deionized water, heat and stir until dissolved, raise the temperature to 72 °C, add 5.85 g of 3-(ethylene oxide-2-yl)pyridine, continue to raise the temperature to 85 °C and react for 3.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate;

[0044] (3) Add 13g of Mannich base intermediate, 8.5g of potassium 2,7-pyridylsulfonate intermediate and 0.06g of potassium hydroxide catalyst to 105mL of N,N-dimethylformamide solvent, stir and mix, heat to 58℃ and react for 3.5h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer.

[0045] (4) Mix 30 mL of anhydrous ethanol and 10 mL of deionized water as a solvent, add 7 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 40 min, add 2.6% hydrochloric acid solution to adjust the pH to 4.7, add 1.45 g of nano silica, sonicate for 52 min, heat to 78 °C and reflux for 4.5 h. After the reaction is complete, wash with anhydrous ethanol, filter and dry to obtain secondary amino nano silica;

[0046] (5) Under a nitrogen atmosphere, 3.45 g of secondary amine nano silica and 5.6 g of phosphorous acid were added to 70 mL of anhydrous ethanol solvent and stirred. The mixture was cooled to 2 °C in an ice bath. 6 mL of 38% formaldehyde solution was added dropwise. After the addition was complete, 0.04 g of glacial acetic acid catalyst was added and the temperature was raised to 75 °C for 6.5 h. After the reaction was completed, 4.8% sodium hydroxide solution was added to adjust the pH to neutral. The ethanol solvent was removed by rotary evaporation, and the mixture was washed and dried to obtain the modified organosilicon monomer.

[0047] (6) Add 1.8g of carboxymethyl cellulose to 120mL of deionized water, sonicate for 15min, add 4.3g of acrylic acid, 2.3g of modified Mannich base monomer, 2.7g of modified organosilicon monomer, and 0.13g of N,N'-methylenebisacrylamide crosslinking agent, stir and mix, purge with nitrogen for 20min to remove oxygen, heat to 63℃, add 0.05g of ammonium persulfate initiator, react for 5h, after the reaction is completed, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel;

[0048] (7) Add 10 parts by weight of calcium chloride, 36 parts by weight of desulfurized gypsum, 6 parts by weight of wood acetate, 20 parts by weight of modified cellulose hydrogel, 1.8 parts by weight of Bacillus subtilis, and 2.4 parts by weight of brown nitrogen-fixing bacteria to a high-speed mixer. After stirring and mixing evenly at 32°C and 125 rpm, granulate the mixture in a granulator at 80 mesh to obtain a saline-alkali land conditioner.

[0049] Example 4

[0050] (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 20 min to remove oxygen, heat to 92℃, and add 1-(2-chloroethyl)piperazine dropwise, wherein the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 5.5:1.13:0.8:0.05:1, heat to 132℃ and react for 4 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate;

[0051] (2) Under a nitrogen atmosphere, add 6.4 g of potassium bisulfite to 40 mL of deionized water, heat and stir until dissolved, raise the temperature to 66 °C, add 5.7 g of 3-(ethylene oxide-2-yl)pyridine, continue to raise the temperature to 80 °C and react for 2.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate;

[0052] (3) Add 12.6 g of Mannich base intermediate, 8.2 g of potassium 2,7-pyridylsulfonate intermediate, and 0.05 g of potassium hydroxide catalyst to 90 mL of N,N-dimethylformamide solvent, stir and mix, heat to 55 °C and react for 3 h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer.

[0053] (4) Mix 40 mL of anhydrous ethanol and 14 mL of deionized water as a solvent, add 8.6 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 50 min, add 2.8% hydrochloric acid solution to adjust the pH to 5, add 1.7 g of nano silica, sonicate for 60 min, heat to 84 °C and reflux for 5.5 h. After the reaction is complete, wash with anhydrous ethanol, filter and dry to obtain secondary amine nano silica;

[0054] (5) Under a nitrogen atmosphere, 3.7 g of secondary amine nano silica and 5.8 g of phosphorous acid were added to 80 mL of anhydrous ethanol solvent, stirred and mixed, cooled to 5 °C in an ice bath, and 6.5 mL of 39% formaldehyde solution was added dropwise. After the addition was complete, 0.06 g of glacial acetic acid catalyst was added, and the temperature was raised to 80 °C and reacted for 8 h. After the reaction was completed, 5% sodium hydroxide solution was added to adjust the pH to neutral, the ethanol solvent was removed by rotary evaporation, and the product was washed and dried to obtain the modified organosilicon monomer.

[0055] (6) Add 1.8g of carboxymethyl cellulose to 120mL of deionized water, sonicate for 15min, add 4.3g of acrylic acid, 2.3g of modified Mannich base monomer, 2.7g of modified organosilicon monomer, and 0.13g of N,N'-methylenebisacrylamide crosslinking agent, stir and mix, purge with nitrogen for 20min to remove oxygen, heat to 63℃, add 0.05g of ammonium persulfate initiator, react for 5h, after the reaction is completed, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel;

[0056] (7) Add 10 parts by weight of calcium chloride, 36 parts by weight of desulfurized gypsum, 6 parts by weight of wood acetate, 20 parts by weight of modified cellulose hydrogel, 1.8 parts by weight of Bacillus subtilis, and 2.4 parts by weight of brown nitrogen-fixing bacteria to a high-speed mixer. After stirring and mixing evenly at 32°C and 125 rpm, granulate the mixture in a granulator at 80 mesh to obtain a saline-alkali land conditioner.

[0057] Example 5

[0058] (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 30 min to remove oxygen, heat to 98℃, and add 1-(2-chloroethyl)piperazine dropwise, wherein the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 6:1.17:1.12:0.06:1, heat to 140℃ and react for 6 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate;

[0059] (2) Under a nitrogen atmosphere, add 7.2 g of potassium bisulfite to 50 mL of deionized water, heat and stir until dissolved, raise the temperature to 78 °C, add 6 g of 3-(ethylene oxide-2-yl)pyridine, continue to raise the temperature to 90 °C and react for 4.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate;

[0060] (3) Add 13.4 g of Mannich base intermediate, 8.8 g of potassium 2,7-pyridylsulfonate intermediate and 0.08 g of potassium hydroxide catalyst to 120 mL of N,N-dimethylformamide solvent, stir and mix, heat to 62 °C and react for 4 h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer.

[0061] (4) Mix 30 mL of anhydrous ethanol and 10 mL of deionized water as a solvent, add 7 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 40 min, add 2.6% hydrochloric acid solution to adjust the pH to 4.7, add 1.45 g of nano silica, sonicate for 52 min, heat to 78 °C and reflux for 4.5 h. After the reaction is complete, wash with anhydrous ethanol, filter and dry to obtain secondary amino nano silica;

[0062] (5) Under a nitrogen atmosphere, 3.45 g of secondary amine nano silica and 5.6 g of phosphorous acid were added to 70 mL of anhydrous ethanol solvent and stirred. The mixture was cooled to 2 °C in an ice bath. 6 mL of 38% formaldehyde solution was added dropwise. After the addition was complete, 0.04 g of glacial acetic acid catalyst was added and the temperature was raised to 75 °C for 6.5 h. After the reaction was completed, 4.8% sodium hydroxide solution was added to adjust the pH to neutral. The ethanol solvent was removed by rotary evaporation, and the mixture was washed and dried to obtain the modified organosilicon monomer.

[0063] (6) Add 1.6g of carboxymethyl cellulose to 100mL of deionized water, sonicate for 10min, add 4.1g of acrylic acid, 2.2g of modified Mannich base monomer, 2.6g of modified organosilicon monomer, and 0.1g of N,N'-methylenebisacrylamide crosslinking agent, stir and mix, purge with nitrogen for 15min to remove oxygen, heat to 58℃, add 0.03g of ammonium persulfate initiator, react for 3h, after the reaction is completed, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel;

[0064] (7) Add 8 parts by weight of calcium chloride, 32 parts by weight of desulfurized gypsum, 4 parts by weight of wood acetate, 18 parts by weight of modified cellulose hydrogel, 1.5 parts by weight of Bacillus subtilis and 2 parts by weight of brown nitrogen-fixing bacteria to a high-speed mixer. After stirring and mixing evenly at 30°C and 100 rpm, granulate the mixture in a granulator at 80 mesh to obtain a saline-alkali land conditioner.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 5 is that step (6) does not contain the modified Mannich base monomer.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 5 is that step (6) does not contain modified organosilicon monomers.

[0069] The experiment was conducted at the National Major Special Project for Salt Drainage via Subsurface Pipes in Kutai Village, Kizilsu Township, Jiashi County, Kashgar Prefecture, Xinjiang. Seven experimental plots, each 2 mu (approximately 0.16 acres) deep, were divided into seven areas. The soil salinity (0-40 cm) in each plot was 5.5 g / kg, pH was 8.40, and moisture content was 9.5%. Before testing, the soil was tilled to a depth of 30 cm in each of the seven plots, and the soil conditioners prepared in Examples 1-5 and Comparative Examples 1-2 were applied at a rate of 200 kg / mu (approximately 100 kg / acre). The soil was then tilled again, buried, and thoroughly mixed. After seven days, the soil salinity, pH, and moisture content were measured. The test results are shown in Table 1.

[0070] Table 1: Salt content, pH value, and water content tests.

[0071]

[0072]

[0073] As shown in Table 1, the saline-alkali soil conditioners in Examples 1-5 of the present invention have better improvement and water absorption and retention effects on saline-alkali soils compared with those in Comparative Examples 1-2.

[0074] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A soil conditioner for saline-alkali land, characterized in that, It includes the following components by weight: 8-12 parts calcium chloride, 32-40 parts desulfurized gypsum, 4-8 parts viniferin, 18-22 parts modified cellulose hydrogel, 1.5-2 parts Bacillus subtilis, and 2-2.8 parts brown nitrogen-fixing bacteria.

2. The saline-alkali land conditioner according to claim 1, characterized in that, The method for preparing the modified cellulose hydrogel includes the following steps: (1) Add N-vinylpyrrolidone, paraformaldehyde, and hydroquinone polymerization inhibitor to anhydrous ethanol solvent, stir and mix, purge with nitrogen for 20-30 min to remove oxygen, heat to 92-98℃, add 1-(2-chloroethyl)piperazine dropwise, heat to 132-140℃ and react for 4-6 h. After the reaction is completed, remove the anhydrous ethanol solvent by rotary evaporation to obtain the Mannich base intermediate. (2) Under a nitrogen atmosphere, add 6.4-7.2 g of potassium bisulfite to 40-50 mL of deionized water, heat and stir until dissolved, and when the temperature is raised to 66-78℃, add 5.7-6 g of 3-(ethylene oxide-2-yl)pyridine, and continue to heat to 80-90℃ for 2.5-4.5 h. After the reaction is completed, cool the reaction solution in an ice-water bath, filter the crystals that precipitate after cooling, and recrystallize to obtain potassium pyridine sulfonate intermediate; (3) Add 12.6-13.4g of Mannich base intermediate, 8.2-8.8g of potassium 2,7-pyridylsulfonate intermediate, and 0.05-0.08g of potassium hydroxide catalyst to 90-120mL of N,N-dimethylformamide solvent, stir and mix, heat to the reaction temperature and react for 3-4h. After the reaction is completed, filter, wash and dry to obtain modified Mannich base monomer; (4) Mix 20-40 mL of anhydrous ethanol and 6-14 mL of deionized water as a solvent, add 5.4-8.6 g of 3-(N-allylamino)propyltrimethoxysilane, sonicate for 30-50 min, add 2.4%-2.8% hydrochloric acid solution to adjust the pH value, add 1.2-1.7 g of nano silica, sonicate for 45-60 min, heat to 72-84℃ and reflux for 3.5-5.5 h. After the reaction is completed, wash with anhydrous ethanol, filter and dry to obtain secondary amino nano silica; (5) Under a nitrogen atmosphere, add 3.2-3.7g of secondary amine nano silica and 5.4-5.8g of phosphorous acid to 60-80mL of anhydrous ethanol solvent, stir and mix, cool in an ice bath to 0-5℃, add 5.5-6.5mL of formaldehyde solution dropwise, after the addition is complete, add 0.02-0.06g of glacial acetic acid catalyst, heat to 70-80℃ and react for 5-8h. After the reaction is complete, add 4.5%-5% sodium hydroxide solution to adjust the pH to neutral, remove the ethanol solvent by rotary evaporation, wash and dry to obtain the modified organosilicon monomer; (6) Add 1.6-2g of carboxymethyl cellulose to 100-150mL of deionized water, sonicate for 10-20min, add 4.1-4.5g of acrylic acid, 2.2-2.4g of modified Mannich base monomer, 2.6-2.8g of modified organosilicon monomer, and 0.1-0.16g of crosslinking agent, stir and mix, purge with nitrogen for 15-25min to remove oxygen, heat to 58-68℃, add 0.03-0.07g of ammonium persulfate initiator, react for 3-7h, after the reaction is complete, cut the gel into small pieces, wash and vacuum dry to obtain modified cellulose hydrogel.

3. The saline-alkali land conditioner according to claim 2, characterized in that, In step (1), the molar ratio of anhydrous ethanol, N-vinylpyrrolidone, paraformaldehyde, hydroquinone, and 1-(2-chloroethyl)piperazine is 5.5-6:1.13-1.17:0.8-1.12:0.05-0.06:

1.

4. The saline-alkali land conditioner according to claim 2, characterized in that, The reaction temperature in step (3) is 55-62℃.

5. The saline-alkali land conditioner according to claim 2, characterized in that, The pH value in step (4) is 4.5-5.

6. The saline-alkali land conditioner according to claim 2, characterized in that, The formaldehyde solution in step (5) has a mass fraction of 37%-39%.

7. The saline-alkali land conditioner according to claim 2, characterized in that, The crosslinking agent in step (6) is N,N'-methylenebisacrylamide.

8. A method for preparing a saline-alkali land conditioner as described in any one of claims 1-7, characterized in that, The preparation method of the saline-alkali land conditioner is as follows: calcium chloride, desulfurized gypsum, wood acetate, modified cellulose hydrogel, Bacillus subtilis, and brown nitrogen-fixing bacteria are added to a high-speed mixer and stirred and mixed evenly at 30-35℃ and 100-150 rpm. The mixture is then granulated at 80 mesh in a granulator to obtain the saline-alkali land conditioner.

Images