Cotton stalk biomass charcoal-based saline-alkali soil improving and repairing material and preparation method thereof

Abstract

The invention discloses a cotton stalk biomass charcoal-based saline-alkali soil improving and repairing material and a preparation method thereof, and relates to the technical field of soil improvement. The cotton stalk biomass charcoal-based saline-alkali soil improving and repairing material is prepared from the following raw materials in parts by mass: 40 to 65 parts of cotton stalk biomass charcoal, 15 to 30 parts of humic acid, 10 to 25 parts of mineral cementing agent, 3 to 8 parts of synergist and 2 to 5 parts of stabilizer. The stabilizer is of a structure shown as # imgabs0 #. Through the molecular design of the stabilizer and the synergistic effect of the biomass charcoal and the mineral cementing agent, the pH value and salinity concentration of the soil are synchronously and efficiently reduced, and the defect that alkali reduction and desalination are difficult to consider at the same time in the traditional technology is overcome. Aiming at the special causes of carbonate type saline-alkali soil in Xinjiang, through dynamic pH buffering of a stabilizer and deep salt leaching of a synergist, the pain point that in the prior art, the restoration effect on regional saline-alkali types is insufficient is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and in particular to a cotton stalk biomass carbon-based saline-alkali land improvement and repair material and a preparation method thereof. Background Art

[0002] Xinjiang is one of the regions in China with the most widespread saline-alkali land. The formation of saline-alkali land there is significantly different from that of ordinary saline-alkali land. Ordinary saline-alkali land is typically caused by high groundwater levels and the accumulation of soluble salts and alkaline substances in the soil. However, the formation of saline-alkali land in Xinjiang is closely related not only to the groundwater level but also to the region's unique climate, geology, and soil parent material.

[0003] Xinjiang's arid climate, low rainfall, and high evaporation rates impede soil water circulation, making it difficult for salt to escape to the surface through leaching, leading to its accumulation in the soil's surface layer. Furthermore, Xinjiang experiences a large temperature difference between day and night, with drastic fluctuations in soil temperature. This accelerates water evaporation, further exacerbating salt accumulation in the surface layer. Furthermore, Xinjiang's largely desert and Gobi landscapes create loose soil with high porosity, which facilitates the capillary action of salt in groundwater to the soil surface, leading to salinization.

[0004] In terms of soil parent material, the soil parent material in Xinjiang is mostly calcareous and carbonate. These parent materials easily release large amounts of alkaline substances such as calcium carbonate and sodium carbonate during weathering. These substances accumulate in the soil, increasing the alkalinity and further exacerbating salinization. The soil parent material of ordinary saline-alkali land is relatively complex and diverse, and the mechanism of salinization is also more complicated.

[0005] The salt composition of Xinjiang's saline-alkali land is also different from that of ordinary saline-alkali land. The salt in ordinary saline-alkali land is mainly sodium chloride, sodium sulfate, etc., while the salt in Xinjiang's saline-alkali land is mainly sodium carbonate, sodium bicarbonate, etc. These salts are more alkaline and more harmful to soil structure and plant growth. The hydrolysis of sodium carbonate and sodium bicarbonate in the soil will produce a large amount of hydroxide ions, making the soil highly alkaline, destroying the soil's aggregate structure, causing the soil to become compacted and poorly aerated, which is not conducive to the growth and development of plant roots. In addition, a highly alkaline environment will also have adverse effects on the physiological functions of plants, such as hindering the plant's absorption of nutrients, affecting the plant's photosynthesis and respiration, and thus reducing the plant's growth rate and yield.

[0006] Due to these unique characteristics of Xinjiang's saline-alkali land, its improvement is more difficult than that of ordinary saline-alkali land. Traditional improvement methods, such as water conservancy and agricultural improvements, often fail to achieve ideal results in Xinjiang. Therefore, there is an urgent need to develop a remediation material tailored to the characteristics of Xinjiang's saline-alkali land to effectively improve soil structure, reduce soil salinity, and enhance soil fertility, thereby ensuring sustainable agricultural development in Xinjiang. Summary of the Invention

[0007] The purpose of the present invention is to address the problems existing in the prior art and provide a cotton stalk biomass charcoal-based saline-alkali land improvement and repair material and a preparation method thereof. By optimizing the formula and process, the soil structure can be significantly improved, the salt and alkali content can be reduced, and the soil fertility and crop yield can be increased.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a cotton stalk biomass charcoal-based saline-alkali land improvement and repair material, which is composed of the following raw materials in the following weight ratios: 40-65 parts of cotton stalk biomass charcoal, 15-30 parts of humic acid, 10-25 parts of mineral binder, 3-8 parts of synergist, and 2-5 parts of stabilizer;

[0009] The stabilizer is a compound represented by Formula 1:

[0010]

[0011] The R1 is selected from the group consisting of: methyl, ethyl, tert-butyl, methoxy, phenyl, and tert-butylphenyl.

[0012] Furthermore, the preparation of the cotton stalk biomass charcoal includes: crushing the cotton stalk to a particle size of ≤5mm, heating to 480-550℃ at 10-15℃ / min under anoxic conditions for 1-2 hours, cooling and soaking in 5% phosphoric acid aqueous solution for 20-30 minutes, filtering, and drying to obtain the cotton stalk biomass charcoal.

[0013] Furthermore, the mineral binder is a mixture of attapulgite and superphosphate, and the mass ratio of the two is (3-5):1.

[0014] Furthermore, the synergist is a mixture of sodium lignin sulfonate and magnesium sulfate, with a mass ratio of (1-2):1.

[0015] Furthermore, the stabilizer is a compound represented by the following structure:

[0016]

[0017]

[0018] Furthermore, the synthesis method of the stabilizer is:

[0019]

[0020] Step 1: Raw materials 1 and 2 are reacted by Williamson reaction to synthesize intermediate 1;

[0021] Step 2: Intermediate 1 and raw material 3 are subjected to esterification reaction to synthesize intermediate 2;

[0022] Step 3: Intermediate 2 and raw material 4 are subjected to Buchwald-Hartwig arylation reaction to synthesize a stabilizer.

[0023] A method for preparing a cotton stalk biomass carbon-based saline-alkali land improvement and repair material comprises the following steps:

[0024] S1. The cotton stalk biochar and humic acid were premixed in a twin-screw mixer for 10-15 minutes at a temperature of 60-70 ° C to obtain material A;

[0025] S2. Add the mineral binder and stabilizer to the material A and continue mixing for 20-30 minutes to obtain material B;

[0026] S3. Add the aqueous solution of the synergist to the material B by spraying, and control the moisture content of the mixed system to ≤8% to obtain material C;

[0027] S4. The C material is extruded and granulated to a particle size of 2-4 mm, and dried at 60° C. to obtain a cotton stalk biomass carbon-based saline-alkali land improvement and repair material.

[0028] Furthermore, the mixer rotates at a speed of 40-60 rpm, and nitrogen is introduced for protection during the mixing process.

[0029] Furthermore, the granulation is carried out using a disc granulator, the pressure is set to 5-8 MPa, and the crushing strength of the finished granules is ≥20N / granule.

[0030] Furthermore, the cotton stalk biomass charcoal-based saline-alkali land improvement and restoration material has an electrical conductivity EC value of ≤2.5mS / cm and a pH value of 7.0-8.5, and is suitable for the restoration of carbonate-type saline-alkali land in Xinjiang.

[0031] The invention discloses an application of a cotton stalk biomass charcoal-based saline-alkali land improvement and repair material. The cotton stalk biomass charcoal-based saline-alkali land improvement and repair material is evenly spread on the surface of the saline-alkali land at an application rate of 1.5-3 tons / mu, and the tillage depth is 20-30 cm.

[0032] The carbonyl oxygen atom and nitrogen atom in the stabilizer core of the present invention can simultaneously react with metal cations (such as Na + , Ca 2+ Mg 2+etc.) to form a stable five-membered ring chelate. Reduce the concentration of free salt ions in the soil and alleviate ion poisoning. In an alkaline environment (such as pH>8.5), the imine group can dissociate to form H + , and OH in the soil - Combined with water, it lowers pH. The aromatic conjugated planes in the parent nucleus can adsorb onto the surface of salt crystals, disrupting crystal growth sites, preventing salt precipitation on the soil surface, and reducing salt spot formation. The C=O and N in the parent nucleus act as hydrogen bond donors / acceptors, forming a cross-linked network with soil colloids (such as humic acid and mineral binders), promoting soil aggregate formation, improving pore structure, and blocking capillary salt rise.

[0033] The cotton stalk biochar of the present invention is treated by immersion in phosphoric acid to form abundant pores and surface phosphate groups, which can strongly adsorb Na + 、CO3 2- Plasma reduces the salt concentration of soil solution. Its porous structure provides loading sites for humic acid and stabilizers, enhancing the dispersion and efficiency of subsequent components. The carboxyl / phenolic hydroxyl groups in humic acid chelate Na + , reducing free salt; promoting soil colloid coagulation and improving aggregate structure. After humic acid is mixed with cotton stalk biochar (step S1), a "charcoal-humic acid" complex is formed, which enhances the dual adsorption capacity of salt ions. The rod-like structure of attapulgite in the mineral binder physically fills the soil capillaries, blocking the path of groundwater salt rise, and superphosphate provides Ca 2+ Replacement of Na on soil colloids + , while Ca 2+ With CO3 2- CaCO3 precipitation is generated to reduce alkali at the source. The two are compounded at a ratio of (3-5):1. The attapulgite carrier slowly releases superphosphate to avoid drastic fluctuations in local pH. The sodium lignin sulfonate in the synergist disperses soil particles and helps Mg 2+ Penetrating deep into the tissues, magnesium sulfate provides essential magnesium to plants. 2+ with Na + Competing for adsorption sites, promoting sodium elution, (1-2): 1 ratio ensures that sodium lignin sulfonate fully encapsulates Mg 2+ , to prevent precipitation and failure in alkaline soil.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The synergistic alkali reduction and desalination capabilities are significantly improved: Through the molecular design of the stabilizer and the synergistic effect of biochar and mineral binders, the soil pH value and salt concentration are simultaneously and efficiently reduced, overcoming the defects of traditional technologies that are difficult to balance alkali reduction and desalination.

[0036] 2. Simultaneous optimization of soil structure improvement and soil fertility enhancement: Based on the physical and chemical dual effects of the "carbon-humic acid" complex load and mineral binder, it significantly promotes the formation of soil aggregates, blocks the capillary rise of salt, and at the same time increases the organic matter content, realizing the integration of saline-alkali land structure restoration and soil fertility improvement.

[0037] 3. Breakthrough in regional adaptability: In view of the special causes of carbonate saline-alkali land in Xinjiang (high sodium carbonate / sodium bicarbonate content and strong alkalinity), the dynamic pH buffering of the stabilizer and the deep salt leaching of the enhancer have solved the pain point of the existing technology's insufficient effect on regional saline-alkali type repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The stabilizer 1 of the present invention 1 HNMR spectrum.

[0039] Figure 2 The invention provides a method for synthesizing the stabilizer. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] Synthesis example 1

[0042] Synthesis of stabilizer 1:

[0043]

[0044] Step 1: Under a nitrogen atmosphere, add 20 g of starting material 1, 17.62 g of starting material 2, 44.37 g of potassium phosphate trihydrate, 0.1 g of pyridine-2-carboxylic acid, 0.8 g of CuI, and 250 g of DMSO to the reaction system, and heat to 85°C and maintain for 16 hours. After cooling, extract the reaction mixture with aqueous ammonia solution and methyl tert-butyl ether. Wash the organic phase five times with water and twice with saturated NaCl solution. Finally, dry the combined organic phases over anhydrous magnesium sulfate, spin dry, and perform column chromatography using a mixture of petroleum ether and ethyl acetate as the eluent to obtain 20.82 g of intermediate 1. MS: 336 (MS+H) + .

[0045] Step 2: Under a nitrogen atmosphere, 20.82 g of intermediate 1, 14.25 g of raw material 3, 3.04 g of concentrated sulfuric acid, and 220 g of tetrahydrofuran were added to the reaction system and heated to 85°C for 6 hours. After the reaction, the reaction was cooled to room temperature, the pH was adjusted to neutral with a 0.1 mol / L sodium bicarbonate aqueous solution, 100 g of water was added, the mixture was shaken, allowed to stand, and extracted. The organic phase was retained, dried over anhydrous magnesium sulfate, and subjected to column chromatography using a mixture of petroleum ether and ethyl acetate as the eluent to obtain 26.70 g of intermediate 2. MS: 509 (MS+H) + .

[0046] Step 3: Under a nitrogen atmosphere, 26.70 g of intermediate 2, 5.98 g of raw material 4, 1.44 g of tris(dibenzylideneacetone)dipalladium, 0.5 g of tri-tert-butylphosphine, 10.1 g of sodium tert-butoxide, and 300 g of toluene were added to the reaction system, the temperature was raised to 120°C, and the reaction was refluxed for 12 hours. After the reaction was completed, the temperature was slightly lowered and the mixture was filtered through diatomaceous earth to remove salts and catalyst. The filtrate was cooled to room temperature and washed three times with water. The organic phase was retained and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate, concentrated by rotary evaporation, and subjected to column chromatography using a mixture of petroleum ether and ethyl acetate as the eluent to obtain 20.44 g of stabilizer 1. MS: 523 (MS+H) + .

[0047] 1H NMR of stabilizer 1-dChloroform: δ8.56-8.49 (m, 1H), 7.86 (dd, 1H), 7.73 (dd, 1H), 6.86 (s, 1H), 6.14 (m, 1H), 5.93 (m, 1H), 5.32 (m, 1H), 4.44 (dd, 1H), 4.22 (dd, 1H), 3.76-3.58 (m, 5H), 3.46-3.32 (m, 4H), 3.28-3.02 (m, 2H), 3.02-2.88 (m, 1H), 2.93-2.77 (m, 2H), 2.56 (m, 1H), 2.54-2.33 (m, 4H), 2.30 (m, 1H), 1.15 (dd, 9H).

[0048] Synthesis Example 2-Synthesis Example 6

[0049] Synthesis Example 2-Synthesis Example 6 refer to Stabilizer 2-Stabilizer 6, refer to the synthesis method of Synthesis Example 1, replace the raw material 4, and keep the rest the same as Synthesis Example 1. Specific structure of raw material 4, structure of stabilizer 2-stabilizer 6 and MS (MS+H) + See the table below for data.

[0050] Example 1

[0051] Preparation of a cotton stalk biomass carbon-based saline-alkali land improvement and repair material:

[0052] Raw material ratio (mass parts): cotton stalk biochar: 55 parts, humic acid: 22 parts, mineral binder: 18 parts (a mixture of attapulgite and superphosphate, the mass ratio of the two is 4:1), synergist: 5 parts (a mixture of sodium lignin sulfonate and magnesium sulfate, the mass ratio of the two is 2:1), stabilizer: 3 parts (stabilizer 1 prepared by Synthesis Example 1).

[0053] Preparation method:

[0054] S1. Place 55 parts of cotton stalk biochar (pulverized to ≤5 mm, carbonized at 525°C for 1.5 hours at a rate of 15°C / min under anoxic conditions, soaked in 5% phosphoric acid for 25 minutes, and then dried) and 22 parts of humic acid in a twin-screw mixer. Mix at 50 rpm and 65°C for 12 minutes under nitrogen to obtain Material A.

[0055] S2. Add 14.4 parts of attapulgite, 3.6 parts of superphosphate and 3 parts of stabilizer 1 to material A, maintain 65°C and 50 rpm and continue mixing for 25 minutes to obtain material B.

[0056] S3. Dissolve 5 parts of synergist (3 parts of sodium lignin sulfonate + 2 parts of magnesium sulfate) in an appropriate amount of water and spray it into material B. Control the moisture content of the mixed system to 7.5% to obtain material C.

[0057] S4. Material C was placed into a disc granulator and extruded into granules with a particle size of 2.5-3.5 mm at a pressure of 6 MPa. The granules were dried in an oven at 60°C to a constant weight to obtain a cotton stalk biomass charcoal-based saline-alkali land improvement and restoration material.

[0058] Example 2-Example 6

[0059] A cotton stalk biomass carbon-based saline-alkali land improvement and repair material was prepared by referring to the preparation method of Example 1, wherein the stabilizer was replaced with stabilizer 2 to stabilizer 6 prepared in Synthesis Examples 2 to 6 in sequence, and the rest remained the same as Example 1.

[0060] Comparative Example 1

[0061] A cotton stalk biomass carbon-based saline-alkali land improvement and repair material was prepared by referring to the preparation method of Example 1, except that the stabilizer was replaced by comparative compound 1, and the rest remained the same as Example 1.

[0062] Comparative compound 1:

[0063] Comparative Example 2

[0064] A cotton stalk biomass carbon-based saline-alkali land improvement and repair material was prepared by referring to the preparation method of Example 1, except that the stabilizer was not added, and the rest remained the same as Example 1.

[0065] Comparative Example 3

[0066] A cotton stalk biomass charcoal-based saline-alkali land improvement and restoration material was prepared by referring to the preparation method of Example 1, except that the mass ratio of the mixture of attapulgite and superphosphate was changed to 8:1, and the rest remained the same as Example 1.

[0067] Comparative Example 4

[0068] A cotton stalk biomass carbon-based saline-alkali land improvement and repair material is prepared by referring to the preparation method of Example 1, and a mixture of sodium lignin sulfonate and magnesium sulfate is prepared in a mass ratio of 5:1, and the rest remains the same as Example 1.

[0069] Performance testing:

[0070] Field tests were conducted in typical carbonate saline-alkali land in Xinjiang (initial pH = 9.8, EC = 8.6 mS / cm), with a tillage depth of 25 cm. The cotton stalk biomass charcoal-based saline-alkali land improvement and restoration material prepared in each embodiment and comparative example was evenly spread at an application rate of 2 tons / mu, rotary tilled and mixed, and the pH, EC, and organic matter increase (%) were re-measured after 60 days. pH was tested according to the HJ962-2018 method, EC (electrical conductivity) was tested according to the HJ802-2016 method, and organic matter was measured according to the NY / T1121.6-2006 method.

[0071]

[0072]

[0073] All examples demonstrated excellent synergistic improvements in saline-alkali soil: soil alkalinity was significantly reduced, salt concentration was significantly lowered, and organic matter content was significantly increased, achieving simultaneous optimization of alkalinity reduction, desalination, and fertilization. The comparative examples, on the other hand, exhibited a step-by-step effect reduction—soil improvement performance deteriorated dramatically when specific stabilizers were missing, and an imbalance in the ratio of key components also weakened the remediation effect. The comparative examples lacking stabilizers in particular exhibited the most severe functional deficiencies. This fully demonstrates the decisive role of stabilizer molecular design, component ratios, and process synergy in the remediation of saline-alkali soil.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A cotton stalk biomass carbon-based saline-alkali land improvement and repair material, characterized in that: The method is composed of the following raw materials in the following mass ratios: 40-65 parts of cotton stalk biochar, 15-30 parts of humic acid, 10-25 parts of mineral binder, 3-8 parts of synergist, and 2-5 parts of stabilizer; The stabilizer is a compound represented by Formula 1: The R1 is selected from the group consisting of: methyl, ethyl, tert-butyl, methoxy, phenyl, and tert-butylphenyl.

2. The cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 1, characterized in that: The preparation of the cotton stalk biomass charcoal comprises: crushing the cotton stalks to a particle size of ≤5mm, heating to 480-550°C at 10-15°C / min under anoxic conditions for 1-2 hours, cooling and soaking in a 5% phosphoric acid aqueous solution for 20-30 minutes, filtering, and drying to obtain the cotton stalk biomass charcoal.

3. The cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 1, characterized in that: The mineral binder is a mixture of attapulgite and superphosphate, and the mass ratio of the two is (3-5):

1.

4. The cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 1, characterized in that: The synergist is a mixture of sodium lignin sulfonate and magnesium sulfate, with a mass ratio of (1-2):

1.

5. The cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 1, characterized in that: The stabilizer is a compound shown in the following structure:

6. A method for preparing a cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The cotton stalk biochar and humic acid were premixed in a twin-screw mixer for 10-15 minutes at a temperature of 60-70 ° C to obtain material A; S2. Add the mineral binder and stabilizer to the material A and continue mixing for 20-30 minutes to obtain material B; S3. Add the aqueous solution of the synergist to the material B by spraying, and control the moisture content of the mixed system to ≤8% to obtain material C; S4. The C material is extruded and granulated to a particle size of 2-4 mm, and dried at 60° C. to obtain a cotton stalk biomass carbon-based saline-alkali land improvement and repair material.

7. The method for preparing a cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 6, characterized in that: The mixer rotates at a speed of 40-60 rpm, and nitrogen is introduced for protection during the mixing process.

8. The method for preparing a cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 6, characterized in that: The granulation is carried out using a disc granulator with a pressure set at 5-8 MPa. The crushing strength of the finished granules is ≥20 N / granule.

9. The cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to claim 1, characterized in that: The cotton stalk biomass charcoal-based saline-alkali land improvement and restoration material has an electrical conductivity EC value of ≤2.5mS / cm and a pH value of 7.0-8.5, and is suitable for the restoration of carbonate-type saline-alkali land in Xinjiang.

10. An application of a cotton stalk biomass carbon-based saline-alkali land improvement and repair material according to any one of claims 1 to 5, characterized in that: A cotton stalk biomass charcoal-based saline-alkali land improvement and restoration material is evenly spread on the surface of the saline-alkali land at an application rate of 1.5-3 tons / mu, and the tillage depth is 20-30 cm.

Images