A composite modified material using ultrasonic electrolytic fly ash and plant oil residue and a preparation method and application thereof

Abstract

This invention provides a composite soil amendment material using ultrasonic electrolysis of fly ash and vegetable oil residue, its preparation method, and its application, belonging to the field of saline-alkali soil improvement technology. The preparation method involves mixing fly ash with an electrolyte solution to obtain a fly ash suspension, followed by ultrasonic electrolytic activation to obtain activated fly ash; inoculating the vegetable oil residue with a fermentation agent, and after anaerobic fermentation, obtaining a vegetable oil residue fertilizer; mixing the activated fly ash and the vegetable oil residue fertilizer and then curing to obtain the composite soil amendment material. The prepared composite soil amendment material is applied to the improvement of saline-alkali soil. This invention uses fly ash from coal-fired power plants and vegetable oil residue as raw materials, which are inexpensive and clean. Furthermore, the soil amendment material prepared by this invention can significantly promote the removal of salt and alkali, improve soil structure, and enhance soil fertility during soil improvement.

Description

Technical Field

[0001] This invention belongs to the field of saline-alkali soil improvement technology, and particularly relates to a composite improvement material using ultrasonic electrolysis of fly ash and vegetable oil residue, its preparation method and application. Background Technology

[0002] Saline-alkali soil is a widely distributed low-yield soil type in my country. Its high salt content, high alkalinity, and lack of organic matter lead to soil compaction and low microbial activity, severely restricting crop growth and the efficient use of land resources. With increasingly scarce agricultural land resources, the improvement and resource utilization of saline-alkali soil has become an important issue for enhancing land productivity and ensuring sustainable agricultural development.

[0003] Studies have shown that various methods, including physical, chemical, and biological methods, can be used to improve saline-alkali soils, such as topsoil replacement, application of chemical amendments, and planting salt-tolerant plants. However, these conventional improvement methods generally have many limitations: First, there are cost and resource issues. Topsoil replacement requires a large amount of high-quality soil, resulting in high transportation and construction costs, and easily leading to the waste of high-quality soil resources. Chemical amendments, such as gypsum and phosphogypsum, can achieve ion exchange to reduce alkali, but they can only improve the chemical properties of the soil and cannot replenish organic matter, easily leading to poor soil fertility. Moreover, some chemical reagents pose a risk of secondary pollution. Second, the improvement effects are singular. Physical tillage can only temporarily improve soil aeration and cannot fundamentally reduce soil salinity and alkalinity. Single biological amendments, such as planting salt-tolerant plants, have a long improvement cycle and slow results, making it difficult to quickly achieve efficient remediation of saline-alkali soils. Third, there is insufficient utilization of solid waste. Fly ash, as a major solid waste from coal-fired power plants, is rich in minerals such as silicon, aluminum, and calcium, which have the potential for ion exchange and salt adsorption, and can be used for saline-alkali soil improvement. However, unactivated fly ash has low activity and limited improvement effect, and its application alone cannot compensate for the lack of organic matter in saline-alkali soil. Vegetable oil residue, as a by-product of oil refining, has the characteristics of large output and rich organic matter and nutrient content. However, its traditional treatment methods, such as feed production and direct composting, have problems such as easy mold growth and long decomposition period, which can easily lead to resource waste and environmental problems. Fourth, there is poor technical synergy. Existing saline-alkali soil improvement technologies mostly adopt single methods and have not achieved the synergistic combination of activation of inorganic mineral amendments and modification of organic fertilizers, making it difficult to solve the multiple problems of high salt content, high alkali content, poor structure, and low fertility of saline-alkali soil at the same time.

[0004] Currently, fly ash-based saline-alkali soil improvement technologies mostly focus on activation methods such as physical grinding and simple chemical activation, resulting in low activation efficiency and insufficient utilization of the ion exchange and adsorption properties of fly ash. Furthermore, the resource utilization of plant oil residue is largely limited to direct composting and returning to the field, without combining it with inorganic amendments such as fly ash to achieve functional complementarity. Therefore, developing a synergistic improvement technology for saline-alkali soil that can achieve efficient activation of fly ash, resource utilization of plant oil residue, and multiple functions including salt and alkali reduction, structural improvement, and soil fertility enhancement has become an urgent technical challenge. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue, along with its preparation method and application. This effectively solves the problems of limited effectiveness, insufficient solid waste utilization, high cost, and long cycle in existing saline-alkali soil improvement methods, achieving high-value resource utilization of fly ash and vegetable oil residue, while simultaneously achieving efficient synergistic improvement of saline-alkali soil.

[0006] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention: This invention provides a method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue, comprising the following steps: (1) Fly ash is mixed with an electrolyte solution to obtain a fly ash suspension, and then electrolytically activated under ultrasonic conditions to obtain activated fly ash; (2) Fermentation agents are introduced into vegetable oil residue, and after anaerobic fermentation, vegetable oil residue water fertilizer is obtained; (3) The activated fly ash is mixed with plant oil residue water fertilizer and then cured to obtain the composite improved material.

[0007] Furthermore, the fly ash mentioned in step (1) is power plant fly ash, and the particle size of the fly ash is ≤0.15 mm; The electrolyte solution is water or calcium acetate solution, preferably calcium acetate solution; The concentration of the calcium acetate solution is 0.05-0.5 mol / L.

[0008] Beneficial effects: This invention selects calcium acetate solution as the electrolyte solution because calcium acetate is easily soluble in water, and after electrolysis, it produces CH3COO. - It decomposes very easily, leaving no residue, and unlike chlorides and sulfates, it does not release Cl- in water. - SO4 2- It poisons plants, but its effects are relatively mild. Furthermore, calcium acetate releases calcium when dissolved in water. 2+ It can displace Na from soil colloids. +This lowers the soil pH. Furthermore, calcium acetate can disrupt the aluminosilicate glass structure in fly ash, increasing its specific surface area and porosity, thus facilitating the adsorption of salt ions from the soil and achieving the goal of desalination.

[0009] If the concentration of calcium acetate solution is too high, excess Ca will... 2+ Disrupting soil aggregate stability leads to soil compaction, poor aeration, and increased susceptibility to waterlogging and salinization. It also generates precipitates that clog the pores of fly ash, reducing its specific surface area and decreasing its adsorption capacity for salt ions. If the concentration of calcium acetate solution is too low, it results in poor conductivity, significantly reducing the efficiency of ultrasonic electrolysis. Furthermore, it leads to incomplete improvement of fly ash structure, low activity, and no significant increase in specific surface area, thus its soil-improving ability is generally limited. 2+ Insufficient release, replacement of Na in the soil + Its ability is relatively weak, and it cannot effectively lower soil pH.

[0010] Further, the ratio of fly ash to electrolyte solution added in step (1) is 1 g: 10 mL.

[0011] Beneficial Effects: This invention limits the addition ratio of fly ash to electrolyte solution to 1 g: 10 mL, providing sufficient dispersion space for the fly ash particles to form a well-flowing suspension. This ensures that each fly ash particle can fully contact the electrolyte solution under the action of ultrasound and stirring, creating uniform conditions for the subsequent electrolysis reaction. The electrolyte solution is the carrier of current; the above-mentioned addition amount ensures sufficient ions in the solution to conduct the current and maintain a stable electrolysis process. Too much electrolyte solution will result in an excessively low concentration of fly ash particles per unit volume, leading to a decreased reaction rate and reduced processing efficiency. Furthermore, it will require increasing the voltage to maintain an effective electrolysis current, causing unnecessary energy waste. Too little electrolyte solution will cause the fly ash suspension to become too viscous, making it difficult to stir evenly. This will cause the fly ash particles to agglomerate, preventing them from fully contacting the electrolyte. Since the electrolysis reaction mainly occurs on the particle surface, the interior of the agglomerated particles cannot be effectively activated, resulting in a decrease in overall activation efficiency. It will also severely hinder the propagation of ultrasound, greatly weakening the physical breaking effect of cavitation.

[0012] Further, the ultrasonic power in step (1) is 400 W, and the stirring speed is 100-400 rpm, preferably 200 rpm; The electrolysis uses platinum electrodes, the electrolysis temperature is 30 ℃, the electrolysis time is 15-45 min, and the electrolysis voltage is 5-20 V, preferably 5-10 V.

[0013] Further, the inoculum amount of the fermentation agent in step (2) is 1.0% of the dry weight of the vegetable oil residue; The vegetable oil residue includes peanut residue, and the particle size of the vegetable oil residue is ≤0.2 mm; The fermentation agent is EM bacteria.

[0014] Beneficial effects: This invention selects peanut residue as the composite amendment material for preparing vegetable oil residue because peanut residue has a high organic matter content, rapid fermentation, and is widely available. This invention pulverizes the vegetable oil residue to a particle size ≤0.2 mm, which increases the contact area between the residue and EM bacteria, avoiding incomplete local fermentation. It also accelerates the dissolution of organic matter in the residue into the nutrient solution, preventing the residue from clumping during fermentation and causing localized mold growth.

[0015] EM bacteria are a mixture of fermenting bacteria such as lactic acid bacteria, yeast, photosynthetic bacteria, and actinomycetes. Compared with single-species bacteria, they can quickly decompose vegetable oil residue and prevent it from becoming smelly or rancid. Moreover, EM bacteria are a complex and effective microbial community, containing four types of symbiotic fermenting bacteria: lactic acid bacteria, yeast, photosynthetic bacteria, and actinomycetes, thereby promoting the fermentation effect.

[0016] Furthermore, the anaerobic fermentation temperature in step (2) is 25 °C, and the fermentation time is 25-45 days, preferably 25 days.

[0017] Further, the solid-liquid mass ratio of the activated fly ash and the plant oil residue fertilizer in step (3) is (1-2):(1-2). The curing temperature was 25 ℃, and the time was 7 days.

[0018] Beneficial Effects: This invention limits the solid-liquid mass ratio of activated fly ash to plant oil residue fertigation to (1-2):(1-2). At this ratio, the porous structure of fly ash can adsorb organic nutrients and active substances in the fertigation, forming a nutrient reservoir. When the material is applied to the soil, these nutrients can be slowly released, providing long-term nutrition for crops and avoiding the risk of rapid nutrient loss or root burn. Moreover, activated fly ash mainly plays a role in improving soil structure, regulating pH, and providing micronutrients; while plant oil residue fertigation provides organic matter, amino acids, and beneficial microorganisms. The combination of the two at this optimal ratio can achieve synergistic effects of physical and biochemical improvement. This ratio ensures sufficient moisture in the system to maintain the activity of microorganisms such as EM bacteria in the fertigation. The growth and metabolism of microorganisms cannot be separated from water, and sufficient moisture is a prerequisite for them to continue to play a role in the soil. At the same time, the fly ash in this ratio acts as a skeleton, ensuring that the composite material has sufficient pores to provide oxygen and prevent an anaerobic environment caused by excessive moisture, thereby ensuring the survival and function of aerobic microorganisms.

[0019] If the solid content is too high, it will lead to insufficient moisture, which will severely inhibit the activity of microorganisms, causing the fermentation process to stagnate. The organic nutrients in the fertilizer cannot be effectively utilized, the biological improvement effect will be lost, and the fly ash cannot fully adsorb and load the effective components in the fertilizer. Simply mixing the two physically will not form an efficient composite system. Moreover, if the liquid content is too high, the excess liquid will destroy the skeletal structure formed by the fly ash, causing it to lose its ability to improve the physical properties of the soil. Excessive water will also displace air in the soil, easily forming an anaerobic environment in some areas. This not only inhibits aerobic microorganisms but also produces harmful substances such as hydrogen sulfide, which will damage the crop roots.

[0020] The second technical solution of the present invention: The present invention also provides a composite modified material prepared by the method for preparing the composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue.

[0021] The third technical solution of the present invention: The present invention also provides an application of the composite modified material in the modification of saline-alkali soil.

[0022] Furthermore, the amount of the composite improvement material applied is 5%-15% of the dry weight of the saline-alkali soil. The composite improvement material is applied to the saline-alkali soil to be improved in proportion, tilled and mixed evenly, and then watered and cured to complete the improvement of the saline-alkali soil.

[0023] Different soil conditioners have varying effects on soil improvement. While considering the effectiveness of soil conditioners, their cost must also be taken into account; too many expensive conditioners are not conducive to large-scale industrial production. This invention uses fly ash from coal-fired power plants and oil residue from vegetable oil extraction as raw materials, which are inexpensive and clean, and better align with the national policy of "using waste to treat waste" for resource utilization. Furthermore, the soil conditioner prepared by this invention can significantly promote salinity removal, improve soil structure, and enhance soil fertility during the soil improvement process.

[0024] The ultrasonic electrolytic fly ash and fermented plant oil residue used in this invention are used synergistically as soil conditioners. Compared with existing fly ash treatment technologies, this method can more effectively avoid the introduction of other metal ions and can also transfer the metal ions in the original fly ash to the aqueous phase and separate them from the original fly ash.

[0025] As shown in the chemical formulas (1) to (7) below, during the ultrasonic electrolysis of fly ash, water oxidation occurs on the anode surface to generate H. + This forms an acidic etching environment (chemical formula (1)), H + Etching the aluminosilicate glass in fly ash disrupts its network structure and releases active Ca. 2+ Al 3+The presence of cations (chemical formulas (2) and (3)) lays the foundation for ion exchange-based desalination. A water reduction reaction occurs on the cathode surface to generate OH-. - This creates an alkaline activating environment (chemical formula (4)), OH - Depolymerizing the silica-oxygen network of fly ash enhances its adsorption and ion exchange properties (chemical formula (5)). Ultrasonic cavitation enhances the mass transfer efficiency of ions in the electrolyte, promoting H+ ion exchange. + OH - The deep etching of fly ash, combined with the reaction of organic acids from fermented plant oil residue fertilizer with alkaline minerals in fly ash (chemical formula (6)), achieves secondary activation of fly ash. Subsequently, humus and metal ions dissolved from fly ash form stable complexes (chemical formula (7)), enhancing the stability and fertilization function of the composite amendment material. The final composite amendment material is applied to saline-alkali land to replace Na in soil colloids. + (Chemical formula (8)) to achieve the purpose of desalination and alkali reduction.

[0026] anode 2H₂O→O₂↑+4H + +4e - (1) Al₂O₃ + 6H₂O + →2Al 3+ +3H2O (2) CaO + 2H+ + →Ca 2+ +H2O (3) cathode 2H2O+2e - →H₂↑+2OH⁻ - (4) SiO2 + 2OH - →SiO3 2- +H2O (5) Collaboration CaCO3 + 2H+ + →Ca 2+ +H2O+CO2↑ (6) Ca 2+ +HA→Ca-HA (7) Soil-Na + +Ca 2+ →Soil-Ca 2+ +Na + (8) The beneficial effects of this invention compared to the prior art are as follows: This invention proposes a new method for improving saline-alkali soil through comprehensive utilization of industrial and agricultural solid waste. It uses fly ash and vegetable oil residue as raw materials to prepare composite improvement materials, which have a significant effect on improving high saline-alkali soil and achieve the goal of "treating waste with waste". Moreover, this invention also has the advantages of low cost, environmental friendliness and easy engineering implementation.

[0027] This invention proposes a low-cost process route for the synergistic improvement of saline-alkali soil. Based on the study of reaction mechanism and combined with the raw material characteristics of fly ash and vegetable oil residue, an optimal improvement technology scheme combining ultrasonic electrolytic activation and anaerobic fermentation is designed.

[0028] This invention establishes an ultrasonic-enhanced fly ash electrolytic activation scheme. The ultrasonic cavitation effect enhances ion mass transfer, promotes deep etching of fly ash, and disperses fine particles to avoid agglomeration, thereby improving its salt adsorption and fixation capacity and material composite compatibility. Moreover, the composite improvement of activated fly ash and fermented plant oil residue in saline-alkali soil achieves multiple synergistic effects, which can not only efficiently reduce salt and alkali and improve soil structure, but also replenish organic matter, activate microbial activity, and realize secondary activation of fly ash, significantly improving plant survival rate and growth height.

[0029] The technical solution of this invention can reduce the cost and environmental risks of the entire industrial chain of saline-alkali soil improvement. Moreover, the preparation method of this invention can be carried out at normal temperature and pressure without the introduction of harmful ions, and is suitable for the application needs of different main saline-alkali soil producing areas in southern Xinjiang. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] The saline-alkali soils described in the following embodiments of the present invention all come from Alar City, Xinjiang (81°17'47.180"E, 40°33'11.034"N), with an initial pH of 8.91.

[0036] Example 1 Investigating the effect of electrolysis voltage on the properties of composite modified materials A method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue includes the following steps: (1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solution with a concentration of 0.1 mol / L to obtain fly ash suspension. Then, it was placed in an ultrasonic instrument. Under the fixed conditions of ultrasonic power of 400 W, stirring speed of 200 rpm, electrolysis temperature of 30 ℃ and electrolysis time of 15 min, four sets of electrolysis voltages of 5 V, 10 V, 15 V and 20 V were set for ultrasonic electrolysis treatment. After electrolysis, the fly ash was filtered and dried to obtain ultrasonically activated fly ash under different voltages.

[0037] (2) Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix evenly. After sealing, anaerobic fermentation is carried out at 25 ℃ for 25 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0038] (3) The ultrasonically activated fly ash under different voltages was mixed with the fermented plant oil residue water fertilizer at a solid-liquid mass ratio of 1:1, and then sealed and cured at 25 ℃ for 7 days to obtain the composite modified material.

[0039] Application method: The composite amendment materials prepared under different voltages were mixed evenly with 400 g of saline-alkali soil at an application rate of 5% of the dry weight of the saline-alkali soil and poured into flower pots. At the same time, a blank group (i.e., no amendment material was applied to the saline-alkali soil) was set up. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The results are shown in Table 1.

[0040] Table 1

[0041] Table 1 shows that as the electrolysis voltage increases, the pH of the improved soil decreases, while the survival rate and average plant height of garlic increase. However, when the voltage exceeds 10V, the pH gradually increases again, the improvement effect weakens, and the survival rate and average plant height of garlic decrease significantly. Therefore, the optimal electrolysis voltage is 10V.

[0042] Example 2 Investigating the effect of electrolyte solution concentration on the properties of composite modified materials A method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue includes the following steps: (1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solutions with concentrations of 0.05 mol / L, 0.1 mol / L, 0.25 mol / L and 0.5 mol / L to obtain fly ash suspensions with different electrolyte solution concentrations. Then, the suspensions were placed in an ultrasonic instrument and subjected to ultrasonic electrolysis under the conditions of ultrasonic power of 400 W, stirring speed of 200 rpm, electrolysis temperature of 30 ℃, electrolysis time of 15 min and electrolysis voltage of 10 V. After electrolysis, the fly ash was filtered and dried to obtain ultrasonically activated fly ash with different electrolyte solution concentrations.

[0043] (2) Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix evenly. After sealing, anaerobic fermentation is carried out at 25 ℃ for 25 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0044] (3) The ultrasonically activated fly ash with different electrolyte solution concentrations was mixed with the fermented plant oil residue water fertilizer at a solid-liquid mass ratio of 1:2, and then sealed and cured at 25 ℃ for 7 days to obtain the composite improved material.

[0045] Application method: The composite soil amendment materials prepared under different electrolyte solution concentrations were mixed evenly with 400 g of saline-alkali soil at an application rate of 10% of the dry weight of the saline-alkali soil and poured into flower pots. At the same time, a blank group (i.e., no amendment material was applied to the saline-alkali soil) was set up. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The results are shown in Table 2.

[0046] Table 2

[0047] Table 2 shows that as the concentration of calcium acetate solution increases, the pH of the improved soil decreases, while the survival rate and average plant height of garlic increase. However, when the concentration of calcium acetate solution exceeds 0.1 mol / L, the soil pH gradually increases again, and the improvement effect weakens. Therefore, 0.1 mol / L is selected as the optimal concentration of calcium acetate solution.

[0048] Example 3 The effects of electrolysis time and solid-liquid mass ratio on the properties of the composite modifier and the effect of application rate on the modification effect were investigated. A method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue includes the following steps: (1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solution with a concentration of 0.1 mol / L to obtain fly ash suspension. Then, it was placed in an ultrasonic instrument and ultrasonic electrolysis was performed under the fixed conditions of ultrasonic power of 400 W, stirring speed of 200 rpm, electrolysis temperature of 30 ℃, electrolysis time of 15 min and electrolysis voltage of 10 V. Electrolysis time was set for 15 min, 30 min and 45 min respectively. After electrolysis, the fly ash was filtered and dried to obtain ultrasonically activated fly ash under different electrolysis times.

[0049] (2) Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix evenly. After sealing, anaerobic fermentation is carried out at 25 ℃ for 25 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0050] (3) The ultrasonically activated fly ash under different electrolysis times was mixed with the fermented plant oil residue water fertilizer at solid-liquid mass ratios of 1:1, 1:2 and 2:1, respectively, and then sealed and cured at 25 ℃ for 7 days to obtain composite modified materials.

[0051] Application method: Composite amendments prepared under different electrolysis times and solid-liquid mass ratios were mixed evenly with 400 g of saline-alkali soil at application rates of 5%, 10%, and 15% of the dry weight of the saline-alkali soil, and poured into flower pots. A blank group (i.e., no amendments were applied to the saline-alkali soil) was also set up. Then, garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of the garlic and the soil improvement index were recorded. The results are shown in Table 3.

[0052] Table 3

[0053] As shown in Table 3, when the electrolysis time is 30 min, the solid-liquid mass ratio is 1:2, and the application rate is 10%, the garlic survival rate and average plant height are optimal, and the improvement effect is the best.

[0054] Comparative Example 1 A method for preparing a modified material using ultrasonic electrolysis of fly ash includes the following steps: 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of 0.1 mol / L calcium acetate solution to obtain a fly ash suspension. The suspension was then placed in an ultrasonic instrument and subjected to ultrasonic electrolysis treatment at fixed conditions of 400 W ultrasonic power, 200 rpm stirring speed, 30 ℃ electrolysis temperature, 15 min electrolysis time, and 10 V electrolysis voltage for 15 min, 30 min, and 45 min respectively. After electrolysis, the fly ash was filtered and dried to obtain ultrasonically activated fly ash under different electrolysis times.

[0055] Application method: The ultrasonically activated fly ash at different electrolysis times was mixed evenly with 400 g of saline-alkali soil at application rates of 5%, 10%, and 15% of the dry weight of the saline-alkali soil, and poured into flower pots. A blank group (i.e., no amendment material was applied to the saline-alkali soil) was set up at the same time. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The results are shown in Table 4.

[0056] Table 4

[0057] Table 4 shows that, under the same electrolysis time conditions, as the amount of amendment applied increases, the pH of the amended soil decreases, while the survival rate and average plant height of garlic increase. However, when the application rate exceeds 10%, although the soil pH continues to decrease, the amendment effect weakens; the optimal application rate is 10%. Under the same application rate conditions, as the electrolysis time extends, the pH of the amended soil decreases, while the survival rate and average plant height of garlic increase. However, when the electrolysis time exceeds 30 minutes, the pH of the amended soil increases, and the amendment effect weakens; the optimal electrolysis time is 30 minutes.

[0058] Comparative Example 2 A method for preparing an improved material using vegetable oil residue includes the following steps: Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix well. After sealing, anaerobic fermentation is carried out at 25 ℃ for 60 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0059] Application method: The fermented plant oil residue was diluted to a liquid fertilizer at a ratio of 1:20. The diluted liquid fertilizer was then mixed with 400g of saline-alkali soil at application rates of 5%, 10%, and 15% of the dry weight of the saline-alkali soil, respectively, and poured into flower pots. A blank group (i.e., no amendment material was applied to the saline-alkali soil) was also set up. Then, the garlic seedlings that had been hydroponically sprouted were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of the garlic and the soil improvement index were recorded. The results are shown in Table 5.

[0060] Table 5

[0061] Table 5 shows that as the application rate of fermented plant oil residue increased, the pH of the improved soil decreased, and the survival rate of garlic increased. Although the pH continued to decrease, it also limited the growth effect of garlic. When the application rate of fermented plant oil residue exceeded 10%, the improvement effect weakened. The optimal application rate of fermented plant oil residue was 10%.

[0062] Comparative Example 3 A method for preparing a composite modified material differs from Example 1 in that: ultrasonic treatment is not performed; only the fly ash is electrolytically activated. The specific preparation method is as follows: 1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solution with a concentration of 0.1 mol / L to obtain a fly ash suspension. Then, under the fixed conditions of electrolysis temperature of 30 ℃ and electrolysis time of 15 min, four sets of electrolysis voltages of 5V, 10V, 15V and 20V were set for electrolysis treatment. After electrolysis, the fly ash was filtered and dried to obtain electrolyzed activated fly ash under different voltages.

[0063] (2) Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix evenly. After sealing, anaerobic fermentation is carried out at 25 ℃ for 25 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0064] (3) The electrolytically activated fly ash under different voltages was mixed with the fermented plant oil residue water fertilizer at a solid-liquid mass ratio of 1:1, and then sealed and cured at 25 ℃ for 7 days to obtain the composite modified material.

[0065] Application method: The composite improvement materials prepared under different voltages in Comparative Example 3 were mixed evenly with 400g of saline-alkali soil at an application rate of 5% of the dry weight of the saline-alkali soil and poured into flower pots. At the same time, a blank group (i.e., no improvement material was applied to the saline-alkali soil) was set up. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The comparison results between Comparative Example 3 and Example 1 (electrolysis voltage 10V) are shown in Table 6.

[0066] Table 6

[0067] As shown in Table 6, compared with Example 1, electrolysis of fly ash alone did not significantly reduce the pH of the improved soil. In fact, the pH of the improved soil increased with the increase of electrolysis voltage, and the survival rate and average plant height of garlic decreased, indicating a weakening of the improvement effect.

[0068] Comparative Example 4 A method for preparing a composite modified material differs from Example 2 in that: electrolytic treatment is not performed; only ultrasonic activation of fly ash is carried out. The specific preparation method is as follows: (1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solutions with concentrations of 0.05 mol / L, 0.1 mol / L, 0.25 mol / L and 0.5 mol / L to obtain fly ash suspensions. Then, the suspensions were placed in an ultrasonic instrument and ultrasonically treated at an ultrasonic power of 400 W and a stirring speed of 200 rpm. The fly ash was then filtered and dried to obtain ultrasonically activated fly ash.

[0069] (2) Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix evenly. After sealing, anaerobic fermentation is carried out at 25 ℃ for 25 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0070] (3) The ultrasonically activated fly ash was mixed with the fermented plant oil residue water fertilizer at a solid-liquid mass ratio of 1:2, and then sealed and cured at 25 ℃ for 7 days to obtain the composite modified material.

[0071] Application method: The composite amendment material prepared in Comparative Example 4 was mixed evenly with 400 g of saline-alkali soil at an application rate of 10% of the dry weight of the saline-alkali soil and poured into flower pots. A blank group (i.e., no amendment material was applied to the saline-alkali soil) was set up at the same time. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The comparison results between Comparative Example 4 and Example 2 (calcium acetate solution concentration 0.1 mol / L) are shown in Table 7.

[0072] Table 7

[0073] As shown in Table 7, compared with Example 2, ultrasonic treatment of fly ash alone resulted in an increase in soil pH, a decrease in garlic survival rate and average plant height, and a weakening of the improvement effect.

[0074] Comparative Example 5 The preparation method of a composite modified material differs from experimental group 5 in that: the peanut residue is not subjected to anaerobic fermentation treatment, but is directly prepared into a water-soluble fertilizer by adding water to the original peanut residue. The specific preparation method is as follows: (1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solution with a concentration of 0.1 mol / L to obtain fly ash suspension. Then, it was placed in an ultrasonic instrument and ultrasonically electrolyzed for 30 min under the fixed conditions of ultrasonic power of 400 W, stirring speed of 200 rpm, electrolysis temperature of 30 ℃, electrolysis time of 15 min and electrolysis voltage of 10 V. After electrolysis, the fly ash was filtered and dried to obtain ultrasonically electrolyzed activated fly ash.

[0075] (2) Mix 500 g of peanut residue (particle size ≤ 0.2 mm) with water at a ratio of 1:20 to make a water-soluble fertilizer.

[0076] (3) The ultrasonically activated fly ash and the water fertilizer were mixed at a solid-liquid mass ratio of 1:2, and then sealed and cured at 25 °C for 7 days to obtain the composite modified material.

[0077] Application method: The composite amendment material prepared in Comparative Example 5 was mixed evenly with 400 g of saline-alkali soil at an application rate of 10% of the dry weight of the saline-alkali soil and poured into flower pots. A blank group (i.e., no amendment material was applied to the saline-alkali soil) was set up at the same time. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The comparison results between Comparative Example 5 and Example 3 (Experimental Group 5) are shown in Table 8.

[0078] Table 8

[0079] As shown in Table 8, compared with Example 3, adding unfermented vegetable oil residue alone did not significantly reduce the pH of the improved soil, and the survival rate and average plant height of garlic also decreased significantly, indicating a weakened improvement effect.

[0080] Comparative Example 6 The method for preparing an improved material differs from experimental group 5 in that: no fermented plant oil residue fertilizer is added, and only ultrasonically electrolytically activated fly ash is used as the improved material.

[0081] Comparative Example 7 The method for preparing an improved material differs from experimental group 5 in Example 3 in that: ultrasonically electrolytically activated fly ash is not added as the improved material, but only fermented plant oil residue water fertilizer is used as the improved material.

[0082] The improved materials prepared in Comparative Examples 6 and 7 were mixed evenly with 400 g of saline-alkali soil at an application rate of 10% of the dry weight of the saline-alkali soil, and poured into flower pots. A blank group (i.e., no improved material was applied to the saline-alkali soil) was set up at the same time. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of garlic and soil improvement indicators were recorded. The comparison results between Comparative Examples 6 and 7 and Example 3 (Experimental Group 5) are shown in Table 9.

[0083] Table 9

[0084] As shown in Table 9, compared with Example 3, adding ultrasonically electrolytically activated fly ash alone did not significantly reduce the soil pH after improvement, and the survival rate and average plant height of garlic were lower, indicating a weakened improvement effect. Adding fermented plant oil residue fertilizer alone also did not significantly reduce the soil pH after improvement, and the survival rate and average plant height of garlic decreased significantly, indicating a weakened improvement effect.

[0085] Comparative Example 8 A method for preparing an improved material differs from experimental group 5 in Example 3 in that: the ultrasonically activated fly ash prepared in step (1) and the fermented plant oil residue slurry prepared in step (2) are applied separately and sequentially to the saline-alkali soil, with each application amount being 5% of the dry weight of the saline-alkali soil (the total application amount of ultrasonically activated fly ash and fermented plant oil residue slurry is 10%). Garlic seedlings that have sprouted hydroponically were transplanted into the saline-alkali soil with the improved material applied, using the same method as in Example 3. At the same time, a blank group (i.e., no improved material was applied to the saline-alkali soil) was set up, and the growth status of garlic and soil improvement indicators were recorded. The comparison results between Comparative Example 8 and Example 3 (experimental group 5) are shown in Table 10.

[0086] Table 10

[0087] As shown in Table 10, compared with Example 3, when ultrasonically activated fly ash and fermented plant oil residue were applied to saline-alkali soil separately, the pH of the improved soil was not significantly reduced, and the survival rate and average plant height of garlic also decreased significantly, indicating a weakened improvement effect.

[0088] In summary, as demonstrated by the above examples and comparative examples, compared with purely physical, chemical, or single biological methods for improving saline-alkali soil, the method of improving saline-alkali soil using ultrasonic electrolysis of fly ash and synergistic fermentation of plant oil residue of the present invention has milder reaction conditions and simpler operation. The composite improvement material prepared by the synergistic improvement method of ultrasonically activated fly ash and anaerobic fermentation of plant oil residue has a good improvement effect on saline-alkali soil, which can significantly reduce soil acidity and alkalinity, and improve the survival rate and average plant height of garlic. Among them, the product prepared by using a 0.1 mol / L calcium acetate solution as the electrolyte solution, an electrolysis time of 30 min, an electrolysis voltage of 10 V, and a solid-liquid mass ratio of ultrasonically activated fly ash and fermented plant oil residue water fertilizer of 1:2 has the best performance, the best improvement effect on saline-alkali soil, and the best plant growth.

[0089] Example 4 A method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue includes the following steps: (1) 50 g of power plant fly ash (particle size ≤ 0.15 mm) was mixed with 500 mL of calcium acetate solution with a concentration of 0.1 mol / L to obtain fly ash suspension. Then, it was placed in an ultrasonic instrument and ultrasonically electrolyzed for 30 min under the conditions of ultrasonic power of 400 W, stirring speed of 200 rpm, electrolysis temperature of 30 ℃, electrolysis time of 15 min and electrolysis voltage of 10 V. After electrolysis, the fly ash was filtered and dried to obtain ultrasonically electrolyzed activated fly ash.

[0090] (2) Add 500 g of peanut residue (particle size ≤ 0.2 mm) to a 5 L fermenter, then add 500 mL of EM bacteria solution with a concentration of 10 g / L and mix evenly. After sealing, anaerobic fermentation is carried out at 25 ℃ for 25 days. After fermentation, solid-liquid separation is performed to obtain fermented plant oil residue water fertilizer.

[0091] (3) The ultrasonically activated fly ash and fermented plant oil residue water fertilizer were mixed at a solid-liquid mass ratio of 1:2, and then sealed and cured at 25 ℃ for 7 days to obtain the composite improved material.

[0092] Application method: The composite improvement material prepared in Example 4 was mixed evenly with 400 g of saline-alkali soil at an application rate of 10% of the dry weight of the saline-alkali soil, and poured into flower pots. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. After 15 days of cultivation, the survival rate of garlic was 86.7%, the soil pH was 7.56, and the average plant height of garlic was 43.4 cm / 15 days.

[0093] Comparative Example 9 A method for preparing a composite modified material differs from Example 4 in that: the power plant fly ash in step (1) is replaced with an equal amount of raw coal fly ash; The remaining preparation methods are the same as in Example 4.

[0094] Application method: The composite improvement material prepared in Comparative Example 9 was mixed evenly with 400g of saline-alkali soil at an application rate of 15% of the dry weight of the saline-alkali soil and poured into flower pots. Then, the garlic seedlings that had been hydroponically sprouted were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of the garlic and the soil improvement index were recorded. The comparison results between Comparative Example 9 and Example 4 are shown in Table 11.

[0095] Table 11

[0096] As shown in Table 11, compared with Example 4, the addition of raw coal ash that has not undergone ultrasonic electrolysis did not significantly reduce the pH of the improved soil, and the survival rate and average plant height of garlic were greatly reduced, indicating a weakened improvement effect.

[0097] Comparative Example 10 A method for preparing a composite modified material differs from Example 4 in that: the fly ash from the power plant in step (1) is replaced in equal amounts with the tailings produced after ultrasonic electrolysis of raw coal; The remaining preparation methods are the same as in Example 4.

[0098] Application method: The composite improvement material prepared in Comparative Example 10 was mixed evenly with 400 g of saline-alkali soil at an application rate of 15% of the dry weight of the saline-alkali soil and poured into flower pots. Then, the garlic seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. The growth status of the garlic and the soil improvement index were recorded. The comparison results between Comparative Example 10 and Example 4 are shown in Table 12.

[0099] Table 12

[0100] As shown in Table 12, compared with Example 4, the soil pH was significantly reduced and the survival rate and average plant height of garlic increased after adding the tailings produced by ultrasonic electrolysis of raw coal. Although it had a certain improvement effect, its effect was not better than that of the soil improved by ultrasonic electrolysis of fly ash, and the improvement effect was low.

[0101] Application Example 1 The composite improvement material prepared in Example 4 was mixed evenly with 400 g of saline-alkali soil at an application rate of 15% of the dry weight of the saline-alkali soil and poured into flower pots. Then, 15 ryegrass seedlings that had been hydroponically germinated were transplanted into flower pots and watered with an appropriate amount of fresh water. At the same time, a blank control group was set up as a reference. The growth status of ryegrass and soil improvement indicators were recorded. The comparison results are shown in Table 13.

[0102] Table 13

[0103] As shown in Table 13, compared with Example 4, replacing the crop with ryegrass resulted in a significant decrease in soil pH, an increase in crop survival rate and average plant height compared with the unimproved saline-alkali soil, and a significant improvement effect.

[0104] Application Example 2 The composite improvement material prepared in Example 4 was mixed evenly with 400 g of saline-alkali soil at an application rate of 15% of the dry weight of the saline-alkali soil and poured into flower pots. Then, the mung bean seedlings that had been hydroponically germinated were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. At the same time, a blank control group was set up as a reference. The growth status of mung beans and soil improvement indicators were recorded. The comparison results are shown in Table 14.

[0105] Table 14

[0106] As shown in Table 14, compared with Example 4, replacing the planted crop with mung bean seedlings significantly reduced the soil pH and increased the crop survival rate and average plant height compared with the unimproved saline-alkali soil, demonstrating a significant improvement effect.

[0107] Application Example 3 The composite improvement material prepared in Example 4 was mixed evenly with 400 g of saline-alkali soil at an application rate of 15% of the dry weight of the saline-alkali soil and poured into flower pots. Then, the hydroponically germinated bok choy seedlings were transplanted into flower pots, 15 seedlings per pot, and watered with an appropriate amount of fresh water. At the same time, a blank control group was set up as a reference. The growth status of the bok choy and the soil improvement index were recorded. The comparison results are shown in Table 15.

[0108] Table 15

[0109] As shown in Table 15, compared with Example 4, replacing the planted crop with Chinese cabbage significantly reduced the soil pH and increased the crop survival rate and average plant height compared with the unimproved saline-alkali soil, demonstrating a significant improvement effect.

[0110] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. The ratio, application amount and process parameters of the composite improvement material can be flexibly adjusted according to the actual salinity of the saline-alkali soil to be improved, regional climate conditions and crop planting needs, and unnecessary technical features can be added or removed to adapt to the saline-alkali soil improvement needs in different scenarios.

[0111] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue, characterized in that, Includes the following steps: (1) Fly ash is mixed with an electrolyte solution to obtain a fly ash suspension, and then electrolytically activated under ultrasonic conditions to obtain activated fly ash; (2) Fermentation agents are introduced into vegetable oil residue, and after anaerobic fermentation, vegetable oil residue water fertilizer is obtained; (3) The activated fly ash is mixed with plant oil residue water fertilizer and then cured to obtain the composite improved material.

2. The method for preparing the composite modified material using ultrasonic electrolytic fly ash and vegetable oil residue according to claim 1, characterized in that, The fly ash mentioned in step (1) is power plant fly ash, and the particle size of the fly ash is ≤0.15 mm; The electrolyte solution is water or calcium acetate solution; The concentration of the calcium acetate solution is 0.05-0.5 mol / L.

3. The method for preparing the composite modified material using ultrasonic electrolytic fly ash and vegetable oil residue according to claim 1, characterized in that, The ratio of fly ash to electrolyte solution added in step (1) is 1 g: 10 mL.

4. The method for preparing the composite modified material using ultrasonic electrolytic fly ash and vegetable oil residue according to claim 1, characterized in that, The ultrasonic power in step (1) is 400 W, and the stirring speed is 100-400 rpm; The electrolysis temperature is 30 ℃, the electrolysis time is 15-45 min, and the electrolysis voltage is 5-20 V.

5. The method for preparing the composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue according to claim 1, characterized in that, The inoculum amount of the fermentation agent in step (2) is 1.0% of the dry weight of the vegetable oil residue; The vegetable oil residue includes peanut residue, and the particle size of the vegetable oil residue is ≤0.2 mm; The fermentation agent is EM bacteria.

6. The method for preparing the composite modified material using ultrasonic electrolytic fly ash and vegetable oil residue according to claim 1, characterized in that, The anaerobic fermentation temperature in step (2) is 25 °C, and the fermentation time is 25-45 days.

7. The method for preparing the composite modified material using ultrasonic electrolytic fly ash and vegetable oil residue according to claim 1, characterized in that, The solid-liquid mass ratio of activated fly ash to plant oil residue slurry in step (3) is (1-2):(1-2). The curing temperature was 25 ℃, and the time was 7 days.

8. A composite modified material prepared by the method for preparing a composite modified material using ultrasonic electrolysis of fly ash and vegetable oil residue as described in any one of claims 1-7.

9. The application of the composite amendment material as described in claim 8 in the improvement of saline-alkali soil.

10. The application according to claim 9, characterized in that, The amount of the composite improvement material applied is 5%-15% of the dry weight of the saline-alkali soil.

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