Multifunctional soil conditioner for assisting permeation of cohesive soil

Abstract

The invention belongs to the cross technical field of soil improvement and industrial waste resource utilization, and particularly relates to a multifunctional soil conditioner for assisting permeation of cohesive soil. The raw materials comprise the following components in parts by weight: 55-75 parts of calcium terephthalate crystals, 5-12 parts of humic acid, 1-4 parts of nano silicon dioxide, 5-8 parts of modified bentonite and 2-5 parts of carboxylated grafted humic acid polyester staple fibers. By designing a synergistic formula of the calcium terephthalate crystals with the sheet structures, the humic acid, the nano silicon dioxide and other environment-friendly components and combining a porous net structure formed by the sheet crystals in the soil, the soil conditioner has the advantages that the balance between the permeation assisting effect and the water retention capacity of the viscous soil is realized; meanwhile, the situation that the activity of soil microorganisms is reduced due to a chemical surfactant conditioner is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the cross technical field of soil improvement and industrial waste resource utilization, in particular to a multifunctional soil conditioner for assisting the infiltration of clay soil. BACKGROUND

[0002] Clay soil has core problems such as low water permeability rate, excessive water holding capacity (easy to accumulate water), poor aeration, etc. due to high clay content (usually > 30%), small pore structure and poor connectivity, which seriously restricts agricultural production and soil ecological health. At the same time, clay soil is easy to form a hard and compacted layer after drying, which increases the tillage resistance by more than 30%, and the soil microbial activity is 25%-40% lower than that of loam, further affecting the nutrient conversion efficiency.

[0003] To solve the problem of clay soil infiltration, the existing technology mainly uses the following three types of conditioners, but all have significant defects: Inorganic mineral conditioners: such as quartz sand, zeolite powder, etc., which increase soil porosity by physical filling. For example, a "quartz sand-vermiculite composite conditioner" promoted by a certain agricultural technology company can increase the permeability of clay soil by 30%, but because quartz sand has no water retention function, the soil water retention rate decreases by 40%. After application in a rice field in Wuxi, Jiangsu, the irrigation frequency needs to be increased by 2-3 times, which in turn increases the production cost. Moreover, this type of conditioner cannot improve soil fertility, and additional fertilizers are needed, which can easily cause secondary soil salinization.

[0004] Chemical surfactant conditioners: such as sodium dodecyl benzene sulfonate, polyoxyethylene ether, etc., which improve permeability by reducing the surface tension of soil particles. For example, a "soil infiltration improver" produced by a certain chemical company uses sodium dodecyl benzene sulfonate as the main component. After application in a clay soil in a greenhouse in Suzhou, the short-term permeability increased by 50%, but after 60 days, the soil urease activity decreased by 32% and the number of actinomycetes decreased by 45%. Moreover, the surfactant residue caused spotted phytotoxicity on Chinese cabbage leaves, posing a significant risk to the quality and safety of agricultural products.

[0005] Biomass conditioners: such as straw charcoal, compost, etc., which form pore structures through biological degradation. For example, a "straw charcoal conditioner" developed by a certain environmental protection company had an infiltration effect that lasted only 3 months (the permeability rate decreased from an initial increase of 25% to less than 10%) in a clay soil test in Changzhou. Moreover, the high pH value of straw charcoal (8.5-9.0) caused soil alkalization, which hindered the growth of rapeseed, which prefers acidic conditions, and reduced plant height by 18%.

[0006] At the same time, the printing and dyeing industry is facing the dilemma of "resource difficulty" in alkali reduction wastewater treatment: the COD concentration of alkali reduction wastewater is as high as 20000 mg / L, and the content of terephthalic acid (PTA) accounts for 75% of the total pollutants. The existing acid precipitation method for recovering PTA has problems such as low purity (only 80%-85%), fine particles (particle size <1 μm), and poor dewatering, etc. For example, a printing and dyeing plant in Zhejiang produces 50 tons of acid precipitation PTA solid waste every day, which cannot be reused and can only be landfilled, not only occupying land resources (0.2 mu of new landfill site is added annually), but also causing the COD of the surrounding groundwater to exceed the standard by 1.5-2 times due to the slow dissolution of PTA, causing secondary pollution.

[0007] In summary, the existing clay soil infiltration conditioner has the following technical problems: 1. The existing clay soil infiltration conditioner cannot balance the infiltration effect and water retention capacity. For example, the inorganic mineral conditioner reduces the water retention rate by more than 30% after infiltration, and the chemical surfactant conditioner easily causes soil microbial activity to decrease; 2. The existing conditioner has single function, only can improve the permeability, cannot realize the soil fertility improvement and heavy metal (such as Cd) solidification at the same time, needs to apply different products for many times, increases the agricultural production cost; 3. The utilization rate of acid precipitation PTA solid waste in the printing and dyeing industry is low (<10%), landfill or incineration is easy to cause secondary pollution, and there is a lack of resource utilization path combined with soil improvement demand; 4. The existing calcium terephthalate preparation process cannot accurately control the crystal size and morphology, resulting in poor dispersibility in soil and unstable infiltration effect (such as large particle size is easy to precipitate, and small particle size is easy to agglomerate). SUMMARY

[0008] To solve the above technical problems, the present application provides the following technical solutions: A multifunctional soil conditioner for clay soil infiltration, comprising raw materials, the raw materials comprising, by weight: calcium terephthalate crystals 55-75 parts, humic acid 5-12 parts, nano silicon dioxide 1-4 parts, modified bentonite 5-8 parts, and carboxylated grafted humic acid polyester short fibers (CH-PET fibers) 2-5 parts.

[0009] As a preferred solution of the multifunctional soil conditioner for clay soil infiltration, the calcium terephthalate crystals have a flaky structure and a particle size of 1-5 μm, and a specific surface area of 30-50 m² / g.

[0010] As a preferred scheme of the multifunctional soil conditioner for assisting the infiltration of clay soil, in the scheme, technical parameters of the carboxylated grafting humic acid polyester short fiber are as follows: length 0.1-0.5mm, diameter 10-20μm, carboxyl content 0.8-1.2mmol / g, and grafting humic acid content 15%-20% (mass fraction); the material is prepared by modifying the waste polyester short fiber (DTY waste silk) in the printing and dyeing industry, has the fiber-like structural stability and the humic acid nutrient slow-release function, and can synergistically enhance the soil pore anti-collapse property and the heavy metal (Pb²+, Cu²+) chelating capacity.

[0011] As a preferred scheme of the multifunctional soil conditioner for assisting the infiltration of clay soil, in the scheme, a preparation method of the multifunctional soil conditioner for assisting the infiltration of clay soil is further included, and specific steps of the method are as follows: S1, alkali reduction wastewater pretreatment: taking alkali reduction wastewater from a printing and dyeing plant, removing suspended impurities through plate and frame filtration (filter cloth aperture 5μm), and removing metal ions such as 、 and the like in the wastewater through ion exchange resin (model D001) adsorption to obtain pretreated wastewater; S2, preparation of calcium terephthalate crystal through multi-stage crystallization: taking the pretreated wastewater as raw material, initiating a primary crystallization reaction through temperature rising and stirring, and combining gas protection and ultrasonic control means to intervene in the crystal growth process to realize accurate control of the crystal morphology and structure, so that calcium terephthalate crystal with a specific spatial structure is finally obtained through separation and drying; S3, preparation of carboxylated grafting humic acid polyester short fiber: taking waste polyester short fiber in the printing and dyeing industry as a base material, removing surface contaminants and introducing active groups through alkaline etching, grafting carboxyl functional groups on the fiber surface through carboxylation modification, and finally grafting humic acid to the fiber surface through cross-linking reaction to complete the functional modification of the waste fiber; S4, compounding and mixing: calcium terephthalate crystal, humic acid, nano silicon dioxide (20-50nm), modified bentonite (3% KH-550 modification), and carboxylated grafting humic acid polyester short fiber are mixed in proportion, are put into a double screw mixer (rotation speed 400-500r / min, temperature 60-80℃) for mixing for 40-45min, are crushed through an ultrafine pulverizer and are passed through an 80-mesh sieve to obtain the optimized multifunctional soil conditioner.

[0012] As a preferred scheme of the multifunctional soil conditioner for assisting the infiltration of clay soil, in the scheme, specific steps of S2 are as follows: S21, first-stage crystallization: the pretreated wastewater is introduced into a crystallization kettle, is heated to 50-60℃, and 1.0-1.2mol / L CaCl2 solution is added dropwise while stirring, so that The molar ratio of terephthalic acid is 1.1:1, and the stirring is maintained for 1h after the dropwise addition is completed to form a primary crystallization solution; S22, second-stage ultrasonic regulation: nitrogen is introduced into the primary crystallization solution while ultrasonic treatment is applied to regulate the crystal growth direction through ultrasonic cavitation effect, so that flaky calcium terephthalate crystals are formed; S23, separation and drying: the crystallization solution is centrifuged, the precipitate is collected, washed with deionized water for 3 times, and dried at 80-100°C under vacuum for 2h to obtain calcium terephthalate crystal powder; S24, low-temperature plasma activation: the dried calcium terephthalate crystals are placed into a low-temperature plasma treatment instrument to remove the trace amount of impurities on the surface of the crystals through plasma bombardment (avoiding local increase of soil salinity), while introducing hydroxyl (-OH) groups on the surface of the crystals to improve the interfacial bonding force with humic acid and nanosilica.

[0013] As a preferred scheme of the multifunctional soil conditioner for assisting the infiltration of clay soil, in the S21, the stirring speed is set to 200-300r / min; in the S22, the nitrogen flow rate is set to 50-100mL / min, the ultrasonic power is set to 300-500W, the ultrasonic frequency is set to 20-30kHz, and the ultrasonic time is set to 30-60min.

[0014] As a preferred scheme of the multifunctional soil conditioner for assisting the infiltration of clay soil, in the S23, the centrifugal speed is set to 4000-5000r / min, and the centrifugal time is set to 10-12min; in the S24, the working gas of the low-temperature plasma treatment instrument is argon, the vacuum degree is 0.1-0.3MPa, the power is 150-200W, and the treatment time is 10-15min.

[0015] As a preferred scheme of the multifunctional soil conditioner for assisting the infiltration of clay soil, in the S3, the specific steps are as follows: S31, raw material pretreatment: take the waste polyester staple fiber (DTY waste silk) from a printing and dyeing factory, cut it into 0.1-0.5mm short sections, soak it in 5% NaOH solution (80°C) for 2h for alkaline hydrolysis etching, remove the surface oil stains and introduce hydroxyl groups, filter it, wash it with deionized water until it is neutral, and dry it; S32, carboxylated modification: put the dried short fibers into 10% maleic anhydride ethanol solution (fiber to solution mass ratio 1:20), and add 0.5% benzoyl peroxide (initiator) to reflux at 80°C for 4h to graft carboxyl groups on the surface of the fibers, filter them, wash them with ethanol for 3 times, and dry them at 60°C to obtain carboxylated polyester staple fibers (carboxyl content 0.8-1.2mmol / g). S33, Humic acid grafting: Carboxylated polyester staple fiber is mixed with 5% humic acid aqueous solution and 1% N,N'-dicyclohexylcarbodiimide (crosslinking agent) is added. The mixture is stirred at 50°C for 3 hours to form ester bonds between the carboxyl group and the hydroxyl group of humic acid. After filtration, the mixture is vacuum dried at 80°C for 1 hour to obtain carboxylated grafted humic acid polyester staple fiber. S34, Silane Coating Modification (using industrial waste liquid): Take the waste liquid generated during the production of silane coupling agent (KH-560) (mainly containing unreacted KH-560 and methyltriethoxysilane, with a solid content of 10%-15%), dilute it with water to a concentration of 5%, and immerse the carboxylated grafted humic acid polyester staple fiber in the diluted solution. Stir at 30°C for 2 hours to form a siloxane (-Si-O-) coating layer on the fiber surface (enhancing the resistance to soil microbial degradation). After filtration, dry at 60°C.

[0016] As a preferred embodiment of the multifunctional soil conditioner for improving the infiltration of cohesive soil according to the present invention, wherein: in step S31, the drying temperature is set to 60-80℃; and in step S32, the mass ratio of carboxylated polyester staple fiber to maleic anhydride ethanol solution is set to 1:20.

[0017] As a preferred embodiment of the multifunctional soil conditioner for improving the infiltration of cohesive soil according to the present invention, in step S33, the mass ratio of carboxylated polyester staple fiber to humic acid aqueous solution is set to 1:15; in step S34, the mass ratio of carboxylated grafted humic acid polyester staple fiber to release liquid is set to 1:10.

[0018] Compared with existing technologies: 1. By designing a synergistic formulation of platy calcium terephthalate crystals with environmentally friendly components such as humic acid and nano silica, combined with the porous network structure formed by the platy crystals in the soil, it has the advantage of achieving a balance between the infiltration effect and water retention capacity of cohesive soil, while avoiding the reduction of soil microbial activity caused by chemical surfactants. 2. By integrating the core function of calcium terephthalate in improving permeability, the soil organic matter enhancement effect of humic acid, and the heavy metal (such as Cd) solidification ability of modified bentonite, a "one agent, multiple effects" composite system is constructed. It has the advantage of simultaneously improving the permeability of clay soil, enhancing soil fertility, and solidifying heavy metals with a single product, without the need for multiple applications of different products, thus reducing agricultural production costs. 3. By using alkali reduction wastewater from the dyeing and printing industry as raw material, and preparing calcium terephthalate crystals through a multi-stage crystallization process after pretreatment, calcium terephthalate crystals can be prepared. This replaces the traditional treatment path of solid waste generated after PTA recovery by acid precipitation. It has the advantages of realizing high-value utilization of PTA solid waste from alkali reduction wastewater and avoiding secondary pollution caused by landfilling or incineration of solid waste. 4. By adopting the multi-stage crystallization process of "primary crystallization + ultrasonic regulation under nitrogen protection", the growth direction and dispersion state of calcium terephthalate crystals are precisely intervened, the problems of uneven crystal size and difficult control of morphology in the traditional preparation process are solved, and the crystals can be uniformly dispersed in the soil, thereby ensuring the stability of the soil infiltration effect of the clay soil. DETAILED DESCRIPTION

[0019] In order to make the object, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below. Example 1

[0020] The present application provides a multifunctional soil conditioner for clay soil infiltration, which comprises raw materials, and the raw materials comprise, by weight, 55 parts of calcium terephthalate crystals, 5 parts of humic acid, 1 part of nano-silicon dioxide, 5 parts of modified bentonite, and 2-5 parts of carboxylated grafted humic acid polyester short fibers (CH-PET fibers).

[0021] The calcium terephthalate crystals have a sheet structure, and the particle size is controlled to be 1 μm, and the specific surface area is 30 m² / g.

[0022] The technical parameters of the carboxylated grafted humic acid polyester short fibers are as follows: length 0.1-0.5 mm, diameter 10 μm, carboxyl content 0.8 mmol / g, and grafted humic acid content 15% (mass fraction). The material is prepared by modifying the waste polyester short fibers (DTY waste silk) in the printing and dyeing industry, and has the stability of fibrous structure and the nutrient slow-release function of humic acid, and can synergistically enhance the soil pore collapse resistance and heavy metal (Pb²+, Cu²+) chelating capacity.

[0023] The present application also provides a preparation method of the multifunctional soil conditioner for clay soil infiltration, and the specific steps are as follows: S1, alkali reduction wastewater pretreatment: taking alkali reduction wastewater from a printing and dyeing plant, removing suspended impurities through plate and frame filtration (filter cloth pore size 5 μm), and removing metal ions such as 、 and the like in the wastewater through ion exchange resin (model D001) adsorption to obtain pretreated wastewater; S2, preparation of calcium terephthalate crystals by multi-stage crystallization: taking the pretreated wastewater as raw material, initiating a primary crystallization reaction by heating and stirring, and then combining gas protection and ultrasonic regulation means to intervene in the crystal growth process, so as to precisely control the crystal morphology and structure, and finally obtaining calcium terephthalate crystals with a specific spatial structure through separation and drying; The specific steps of S2 are as follows: S21, first-stage crystallization: introducing the pretreated wastewater into a crystallization kettle, heating to 50℃, and adding 1.0 mol / L CaCl2 solution while stirring, and controlling the pH value to be 6-8 The molar ratio of terephthalic acid to terephthalic acid was 1.1:1. After the addition was completed, the mixture was kept at the temperature and stirred for 1 hour to form a primary crystallization solution. The stirring speed was set to 200 r / min. S22, Second-stage ultrasonic control: Nitrogen gas is introduced into the primary crystallization liquid, and ultrasonic treatment is applied simultaneously to control the crystal growth direction through ultrasonic cavitation effect, forming plate-like calcium terephthalate crystals; wherein, the nitrogen gas flow rate is set to 50 mL / min, the ultrasonic power is set to 300 W, the ultrasonic frequency is set to 20 kHz, and the ultrasonic time is set to 30 min. S23, Separation and Drying: Centrifuge the crystallizing liquid, collect the precipitate, wash it three times with deionized water, and vacuum dry it at 80℃ for 2 hours to obtain calcium terephthalate crystal powder; wherein, the centrifugation speed is set to 4000 r / min and the centrifugation time is set to 10 min. S24, Low-temperature plasma activation: The dried calcium terephthalate crystals are placed in a low-temperature plasma treatment instrument to remove trace amounts of residual calcium terephthalate from the crystal surface through plasma bombardment. (To avoid localized increases in soil salinity), hydroxyl (-OH) groups are introduced onto the crystal surface to enhance the interfacial bonding with humic acid and nano-silica; the working gas of the low-temperature plasma treatment instrument is argon, the vacuum degree is 0.1MPa, the power is 150W, and the treatment time is 10min. S3, Preparation of carboxylated humic acid-grafted polyester staple fiber: Using waste polyester staple fiber from the dyeing and printing industry as the base material, surface contaminants are first removed by alkaline etching and active groups are introduced, then carboxyl functional groups are grafted onto the fiber surface through carboxylation modification, and finally humic acid is grafted onto the fiber surface through crosslinking reaction to complete the functional modification of waste fiber. The specific steps of S3 are as follows: S31, Raw material pretreatment: Take waste polyester staple fiber (DTY waste yarn) from the printing and dyeing plant, cut it into 0.1mm short segments, soak it in 5% NaOH solution (80℃) for 2h for alkaline etching, remove surface oil and introduce hydroxyl groups, filter it, wash it with deionized water until neutral, and dry it; the drying temperature is set at 60℃. S32, Carboxylation Modification: The dried short fibers were immersed in a 10% maleic anhydride ethanol solution (fiber to solution mass ratio 1:20), and 0.5% benzoyl peroxide (initiator) was added. The mixture was refluxed at 80℃ for 4 hours to graft carboxyl groups onto the fiber surface. After filtration, the fibers were washed three times with ethanol and dried at 60℃ to obtain carboxylated polyester short fibers (carboxyl content 0.8 mmol / g). The mass ratio of carboxylated polyester short fibers to maleic anhydride ethanol solution was set to 1:20. S33, Humic Acid Grafting: Carboxylated polyester staple fiber is mixed with 5% humic acid aqueous solution, and 1% N,N'-dicyclohexylcarbodiimide (crosslinking agent) is added. The mixture is stirred at 50°C for 3 hours to allow the carboxyl groups to form ester bonds with the hydroxyl groups of humic acid. After filtration, the mixture is vacuum dried at 80°C for 1 hour to obtain carboxylated grafted humic acid polyester staple fiber. The mass ratio of carboxylated polyester staple fiber to humic acid aqueous solution is set to 1:15. S34, Silane Coating Modification (using industrial waste liquid): Take the waste liquid generated during the production of silane coupling agent (KH-560) (mainly containing unreacted KH-560 and methyltriethoxysilane, solid content 10%), dilute it with water to a concentration of 5%, and immerse carboxylated grafted humic acid polyester staple fiber in the diluted solution. Stir at 30℃ for 2 hours to form a siloxane (-Si-O-) coating layer on the fiber surface (enhancing resistance to soil microbial degradation). After filtration, dry at 60℃. The mass ratio of carboxylated grafted humic acid polyester staple fiber to the released liquid is set to 1:10. S4, Compound Mixing: Calcium terephthalate crystals, humic acid, nano silica (20nm), modified bentonite (3% KH-550 modified), and carboxylated grafted humic acid polyester short fibers are mixed in proportion, put into a twin-screw mixer (speed 400r / min, temperature 60℃) and mixed for 40min. Then, it is pulverized by an ultra-fine pulverizer and passed through an 80-mesh sieve to obtain the optimized multifunctional soil conditioner.

[0024] Example 2: This invention provides a multifunctional soil conditioner for improving the infiltration of cohesive soil, comprising raw materials, wherein the raw materials include, by weight: 65 parts calcium terephthalate crystals, 8.5 parts humic acid, 2.5 parts nano silica, 6.5 parts modified bentonite, and 3.5 parts carboxylated grafted humic acid polyester staple fiber (CH-PET fiber).

[0025] The calcium terephthalate crystals have a plate-like structure, a particle size controlled at 2.5 μm, and a specific surface area of ​​40 m² / g.

[0026] The technical parameters of the carboxylated grafted humic acid polyester staple fiber are: length 0.3 mm, diameter 15 μm, carboxyl content 1.0 mmol / g, and grafted humic acid content 17.5% (mass fraction). This material is prepared by modifying waste polyester staple fiber (DTY waste yarn) from the dyeing and printing industry. It has both fibrous structure stability and humic acid nutrient slow release function, and can synergistically enhance the soil porosity resistance and heavy metal (Pb²+, Cu²+) chelation ability.

[0027] It also includes a method for preparing a multifunctional soil conditioner for improving the infiltration of cohesive soils, the specific steps of which are as follows: S1, Alkali Reduction Wastewater Pretreatment: Alkali reduction wastewater from a dyeing and printing plant is collected, filtered through a plate and frame filter (5μm filter cloth pore size) to remove suspended impurities, and then adsorbed through an ion exchange resin (model D001) to remove impurities from the wastewater. , Metal ions are collected to obtain pretreated wastewater. S2, Multi-stage crystallization preparation of calcium terephthalate crystals: Using pretreated wastewater as raw material, the primary crystallization reaction is initiated by heating and stirring, and then the crystal growth process is intervened by gas protection and ultrasonic control to achieve precise control of crystal morphology and structure. Finally, calcium terephthalate crystals with specific spatial structure are obtained by separation and drying. The specific steps of S2 are as follows: S21, First-stage crystallization: Pretreated wastewater is introduced into a crystallization vessel, heated to 55℃, and a 1.1 mol / L CaCl2 solution is added dropwise while stirring, controlling the temperature... The molar ratio of terephthalic acid to terephthalic acid was 1.1:1. After the addition was completed, the mixture was kept at a constant temperature and stirred for 1 hour to form a primary crystallization solution. The stirring speed was set to 250 r / min. S22, Second-stage ultrasonic control: Nitrogen gas is introduced into the primary crystallization liquid, and ultrasonic treatment is applied simultaneously to control the crystal growth direction through ultrasonic cavitation effect, forming plate-like calcium terephthalate crystals; wherein, the nitrogen gas flow rate is set to 75 mL / min, the ultrasonic power is set to 400 W, the ultrasonic frequency is set to 25 kHz, and the ultrasonic time is set to 45 min. S23, Separation and Drying: Centrifuge the crystallizing liquid, collect the precipitate, wash it three times with deionized water, and vacuum dry it at 90℃ for 2 hours to obtain calcium terephthalate crystal powder; wherein, the centrifugation speed is set to 4500 r / min and the centrifugation time is set to 11 min. S24, Low-temperature plasma activation: The dried calcium terephthalate crystals are placed in a low-temperature plasma treatment instrument to remove trace amounts of residual calcium terephthalate from the crystal surface through plasma bombardment. (To avoid localized increases in soil salinity), hydroxyl (-OH) groups are introduced onto the crystal surface to enhance the interfacial bonding with humic acid and nano-silica; the working gas of the low-temperature plasma treatment instrument is argon, the vacuum degree is 0.2MPa, the power is 175W, and the treatment time is 12.5min. S3, Preparation of carboxylated humic acid-grafted polyester staple fiber: Using waste polyester staple fiber from the dyeing and printing industry as the base material, surface contaminants are first removed by alkaline etching and active groups are introduced, then carboxyl functional groups are grafted onto the fiber surface through carboxylation modification, and finally humic acid is grafted onto the fiber surface through crosslinking reaction to complete the functional modification of waste fiber. The specific steps of S3 are as follows: S31, Raw material pretreatment: Take waste polyester staple fiber (DTY waste yarn) from the printing and dyeing plant, cut it into 0.3mm short segments, soak it in 5% NaOH solution (80℃) for 2h for alkaline etching, remove surface oil and introduce hydroxyl groups, filter it, wash it with deionized water until neutral, and dry it; the drying temperature is set at 70℃. S32, Carboxylation Modification: The dried short fibers were immersed in a 10% maleic anhydride ethanol solution (fiber to solution mass ratio 1:20), and 0.5% benzoyl peroxide (initiator) was added. The mixture was refluxed at 80℃ for 4 hours to graft carboxyl groups onto the fiber surface. After filtration, the fibers were washed three times with ethanol and dried at 60℃ to obtain carboxylated polyester short fibers (carboxyl content 1.0 mmol / g). The mass ratio of carboxylated polyester short fibers to maleic anhydride ethanol solution was set to 1:20. S33, Humic Acid Grafting: Carboxylated polyester staple fiber is mixed with 5% humic acid aqueous solution, and 1% N,N'-dicyclohexylcarbodiimide (crosslinking agent) is added. The mixture is stirred at 50°C for 3 hours to allow the carboxyl groups to form ester bonds with the hydroxyl groups of humic acid. After filtration, the mixture is vacuum dried at 80°C for 1 hour to obtain carboxylated grafted humic acid polyester staple fiber. The mass ratio of carboxylated polyester staple fiber to humic acid aqueous solution is set to 1:15. S34, Silane Coating Modification (using industrial waste liquid): Take the waste liquid generated during the production of silane coupling agent (KH-560) (mainly containing unreacted KH-560 and methyltriethoxysilane, solid content 12.5%), dilute with water to a concentration of 5%, and immerse carboxylated grafted humic acid polyester staple fiber in the diluted solution. Stir at 30℃ for 2 hours to form a siloxane (-Si-O-) coating layer on the fiber surface (enhancing resistance to soil microbial degradation). After filtration, dry at 60℃. The mass ratio of carboxylated grafted humic acid polyester staple fiber to the released liquid is set to 1:10. S4, Compound Mixing: Calcium terephthalate crystals, humic acid, nano silica (35nm), modified bentonite (3% KH-550 modified), and carboxylated grafted humic acid polyester short fibers are mixed in proportion, put into a twin-screw mixer (speed 450r / min, temperature 70℃) and mixed for 42.5min, then pulverized by an ultra-fine pulverizer and passed through an 80-mesh sieve to obtain the optimized multifunctional soil conditioner.

[0028] Example 3: This invention provides a multifunctional soil conditioner for improving the infiltration of cohesive soil, comprising raw materials, which by weight include: 75 parts calcium terephthalate crystals, 12 parts humic acid, 4 parts nano silica, 8 parts modified bentonite, and 5 parts carboxylated grafted humic acid polyester staple fiber (CH-PET fiber).

[0029] The calcium terephthalate crystals have a plate-like structure, with a particle size controlled at 5 μm and a specific surface area of ​​50 m² / g.

[0030] The technical parameters of the carboxylated grafted humic acid polyester staple fiber are: length 0.5 mm, diameter 20 μm, carboxyl content 1.2 mmol / g, and grafted humic acid content 20% (mass fraction). This material is prepared by modifying waste polyester staple fiber (DTY waste yarn) from the dyeing and printing industry. It has both fibrous structure stability and humic acid nutrient slow release function, and can synergistically enhance the soil porosity resistance to collapse and the chelation ability of heavy metals (Pb²+, Cu²+).

[0031] It also includes a method for preparing a multifunctional soil conditioner for improving the infiltration of cohesive soils, the specific steps of which are as follows: S1, Alkali Reduction Wastewater Pretreatment: Alkali reduction wastewater from a dyeing and printing plant is collected, filtered through a plate and frame filter (5μm filter cloth pore size) to remove suspended impurities, and then adsorbed through an ion exchange resin (model D001) to remove impurities from the wastewater. , Metal ions are collected to obtain pretreated wastewater. S2, Multi-stage crystallization preparation of calcium terephthalate crystals: Using pretreated wastewater as raw material, the primary crystallization reaction is initiated by heating and stirring, and then the crystal growth process is intervened by gas protection and ultrasonic control to achieve precise control of crystal morphology and structure. Finally, calcium terephthalate crystals with specific spatial structure are obtained by separation and drying. The specific steps of S2 are as follows: S21, First-stage crystallization: Pretreated wastewater is introduced into a crystallization vessel, heated to 60℃, and a 1.2 mol / L CaCl2 solution is added dropwise while stirring, controlling the temperature... The molar ratio of terephthalic acid to terephthalic acid was 1.1:1. After the addition was completed, the mixture was kept at a constant temperature and stirred for 1 hour to form a primary crystallization solution. The stirring speed was set to 300 r / min. S22, Second-stage ultrasonic control: Nitrogen gas is introduced into the primary crystallization liquid, and ultrasonic treatment is applied simultaneously to control the crystal growth direction through ultrasonic cavitation effect, forming plate-like calcium terephthalate crystals; wherein, the nitrogen gas flow rate is set to 100 mL / min, the ultrasonic power is set to 500 W, the ultrasonic frequency is set to 30 kHz, and the ultrasonic time is set to 60 min. S23, Separation and Drying: Centrifuge the crystallizing liquid, collect the precipitate, wash it three times with deionized water, and vacuum dry it at 100℃ for 2 hours to obtain calcium terephthalate crystal powder; wherein, the centrifugation speed is set to 5000 r / min and the centrifugation time is set to 12 min. S24, Low-temperature plasma activation: The dried calcium terephthalate crystals are placed in a low-temperature plasma treatment instrument to remove trace amounts of residual calcium terephthalate from the crystal surface through plasma bombardment. (To avoid localized increases in soil salinity), hydroxyl (-OH) groups are introduced onto the crystal surface to enhance the interfacial bonding with humic acid and nano-silica; the working gas of the low-temperature plasma treatment instrument is argon, the vacuum degree is 0.3MPa, the power is 200W, and the treatment time is 15min. S3, Preparation of carboxylated humic acid-grafted polyester staple fiber: Using waste polyester staple fiber from the dyeing and printing industry as the base material, surface contaminants are first removed by alkaline etching and active groups are introduced, then carboxyl functional groups are grafted onto the fiber surface through carboxylation modification, and finally humic acid is grafted onto the fiber surface through crosslinking reaction to complete the functional modification of waste fiber. The specific steps of S3 are as follows: S31, Raw material pretreatment: Take waste polyester staple fiber (DTY waste yarn) from the printing and dyeing plant, cut it into 0.5mm short segments, soak it in 5% NaOH solution (80℃) for 2h for alkaline etching, remove surface oil and introduce hydroxyl groups, filter it, wash it with deionized water until neutral, and dry it; the drying temperature is set at 80℃. S32, Carboxylation Modification: The dried short fibers were immersed in a 10% maleic anhydride ethanol solution (fiber to solution mass ratio 1:20), and 0.5% benzoyl peroxide (initiator) was added. The mixture was refluxed at 80℃ for 4 hours to graft carboxyl groups onto the fiber surface. After filtration, the fibers were washed three times with ethanol and dried at 60℃ to obtain carboxylated polyester short fibers (carboxyl content 0.8-1.2 mmol / g). The mass ratio of carboxylated polyester short fibers to maleic anhydride ethanol solution was set to 1:20. S33, Humic Acid Grafting: Carboxylated polyester staple fiber is mixed with 5% humic acid aqueous solution, and 1% N,N'-dicyclohexylcarbodiimide (crosslinking agent) is added. The mixture is stirred at 50°C for 3 hours to allow the carboxyl groups to form ester bonds with the hydroxyl groups of humic acid. After filtration, the mixture is vacuum dried at 80°C for 1 hour to obtain carboxylated grafted humic acid polyester staple fiber. The mass ratio of carboxylated polyester staple fiber to humic acid aqueous solution is set to 1:15. S34, Silane Coating Modification (Utilizing Industrial Waste Liquid): Take the waste liquid generated during the production of silane coupling agent (KH-560) (mainly containing unreacted KH-560 and methyltriethoxysilane, with a solid content of 15%), dilute it with water to a concentration of 5%, and immerse carboxylated grafted humic acid polyester staple fibers in the diluted solution. Stir at 30°C for 2 hours to form a siloxane (-Si-O-) coating layer on the fiber surface (enhancing resistance to soil microbial degradation). After filtration, dry at 60°C. The mass ratio of carboxylated grafted humic acid polyester staple fibers to the released liquid is set to 1:10. S4, Compound Mixing: Calcium terephthalate crystals, humic acid, nano silica (50nm), modified bentonite (3% KH-550 modified), and carboxylated grafted humic acid polyester short fibers are mixed in proportion, put into a twin-screw mixer (speed 500r / min, temperature 80℃) and mixed for 45min. Then, it is pulverized by an ultra-fine pulverizer and passed through an 80-mesh sieve to obtain the optimized multifunctional soil conditioner.

[0032] The following data were obtained by comparing the multifunctional soil conditioners for improving the infiltration of cohesive soils prepared in Examples 1-3 above:

[0033] As shown in the table above, the multifunctional soil conditioners for improving the infiltration of cohesive soil prepared in Examples 1-3 all showed good performance in terms of improving infiltration and water retention balance, as well as multifunctional synergistic effects. After use, Example 2 showed the best results.

[0034] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A multifunctional soil conditioner for assisting the percolation of clayey soils, comprising raw materials, characterized in that, The raw materials include, by weight, calcium terephthalate crystals 55-75 parts, humic acid 5-12 parts, nano-silicon dioxide 1-4 parts, modified bentonite 5-8 parts, and carboxylated grafted humic acid polyester short fibers 2-5 parts.

2. A multifunctional soil conditioner for assisting the percolation of clayey soils according to claim 1, characterized in that, The calcium terephthalate crystals have a flaky structure, a particle size controlled within 1-5 μm, and a specific surface area of 30-50 m² / g.

3. The multifunctional soil conditioner for assisting the percolation of clayey soil according to claim 1, wherein The carboxylated grafted humic acid polyester short fibers have a length of 0.1-0.5 mm, a diameter of 10-20 μm, a carboxyl content of 0.8-1.2 mmol / g, and a grafted humic acid content of 15%-20%.

4. The multifunctional soil conditioner for assisting the percolation of clayey soil according to claim 1, wherein The application further discloses a preparation method of the multifunctional soil conditioner for clay soil. S1, alkali reduction wastewater pretreatment: taking alkali reduction wastewater from a printing and dyeing plant, removing suspended impurities through a plate frame filter, and removing metal ions in the wastewater through ion exchange resin adsorption to obtain pretreated wastewater; S2, preparation of calcium terephthalate crystals through multi-stage crystallization: taking the pretreated wastewater as raw materials, initiating a primary crystallization reaction through temperature rising and stirring, and combining gas protection and ultrasonic control means to intervene in the crystal growth process, so that the crystal morphology and structure are precisely controlled, and finally, calcium terephthalate crystals with a specific spatial structure are obtained through separation and drying; S3, preparation of carboxylated grafted humic acid polyester short fibers: taking waste polyester short fibers in the printing and dyeing industry as a substrate, removing surface contaminants and introducing active groups through alkaline etching, grafting carboxyl functional groups on the fiber surface through carboxylation modification, and finally grafting humic acid onto the fiber surface through cross-linking reaction to complete the functional modification of the waste fibers; S4, compounding and mixing: mixing calcium terephthalate crystals, humic acid, nano-silicon dioxide, modified bentonite and carboxylated grafted humic acid polyester short fibers according to a proportion, feeding into a double screw mixer for mixing for 40-45 min, crushing through a super micro pulverizer and passing through an 80-mesh sieve to obtain an optimized multifunctional soil conditioner.

5. The multifunctional soil conditioner for the assisted infiltration of clayey soils according to claim 4, characterized in that, The specific steps of S2 are as follows: S21, first stage crystallization: the pretreated wastewater is introduced into a crystallization kettle, heated to 50-60℃, 1.0-1.2 mol / L CaCl2 solution is added dropwise while stirring, and the temperature is controlled The molar ratio of terephthalic acid is 1.1:1, and after the dropwise addition is completed, the temperature is kept for 1 h to form a primary crystallization liquid; S22, second-stage ultrasonic control: introducing nitrogen into the primary crystallization solution while applying ultrasonic treatment to control the crystal growth direction through ultrasonic cavitation effect, so that flaky calcium terephthalate crystals are formed; S23, separation and drying: centrifuging the crystallization solution, collecting the precipitate, washing the precipitate with deionized water for 3 times, and vacuum drying at 80-100 DEG C for 2 h to obtain calcium terephthalate crystal powder; S24, low temperature plasma activation: after drying, the calcium terephthalate crystal is put into a low temperature plasma treatment instrument to remove the trace amount of crystal surface residues by plasma bombardment At the same time, the hydroxyl groups are introduced on the crystal surface, and the interfacial binding force with humic acid and nano-silicon dioxide is improved.

6. A multi-functional soil conditioner for assisting the percolation of clayey soil according to claim 5, wherein In S21, the stirring speed is set to 200-300 r / min; in S22, the nitrogen flow rate is set to 50-100 mL / min, the ultrasonic power is set to 300-500 W, the ultrasonic frequency is set to 20-30 kHz, and the ultrasonic time is set to 30-60 min.

7. The multifunctional soil conditioner for assisting the percolation of clayey soil according to claim 5, wherein In S23, the centrifugal speed is set to 4000-5000 r / min, and the centrifugal time is set to 10-12 min; in S24, the working gas of the low-temperature plasma treatment instrument is argon, the vacuum degree is 0.1-0.3 MPa, the power is 150-200 W, and the treatment time is 10-15 min.

8. The multifunctional soil conditioner for assisted infiltration of clayey soil according to claim 4, wherein, The specific steps of S3 are as follows: S31, raw material pretreatment: taking the waste polyester staple fiber from a printing and dyeing factory, cutting into 0.1-0.5mm short segments, soaking in 5% NaOH solution for 2h for alkaline etching, removing surface oil stains and introducing hydroxyl groups, washing with deionized water to neutral after filtration, and drying; S32, carboxylation modification: putting the dried short fibers into 10% maleic anhydride ethanol solution and adding 0.5% benzoyl peroxide, refluxing at 80℃ for 4h to graft carboxyl groups on the surface of the fibers, washing with ethanol for 3 times after filtration, drying at 60℃, and obtaining carboxylated polyester staple fiber; S33, humic acid grafting: mixing the carboxylated polyester staple fiber with 5% humic acid aqueous solution and adding 1% N,N'-dicyclohexyl carbodiimide, stirring at 50℃ for 3h to form ester bonds between carboxyl groups and hydroxyl groups of humic acid, filtering and drying at 80℃ for 1h under vacuum, and obtaining carboxylated grafting humic acid polyester staple fiber; S34, silane coating modification: taking the waste liquid generated in the production process of silane coupling agent, diluting with water to 5% concentration, and immersing the carboxylated grafting humic acid polyester staple fiber in the dilute liquid, stirring at 30℃ for 2h to form a siloxane coating layer on the surface of the fibers, filtering and drying at 60℃.

9. The multifunctional soil conditioner for assisted infiltration of clayey soils according to claim 8, characterized in that, In the S31, the drying temperature is set to 60-80℃; in the S32, the mass ratio of carboxylated polyester staple fiber to maleic anhydride ethanol solution is 1:

20.

10. The multifunctional soil conditioner for assisting the percolation of clayey soil according to claim 8, wherein In the S33, the mass ratio of carboxylated polyester staple fiber to humic acid aqueous solution is 1:15; in the S34, the mass ratio of carboxylated grafting humic acid polyester staple fiber to the release liquid is 1:10.

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