Soil conditioner and preparation method thereof

Abstract

The invention relates to the technical field of soil amendment preparation, in particular to a soil amendment and a preparation method thereof. The soil conditioner comprises porous biochar-based microspheres, wherein the porous biochar-based microspheres are prepared from food sludge-based biochar, cellulose-based biochar, a monatomic modified zeolite agent and a binder; the food sludge-based biochar is prepared by pyrolyzing food sludge; the cellulose-based biochar is prepared by pyrolyzing a waste biomass material rich in cellulose; the binder is a disintegrable organic binder matched with at least one of illite powder, bentonite powder, dolomite powder, diatomite powder, kaolin powder, montmorillonite powder and attapulgite powder; the disintegrable organic binder is at least one of starch, polyvinyl alcohol and polylactic acid. The soil conditioner disclosed by the invention can adsorb and remove heavy metal elements, adjust the pH value of soil, improve the structure and physicochemical properties of the soil and the water, soil and fertilizer retention capability, and also can effectively promote the growth and development of crops to achieve the effect of increasing the yield and income of the crops.

Description

Technical Field

[0001] The present application relates to the technical field of soil conditioner preparation, and in particular to a soil conditioner and a preparation method thereof. Background Art

[0002] Food sludge, as a by-product of food wastewater treatment generated by food companies, contains a variety of components such as organic matter, inorganic matter, microorganisms, and also contains harmful organic matter, heavy metals, and harmful pathogens. If improperly handled, it may cause serious environmental damage and secondary pollution, and impose a serious burden on the environment and the economy.

[0003] There are five main existing sludge treatment methods:

[0004] 1. Compression treatment method: compressing the sludge under high pressure to make it into a hard solid, and then burying it underground will not only occupy land resources, but also cause soil pollution and groundwater pollution in the landfill area.

[0005] 2. Composting method: compost sludge and organic waste together. After a period of fermentation, the organic matter in the sludge is decomposed into fertilizer by microorganisms. The composting method has a long sludge treatment cycle, low heavy metal removal efficiency and is prone to secondary pollutants.

[0006] 3. Incineration method: Incineration of sludge at high temperature can completely eliminate organic matter, pathogens, etc. in the sludge. However, the incineration method consumes energy to incinerate sludge and produces harmful gases such as carbon dioxide.

[0007] 4. Melting method: Heat the sludge to a high temperature to melt it into a glassy state, which can fix the pollutants. However, this method requires high technical support and expensive equipment, and cannot achieve industrial batch processing of sludge.

[0008] 5. Landfill method: As an early common sludge treatment method, its hazards have gradually become apparent. Although the sludge is transported to a special landfill, buried underground and covered with an impermeable layer and a corrosion-resistant cover, the landfilled sludge will pollute the soil and groundwater in the landfill area. There are reports of soil and groundwater pollution caused by this type of landfill method for sludge treatment, and the landfill method has gradually been eliminated.

[0009] In order to solve the environmental and economic hazards caused by food sludge, an environmentally friendly method for treating food sludge is urgently needed. To this end, the inventor provides a soil conditioner prepared from food sludge and a preparation method thereof, turning food sludge into treasure for use in the production of soil conditioners to meet the requirements of sustainable green development. Summary of the invention

[0010] In order to solve the environmental and economic hazards caused by food sludge, the present invention provides a soil conditioner and a preparation method thereof, which turns food sludge into treasure. Food sludge-based carbon materials are obtained by high-temperature pyrolysis of food sludge and are used in the production of soil conditioners.

[0011] The soil conditioner provided by the present invention is realized by the following technical scheme:

[0012] A soil conditioner, comprising porous biochar-based microspheres, wherein the porous biochar-based microspheres are made of food sludge-based biochar, cellulose-based biochar, a single-atom modified zeolite agent, and a binder; the food sludge-based biochar is made by pyrolysis of food sludge; the cellulose-based biochar is made by pyrolysis of waste biomass materials rich in cellulose; the waste biomass materials rich in cellulose include rice straw, wheat straw, corn straw, sorghum straw, reed straw, waste wood chips, broken dead branches, broken dead bark, broken leaves, broken dead grass, broken coconut shells, bagasse, coffee grounds, At least one of peanut shell residues; the single-atom modified zeolite agent includes a porous zeolite agent carrier and a single-atom metal loaded on the surface and pore wall of the porous zeolite agent carrier, the single-atom metal includes at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the single-atom metal loading rate in the single-atom modified zeolite agent is 1-5wt%; the binder is a disintegrable organic binder combined with at least one of illite powder, bentonite powder, dolomite powder, diatomaceous earth powder, kaolin powder, montmorillonite powder, and attapulgite powder; the disintegrable organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid.

[0013] The present invention effectively removes harmful pathogens, organic pollutants and heavy metal particles in food sludge through a specific pyrolysis process. The obtained food sludge-based biochar has the advantages of high porosity, high surface area and low heavy metal content, turning food sludge into treasure for the production of soil conditioner.

[0014] Necessity of adding cellulose-based biochar materials: As a peat material, food sludge-based biochar has less inorganic carbon and beneficial trace mineral particles than cellulose-based biochar materials. In order to restore soil fertility during soil remediation, food sludge-based biochar and cellulose-based biochar materials are compounded to form biochar materials to better meet the needs of soil remediation. Cellulose-based biochar materials have a wide range of synthetic sources and low preparation costs. The mixed use of the two is also conducive to reducing the overall production cost of soil conditioners. Among the existing soil remediation products, the production cost of soil conditioners is also the main factor restricting their promotion and application.

[0015] The food sludge-based biochar and cellulose-based biochar materials in the porous biochar-based microspheres can significantly reduce the effective state of heavy metals in the soil and reduce their migration in the environmental medium, thereby reducing the biological toxicity of heavy metals in the soil. In addition, the food sludge-based biochar and cellulose-based biochar materials in the porous biochar-based microspheres have a significant effect on Al 3+ It has strong adsorption and fixation capabilities, regulates the composition of soil exchangeable acid, and reduces soil exchangeable Al 3+ Increasing the proportion of exchangeable acid in the soil can effectively alleviate the problem of soil aluminum toxicity, thereby promoting the growth and development of crops.

[0016] The high porosity and high surface area structure of food sludge-based biochar and cellulose-based biochar materials in porous biochar-based microspheres can effectively absorb water, retain water and fertilizer, increase soil porosity, reduce soil nutrient loss, and improve soil physical properties.

[0017] In summary, the soil conditioner provided by the present invention can adsorb and remove heavy metal elements and trivalent aluminum ions, reduce heavy metal hazards and aluminum poisoning; + The association reaction increases the soil, thereby adjusting the soil pH value, increasing soil porosity, reducing soil nutrient loss, improving soil physical properties, and enhancing the ability to retain water, soil, and fertilizer, thereby promoting the growth and development of crops and achieving the effect of increasing crop production and income.

[0018] Preferably, the single-atom modified zeolite agent accounts for 0.5-2.0wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8-20wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 78-90wt% of the total mass of the porous biochar-based microspheres; the mass ratio of food sludge-based biochar to the cellulose-based biochar is (1-4):(1-4).

[0019] The adoption of the above technical solution is helpful to reduce the overall production cost of soil conditioners.

[0020] Preferably, the preparation method of the food sludge-based biochar is as follows:

[0021] Step 1, taking 10 parts of food sludge and mixing them evenly with 90-190 parts of water to obtain a sludge suspension;

[0022] Step 2, adding an organic complex to the sludge suspension under stirring at a speed of 100 to 300 rpm, wherein the organic complex accounts for 0.01 to 0.10 wt% of the mass of the food sludge, and the organic complex is divided into at least three portions, and the interval time between two portions of the organic complex is 15 to 30 minutes. After the addition of the organic complex is completed, the stirring speed is continued at 100 to 300 rpm for 30 to 60 minutes;

[0023] Step 3, adding a pH regulator to the sludge suspension, adjusting the pH value of the sludge suspension to 6.8-7.1 after the pH regulator is added, adding magnetic single-atom modified halloysite, the magnetic single-atom modified halloysite accounts for 0.05-0.50wt% of the mass of the food sludge, and the magnetic single-atom modified halloysite is divided into at least three portions, the interval time between two portions of the magnetic single-atom modified halloysite is 15-30min, and after the addition of the magnetic single-atom modified halloysite is completed, the stirring speed is maintained at 100-300rpm for 30-60min;

[0024] Step 4, standing for 12-24 hours under ultraviolet light, extracting the upper water body to the sewage network, and performing dry-wet separation treatment on the food sludge treated with the organic complex + magnetic single atom modified halloysite to obtain food sludge pellets, the water content of the food sludge pellets is 25-40wt%;

[0025] Step 5, drying the food sludge pellets in step 4 at 120-160° C. to make the water content in the food sludge pellets less than 3.0%, grinding and crushing the dried food sludge pellets to obtain food sludge crushed materials, performing magnetic separation on the food sludge crushed materials, and sieving and recovering the magnetic single-atom modified halloysite and the food sludge crushed materials to be pyrolyzed after the magnetic separation;

[0026] Step six, pyrolyzing the food sludge crushed material to be pyrolyzed in step five to obtain food sludge-based biochar with high specific surface area and high porosity.

[0027] The present invention adopts the latest single-atom catalyst technology to degrade organic matter and disinfect harmful pathogens in food sludge, and combines it with a specific pyrolysis process to effectively remove harmful pathogens, organic pollutants, and heavy metal particles in food sludge. The obtained food sludge-based biochar has the advantages of high porosity, high surface area, and low heavy metal content, turning food sludge into treasure and solving the secondary pollution problem existing in traditional pyrolysis processes.

[0028] Preferably, the magnetic single-atom modified halloysite includes single-atom modified halloysite and nanomagnetic particles grafted on the surface of the single-atom modified halloysite, and the loading rate of nanomagnetic particles in the magnetic single-atom modified halloysite is 0.5-5wt%; the single-atom modified halloysite includes halloysite with an average particle size of 0.5-20 microns and single-atom metals loaded on the surface of the halloysite and the surface of the pore wall, and the single-atom metal includes at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the loading rate of single-atom metals in the single-atom modified halloysite is 1-5wt%.

[0029] Preferably, the nano magnetic particles are nano ferroferric oxide with a particle size distribution of 5-30 nm.

[0030] The magnetic single-atom modified halloysite in the present invention can degrade organic matter in food sludge and disinfect harmful pathogens, and can also be recycled and reused through magnetic separation technology, which greatly reduces the cost of harmless treatment of food sludge, is conducive to reducing the total production cost of soil conditioners, and thus improves the competitiveness of this product.

[0031] Preferably, the preparation method of the magnetic single-atom modified halloysite is as follows:

[0032] Step 1, preparation of single atom modified halloysite;

[0033] Step 2, 10 parts of single-atom modified halloysite and 40-90 parts of 0.5-2wt% epoxy silane aqueous solution are mixed evenly and then subjected to ultrasonic dispersion treatment for 0.5-1h, and after the ultrasonic dispersion treatment is completed, reduced pressure filtration is performed, and the obtained solid is vacuum dried to obtain epoxy silane grafted single-atom modified halloysite;

[0034] Step 3, 10 parts of nano-magnetic particles and 40-90 parts of an aqueous solution of aminosilane with a concentration of 0.5-2wt% are mixed evenly, and then ultrasonic dispersion treatment is performed for 0.5-1h. After the ultrasonic dispersion treatment is completed, vacuum filtration is performed, and the obtained solid is vacuum dried to obtain aminosilane-grafted modified nano-magnetic particles;

[0035] Step 4: Disperse 10 parts of epoxy silane grafted modified single-atom modified halloysite and 0.053-0.53 parts of amino silane grafted modified nanomagnetic particles in 90-190 parts of polar aprotic organic solvent and mix them evenly. Then, heat the temperature to 45-60°C, maintain the temperature at 45-60°C for 1-4 hours of ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 30-44kHz, the ultrasonic dispersion power is 200-600W, and after the ultrasonic dispersion treatment is completed, reduce pressure filtration is performed, and the filtrate is vacuum dried. The solid obtained is ball-milled to obtain magnetic single-atom modified halloysite, and the nanomagnetic particles are grafted to the surface of the single-atom modified halloysite through amide bonds.

[0036] The preparation process of the magnetic single-atom modified halloysite provided by the present invention is relatively simple, and the nanomagnetic particles can be firmly grafted to the surface of the single-atom modified halloysite through amide bonds, thereby ensuring the efficiency of magnetic separation and recovery of the magnetic single-atom modified halloysite, thereby reducing the use cost of food sludge biochar materials.

[0037] Preferably, in the step six, 100 parts of the food sludge crushed material to be pyrolyzed in the step five are weighed and mixed evenly with 0.5-2 parts of thiosemicarbazide, and then placed in a muffle furnace for pyrolysis treatment. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 5-10°C / min and maintained for 5-10min, then heated to 360-420°C at a heating rate of 10-20°C / min and kept warm for 40-50min, then heated to 560-650°C at a heating rate of 5-10°C / min and kept warm for 10-15min, finally heated to 160-240°C at a cooling rate of 5-10°C / min, and then the furnace is opened and naturally cooled to room temperature, and the obtained solid is ball-milled to obtain food sludge-based biochar.

[0038] Preferably, in the step six, 100 parts of the food sludge crushed material to be pyrolyzed in the step five are weighed and mixed evenly with 1.2-1.6 parts of thiosemicarbazide, and then placed in a muffle furnace for pyrolysis treatment. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 10°C / min and maintained for 10 minutes, then heated to 400-420°C at a heating rate of 20°C / min and kept warm for 45 minutes, then heated to 580-600°C at a heating rate of 10°C / min and kept warm for 15 minutes, finally heated to 180-200°C at a cooling rate of 10°C / min, and then the furnace is opened and naturally cooled to room temperature, and the obtained solid is ball-milled to obtain food sludge-based biochar.

[0039] The pyrolyzed food sludge crushed material is mixed with thiocarbazide, which is graded into ammonia and hydrogen sulfide gas at 225-230°C. At high temperature (360-650°C), ammonia and hydrogen sulfide gas can modify the outer surface and pore wall surface of food sludge biochar with nitrogen and sulfur functions, and graft nitrogen and sulfur functional positions, amino groups, sulfur-containing functional groups, and carboxyl functional groups on the surface of food sludge biochar and the inner wall surface of its pores, further improving the water and fertilizer retention performance while also increasing soil fertility and enhancing the ability to adsorb, passivate and eliminate heavy metal ions.

[0040] Preferably, the porous biochar-based microspheres also include calcined shell powder and porous coal gangue powder, the calcined shell powder accounts for 5-10wt% of the total mass of the porous biochar-based microspheres, and the porous coal gangue powder accounts for 5-10wt% of the total mass of the porous biochar-based microspheres; the single-atom modified zeolite agent accounts for 0.5-2.0wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8-20wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 58-80wt% of the total mass of the porous biochar-based microspheres; the mass ratio of the food sludge-based biochar to the cellulose-based biochar is (1-4):(1-4).

[0041] In order to optimize the production cost of soil conditioners, low-cost calcined shell powder and porous coal gangue powder are doped into the soil conditioners. That is, the production cost of calcined shell powder and porous coal gangue powder is lower than the production cost of food sludge biochar. Appropriate doping with calcined shell powder and porous coal gangue powder can reduce the production cost of soil conditioners, and also give soil conditioners new advantages in soil remediation.

[0042] Calcined shell powder can reduce the aluminum content in cation exchange complexes, adjust soil pH, and alleviate soil acidification problems. The calcium ions contained in shell powder react with the Na+ on the surface of soil colloids. + Mg 2+ Exchange can change the soil from hydrophilic colloid to hydrophobic colloid, improve soil structure and permeability, and achieve the effect of desalination and inhibiting salt return.

[0043] Porous gangue powder contains rich organic matter that can provide nutrients and water to promote plant growth; it contains rich minerals that can provide trace elements and mineral nutrients in the soil to meet the growth needs of plants. Using waste porous gangue powder as an auxiliary material for soil conditioner solves the problem of waste hazards of porous gangue powder, and using it as a soil conditioner can increase soil fertility, improve soil structure, increase soil water retention and aeration, and improve soil fertility and plant growth ability.

[0044] The porous coal gangue powder is made of 95 parts of coal gangue powder, 5 parts of cement, 0.05 parts of aluminum powder, and water (water-cement ratio is 0.60-0.65). The accurately measured coal gangue powder, cement, aluminum powder, and water are stirred to make a foaming slurry casting mold and cured in a 70°C curing box for 12 hours. After demolding, it is dried in a 105°C drying oven for 24 hours and then crushed to obtain the powder.

[0045] Preferably, the soil conditioner comprises porous biochar-based microspheres, degradable compound fertilizer capsules, degradable organic complex capsules, and degradable organic fertilizer capsules; the amount of porous biochar-based microspheres added to the soil conditioner is 75-90wt%; the amount of degradable compound fertilizer capsules added to the soil conditioner is 4-10wt%; the amount of degradable organic complex capsules added to the soil conditioner is 2-10wt%; the amount of degradable organic fertilizer capsules added to the soil conditioner is 4-10wt%.

[0046] The function of degradable compound fertilizer capsules: Under water erosion, the outer degradable film of the degradable compound fertilizer capsules breaks and slowly releases the compound fertilizer glue, which can effectively improve soil fertility and promote the growth and development of crops.

[0047] The function of degradable organic complex capsules: Under water erosion, the outer degradable film of the degradable organic complex capsules ruptures and slowly releases the organic complex. On the one hand, it can effectively complex and remove heavy metal particles and reduce the toxicity of heavy metal ions. On the other hand, the selection of organic complexes of different acid and alkali types can also adjust the pH value of the soil, improve the soil structure and physical properties, and create a soil environment that is conducive to the growth and development of crops, which is of positive significance to increasing crop yields and income.

[0048] The function of degradable organic fertilizer capsules: the outer degradable film of the degradable organic fertilizer capsules breaks and slowly releases organic fertilizer, which can improve soil fertility on the one hand; on the other hand, it can introduce beneficial microbial flora, improve the soil microbial flora environment, and create a soil environment that is conducive to the growth and development of crops, which has positive significance for increasing crop yields and incomes, and is also conducive to the degradation and harmless treatment of the degradable film.

[0049] In summary, soil conditioners made from porous biochar-based microspheres, degradable compound fertilizer capsules, degradable organic complex capsules, and degradable organic fertilizer capsules have better advantages in soil remediation.

[0050] The preparation method of the soil conditioner provided by the present invention is achieved through the following technical scheme:

[0051] A method for preparing a soil conditioner comprises the following steps:

[0052] Step 1, preparation of food sludge-based biochar;

[0053] Step 2: accurately measuring food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder, and then evenly mixing them in a granulator for granulation to obtain porous biochar-based microspheres with a particle size of 0.5-2 cm;

[0054] Step 3, mixing the degradable compound fertilizer capsules, the degradable organic complex capsules, and the degradable organic fertilizer capsules with the porous biochar-based microspheres in step 2 according to a ratio to obtain a soil conditioner composition;

[0055] The organic complex contained in the degradable organic complex capsule in the soil conditioner composition is selected according to the acidity and alkalinity of the soil to be improved;

[0056] When the soil to be improved is acidic, the organic complex contained in the degradable organic complex capsule is an alkaline organic complex;

[0057] When the soil to be improved is alkaline, the organic complex contained in the degradable organic complex capsule is an acidic organic complex.

[0058] The preparation method of the invention is relatively simple, the difficulty of granulation is relatively low, and it is easy to realize industrial production and manufacturing.

[0059] In summary, this application has the following advantages:

[0060] 1. The present invention turns food sludge into treasure. The food sludge is subjected to harmless high-temperature pyrolysis treatment through a specific pyrolysis process and single-atom sterilization and catalytic technology. The obtained food sludge-based carbon material has the advantages of high porosity, high surface area and low heavy metal content, and is used for the production of soil conditioners.

[0061] 2. The soil conditioner of the present invention can adsorb and remove soluble heavy metal elements and aluminum elements, reduce the hazards of heavy metals and aluminum toxicity, and can also adjust the soil pH value, improve the soil structure and physical properties and the ability to retain water, soil and fertilizer, thereby promoting the growth and development of crops and achieving the effect of increasing crop production and income.

[0062] 3. The preparation method of the present invention is relatively simple, and the difficulty of granulation is relatively low, which is convenient for industrial production, reduces the production cost of soil conditioners, obtains product price competitive advantages, and is convenient for market promotion and application.

[0063] 4. According to the soil remediation survey information, the inventor compounded porous biochar-based microspheres, degradable compound fertilizer capsules, degradable organic complex capsules, and degradable organic fertilizer capsules to make a soil conditioner. The soil conditioner has the function of slow-release compound fertilizer gel, organic complex, and organic fertilizer, which prolongs the continuous remediation life of the soil remediation agent, is beneficial to improving the physical properties of the soil, enhances the resistance of the remediated soil to damage, creates a soil environment for the growth and development of crops, and thereby achieves the goal of increasing crop production and income. DETAILED DESCRIPTION

[0064] In order to further understand the creativity of the present invention, the technical scheme of the present invention is described and explained in combination with embodiments and comparative examples. The specific embodiments are merely explanations of the present application and are not limitations of the present invention. After reading this specification, those skilled in the art can make modifications to the embodiments as needed without any creative contribution, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

[0065] Example

[0066] A soil conditioner at least comprises porous biochar-based microspheres, which are made of food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite and a binder.

[0067] The single-atom modified zeolite agent accounts for 0.5-2.0wt% of the total mass of the porous biochar-based microspheres. The specific amount of the single-atom modified zeolite agent needs to be tested for harmful microorganisms in the soil to be repaired. When the soil to be repaired is medical waste or biologically contaminated soil, the amount of the single-atom modified zeolite agent added to the porous biochar-based microspheres is controlled to be 1.5-2.0wt%. Based on the common repair of soil with continuous cropping obstacles or acidic or alkaline soil, there are relatively few harmful microorganisms, and the amount of the single-atom modified zeolite agent added to the porous biochar-based microspheres is controlled to be 0.5-1.0wt%. The amount of the single-atom modified zeolite agent added in the small test is 1.0wt%.

[0068] The single-atom modified zeolite agent can be commissioned to Guangxi Liankehua New Materials Co., Ltd. or Beijing Single Atom Catalysis Technology Co., Ltd. for synthesis. The defective sites on the surface and pores of the single-atom modified zeolite agent are loaded with single-atom metals through chemical bonds, and the single-atom metals include at least one of Fe, Ag, Cu, Zn, Ce, and Ti. The porous zeolite agent carrier is selected as 4A zeolite powder with an average particle size of 0.5-50 microns. Preferably, the porous zeolite agent carrier is a 4A zeolite powder with a particle size distribution of 20-38 microns, and the 4A zeolite powder is first sieved with a 400-mesh screen, and the resulting sieved material is sieved with a 625-mesh screen, and the sieved material of the 625-mesh screen is a 4A zeolite powder with a particle size distribution of 20-38 microns.

[0069] In order to facilitate readers to understand the single-atom modified zeolite agent preparation technology, the following single-atom modified zeolite agent preparation method is provided: first, 4A zeolite powder with a particle size distribution of 20-38 μm is calcined and activated at 200°C for 2 hours and set aside; then, a 10-20 g / L aqueous solution of acetylacetonate solution (acetylacetonate iron, acetylacetonate silver, acetylacetonate copper, acetylacetonate zinc, acetylacetonate cerium, acetylacetonate titanium) is added to the 4A zeolite powder with a particle size distribution of 20-38 μm at a drop rate of 80-120 μL / s, wherein the metal content in the acetylacetonate solution accounts for 0.5 of the total mass ratio of the metal in the 4A zeolite powder and the acetylacetonate solution. -5wt%, the obtained solution is evenly dispersed by ultrasonic treatment for 30-60min under the condition of ultrasonic frequency of 40-100kHz, and then the mixed solution is stirred at 80-120r / min for 12-16h; the obtained mixed solution is heated to the boiling point of water, volatilized at high temperature, the solvent is evaporated, and fully ground with a planetary ball mill at a speed of 40-60r / min for 0.5-1 hour to obtain a solid powder; the obtained solid powder is heated in an air atmosphere at a temperature of 400-420°C for 2h, cooled to room temperature, and ground with a planetary ball mill at a speed of 60-80r / min for 10-30min to obtain a finished product.

[0070] Preferably, the single-atom metal is Fe or Ti, and the mass ratio of single-atom Fe to Ti is 2:1. The single-atom metal loading rate in the single-atom modified zeolite agent is 1 to 5 wt %. Preferably, the single-atom metal loading rate in the single-atom modified zeolite agent is 3 to 5 wt %. Further preferably, the single-atom metal loading rate in the single-atom modified zeolite agent is 5 wt %. Under industrial mass production, the use cost of the atom-modified zeolite agent is relatively cheap.

[0071] On the one hand, the single-atom modified zeolite agent can play an excellent role in sterilization and disinfection in the soil, effectively removing harmful pathogens (bacteria, viruses, etc.) in the soil. On the other hand, the single-atom modified zeolite agent with a porous structure can adsorb organic pollutants. Under sunlight (specifically ultraviolet rays in sunlight), the single-atom metal can catalyze the decomposition of organic pollutants, which can play a role in decomposing organic pollutants. At the same time, the porous structure of zeolite can also improve water and fertilizer retention, improve soil remediation efficiency, and effectively improve the physical and chemical properties of the soil. In addition, the single-atom modified zeolite agent with a porous structure can increase the content of exchangeable ions and also adsorb heavy metal ions, thereby improving the soil's anti-erosion ability, passivating soil heavy metals, reducing heavy metal pollution, reducing crop stress, and achieving the purpose of increasing crop production and income.

[0072] The binder accounts for 8-20wt% of the total mass of the porous biochar-based microspheres. The binder is a key material for the granulation of porous biochar-based microspheres. The binder selected in the present invention is a compound of a disintegrable organic binder and an inorganic binder. The inorganic binder is at least one of illite powder, bentonite powder, dolomite powder, diatomaceous earth powder, kaolin powder, montmorillonite powder, and attapulgite powder. The above-mentioned inorganic binders all have a porous structure, which can play a role in repairing the soil, increasing the fertility of the soil, improving the structure of the soil, increasing the water retention and air permeability of the soil, and improving the fertility of the soil and the growth ability of plants.

[0073] In order to facilitate transportation and use, the designed particle size of porous biochar-based microspheres is between 0.8-3.0cm, while the particle size of porous biochar-based microspheres is between 0.8-3.0cm, which is not a favorable factor for soil remediation. The porous biochar-based microspheres are relatively small, and the larger the contact area with the soil, the higher the soil remediation efficiency. Therefore, a disintegrable organic binder is added to the binder of the porous biochar-based microspheres. The disintegrable organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid. The disintegrable organic binder can disintegrate in water under external moisture erosion, which can realize that the porous biochar-based microspheres can disintegrate into porous biochar-based disintegrated microspheres with smaller particle sizes under external moisture erosion. The contact area between the obtained porous biochar-based disintegrated microspheres and the soil is relatively large, which can effectively improve the soil remediation efficiency.

[0074] Preferably, the binder is made of kaolin powder and starch, and the starch content in the binder can be controlled to 20-40wt%. Kaolin powder and starch are widely available and have relatively low procurement costs. Under the premise of ensuring the soil remediation effect, the production cost of the porous biochar-based microspheres is controlled to enhance the competitive advantage of the product.

[0075] Food sludge, as a byproduct of food wastewater treatment produced by food companies, contains a variety of components such as organic matter, inorganic matter, microorganisms, and also contains harmful organic matter, heavy metals, and harmful pathogens. It requires professional treatment. If it is not handled properly, it may cause serious environmental damage and secondary pollution, causing a serious burden on the environment and the economy. The core technical solution of the present invention is to solve the pollution problem of food sludge. Food sludge is pyrolyzed at high temperature to obtain food sludge-based carbon materials for the production of soil conditioners.

[0076] The inorganic carbon SIC and organic carbon SOC contained in the food sludge-based charcoal production material are relatively less than those of cellulose-based biochar. In soil remediation, exogenous supplementation of inorganic carbon SIC and organic carbon SOC can improve soil fertility and anti-erosion effects, which is beneficial to increase crop yields and income. To this end, the biochar in the porous biochar-based microspheres is made of a compound of food sludge-based biochar and cellulose-based biochar. The total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 78 to 90 wt % of the total mass of the porous biochar-based microspheres. The mass ratio of food sludge-based biochar to cellulose-based biochar is (1 to 4): (1 to 4). Preferably, the mass ratio of food sludge-based biochar to cellulose-based biochar is 3:1.

[0077] There is already a large amount of literature on cellulose-based biochar, which is made by pyrolysis of waste biomass materials rich in cellulose. Waste biomass materials rich in cellulose include at least one of rice straw, wheat straw, corn straw, sorghum straw, reed straw, waste wood chips, dead branch crushed materials, dead bark crushed materials, leaf crushed materials, dead grass crushed materials, coconut shell crushed materials, bagasse, coffee grounds, and peanut shell residue. Cellulose-based biochar materials can be directly purchased from existing cellulose-based biochar materials (corn straw biochar from Henan Xingnuo Environmental Protection Materials Co., Ltd., corn, wheat, and rice straw biochar from Henan Jiahe Water Purification Materials Co., Ltd.), or they can be commissioned to companies for customized production and preparation.

[0078] Food sludge-based biochar is made by pyrolysis of food sludge. It should be noted that there are also technologies in the prior art for pyrolyzing sludge into biochar, such as thermal degradation in an inert atmosphere. The temperature range of pyrolysis is 300-1000°C, which can convert sewage sludge into fixed carbon, ash, bio-oil, combustible gas and water vapor. However, the existing sludge treatment technology has the following problems: 1. The porosity of biochar is inversely proportional to the pyrolysis temperature. If you want to obtain a biochar material with a high porosity, the pyrolysis temperature is low, which will not completely disinfect and decompose the harmful pathogens and organic pollution in the sludge; and at a high pyrolysis temperature, although the harmful pathogens and organic pollution in the sludge are disinfected and decomposed relatively thoroughly, the porosity of the biochar material is affected, which will eventually affect the repair effect of the soil conditioner, and the remaining heavy metal particles are also prone to secondary pollution. To this end, the inventor provides a method for preparing a food sludge-based biochar material that efficiently removes heavy metal particles and obtains a relatively high porosity and specific surface area. The specific preparation method is as follows:

[0079] Step 1, taking 10 parts of food sludge and mixing them evenly with 90-190 parts of water to obtain a sludge suspension;

[0080] Step 2: adding an organic complex to the sludge suspension under stirring at a speed of 100 to 300 rpm, wherein the organic complex accounts for 0.01 to 0.10 wt% of the mass of the food sludge, and the organic complex is divided into at least three portions, and the interval between two portions of the organic complex is 15 to 30 minutes. After the addition of the organic complex is completed, the stirring speed is continued at 100 to 300 rpm for 30 to 60 minutes;

[0081] The organic complex is at least one of aminocarboxylates and organic phosphonates.

[0082] Aminocarboxylate organic complexes such as trisodium nitrilotriacetate, sodium EDTA, ethylenediaminetetraacetic acid TEA, diethylenetriaminepentacarboxylic acid pentasodium, etc. Organic phosphonate organic complexes such as diethylenetriaminepentamethylenephosphonic acid heptasodium salt, ethylenediaminetetramethylenephosphonic acid pentasodium salt, hexamethylenediaminetetramethylenephosphonic acid hexasodium salt, etc.

[0083] The amount of organic complex added is determined by the heavy metal ion content measured in the sludge suspension. The organic complex is added in excess, that is, the actual added mass of the organic complex is 1.05-1.1 times the standard complex amount of the organic complex and heavy metal ions. The organic complex can effectively remove heavy metal ions.

[0084] Step three, adding a pH regulator to the sludge suspension, the pH regulator is tartaric acid and / or phosphoric acid, and the pH value of the sludge suspension is adjusted to 6.8-7.1 after the pH regulator is added, adding magnetic single-atom modified halloysite to disinfect harmful pathogens and effectively passivate heavy metal particles, the magnetic single-atom modified halloysite accounts for 0.05-0.50wt% of the mass of food sludge, and the amount of magnetic single-atom modified halloysite added is determined by the content of harmful pathogens in the sludge suspension. In a small test, 0.05wt% of magnetic single-atom modified halloysite can effectively remove more than 95% of harmful pathogens, and the magnetic single-atom modified halloysite is divided into at least three portions, the interval time between two portions of magnetic single-atom modified halloysite is 15-30min, and after the addition of the magnetic single-atom modified halloysite is completed, the stirring speed is maintained at 100-300rpm for 30-60min;

[0085] Step 4, standing under ultraviolet light for 12-24 hours, extracting the upper water body to the sewage network, the output upper water body after being treated with organic complex and magnetic single atom modified halloysite has relatively low content of heavy metal ions and harmful pathogens, and can be directly discharged into the sewage network or used as the ingredient water body in step 1, and the food sludge treated with organic complex + magnetic single atom modified halloysite is subjected to dry-wet separation treatment to obtain food sludge pellets, and the water content of the food sludge pellets is 25-40wt%;

[0086] Step 5, placing the food sludge pellets in step 4 in an oven, adjusting the drying temperature to 120-160° C. for drying, so that the water content in the food sludge pellets is less than ≤3.0%, and then grinding and crushing the dried food sludge pellets to obtain food sludge crushed materials, performing magnetic separation on the food sludge crushed materials, and sieving and recovering the magnetic single-atom modified halloysite and the food sludge crushed materials to be pyrolyzed after the magnetic separation. Preferably, the obtained food sludge crushed materials to be pyrolyzed are subjected to gravity sieving to remove heavy metal organic complexes;

[0087] Step six, pyrolyzing the food sludge crushed material to be pyrolyzed in step five to obtain food sludge-based biochar with high specific surface area and high porosity. Specifically, weighing 100 parts of the food sludge crushed material to be pyrolyzed in step five and mixing them evenly with 0.5-2 parts of thiosemicarbazide are placed in a muffle furnace for pyrolysis treatment. Thiosemicarbazide is classified into ammonia and hydrogen sulfide gas at 225-230°C, which can introduce nitrogen and sulfur functional sites, amino groups, sulfur-containing functional groups, and carboxyl functional groups to the surface of biochar, thereby improving the heavy metal ion passivation and elimination performance of the final food sludge-based biochar. In a nitrogen atmosphere, first heat at 5-10°C / min. The method comprises the following steps: heating the mixture to 225-230°C at a rate of 100-200°C and maintaining the mixture for 5-10 minutes, heating the mixture to 360-420°C at a rate of 10-20°C / min and maintaining the mixture for 40-50 minutes, then heating the mixture to 560-650°C at a rate of 5-10°C / min and maintaining the mixture for 10-15 minutes, and finally heating the mixture to 160-240°C at a rate of 5-10°C / min and naturally cooling the mixture to room temperature. The solid matter is ball-milled to obtain food sludge-based biochar. The specific pyrolysis process can obtain food sludge-based biochar with high porosity, high specific surface area and low content of heavy metal particles.

[0088] Preferably, in step six, 100 parts of the food sludge crushed material to be pyrolyzed are weighed and mixed evenly with 1.2-1.6 parts of thiosemicarbazide, and then placed in a muffle furnace for pyrolysis treatment. Under a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 10°C / min and maintained for 10 minutes, then heated to 400-420°C at a heating rate of 20°C / min and kept warm for 45 minutes, then heated to 580-600°C at a heating rate of 10°C / min and kept warm for 15 minutes, finally heated to 180-200°C at a cooling rate of 10°C / min, and then the furnace is opened and naturally cooled to room temperature. The obtained solid matter is ball-milled to obtain food sludge-based biochar.

[0089] The magnetic single atom modified halloysite in step three can be magnetically separated and recycled in step five. The recovery rate of the magnetic single atom modified halloysite is above 75%, which effectively reduces the production cost of food sludge-based biochar.

[0090] The magnetic single-atom modified halloysite can be commissioned to Guangxi Liankehua New Materials Co., Ltd. or Beijing Single Atom Catalysis Technology Co., Ltd. for synthesis. The magnetic single-atom modified halloysite includes single-atom modified halloysite and nanomagnetic particles grafted on the surface of the single-atom modified halloysite. The loading rate of the nanomagnetic particles in the magnetic single-atom modified halloysite is 0.5-5wt%. The nanomagnetic particles can be commercially available nano-ferroferric oxide with a particle size of 5-30nm. The loading rate of nano-ferroferric oxide affects the recovery rate of the magnetic single-atom modified halloysite. When the loading rate of the nanomagnetic particles is 3-5wt%, the recovery rate of the magnetic single-atom modified halloysite can reach more than 85%.

[0091] The single-atom modified halloysite can be commissioned to Guangxi Liankehua New Materials Co., Ltd. or Beijing Single Atom Catalysis Technology Co., Ltd. for synthesis. The single-atom modified halloysite includes halloysite with an average particle size of 0.5-20 microns and a single-atom metal loaded on the surface of the halloysite and the surface of the pore wall, the single-atom metal includes at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the single-atom metal loading rate in the single-atom modified halloysite is 1-5wt%. Preferably, the single-atom metal is Fe, Ag, and Ti, and the mass ratio of Fe, Ag, and Ti is 5:2:3. The single-atom modified halloysite can sterilize and disinfect while decomposing organic pollutants. The single-atom metal loading rate affects the sterilization and disinfection ability of the magnetic single-atom modified halloysite, and the preferred single-atom metal loading rate is 2-5%.

[0092] The preparation method of magnetic single atom modified halloysite is as follows:

[0093] Step 1, preparation of single-atom modified halloysite:

[0094] S1.1, ball-milling the halloysite to an average particle size of 0.5-20 μm, and calcining and activating at 180-200° C. for 1-2 h;

[0095] S1.2, adding 10-20 g / L of an aqueous solution of acetylacetonate solution (ferrous acetylacetonate, silver acetylacetonate, copper acetylacetonate, zinc acetylacetonate, cerium acetylacetonate, titanium acetylacetonate) to halloysite with an average particle size of 0.5-20 μm at a dropping speed of 80-120 μL / s, wherein the metal content in the acetylacetonate solution accounts for 0.5-5 wt % of the total mass ratio of the metals in the halloysite and the acetylacetonate solution, and the obtained solution is subjected to ultrasonic dispersion treatment at an ultrasonic frequency of 40-100 kHz for 0.5-1 h, and then the mixed solution is stirred at 60-100 r / min for 12-16 h;

[0096] S1.3: The mixed solution obtained in S1.2 is heated to the boiling point of water, evaporated at high temperature, the solvent is evaporated, and fully ground with a planetary ball mill at a speed of 40-60 r / min for 0.5-1.0 hour to obtain a solid powder;

[0097] S1.4, the obtained solid powder is heated in an air atmosphere at a temperature of 360-400°C for 2-3h, cooled to room temperature, placed in a planetary ball mill, and ground at a speed of 40-80r / min for 30-60min to obtain single-atom modified halloysite, and the particle size of the single-atom modified halloysite is regulated by the speed and time of the planetary ball mill;

[0098] Step 2, 10 parts of single-atom modified halloysite and 40-90 parts of 0.5-2wt% epoxy silane aqueous solution are mixed evenly and then subjected to ultrasonic dispersion treatment for 0.5-1h, and after the ultrasonic dispersion treatment is completed, reduced pressure filtration is performed, and the obtained solid is vacuum dried to obtain epoxy silane grafted single-atom modified halloysite;

[0099] Step 3, 10 parts of nano-magnetic particles and 40-90 parts of an aqueous solution of aminosilane with a concentration of 0.5-2wt% are mixed evenly, and then ultrasonic dispersion treatment is performed for 0.5-1h. After the ultrasonic dispersion treatment is completed, vacuum filtration is performed, and the obtained solid is vacuum dried to obtain aminosilane-grafted modified nano-magnetic particles;

[0100] Step 4: disperse 10 parts of epoxysilane grafted modified single-atom modified halloysite and 0.053-0.53 parts of aminosilane grafted modified nanomagnetic particles in 90-190 parts of polar aprotic organic solvent (such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEMA), dimethyl sulfoxide (DMSO), acetone, etc.) and mix them evenly, heat them to 45-60°C, maintain 45-60°C for 1-4h ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 30-44kHz, the ultrasonic dispersion power is 200-600W, and after the ultrasonic dispersion treatment is completed, vacuum filtration is performed, and the filtrate is vacuum dried. The obtained solid is ball-milled to obtain magnetic single-atom modified halloysite, and the nanomagnetic particles are grafted to the surface of the single-atom modified halloysite through amide bonds.

[0101] A method for preparing a soil conditioner comprises the following steps: first preparing food sludge-based biochar; then uniformly mixing accurately measured food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder, and placing the mixture in a granulator for granulation treatment to obtain porous biochar-based microspheres with a particle size of 0.8-3 cm, which are the soil conditioner.

[0102] In order to reduce the production cost of porous biochar-based microspheres and improve the soil remediation effect, the porous biochar-based microspheres are also mixed with calcined shell powder and porous coal gangue powder.

[0103] In the formula of porous biochar-based microspheres, calcined shell powder accounts for 5-10wt% of the total mass of porous biochar-based microspheres, and porous coal gangue powder accounts for 5-10wt% of the total mass of porous biochar-based microspheres. The single-atom modified zeolite agent accounts for 0.5-2.0wt% of the total mass of porous biochar-based microspheres. The binder accounts for 8-20wt% of the total mass of porous biochar-based microspheres. The total mass of food sludge-based biochar and cellulose-based biochar accounts for 58-80wt% of the total mass of porous biochar-based microspheres. The mass ratio of food sludge-based biochar to cellulose-based biochar is (1-4):(1-4), and the preferred mass ratio of the two is 3:1.

[0104] In order to cope with different types of soil repair (acidic soil and alkaline soil) and promote crop yield and income, the soil conditioner includes porous biochar-based microspheres, degradable compound fertilizer capsules, degradable organic complex capsules, and degradable organic fertilizer capsules. The amount of porous biochar-based microspheres added in the soil conditioner is 75-90wt%. The amount of degradable compound fertilizer capsules added in the soil conditioner is 4-10wt%. The amount of degradable organic complex capsules added in the soil conditioner is 2-10wt%. The amount of degradable organic fertilizer capsules added in the soil conditioner is 4-10wt%. The preparation method of the above-mentioned soil conditioner comprises the following steps:

[0105] Step 1, preparation of food sludge-based biochar;

[0106] Step 2: Mix accurately measured food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder evenly, and place in a granulator for granulation treatment to obtain porous biochar-based microspheres with a particle size of 0.8-3 cm;

[0107] Step three, mixing the degradable compound fertilizer capsules, the degradable organic complex capsules, and the degradable organic fertilizer capsules with the porous biochar-based microspheres in step two according to a proportion to obtain a soil conditioner composition.

[0108] The organic complex contained in the degradable organic complex capsule in the soil conditioner composition is selected according to the acidity and alkalinity of the soil to be improved;

[0109] When the soil to be improved is acidic, the organic complex contained in the degradable organic complex capsule is an alkaline organic complex, such as aminocarboxylate organic complex: trisodium nitrilotriacetate, sodium EDTA, TEA salt of ethylenediaminetetraacetic acid, pentasodium diethylenetriaminepentacarboxylate, etc.

[0110] When the soil to be improved is alkaline, the organic complex contained in the degradable organic complex capsule is an acidic organic complex, such as complex acid: tartaric acid, citric acid, phosphoric acid, hexamethylenediaminetetramethylenephosphonic acid, phosphoric acid and the like.

[0111] The degradable compound fertilizer capsule comprises a degradable coating film and a compound fertilizer filled in the coating film. The coating film can be selected from polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly 3-hydroxyalkanoate PHA, poly ε-caprolactone PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, carbon dioxide copolymer, etc., or a composite coating film composed of at least one of starch and polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly 3-hydroxyalkanoate PHA, poly ε-caprolactone PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, and carbon dioxide copolymer.

[0112] The coating film is preferably polyvinyl alcohol PVA and starch. Polyvinyl alcohol PVA has a polymerization degree of 2200-2400, a molecular weight of 80,000-90,000, and an alcoholysis degree of 97%. The function of the degradable compound fertilizer capsule: under water erosion, the outer coating film of the degradable compound fertilizer capsule breaks and slowly releases the compound fertilizer glue, which can effectively improve soil fertility and promote the growth and development of crops. Or the coating film is preferably.

[0113] Compound fertilizers are configured according to the trace element requirements of the crops to be repaired. Compound fertilizers can be selected from nitrogen fertilizers (such as ammonium nitrogen fertilizers, nitrate nitrogen fertilizers, ammonium nitrate nitrogen fertilizers), potash fertilizers (potassium chloride, potassium sulfate, potassium nitrate, monopotassium phosphate, potassium dihydrogen phosphate, potassium polyphosphate, potassium polyphosphate, organic potassium, plant ash), phosphate fertilizers (such as superphosphate, double superphosphate, monoammonium phosphate, diammonium phosphate), magnesium fertilizers (such as magnesium sulfate, magnesium chloride, magnesite, dolomite, calcium magnesium phosphate), boron fertilizers (such as borax, boric acid, boron-containing superphosphate, boron magnesium phosphate, fluid boron, sugar alcohol boron, amino acid boron, amino acid boron calcium fertilizer, boron calcium magnesium, and solubor), manganese fertilizers (such as manganese sulfate, manganese chloride, manganese oxide, manganese carbonate), zinc fertilizers (such as zinc sulfate, zinc chloride, zinc oxide), and molybdenum fertilizers (such as ammonium molybdate, sodium molybdate, molybdenum trioxide, and molybdenum disulfide). Ammonium nitrogen fertilizers include ammonium bicarbonate, ammonium sulfate, ammonium chloride, and ammonia water. Nitrate nitrogen fertilizers such as sodium nitrate, calcium nitrate, ammonium nitrate, etc. Amide nitrogen fertilizers such as urea. An appropriate amount of water retaining agent (humic acid copolymer, sodium polyacrylate, polyvinyl alcohol, polyglutamic acid polyacrylamide modified biochar, sodium polyacrylate modified bentonite, etc.) can also be added to compound fertilizers.

[0114] The degradable organic complex capsule includes a degradable coating film and an organic complex filled in the coating film. When the soil to be improved is acidic, the organic complex contained in the degradable organic complex capsule is an alkaline organic complex, such as aminocarboxylate organic complexes: trisodium nitrilotriacetate, sodium EDTA, ethylenediaminetetraacetic acid TEA salt, diethylenetriaminepentacarboxylic acid pentasodium, etc. When the soil to be improved is alkaline, the organic complex contained in the degradable organic complex capsule is an acidic organic complex such as complex acid: tartaric acid, citric acid, phosphoric acid, hexamethylenediaminetetramethylenephosphonic acid, phosphoric acid, etc.

[0115] The coating film in the degradable organic complex capsule can be selected from polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly 3-hydroxyalkanoate PHA, poly ε-caprolactone PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, carbon dioxide copolymer, etc. or a composite coating film composed of at least one of starch and polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly 3-hydroxyalkanoate PHA, poly ε-caprolactone PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, and carbon dioxide copolymer. The coating film is preferably polyvinyl alcohol PVA and starch. Polyvinyl alcohol PVA has a degree of polymerization of 2200-2400, a molecular weight of 80,000-90,000, and a degree of alcoholysis of 97%.

[0116] The function of degradable organic complex capsules: Under water erosion, the outer degradable film of the degradable organic complex capsules ruptures and slowly releases the organic complex. On the one hand, it can effectively complex and remove heavy metal particles and reduce the toxicity of heavy metal ions. On the other hand, the selection of organic complexes of different acid and alkali types can also adjust the pH value of the soil, improve the soil structure and physical properties, and create a soil environment that is conducive to the growth and development of crops, which is of positive significance to increasing crop yields.

[0117] The degradable organic fertilizer capsule comprises a degradable coating film and organic fertilizer filled in the coating film.

[0118] The coating film in the degradable organic fertilizer capsule can be selected from polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly 3-hydroxyalkanoate PHA, poly ε-caprolactone PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, carbon dioxide copolymer, etc. or a composite coating film composed of at least one of starch, polylactic acid resin, polyvinyl alcohol resin, polylactic acid PLA, poly 3-hydroxyalkanoate PHA, poly ε-caprolactone PCL, polyester-PBS / PBSA, aliphatic aromatic copolyester, polyvinyl alcohol PVA, and carbon dioxide copolymer. The coating film is preferably polyvinyl alcohol PVA and starch. Polyvinyl alcohol PVA has a degree of polymerization of 2200-2400, a molecular weight of 80,000-90,000, and a degree of alcoholysis of 97%.

[0119] The function of degradable organic fertilizer capsules: the outer degradable film of the degradable organic fertilizer capsules breaks and slowly releases organic fertilizer, which can improve soil fertility on the one hand; on the other hand, it can introduce beneficial microbial flora, improve the soil microbial flora environment, and create a soil environment that is conducive to the growth and development of crops, which has positive significance for increasing crop yields and incomes, and is also conducive to the degradation and harmless treatment of the degradable film.

[0120] The soil conditioner composition made of porous biochar-based microspheres, degradable compound fertilizer capsules, degradable organic complex capsules, and degradable organic fertilizer capsules has the effects of slow-release compound fertilizer gel, organic complex, and organic fertilizer, extending the continuous repair life of the soil repair agent, which is beneficial to improving the physical properties of the soil, enhancing the anti-damage ability of the repaired soil, creating a soil environment that is conducive to the growth and development of crops, and achieving the purpose of increasing crop yields. In addition, the soil conditioner composition can reduce the frequency of crop fertilizer application, and the slow-release compound fertilizer gel can meet the growth needs of crops, thereby reducing the input cost of crop fertilizers.

[0121] Example 1: A soil conditioner is a porous biochar-based microsphere with a particle size of 10±1 mm. The porous biochar-based microsphere is made of 67.5 parts of food sludge-based biochar, 22.5 parts of cellulose-based biochar (corn straw biochar from Henan Xingnuo Environmental Protection Materials Co., Ltd.), 1 part of single-atom modified zeolite agent (customized outsourced), 5.4 parts of kaolin (325 mesh white calcined kaolin, purchased from Lingshou County Zhuolei Building Materials Co., Ltd.), and 3.6 parts of starch (industrial grade corn starch, purchased from Jinan Deqiao Chemical Technology Co., Ltd.).

[0122] The preparation method of magnetic single-atom modified halloysite (outsourced customization) is as follows:

[0123] Step 1, preparation of single-atom modified halloysite:

[0124] S1.1, place halloysite (500 mesh halloysite powder, Lingshou County Nanyu Mineral Products Processing Plant) in a planetary ball mill and grind at 60 rpm for 10 min to obtain a medium particle size D 50 =16 μm ultrafine halloysite, the obtained ultrafine halloysite is placed in a muffle furnace and calcined and activated at 200° C. for 2 h for standby use;

[0125] S1.2, add 20 g / L acetylacetonate solution (1L acetylacetonate solution contains 10 g acetylacetonate iron, 4 g acetylacetonate silver, and 6 g acetylacetonate titanium) to the medium particle size D prepared in S1.1 at a dropwise rate of 100 μL / s. 50=16 μm ultrafine halloysite, the content of metal elements (iron + silver + titanium) in the acetylacetonate solution accounts for 2 wt% of the total mass ratio of the metal elements (iron + silver + titanium) in the ultrafine halloysite and the acetylacetonate solution, the obtained solution is subjected to ultrasonic dispersion treatment at an ultrasonic frequency of 100 kHz for 1 hour, and then the mixed solution is stirred at 100 r / min for 12 hours;

[0126] S1.3: The mixed solution obtained in S1.2 is heated to the boiling point of water, evaporated at high temperature, the solvent is evaporated, and fully ground with a planetary ball mill at a speed of 60 r / min for 0.5 hours to obtain a solid powder;

[0127] S1.4, the obtained solid powder was heated in air atmosphere at 400°C for 2 h, cooled to room temperature, placed in a planetary ball mill, and ground at 50 r / min for 30 min to obtain a medium particle size D 50 = 10 μm single-atom modified halloysite;

[0128] Step 2, 10 parts of the single-atom modified halloysite prepared in S1.4 and 90 parts of a 1wt% aqueous solution of γ-glycidyloxypropyltrimethoxysilane (KH560) are mixed evenly and subjected to ultrasonic dispersion treatment for 1 hour, with an ultrasonic frequency of 40kHz and a power of 400W. After the ultrasonic dispersion treatment is completed, the reduced pressure filtration is performed, and the obtained solid is vacuum dried at 85°C for 4.0 hours to obtain γ-glycidyloxypropyltrimethoxysilane grafted modified single-atom modified halloysite;

[0129] Step 3, 10 parts of nano magnetic particles (nano ferroferric oxide with a particle size of 10-30 nm, Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.) and 90 parts of γ-aminopropyltriethoxysilane (KH550) aqueous solution with a concentration of 1.5wt% are mixed evenly and then subjected to ultrasonic dispersion treatment for 1 hour, with an ultrasonic frequency of 40kHz and a power of 400W. After the ultrasonic dispersion treatment is completed, reduced pressure filtration is performed, and the obtained solid is vacuum dried at 85°C for 4.0 hours to obtain γ-aminopropyltriethoxysilane grafted modified nano magnetic particles;

[0130] Step 4: Disperse 10 parts of epoxysilane grafted modified single atom modified halloysite and 0.4 parts of γ-aminopropyltriethoxysilane grafted modified nanomagnetic particles in step 3 in 150 parts of N,N-dimethylformamide and mix them evenly. Heat the mixture in a water bath to 50°C, maintain the temperature at 50°C for 90 minutes for ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 40kHz, the ultrasonic dispersion power is 400W, and the ultrasonic dispersion treatment is completed. The vacuum filtration is performed, and the obtained filtrate is vacuum dried at 85°C for 4.0 hours. The obtained solid is placed in a planetary ball mill for ball milling treatment, the ball milling speed is 60rpm, and the ball milling time is 15 minutes. After the ball milling is completed, the medium particle size D is obtained. 50 = 10 μm magnetic single atom modified halloysite.

[0131] The specific preparation method of food sludge-based biochar is as follows:

[0132] Step 1: Pour 10L of food sludge and 190L of tap water into a 300L stainless steel reactor, adjust the speed to 300rpm and stir for 1h to obtain a sludge suspension;

[0133] Step 2, under stirring at 300 rpm, add 8 g of diethylenetriamine pentacarboxylic acid pentasodium (CAS: 140-01-2) to the sludge suspension in the stainless steel reactor, divide the diethylenetriamine pentacarboxylic acid pentasodium into four parts, each of which has a mass of 2 g, and the interval between adding two parts of diethylenetriamine pentacarboxylic acid pentasodium is 15 min. After the organic complex is completed, continue to stir at 300 rpm for 30 min;

[0134] Step three, add tartaric acid, a pH regulator, to the sludge suspension, adjust the pH value of the sludge suspension to 7.0 after the pH regulator is added, add 15g of magnetic single-atom modified halloysite to disinfect harmful pathogens and effectively passivate heavy metal particles, divide the magnetic single-atom modified halloysite into three parts, each part of the magnetic single-atom modified halloysite has a mass of 5g, and the interval time for adding two parts of the magnetic single-atom modified halloysite is 15min. After the addition of the magnetic single-atom modified halloysite is completed, continue to maintain the stirring speed at 300rpm for 30min;

[0135] Step 4, turn on the ultraviolet lamp located at the top of the stainless steel reactor, stir at a speed of 300 rpm for 2 hours under ultraviolet light and then let it stand for 12 hours, extract the upper water body to the sewage network, and the output upper water body is treated with organic complexes and magnetic single-atom modified halloysite, and the content of heavy metal ions and harmful pathogens contained in it is relatively low, and can be directly discharged into the sewage network or used as the ingredient water body in step 1. The food sludge treated with organic complexes + magnetic single-atom modified halloysite is discharged from the bottom of the stainless steel reactor, and the obtained food sludge is input into a spiral extrusion dry-wet separator for dry-wet separation treatment to obtain food sludge pellets, and the measured water content of the food sludge pellets is 32.4wt%;

[0136] Step 5, placing the food sludge pellets in step 4 in an oven so that the water content in the food sludge pellets is less than ≤3.0%, adjusting the drying temperature to 150° C. for drying for 4.0 hours, and the water content in the food sludge pellets is 2.8%, and then the dried food sludge pellets are input into an industrial ball mill for grinding and crushing to obtain food sludge crushed material, and the food sludge crushed material is input into a belt-type permanent magnetic powder deironing machine for magnetic separation treatment, and the belt-type permanent magnetic powder deironing machine is used for magnetic separation to recover magnetic single-atom modified halloysite, and the yield of recovered magnetic single-atom modified halloysite is 85.6wt%; the food sludge crushed material to be pyrolyzed output by the belt-type permanent magnetic powder deironing machine is input into a wind specific gravity separator for gravity screening treatment, and some heavy metal organic complexes are removed to obtain dry food sludge crushed material to be pyrolyzed;

[0137] Step 6: Place the food sludge crushed material to be pyrolyzed in step 5 in a muffle furnace for pyrolysis treatment. In a nitrogen atmosphere, first heat it to 230°C at a heating rate of 10°C / min and maintain it for 10 minutes, then heat it to 400°C at a heating rate of 20°C / min and maintain it for 45 minutes, then heat it to 600°C at a heating rate of 10°C / min and maintain it for 15 minutes, finally heat it to 200°C at a cooling rate of 10°C / min, open the furnace and cool it naturally to room temperature, and put the obtained solid into an industrial ball mill for ball milling and refinement to obtain a medium particle size D 50 =20μm food sludge-based biochar, average pore size 10.8nm, specific surface area 364m 2 / g. Food sludge-based biochar and cadmium-containing wastewater (Cb 2+ :50mg / L), the solid-liquid ratio was 0.1g / L, the solution pH was 5.0, and the adsorption capacity of food sludge-based biochar was 359mg / L at 25°C.

[0138] The specific preparation method of the single-atom modified zeolite agent is as follows: first, 4A zeolite powder with a particle size distribution of 20-38 μm is calcined and activated at 200° C. for 2 hours and set aside; then, an aqueous solution of 18 g / L acetylacetonate solution (1L acetylacetonate solution contains 12 g acetylacetonate iron and 6 g acetylacetonate iron titanium) is added to the 4A zeolite powder with a particle size distribution of 20-38 μm at a dropping speed of 100 μL / s, wherein the total mass of iron and titanium in the acetylacetonate solution accounts for 4wt% of the total mass ratio of iron + titanium in the 4A zeolite powder and the acetylacetonate solution. %, the obtained solution was uniformly dispersed by ultrasonic treatment for 30 min under the condition of ultrasonic frequency of 100 kHz, and then the mixed solution was stirred at 100 r / min for 12 h; the obtained mixed solution was heated to the boiling point of water, volatilized at high temperature, the solvent was evaporated, and fully ground for 0.5 h at a speed of 50 r / min using a planetary ball mill to obtain a solid powder; the obtained solid powder was heated for 2 h at a temperature of 400°C in an air atmosphere, cooled to room temperature, and ground for 10 min at a speed of 60 r / min using a planetary ball mill to obtain a medium particle size D 50 =25μm single atom modified zeolite agent.

[0139] A preparation method of a soil conditioner is as follows: 67.5 parts of food sludge-based biochar, 22.5 parts of cellulose-based biochar, 1 part of single-atom modified zeolite, 5.4 parts of 325-mesh white calcined kaolin, and 3.6 parts of industrial-grade corn starch are placed in a high-speed dispersion kettle and dispersed and mixed at 400 rpm for 1 hour. After uniform mixing, the resulting mixture is placed in a HLSG-50 wet mixing granulator for granulation treatment to obtain porous biochar-based microspheres with a particle size of 10±1 mm, which are the soil conditioner.

[0140] In order to study the effect of nano-ferroferric oxide content in magnetic single-atom modified halloysite on the yield of magnetic single-atom modified halloysite recovered by magnetic separation in step five of preparing food sludge-based biochar, the food sludge-based biochar preparation processes of Examples 2-4 and Comparative Examples 1-2 were tested.

[0141] The difference between Example 2 and Example 1 is that in step 4 of the preparation method of magnetic single-atom modified halloysite, 10 parts of epoxy silane grafted single-atom modified halloysite and 0.06 parts of γ-aminopropyltriethoxysilane grafted modified nanomagnetic particles in step 3 are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly, heated in a water bath to 50°C, maintained at 50°C for 90 minutes of ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 40kHz, the ultrasonic dispersion power is 400W, and the ultrasonic dispersion treatment is completed. The reduced pressure filtration is performed, and the obtained filtrate is vacuum dried, and the vacuum drying treatment is performed at 85°C for 4.0 hours. The obtained solid is placed in a planetary ball mill for ball milling and refining treatment, the ball milling speed is 60rpm, the ball milling time is 15min, and the medium particle size D is obtained after the ball milling and refining is completed. 50=10 μm magnetic single atom modified halloysite, and the rest of the preparation steps are the same. In step 5 of the food sludge-based biochar preparation process, the recovery rate of magnetic single atom modified halloysite is 75.8%.

[0142] The difference between Example 3 and Example 1 is that in step 4 of the preparation method of magnetic single-atom modified halloysite, 10 parts of epoxy silane grafted single-atom modified halloysite and 0.31 parts of γ-aminopropyltriethoxysilane grafted modified nanomagnetic particles in step 3 are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly, heated in a water bath to 50°C, maintained at 50°C for 90 minutes of ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 40kHz, the ultrasonic dispersion power is 400W, and the ultrasonic dispersion treatment is completed. The reduced pressure filtration is performed, and the obtained filtrate is vacuum dried, and the vacuum drying treatment is performed at 85°C for 4.0 hours. The obtained solid is placed in a planetary ball mill for ball milling and refining treatment, the ball milling speed is 60rpm, the ball milling time is 15min, and the medium particle size D is obtained after the ball milling and refining is completed. 50 =10 μm magnetic single atom modified halloysite, and the rest of the preparation steps are the same. The yield of magnetic single atom modified halloysite recovered in step 5 of the food sludge-based biochar preparation process is 83.8%.

[0143] The difference between Example 4 and Example 1 is that in step 4 of the preparation method of magnetic single-atom modified halloysite, 10 parts of epoxy silane grafted single-atom modified halloysite and 0.50 parts of γ-aminopropyltriethoxysilane grafted modified nanomagnetic particles in step 3 are dispersed in 150 parts of N,N-dimethylformamide and mixed evenly, heated in a water bath to 50°C, maintained at 50°C for 90 minutes of ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 40kHz, the ultrasonic dispersion power is 400W, and the ultrasonic dispersion treatment is completed. The reduced pressure filtration is performed, and the obtained filtrate is vacuum dried, and the vacuum drying treatment is performed at 85°C for 4.0 hours. The obtained solid is placed in a planetary ball mill for ball milling and refining treatment, the ball milling speed is 60rpm, the ball milling time is 15min, and the medium particle size D is obtained after the ball milling and refining is completed. 50 =10 μm magnetic single atom modified halloysite, and the rest of the preparation steps are the same. The yield of magnetic single atom modified halloysite recovered in step 5 of the food sludge-based biochar preparation process is 87.2%.

[0144] The difference between Comparative Example 1 and Example 1 is that in step 4 of the preparation method of magnetic single-atom modified halloysite, 10 parts of epoxy silane grafted single-atom modified halloysite and 0.02 parts of γ-aminopropyltriethoxysilane grafted modified nanomagnetic particles in step 3 are dispersed in 150 parts of N, N-dimethylformamide and mixed evenly, heated in a water bath to 50°C, maintained at 50°C for 90min ultrasonic dispersion treatment, ultrasonic dispersion frequency of 40kHz, ultrasonic dispersion power of 400W, after ultrasonic dispersion treatment is completed, reduced pressure filtration is performed, and the obtained filtrate is vacuum dried, vacuum dried at 85°C for 4.0h, and the obtained solid is placed in a planetary ball mill for ball milling treatment, the ball milling speed is 60rpm, the ball milling time is 15min, and the medium particle size D is obtained after the ball milling is completed. 50 =10 μm magnetic single atom modified halloysite, and the rest of the preparation steps are the same. The yield of magnetic single atom modified halloysite recovered in step 5 of the food sludge-based biochar preparation process is 25.4%.

[0145] The difference between Comparative Example 2 and Example 1 is that in step 4 of the preparation method of magnetic single-atom modified halloysite, 10 parts of epoxy silane grafted single-atom modified halloysite and 0.6 parts of γ-aminopropyl triethoxysilane grafted modified nanomagnetic particles in step 3 are dispersed in 150 parts of N, N-dimethylformamide and mixed evenly, heated in a water bath to 50°C, maintained at 50°C for 90 minutes of ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 40kHz, the ultrasonic dispersion power is 400W, and the ultrasonic dispersion treatment is completed. The reduced pressure filtration is performed, and the obtained filtrate is vacuum dried, and the vacuum drying treatment is performed at 85°C for 4.0h. The obtained solid is placed in a planetary ball mill for ball milling and refining treatment, the ball milling speed is 60rpm, the ball milling time is 15min, and the medium particle size D is obtained after the ball milling is completed. 50 =10 μm magnetic single atom modified halloysite, and the rest of the preparation steps are the same. The yield of magnetic single atom modified halloysite recovered in step 5 of the food sludge-based biochar preparation process is 87.6%.

[0146] By comparing Examples 1-4 and Comparative Examples 1-2, it can be seen that when the loading rate of the nanomagnetic particles is controlled to be 0.5-5wt%, the recovery rate of the magnetic single atom modified halloysite is relatively high, which can reduce the preparation cost of food sludge biochar. Preferably, when the loading rate of the nanomagnetic particles is controlled to be 3-5wt%, the recovery rate of the magnetic single atom modified halloysite can be more than 80wt%, which can effectively reduce the preparation cost of food sludge biochar.

[0147] In order to study the effect of the addition of magnetic single atom modified halloysite and organic complex on the physicochemical properties of the prepared food sludge-based biochar, the food sludge-based biochar preparation process of comparative examples 3-4 was tested.

[0148] The difference between Comparative Example 3 and Example 1 is: in step 2 of the food sludge-based biochar preparation method, stirring at a speed of 300 rpm for 75 minutes; step 3, adding calcium hydroxide to the sludge suspension, adjusting the pH value of the sludge suspension to 7.0 after the pH adjuster is added, adding 15g of magnetic single-atom modified halloysite to disinfect harmful pathogens and effectively passivate heavy metal particles, dividing the magnetic single-atom modified halloysite into three portions, each portion of magnetic single-atom modified halloysite has a mass of 5g, and the interval time for adding two portions of magnetic single-atom modified halloysite is 15 minutes. After the addition of the magnetic single-atom modified halloysite is completed, the stirring speed is continued to be maintained at 300 rpm for 30 minutes, and the remaining preparation steps are the same.

[0149] The difference between Comparative Example 4 and Example 1 is as follows: in step 3 of the method for preparing food sludge-based biochar, a pH regulator - tartaric acid is added to the sludge suspension, and the pH value of the sludge suspension is adjusted to 7.0 after the addition of the pH regulator, and the stirring speed is maintained at 300 rpm for 60 minutes; step 5, the food sludge pellets in step 4 are placed in an oven so that the water content in the food sludge pellets is less than ≤3.0%, and the drying temperature is adjusted to 150°C for drying for 4.0 hours, and the water content in the food sludge pellets is 2.8%. The dried food sludge pellets are then input into an industrial ball mill for grinding and crushing to obtain food sludge crushed material, and then the food sludge crushed material is gravity screened, and input into a wind specific gravity separator for gravity screening to remove part of the heavy metal organic complexes to obtain dry food sludge crushed material to be pyrolyzed, and the remaining preparation steps are the same.

[0150] The content of heavy metals in the raw material - food sludge was determined (the content of heavy metal elements is as follows: Pb content 238.4 mg / kg, Cb content 6.9 mg / kg, Hg content 3.3 mg / kg, Cr content 68.6 mg / kg, As content 15.2 mg / kg, total heavy metal content (M1) 332.4 mg / kg).

[0151] The heavy metal content of the food sludge-based biochar in Example 1 and Comparative Examples 3-4 was tested, and the Pb content, Cb content, Hg content, Cr content, As content and the total heavy metal content M2 were measured respectively. The heavy metal element removal rate of the pyrolysis process was calculated as P = (332.4-M2)*100 / 332.4. In order to clearly reflect the effect of the addition of magnetic single-atom modified halloysite and organic complex on the physicochemical properties of the prepared food sludge-based biochar, the test parameters were integrated and tabulated, see Table 1: Parameter table of heavy metal content in food sludge-based biochar in Example 1 and Comparative Examples 3-4.

[0152] Table 1: Parameters of heavy metal content in food sludge-based biochar in Example 1 and Comparative Examples 3-4

[0153]

[0154]

[0155] Combining Example 1 with Comparative Examples 3-4 and comparing with Table 1, it can be seen that the compound addition of magnetic single-atom modified halloysite and organic complex can reduce the heavy metal content in food sludge-based biochar.

[0156] Experimental study on heavy metal removal from food sludge-based biochar: Using Cb 2+ Cr 3+ , Pb 2+ The standard solutions with a mass concentration of 1000 mg / L were mixed and diluted 10 times to prepare a mixed standard solution. The Cb content in the solution was measured by ICP. 2+ Cr 3+ , Pb 2+ The concentrations of the solution were 102.5 mg / L, 98.9 mg / L and 104.3 mg / L, respectively. The pH of the solution was adjusted to 6. 60 mL of the solution and 0.10 g of biochar were added to 100 mL centrifuge tubes, respectively. The adsorption was shaken at room temperature for 24 h, and then filtered with filter paper. The Cb content in the solution was determined by ICP. 2+ Cr 3+ , Pb 2+ The mass concentration of heavy metals was calculated and the removal rate and removal amount of food sludge-based biochar were calculated. The experimental results are shown in Table 2:

[0157] Table 2: Heavy metal removal parameters of food sludge-based biochar in Example 1 and Comparative Examples 3-4

[0158] <![CDATA[Cb 2+ Removal rate (%)]]> <![CDATA[Cr 3+ Removal rate (%)]]> <![CDATA[Pb 2+ Removal rate (%)]]> Total removal rate (%) Example 1 40.2 98.5 96.1 78.2 Comparative Example 3 37.1 93.8 92.7 74.5 Comparative Example 4 35.9 94.6 93.5 74.7

[0159] Combining Example 1 with Comparative Examples 3-4 and comparing with Table 2, it can be seen that the residual heavy metal content in the food sludge-based biochar has a negative impact on the heavy metal removal performance of the food sludge-based biochar material.

[0160] The difference between Example 5 and Example 1 is that: in step 6 of the method for preparing food sludge-based biochar, 100 parts of the crushed food sludge to be pyrolyzed in step 5 are weighed and mixed evenly with 1.5 parts of thiosemicarbazide, and in a nitrogen atmosphere, the mixture is first heated to 230°C at a heating rate of 10°C / min and maintained for 10 minutes, then heated to 400°C at a heating rate of 20°C / min and kept warm for 45 minutes, then heated to 600°C at a heating rate of 10°C / min and kept warm for 15 minutes, and finally heated to 200°C at a cooling rate of 10°C / min and then naturally cooled to room temperature, and the obtained solid matter is put into an industrial ball mill for ball milling and refinement to obtain a medium particle size D 50=20μm food sludge-based biochar, average pore size 10.2nm, specific surface area 369.2m 2 / g. Food sludge-based biochar and cadmium-containing wastewater (Cb 2+ :50mg / L) solid-liquid ratio is 0.1g / L, solution pH is 5.0, and the adsorption capacity of food sludge-based biochar at 25°C is 372mg / L. The heavy metal removal parameters of the food sludge-based biochar prepared in Example 5 are as follows: Cb 2+ Removal rate: 51.4%, Cr 3+ Removal rate 99.8%, Pb 2+ The removal rate was 99.5% and the total removal rate was 83.6%. Comparison between Example 1 and Example 5 shows that the addition of thiosemicarbazide in the pyrolysis process can improve the heavy metal removal capacity of the prepared food sludge-based biochar material.

[0161] The difference between Example 6 and Example 1 is that a soil conditioner is a porous biochar-based microsphere with a particle size of 10±1 mm, and the porous biochar-based microsphere is made of 56.25 parts of food sludge-based biochar, 18.75 parts of cellulose-based biochar (corn straw biochar from Henan Xingnuo Environmental Protection Materials Co., Ltd.), 8 parts of calcined shell powder (325 mesh. Lingshou County Kaiqi Mineral Products Processing Plant), 7 parts of porous coal gangue powder (calcined 1250 mesh coal gangue powder, customized by Lingshou County Jingjia Mineral Products Processing Plant), 1 part of single-atom modified zeolite agent (customized outsourced), 5.4 parts of kaolin (325 mesh white calcined kaolin, purchased from Lingshou County Zhuolei Building Materials Co., Ltd.), and 3.6 parts of starch (industrial grade corn starch, purchased from Jinan Deqiao Chemical Technology Co., Ltd.).

[0162] The difference between Example 7 and Example 5 is that a soil conditioner is made of 85 parts of the porous biochar-based microspheres prepared in Example 5, 6 parts of degradable compound fertilizer capsules, 3 parts of degradable organic complex capsules, and 6 parts of degradable organic fertilizer capsules.

[0163] The coating films of the degradable compound fertilizer capsules, the degradable organic complex capsules and the degradable organic fertilizer capsules are made of 20 parts of starch and 80 parts of polyvinyl alcohol (PVA), and the film thickness is controlled to be 80-100 microns.

[0164] The compound fertilizer in the degradable compound fertilizer capsule is a mixture of potassium dihydrogen phosphate, calcium nitrate and diammonium phosphate in a mass ratio of 1:1:1. The degradable compound fertilizer capsule is made by a coating machine and has a particle size of 5-6mm.

[0165] The organic complex in the degradable organic complex capsule is diethylenetriamine pentacarboxylic acid pentasodium. The degradable organic complex capsule is prepared by a coating machine and has a particle size of 5-6 mm.

[0166] The organic fertilizer in the degradable organic fertilizer capsule is sheep manure organic fertilizer YJF-012 produced by Dongying Kunbao Organic Fertilizer Co., Ltd. The degradable organic fertilizer capsule is made by a coating machine and has a particle size of 5-6mm.

[0167] A soil simulation experiment was conducted on the soil conditioners in Example 1 and Examples 5-7. The experimental method is as follows: soil contaminated by dyeing and finishing wastewater around the dyeing cluster area of ​​Honghe Town Industrial Park, Xiuzhou District, Jiaxing City was used, and 10 portions of 0-30 cm surface soil were randomly collected. The 10 randomly collected portions of surface soil were air-dried, ground, sieved, and mixed to obtain soil samples to be repaired. The physical and chemical properties of the soil samples to be repaired were measured and recorded and tabulated. The soil samples to be repaired were filled in the experimental area (specifications: length 3m*width 3m depth 0.3m), 2 kg of soil conditioner was artificially spread on the surface of the soil to be repaired on the surface of the experimental area, and then a 10-15 cm tillage was carried out, and then the surface of the soil to be repaired was sprayed with atomized water. Atomized water was sprayed once every 24 hours, and the amount of atomized water sprayed each time was 50 g / m 2 After seven days, the soil in the experimental area to be repaired was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours. The amount of atomized water sprayed each time was 50g / m 2 , after seven days, the physical and chemical properties of the soil were measured, recorded and tabulated.

[0168] Table 3: Physical and chemical property parameters of soil repaired by soil conditioners in Example 1, Examples 5-7

[0169] Original soil Example 1 Example 5 Example 6 Example 7 Organic matter g / kg 16.56 20.71 21.15 20.94 22.37 Pb content mg / kg 143.5 27.27 21.54 24.54 19.09 Cb content mg / kg 1.53 1.01 0.93 0.90 0.86 Hg content mg / kg 3.84 1.03 0.98 0.99 0.83 Cr content mg / kg 28.3 5.52 5.41 5.35 4.19 As content mg / kg 6.51 0.90 0.81 0.87 0.68 pH 4.87 6.15 6.07 6.28 6.57 Catalase mL / g 3.15 3.87 3.94 4.06 4.13

[0170] By comparing Example 1, Examples 5-7 and Table 3, it can be seen that after 14 days of use of the soil conditioner, the soil fertility (organic matter) increased, the harmful heavy metals lead, chromium, cadmium, mercury, and arsenic were effectively adsorbed and reduced to below the risk control value, and the soil pH value increased by more than 1.20, effectively improving the physical and chemical properties of the soil.

[0171] In order to understand the long-term repair effect of the soil repair agent, a 7*9-day soil repair simulation experiment was carried out using the soil conditioner in Example 5. The soil sample to be repaired was filled in the experimental area (specification length 3m*width 3m depth 0.3m), 2kg of soil conditioner was artificially spread on the surface of the soil to be repaired on the surface of the experimental area, and then a 10-15cm tillage was carried out, and then the surface of the soil to be repaired was sprayed with atomized water. Atomized water was sprayed once every 24h, and the spraying amount of atomized water each time was 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 7d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2After seven days, the soil physical and chemical properties parameters T were tested. 14d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 21d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 28d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 35d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 42d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 49d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 54d Then, the soil to be repaired in the experimental area was tilled to a depth of 10-15 cm and sprayed with atomized water every 24 hours, with a spraying amount of 50g / m 2 After seven days, the soil physical and chemical properties parameters T were tested. 63d , the physical and chemical properties of soil 7d To T 63d Make measurements, record and tabulate.

[0172] Table 4: Parameters of the soil conditioner simulation experiment for 7*9 days in Example 5

[0173]

[0174] As can be seen from Table 5, the soil conditioner in Example 5 has an inflection point at 13-16 days. The soil conditioner has a fast adsorption and removal efficiency for heavy metals within 16 days after use and can adjust the soil pH value relatively quickly. Therefore, the use instructions of the soil conditioner in Example 5 are as follows: The soil conditioner provided by the present invention is used to repair acidic medium-sized heavy metal contaminated soil. After 14 days of use, the soil repair effect begins to show, and after 35 days of use, the soil repair effect is more obvious, which has met the requirements for common crop planting.

[0175] In summary, the soil conditioner of the present invention can absorb and remove heavy metal elements, adjust the soil pH value, improve the soil structure and physical and chemical properties, and the ability to retain water, soil and fertilizer, and can also effectively promote the growth and development of crops, thereby achieving the effect of increasing crop production and income.

Claims

1. A soil conditioner, characterized in that: The porous biochar-based microspheres include food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite, and a binder; the food sludge-based biochar is made by pyrolysis of food sludge; the cellulose-based biochar is made by pyrolysis of cellulose-rich waste biomass materials; the cellulose-rich waste biomass materials include rice straw, wheat straw, corn straw, sorghum straw, reed straw, waste wood chips, dead tree branch crushed materials, dead tree bark crushed materials, leaf crushed materials, dead grass crushed materials, coconut shell crushed materials, bagasse, coffee grounds, peanut shell residue at least one of; the single-atom modified zeolite agent comprises a porous zeolite agent carrier and a single-atom metal loaded on the surface and pore wall of the porous zeolite agent carrier, the single-atom metal comprises at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the single-atom metal loading rate in the single-atom modified zeolite agent is 1 to 5wt%; the binder is a disintegrable organic binder combined with at least one of illite powder, bentonite powder, dolomite powder, diatomaceous earth powder, kaolin powder, montmorillonite powder, and attapulgite powder; the disintegrable organic binder is at least one of starch, polyvinyl alcohol, and polylactic acid.

2. A soil conditioner according to claim 1, characterized in that: The single-atom modified zeolite agent accounts for 0.5-2.0wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8-20wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 78-90wt% of the total mass of the porous biochar-based microspheres; the mass ratio of the food sludge-based biochar to the cellulose-based biochar is (1-4):(1-4).

3. A soil conditioner according to claim 2, characterized in that: The preparation method of the food sludge-based biochar is as follows: Step 1, taking 10 parts of food sludge and mixing them evenly with 90-190 parts of water to obtain a sludge suspension; Step 2: adding an organic complex to the sludge suspension under stirring at a speed of 100 to 300 rpm, wherein the organic complex accounts for 0.01 to 0.10 wt% of the mass of the food sludge, and the organic complex is divided into at least three portions, with an interval of 15 to 30 minutes between two portions of the organic complex. After the addition of the organic complex is completed, stirring is continued at a speed of 100 to 300 rpm for 30 to 60 minutes; Step 3, adding a pH regulator to the sludge suspension, adjusting the pH value of the sludge suspension to 6.8-7.1 after the pH regulator is added, adding magnetic single-atom modified halloysite, the magnetic single-atom modified halloysite accounts for 0.05-0.50wt% of the mass of the food sludge, and the magnetic single-atom modified halloysite is divided into at least three portions, the interval time between two portions of the magnetic single-atom modified halloysite is 15-30min, and after the addition of the magnetic single-atom modified halloysite is completed, the stirring speed is maintained at 100-300rpm for 30-60min; Step four, standing under ultraviolet light for 12-24h, extracting the upper water body to the sewage network, and performing dry-wet separation treatment on the food sludge treated with organic complex + magnetic single atom modified halloysite to obtain food sludge pellets, the water content of the food sludge pellets is 25-40wt%; Step 5, drying the food sludge pellets in step 4 at 120-160° C. to make the water content in the food sludge pellets less than 3.0%, grinding and crushing the dried food sludge pellets to obtain food sludge crushed materials, performing magnetic separation on the food sludge crushed materials, and sieving and recovering the magnetic single-atom modified halloysite and the food sludge crushed materials to be pyrolyzed after the magnetic separation; Step six, pyrolyzing the food sludge crushed material to be pyrolyzed in step five to obtain food sludge-based biochar with high specific surface area and high porosity.

4. A soil conditioner according to claim 3, characterized in that: The magnetic single-atom modified halloysite includes single-atom modified halloysite and nanomagnetic particles grafted on the surface of the single-atom modified halloysite, and the loading rate of the nanomagnetic particles in the magnetic single-atom modified halloysite is 0.5-5wt%; the single-atom modified halloysite includes halloysite with an average particle size of 0.5-20 microns and single-atom metals loaded on the surface of the halloysite and the surface of the pore wall, and the single-atom metals include at least one of Fe, Ag, Cu, Zn, Ce, and Ti, and the loading rate of the single-atom metals in the single-atom modified halloysite is 1-5wt%.

5. A soil conditioner according to claim 4, characterized in that: The preparation method of the magnetic single-atom modified halloysite is as follows: Step 1, preparation of single atom modified halloysite; Step 2: 10 parts of single-atom modified halloysite and 40-90 parts of 0.5-2wt% epoxy silane aqueous solution are mixed evenly, and then ultrasonic dispersion treatment is performed for 0.5-1h. After the ultrasonic dispersion treatment is completed, reduced pressure filtration is performed, and the obtained solid is vacuum dried to obtain epoxy silane grafted single-atom modified halloysite; Step 3, 10 parts of nano-magnetic particles and 40-90 parts of an aqueous solution of aminosilane with a concentration of 0.5-2wt% are mixed evenly, and then ultrasonic dispersion treatment is performed for 0.5-1h. After the ultrasonic dispersion treatment is completed, vacuum filtration is performed, and the obtained solid is vacuum dried to obtain aminosilane-grafted modified nano-magnetic particles; Step 4: Disperse 10 parts of epoxy silane grafted modified single-atom modified halloysite and 0.053-0.53 parts of amino silane grafted modified nanomagnetic particles in 90-190 parts of polar aprotic organic solvent and mix them evenly. Then, heat the temperature to 45-60°C, maintain the temperature at 45-60°C for 1-4 hours of ultrasonic dispersion treatment, the ultrasonic dispersion frequency is 30-44kHz, the ultrasonic dispersion power is 200-600W, and after the ultrasonic dispersion treatment is completed, reduce pressure filtration is performed, and the filtrate is vacuum dried. The solid obtained is ball-milled to obtain magnetic single-atom modified halloysite, and the nanomagnetic particles are grafted to the surface of the single-atom modified halloysite through amide bonds.

6. A soil conditioner according to claim 3, characterized in that: In the step six, 100 parts of the food sludge crushed material to be pyrolyzed in the step five are weighed and mixed evenly with 0.5-2 parts of thiosemicarbazide, and then placed in a muffle furnace for pyrolysis treatment. In a nitrogen atmosphere, the material is first heated to 225-230°C at a heating rate of 5-10°C / min and maintained for 5-10min, then heated to 360-420°C at a heating rate of 10-20°C / min and kept warm for 40-50min, then heated to 560-650°C at a heating rate of 5-10°C / min and kept warm for 10-15min, finally heated to 160-240°C at a cooling rate of 5-10°C / min, then opened the furnace and naturally cooled to room temperature, and the obtained solid matter is ball-milled to obtain food sludge-based biochar.

7. A soil conditioner according to claim 6, characterized in that: In the step six, 100 parts of the food sludge crushed material to be pyrolyzed in the step five are weighed and mixed evenly with 1.2-1.6 parts of thiosemicarbazide, and then placed in a muffle furnace for pyrolysis treatment. In a nitrogen atmosphere, the mixture is first heated to 225-230°C at a heating rate of 10°C / min and maintained for 10 minutes, then heated to 400-420°C at a heating rate of 20°C / min and kept warm for 45 minutes, then heated to 580-600°C at a heating rate of 10°C / min and kept warm for 15 minutes, finally heated to 180-200°C at a cooling rate of 10°C / min, then opened the furnace and naturally cooled to room temperature, and the obtained solid matter is ball-milled to obtain food sludge-based biochar.

8. A soil conditioner according to claim 1, characterized in that: The porous biochar-based microspheres also include calcined shell powder and porous coal gangue powder, the calcined shell powder accounts for 5-10wt% of the total mass of the porous biochar-based microspheres, and the porous coal gangue powder accounts for 5-10wt% of the total mass of the porous biochar-based microspheres; the single-atom modified zeolite agent accounts for 0.5-2.0wt% of the total mass of the porous biochar-based microspheres; the binder accounts for 8-20wt% of the total mass of the porous biochar-based microspheres; the total mass of the food sludge-based biochar and the cellulose-based biochar accounts for 58-80wt% of the total mass of the porous biochar-based microspheres; the mass ratio of the food sludge-based biochar to the cellulose-based biochar is (1-4):(1-4).

9. A soil conditioner according to claim 1 or 8, characterized in that: The soil conditioner includes porous biochar-based microspheres, degradable compound fertilizer capsules, degradable organic complex capsules, and degradable organic fertilizer capsules; the amount of porous biochar-based microspheres added to the soil conditioner is 75-90wt%; the amount of degradable compound fertilizer capsules added to the soil conditioner is 4-10wt%; the amount of degradable organic complex capsules added to the soil conditioner is 2-10wt%; and the amount of degradable organic fertilizer capsules added to the soil conditioner is 4-10wt%.

10. A method for preparing the soil conditioner according to claim 9, characterized in that: The following steps are involved: Step 1, preparation of food sludge-based biochar; Step 2: evenly mix the accurately measured food sludge-based biochar, cellulose-based biochar, single-atom modified zeolite agent, and binder, and place them in a granulator for granulation to obtain porous biochar-based microspheres with a particle size of 0.8-3 cm; Step 3, mixing the degradable compound fertilizer capsules, the degradable organic complex capsules, and the degradable organic fertilizer capsules with the porous biochar-based microspheres in step 2 according to a ratio to obtain a soil conditioner composition; The organic complex contained in the degradable organic complex capsule in the soil conditioner composition is selected according to the acidity and alkalinity of the soil to be improved; When the soil to be improved is acidic, the organic complex contained in the degradable organic complex capsule is an alkaline organic complex; When the soil to be improved is alkaline, the organic complex contained in the degradable organic complex capsule is an acidic organic complex.

Images