Nanometer suspension slow-release water-soluble fertilizer

Abstract

The invention discloses a nano suspension slow-release water-soluble fertilizer. A polymer biodegradable film material is pretreated and then is subjected to a condensation reaction with an aldehyde substance under an acidic condition, and then a nitrogen-containing fertilizer is added; adding a dispersing agent and sodium silicate to obtain a solution A; performing cross-linking reaction on fatty alcohol-polyoxyethylene ether and carboxymethyl cellulose, and then adding liquid oil to obtain a solution B; mixing the solution A and the solution B, adding water glass, adjusting the pH to be nearly neutral, and adding an anti-crystallization material to obtain a solution C; and adding an anti-skinning agent and a slow-release inhibiting material into the solution C, uniformly mixing, and adding into the fertilizer. The fertilizer prepared from the waste polymer biodegradable film material has the characteristics of high suspension degree, high stability, high fluidity and homogeneous phase, and is easily compounded with other elements and media. The method is simple and easy to apply, saves energy and raw materials, and is low in production cost and remarkable in synergism.

Description

Technical Field

[0001] The present application relates to the technical field of water-soluble fertilizers, and in particular to a nano-suspended slow-release water-soluble fertilizer. Background Art

[0002] With the rapid development of water-fertilizer integration technology, the development trend of instant, compound, liquid and concentrated fertilizers is becoming more and more obvious, especially the proportion of liquid compound fertilizers is increasing year by year. Liquid fertilizer is a fluid fertilizer, which is increasingly accepted by people because of its uniform composition, high nutrient activity, flexible formula, simple production, convenient use, and wide source of raw materials. At present, liquid fertilizers include clear liquid type and suspended type. Clear liquid liquid fertilizers are completely dissolved and easy to fertilize. In order to meet the needs of water-fertilizer integration, most of them are clear liquid fertilizers. However, the low nutrient content of clear liquid fertilizers and high raw material and transportation costs have become the key to hindering their application and development. On the other hand, the current traditional compound fertilizer production capacity is in excess and urgently needs to be upgraded to adapt to the development of water-fertilizer integration. However, in the compound fertilizer industry, most of the fertilizer sources come from crude chemicals and minerals, and the fertilizers contain more insoluble matter. Therefore, preparing the fertilizer containing insoluble matter into liquid fertilizer in advance and suspending the insoluble matter has become the key to the transformation of traditional compound fertilizers to water-fertilizer integration.

[0003] The compound fertilizer containing insoluble solid fertilizer particles is dispersed through a suspension aid to form a suspended liquid fertilizer, which has the advantages of low production cost, high nutrient content, easy compounding, direct absorption by crops, convenient formula fertilization (balanced fertilization) and mechanized fertilization, etc. It can fully meet the needs of water-fertilizer integration, not only solve the problem of high cost of water-soluble fertilizers, but also reduce the purification and drying processes of fertilizers, which has positive significance in terms of saving energy, protecting the environment, and improving fertilizer utilization efficiency. Generally speaking, every 10% increase in fertilizer concentration can reduce fertilizer packaging, storage, transportation and management costs by about 20%. Therefore, suspended fertilizers are the future development trend of liquid fertilizers.

[0004] The shortcomings and deficiencies of current suspended fertilizer technology are: (1) Suspending agents are added to physically mix the raw materials; and the added suspending agents are mainly xanthan gum, cellulose and clay minerals. The amount of suspending agent used in the preparation of suspended fertilizer is large, and about 20-120 parts by weight of suspending agent are required for every 1,000 parts by weight, which greatly increases the cost of fertilizer. (2) Since only one suspension action is performed, the suspended fertilizer produced has a limited suspension time, is prone to sedimentation after long-term storage, and has poor stability and suspension properties. The suspension effect is even worse when encountering fertilizers with high salt content, and it is difficult to produce stable suspended fertilizers. This makes the market application effect of suspended fertilizers poor and difficult to promote. In addition, the nitrogen utilization rate of suspended liquid fertilizers used in greenhouse vegetables is only 20-30%, and the phosphorus utilization rate is only 10-20%, which is far lower than the average utilization rate of nitrogen and phosphorus nutrients in field crop fertilizers; and although liquid fertilizers use spray and drip irrigation facilities, they are still applied with water, which still causes a large amount of nitrogen nutrients to leached into the deep soil layer, polluting the soil and groundwater. For example, compared with the application of urea, the application of urea ammonium nitrate solution fertilizer (UAN) will increase the ammonia volatilization rate by 9.0% to 20.0%, and increase the risk of nitrate nitrogen leaching by 34%-46%. Therefore, it is urgent to slow-release liquid fertilizer nutrients to improve nutrient utilization and reduce losses. Patent application number CN104591930A discloses a slow-release suspension liquid compound fertilizer and its preparation method and use method, but the patent has the following shortcomings: (1) The raw materials are combined by physical mixing rather than chemical reaction. Theoretically, it will inevitably stratify and produce precipitation in a short time; (2) The high temperature of 65-80°C is used in the preparation process, which has a serious impact on the effect of the added inhibitor and easily leads to the decomposition and failure of the inhibitor; (3) The high shear speed is only 2000-4000 rpm, which is too low to achieve the high shear effect. The particle size of the material is difficult to reach the nanometer or molecular level, and it is difficult to ensure the suspension state, which is easy to cause stratification or precipitation, and even cause blockage when passing through the dripping facility; (4) In terms of slow release effect, the entire suspension system does not produce slow release effect through chemical synthesis or molecular bond complexation, but directly adds external slow release fertilizer to the suspension system. Although an emulsifier is added, the emulsifier is a single compound of polyoxyethylene ether, and no complex system is formed. The complexation function is weak, and the slow release effect of nutrients is difficult to reflect.

[0005] In summary, there is an urgent need to develop a liquid fertilizer with high suspension, stability, fluidity, and both rapid and slow-release properties of nutrients.

[0006] In addition, to solve the problem of plastic pollution, biodegradable plastics have been used in daily life. However, due to the difficulty of recycling and disposal, the problem of biodegradable plastic pollution is becoming more and more serious. Therefore, it is urgent to provide a wider range of methods for the reuse of biodegradable plastics. Summary of the invention

[0007] The present invention provides a nano-suspension slow-release water-soluble fertilizer, and the preparation method of the water-soluble fertilizer comprises the following steps:

[0008] (1) Pre-treating the discarded polymer biodegradable membrane material and reacting it with an aldehyde substance under acidic conditions, adjusting the pH value of the liquid phase to neutral after the reaction, and preparing a colloidal suspension phase system; adding a nitrogen-containing fertilizer to the suspension phase system to react with the aldehyde substance to neutralize the excess aldehyde substance and stabilize the colloidal properties of the suspension system;

[0009] (2) In order to enhance the stability and sustained release effect of the above suspension system, a dispersant is added to disperse and emulsify the above system under continuous stirring, and then sodium carbonate is added to enhance the colloidal properties of the suspension system and remove the foam effect, thereby obtaining solution A;

[0010] (3) After the above steps, the stability, fluidity and suspension of the prepared suspension system are not enough, and further chemical cross-linking reaction is required to enhance the effect. A certain amount of fatty alcohol polyoxyethylene ether with emulsification and diffusion effects is taken to undergo cross-linking reaction with carboxymethyl cellulose with suspension, bonding and stabilization effects under continuous stirring, thereby enhancing the suspension and stability of the system, and then liquid oil is added for homogenization to obtain solution B with the function of enhancing the suspension, stability and homogeneity of the system;

[0011] (4) Solution A is added to solution B. In order to form an organic whole, water glass is further added under continuous stirring. After adjusting the pH of the solution to be close to neutral, an anti-crystallization material is added, stirred and allowed to stand to obtain solution C. Through chemical cross-linking reaction and complex reaction, the system now has strong suspension, stability, anti-crystallization, colloid and homogeneity. The preparation method of the anti-crystallization material is as follows: paraffin wax and liquid oil are mixed, and then a paraffin wax emulsifier is added and stirred to prepare the anti-crystallization material;

[0012] (5) In order to further enhance the sustained release of solution C, after high shearing of solution C, an anti-skinning agent is added, and then a slow-release inhibitor material is added and mixed, and then high sheared again and added to the fertilizer and high sheared again to obtain the nano-suspension slow-release water-soluble fertilizer; the slow-release inhibitor material is obtained by combining urease inhibitor (NBPT) and / or nitrification inhibitor (DMPP) with montmorillonite after polyamino acid complexation. At this time, the water-soluble fertilizer has already bonded and adsorbed the inhibitor material and part of the fertilizer nutrients into the suspension colloid and embedded and adsorbed into the montmorillonite, playing a role in protecting the inhibitor and enhancing the slow release function of the inhibitor. In addition, the raw material has become nano-scale after high shearing, and the stability, dispersibility and fluidity are better.

[0013] Specifically, the method for preparing the water-soluble fertilizer further comprises one or more of the following (1)-(8):

[0014] (1) The polymer biodegradable film material is selected from one or more of poly (3-hydroxybutyrate-CO-3-hydroxyvalerate) (PHBV), polylactic acid (also known as lactide, PLA), polyhydroxyalkanoate (PHA), polybutylene terephthalate (PBAT), and polyvinyl alcohol (PVA);

[0015] (2) The pretreatment includes: sorting, washing, drying and crushing the polymer biodegradable film material in sequence; more specifically, sorting and washing the polymer biodegradable film material in sequence to remove impurities to make its surface smooth, and then drying it at 40-80°C, and crushing it to less than 5 mm after drying.

[0016] (3) The nitrogen-containing fertilizer is selected from one or more of urea, monoammonium phosphate, and diammonium phosphate;

[0017] (4) In step (2), the dispersant is selected from one or more of sodium dibutylnaphthalene sulfonate, sodium dodecylbenzene sulfonate, secondary alkyl ammonium sulfate, and pentadecylsulfonyl chloride;

[0018] (5) The preparation method of the anti-crystallization material is as follows: after mixing 100-145g of paraffin with 75-200g of liquid oil, 140-300g of paraffin emulsifier is added and stirred evenly; more specifically, the liquid oil is selected from soybean oil or diesel.

[0019] (6) The preparation method of the sustained-release inhibitor material is as follows: 10-50 g of urease inhibitor and / or nitrification inhibitor is added to 40-200 g of polylactic acid and stirred at 20-50° C., and then 25-50 g of montmorillonite is added and high sheared until uniform;

[0020] (7) the anti-skinning agent is selected from butanone oxime, silicon dioxide, aniline or azobenzene;

[0021] (8) In step (5), solution C is subjected to high shearing at 10,000-30,000 rpm for 10-25 min, and then the anti-skinning agent and the slow-release inhibitor are added and stirred at 25-50° C. After the solution is clarified, the fertilizer is added at high shearing at 10,000-20,000 rpm for 10-25 min, and after mixing, the solution is subjected to high shearing at 10,000-20,000 rpm for 10-20 min.

[0022] More specifically, the preparation method of the water-soluble fertilizer comprises the following steps:

[0023] (1) adding 75-120 g of pretreated polymer biodegradable film material to 500 ml-1000 ml of water at a temperature greater than 85° C. and heating the water under constant stirring until dissolved; adjusting the solution to a pH of 2-5 with sulfuric acid, adding 15-45 ml of formaldehyde after the water temperature drops to 40-60° C., controlling the solution temperature to 60-80° C., stirring for 30-60 min, then adding 10-60 ml of formaldehyde, and adjusting the solution pH to 6-8 with KOH; then adding 150-450 g of nitrogen-containing fertilizer dissolved in 20-60 g of water at 25-50° C. under constant stirring;

[0024] (2) adding 2-8 g of dispersant and 30-50 ml of sodium carbonate in sequence under continuous stirring, stirring and standing to obtain solution A;

[0025] (3) adding 5-15 g of carboxymethyl cellulose powder to 45-65 ml of water to obtain a carboxymethyl cellulose solution; weighing 15-45 g of fatty alcohol polyoxyethylene ether and adding it to 100-220 ml of water, stirring at 50° C., then adding the carboxymethyl cellulose solution and stirring evenly, then adding 30-55 g of liquid oil and stirring evenly, adding water to 500-700 ml, continuing to stir and standing to obtain a solution B;

[0026] (4) adding solution A accounting for 5-20% of the weight of solution B to solution B, adding 50-120 ml of water glass with a mass percentage concentration of 10%-22% under continuous stirring, and adjusting the pH of the solution to 6.5-7.5 with dilute HCl; taking 500-650 g of the solution after standing, adding 55-220 g of anti-crystallization material, stirring and standing to obtain solution C; the preparation method of the anti-crystallization material is as follows: after mixing 30-105 g of paraffin and 55-200 g of liquid oil, adding 120-260 g of paraffin emulsifier and stirring evenly;

[0027] (5) Place solution C in a high-speed shearing device and high-shear for 10 to 25 minutes at 10,000 to 30,000 rpm, add an anti-skinning agent accounting for 0.01% to 0.11% of the volume of solution C, and then add 7 to 20 g of a slow-release inhibitor and stir for 30 minutes, while maintaining the system temperature at 25 to 50° C.; after the solution is clarified, high-shear for 10 to 25 minutes at 10,000 to 20,000 rpm, then reduce the speed to 120 rpm and maintain continuous stirring at 25 to 50° C., while stirring, add 0.5% to 10% of the fertilizer weight. % is added to the fertilizer, mixed and stirred evenly, then cooled to 30-40°C, the rotation speed is increased to 10000-20000rpm again and high sheared for 15-20min, and after the solution is clarified, it is allowed to stand for 6-24 hours to prepare the nano-suspension slow-release water-soluble fertilizer; the preparation method of the slow-release inhibitor material is as follows: 100g of polylactic acid is heated to 20-50°C and stirred to dissolve evenly, 10-50g of urease inhibitor and / or nitrification inhibitor are added in portions, and after stirring, 25-50g of montmorillonite and 20g of water are added and high sheared until uniform.

[0028] The fertilizer in step (5) can be a compound fertilizer consisting of 0.5-3.5 kg of water, 2.0-7.5 kg of urea, 1.1-5.5 kg of diammonium phosphate and 1.1-5.8 kg of potassium sulfate; or it can be a urea ammonium nitrate solution containing 28-35% nitrogen.

[0029] The beneficial effects of the present invention include:

[0030] 1. The present invention adopts a chemical method to prepare the suspension system, rather than a physical method, that is, to achieve the suspension effect by adding a suspending agent for mixing. This system is chemically bonded, more stable and uniform, and reduces production costs;

[0031] 2. The present invention adopts liquid phase chemical method, high shear and heterogeneous co-polymerization technology to further prepare nanocomposite colloidal suspension dispersed phase system. Nanocomposite materials are different from nanocrystalline materials and nanophase materials. Their colloidal particles have excellent dispersibility and small mass in suspended fertilizers. Their nanopores have a sufficiently large surface area and bonding effect. (i) They can adsorb and collect crystalline particles, and limit the inhibitor from being decomposed too quickly during storage through the spatial effect of colloidal particle dispersion. (ii) The prepared anti-crystallization material can adapt to certain temperature changes and has the characteristics of enhancing the stability and homogeneity of the colloid, which comprehensively plays a role in making the inhibitor suspended stably for a long time.

[0032] 3. The present invention prepares nitrogen slow-release function through chemical reaction, and adopts organic intercalation composite technology, high molecular polymer complexation and microemulsification coupling technology to embed and adsorb inhibitory materials and nutrient elements. The free inhibitory materials and nutrient elements are chelated to a certain extent by polyamino acid at the same time, thereby realizing the suspension, slow release and conversion of nutrients and inhibitory materials;

[0033] 4. The present invention prepares nano-suspension slow-release water-soluble fertilizer by rationally adjusting the parameters of suspension phase system such as polymer materials, slow-release inhibitor materials, and anti-crystallization materials. This kind of fertilizer has high suspension, high stability, high fluidity and homogeneous characteristics, and is easy to compound with other elements and media. It is easy to apply, not only saves energy and raw materials, but also has low production costs and significant efficiency improvement;

[0034] 5. The present invention utilizes discarded polymer biodegradable film materials as suspension materials to prepare nano-suspended slow-release water-soluble fertilizers, thereby realizing resource utilization, high efficiency, and ecologicalization of discarded pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The particle size distribution diagram of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2;

[0036] Figure 2 This is an electron microscope image of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2;

[0037] Figure 3 The actual image and apparent state of the nano-suspended slow-release water-soluble fertilizer prepared in Example 2;

[0038] Figure 4 This is a graph showing the change in soil ammonium nitrogen content under different fertilization treatments in the slow-release test a of test example (5);

[0039] Figure 5 This is a graph showing the change in soil ammonium nitrogen content under different fertilization treatments in the slow-release test b of test example (5);

[0040] Figure 6 The yield of cabbage under different fertilization treatments in the field application experiment 1 of the experimental example (6);

[0041] Figure 7 This is the yield of cabbage under different fertilization treatments in Experimental Example (6) Field Application Experiment 2. DETAILED DESCRIPTION

[0042] The present invention is further illustrated and described below in conjunction with embodiments, but the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the present invention and embodiments, all other inventions and embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0044] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0045] Example 1: Preparation of a nano-suspension slow-release water-soluble fertilizer

[0046] The steps include:

[0047] (0) Collect the discarded polymer biodegradable film materials on the market, screen and wash them to remove impurities and make their surfaces smooth, then dry the materials at 40-80°C, crush them to less than 5 mm after drying, and crush them into materials of a certain size, which is conducive to the subsequent modification and preparation of water-soluble fertilizers.

[0048] (1) Add 500ml-1000ml of water to a beaker, place it in a water bath, and heat it while stirring constantly to keep the water temperature above 85°C. Dissolve 75-120g of crushed polymer biodegradable film material (after the reaction, the biodegradable film material can be used as a suspension material to suspend, complex, and absorb nutrients) in a beaker. Adjust the solution to a pH of 2-5 with sulfuric acid. After lowering the water temperature in the beaker to 40-60°C, add 15-45ml of formaldehyde, control the solution temperature to 60-80°C, and stir for 30-60 minutes to allow the biodegradable plastic material to undergo a condensation reaction with the aldehyde substance under acidic conditions. Then, add 10-60ml of formaldehyde according to the thoroughness of the reaction, and adjust the solution pH to 6-8 with KOH to prepare a colloidal suspension phase system. Then, 150-450g of nitrogen-containing fertilizer dissolved in 20-60g of 25-50°C water is added under constant stirring to fully react. The nitrogen-containing fertilizer reacts with aldehydes to form urea-formaldehydes, thereby achieving the slow release of nitrogen nutrients in the suspension system. The nitrogen-containing fertilizer here plays the role of regulating the acid-base environment, promoting and participating in the chemical reaction process, forming the slow release of nitrogen, and neutralizing excess reactants. Then, 2-8g of dispersant and 30-50ml of sodium silicate (sodium silicate) are added in sequence, and solution A is obtained after stirring and standing. Adding the pulling powder can disperse and emulsify the above system, and adding sodium silicate can enhance the colloidal properties of the suspension system and the effect of removing foam.

[0049] (2) Weigh 100-220 ml of water and put it into another beaker, add 15-45 g of fatty alcohol polyoxyethylene ether, and stir continuously at 50° C.; add 5-15 g of carboxymethyl cellulose powder into 45-65 ml of water to obtain a carboxymethyl cellulose solution, add the obtained carboxymethyl cellulose solution into the beaker and stir evenly, then add 30-55 g of liquid oil, stir evenly, add water to 500-700 ml, continue to stir and stand to obtain solution B. Fatty alcohol polyoxyethylene ether has emulsifying and diffusing effects, and cross-links with carboxymethyl cellulose having suspending, bonding and stabilizing effects under continuous stirring, thereby enhancing the suspension and stability of the system, and then diesel is added for homogenization to obtain solution B having the function of enhancing the suspension and stability homogeneity of the system.

[0050] (3) Add 5-20% (the weight ratio of solution A to solution B) of solution A to solution B. In order to form an organic whole, add 50-120 ml of water glass with a mass percentage concentration of 10%-22% under continuous stirring, and adjust the pH of the solution to 6.5-7.5 with dilute HCl. After standing, take out 500-650 g of the solution, add 55-220 g of anti-crystallization material, stir and stand to obtain solution C. The preparation method of the anti-crystallization material is as follows: After mixing 30-105 g of paraffin with 55-200 g of liquid oil, add 120-260 g of paraffin emulsifier and stir evenly. Through chemical cross-linking reaction and complex reaction, the system now has strong suspension, stability, anti-crystallization, colloid and homogeneity.

[0051] (4) In order to further enhance the sustained release of system C, solution C was placed in a high-speed shearing device at 10,000-30,000 rpm for 10-25 min, an anti-skinning agent accounting for 0.01% to 0.11% of the volume of solution C was added, and then 7-20 g of sustained release inhibitor material was added and stirred for 30 min. While stirring, the system temperature was maintained at 25-50°C. After the solution is clarified, high shearing is performed at 10000-20000 rpm for 10-25 minutes, then the speed is reduced to 100-120 rpm, and stirring is continued at 25° C.-50° C., and fertilizer (the fertilizer here mainly serves the purpose of providing nutrients) is added in a proportion of 0.5%-10% of the fertilizer weight while stirring, and after mixing and stirring evenly, the temperature is reduced to 30-40° C., and the speed is increased to 10000-20000 rpm again, and stirred for 15-20 minutes three times. After the solution is clarified, it is allowed to stand for 6-24 hours to prepare a nano-suspended slow-release water-soluble fertilizer with strong suspension, fluidity, stability, slow-release and homogeneity. The preparation method of the slow-release inhibitor material is as follows: 100g of polylactic acid (PLA) is heated to 20-50°C and stirred to dissolve uniformly, 10-50g of inhibitor material (the inhibitor material is a urease inhibitor (NBPT) and / or a nitrification inhibitor (DMPP)) is added in portions, 25-50g of montmorillonite and 20g of water are added after stirring, and high shearing is performed until uniform. The fertilizer can be a compound fertilizer composed of 0.5-3.5kg of water, 2.0-7.5kg of urea, 1.1-5.5kg of diammonium phosphate and 1.1-5.8kg of potassium sulfate, or a urea ammonium nitrate solution containing 28-35% nitrogen.

[0052] Example 2: Preparation of a nano-suspension slow-release water-soluble fertilizer

[0053] The steps include:

[0054] (0) Collect discarded polyvinyl alcohol biodegradable film materials on the market, wash them and dry them at 60°C to remove impurities and make their surfaces smooth, and then crush them into 5 mm pieces after drying.

[0055] (1) Add 750 ml of water to a beaker, place it in a water bath, and heat it while stirring to keep the water temperature above 90°C. Place 90 g of crushed polyvinyl alcohol biodegradable film in a beaker and dissolve it (the dissolution process lasts about 2 hours). Adjust the solution to a pH of 3.9 with 98% sulfuric acid. After the water temperature in the beaker drops below 50°C, add 30 ml of malondialdehyde. Control the solution temperature to about 70°C and stir for about 40 minutes to allow the polyvinyl alcohol biodegradable film material to undergo a condensation reaction with the aldehyde substance under acidic conditions. Then add 30 ml of malondialdehyde and adjust the solution pH to 7 with calcium hydroxide to prepare a colloidal suspension phase system. Then add 200 g of diammonium phosphate and 50 g of water while stirring to dissolve it. The reaction is fully carried out, and the nitrogen-containing fertilizer reacts with the aldehyde substance to form urea-formaldehyde substances, thereby achieving a slow release of nitrogen nutrients in the suspension system. Then, add 5 g of sodium dodecylbenzene sulfonate and 30 ml of sodium caustic soda in succession, stir and let stand to obtain solution A. The addition of sodium dodecylbenzene sulfonate can disperse and emulsify the above system, and the addition of sodium carbonate can enhance the colloidal properties of the suspension system and remove foam.

[0056] (2) Weigh 160 ml of water and put it into another beaker, add 25 g of fatty alcohol polyoxyethylene ether, and stir continuously at 35°C; add 10 g of carboxymethyl cellulose powder into 53 ml of water to obtain a carboxymethyl cellulose solution, add the obtained carboxymethyl cellulose solution into the beaker and stir evenly, then add 46 g of soybean oil, stir evenly, add water to 600 ml, continue to stir and stand to obtain solution B. Fatty alcohol polyoxyethylene ether has emulsifying and diffusing effects, and cross-links with carboxymethyl cellulose, which has suspending, bonding and stabilizing effects, under continuous stirring, thereby enhancing the suspension and stability of the system, and then soybean oil is added for homogenization to obtain solution B with the function of enhancing the suspension and stability homogeneity of the system.

[0057] (3) 7% (the weight ratio of solution A to solution B) of solution A is added to solution B. In order to form an organic whole, 80 ml of water glass (i.e., sodium silicate aqueous solution) with a mass percentage concentration of 16% is added under continuous stirring, and the pH of the solution is adjusted to 7.0 with dilute HCl. After standing, 550 g of the solution is taken, 160 g of anti-crystallization material is added, and solution C is obtained after stirring and standing. The preparation method of the anti-crystallization material is as follows: 75 g of paraffin is mixed with 112 g of soybean oil, and 200 g of paraffin emulsifier is added and stirred evenly. Through chemical cross-linking reaction and complex reaction, the system now has strong suspension, stability, anti-crystallization, colloid and homogeneity.

[0058] (4) In order to further enhance the sustained release property of system C, 650 ml of solution C was placed in a high-speed shearing device and subjected to high shearing at 20,000 rpm for 18 min. 0.08% of the volume of solution C was added with anti-skinning agent silica, and then 13 g of sustained release inhibitor material was added and stirred for 30 min. While stirring, the system temperature was maintained at 35° C. After the solution was clarified, the high shearing was performed at 10,000 rpm for 10 min, and then the speed was reduced to 100 rpm. Stirring was continued at 35° C. While stirring, 0.5 kg of water, 2.0 kg of urea, 1.1 kg of diammonium phosphate and 1.1 kg of potassium sulfate were added in sequence. After the mixture was evenly stirred, the temperature was reduced to 30° C. The speed was increased to 10,000 rpm again and stirred for 5 min. Stirring was repeated 3 times. After the solution was clarified, it was allowed to stand for 6 hours to prepare a nano-suspended slow-release water-soluble fertilizer with strong suspension, fluidity, stability, sustained release and homogeneity. The preparation method of the sustained-release inhibitory material is as follows: heat 100g of polylactic acid to 30°C and stir to dissolve evenly, add 30g of inhibitory material (urease inhibitor) in batches and stir evenly, then add 36g of bentonite and 15g of water and high shear at 10000rpm for 5 minutes.

[0059] Example 3: Preparation of a nano-suspension slow-release water-soluble fertilizer

[0060] The steps include:

[0061] (0)-(3) are the same as steps (0)-(3) of Example 2.

[0062] (4) In order to further enhance the sustained release property of system C, 600 ml of solution C was placed in a high-speed shearing device and subjected to high shearing at 10,000 rpm for 10 min, 0.02% of the volume of solution C was added with anti-skinning agent silica, and 8 g of sustained release inhibitor material was added and stirred for 30 min. While stirring, the system temperature was maintained at 35° C. After the solution was clarified, it was subjected to high shearing at 10,000 rpm for 10 min, and then allowed to stand for 24 hours before storage. 2.5 g of the storage solution was added to 100 g of 30% urea ammonium nitrate solution (UAN, urea nitrogen, ammonium nitrogen, and nitrate nitrogen accounted for 50%, 25%, and 25% respectively) fertilizer containing N, and stirred at 35° C. and 120 rpm. After stirring evenly, the temperature was reduced to 30° C., the rotation speed was increased to 10,000 rpm again, and stirred for 5 min. Stirring was repeated 3 times. After the solution was clarified, it was allowed to stand for 6 hours to prepare a nano-suspended slow-release liquid fertilizer with strong suspension, fluidity, stability, sustained release, and homogeneity. The preparation method of the sustained-release inhibitory material is as follows: heat 100g of polylactic acid to 40°C and stir to dissolve evenly, add 25g of inhibitory material (nitrification inhibitor) in batches and stir evenly, then add 50g of bentonite and 12g of water and high shear at 10000rpm for 5 minutes.

[0063] Test example: Performance test of nano-suspended slow-release water-soluble fertilizer

[0064] (1) The particle size analysis of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2 was performed. The results are as follows: Figure 1 and Figure 2 shown.

[0065] from Figure 1 It can be seen that the particle sizes of nutrient ions in the nano-suspension slow-release water-soluble fertilizer prepared in Example 2 are almost all below 100 nm, concentrated at 50 nm, reaching the nanometer level.

[0066] from Figure 2 Scanning electron microscope photos further show that the surface of the nano-suspended slow-release water-soluble fertilizer prepared in Example 2 is very smooth, and the particle size of the suspended material in some areas is below 5nm, which indicates that the nano-suspended slow-release water-soluble fertilizer prepared in Example 2 has good suspension, dispersibility and homogeneity.

[0067] (2) Observation of the fluidity of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2

[0068] from Figure 3 It can be seen that the nano-suspension slow-release water-soluble fertilizer (with dye added) prepared in Example 2 has good fluidity, is as viscous as milk and can flow freely without stratification. The nano-suspension slow-release water-soluble fertilizer (suspension fertilizer) diluted 100 times can be completely dissolved within 30 seconds under normal stirring conditions, which is conducive to drip irrigation, sprinkler irrigation and flushing of suspension fertilizer.

[0069] (3) Testing the nutrient quality index of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2

[0070] The results are shown in Table 1. It can be seen from Table 1 that the total nutrient N+P205+K20 of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2 is 472 g / L, and the content of each nutrient is N: 238 g / L; P205: 112 g / L; K20: 122 g / L; indicating that the nutrient content of the nano-suspension slow-release water-soluble fertilizer prepared in Example 2 of the present invention meets the standard requirements.

[0071] Table 1 Nutrient quality index test results

[0072] Detection indicators Fertilizer parameter indicators required by the standard Example 2 Water-soluble fertilizer content N ≥40 g / L 238 g / L <![CDATA[P2O5]]> ≥40 g / L 112 g / L <![CDATA[K2O]]> ≥40 g / L 122 g / L <![CDATA[N+P2O5+K2O]]> ≥400 g / L 472 g / L pH 3～9 7.1

[0073] (4) Stability test

[0074] a. According to the preparation method of Example 2, suspension fertilizer treatments A (the amount of fertilizer added in step (4) is as follows: 3.5 kg urea, 2.1 kg diammonium phosphate and 2.8 kg potassium sulfate), B (the amount of fertilizer added in step (4) is as follows: 4.5 kg urea, 2.1 kg diammonium phosphate and 3.8 kg potassium sulfate), and C (the amount of fertilizer added in step (4) is as follows: 5.5 kg urea, 2.1 kg diammonium phosphate and 4.8 kg potassium sulfate) with different nitrogen, phosphorus and potassium nutrient ratios are designed, and comparative treatments A1, B1, and C1 without adding anti-crystallization material in step (3) are set respectively. All treated samples were placed in 500 mL transparent bottles for storage experiments, stored at 5, 25 and 50 ° C for 2 months, and observed whether there was crystallization or precipitation at the bottom of the solution to investigate the stability of the experimental samples. The storage results are shown in Table 2 below.

[0075] Table 2 Storage conditions of samples with different treatments

[0076]

[0077] Note: In the table: "None" means no obvious crystallization or precipitation after 2 months of storage; "Yes in 1 week" means obvious crystallization or precipitation after 7 days of storage; "Yes in 2 weeks" means obvious crystallization or precipitation after 14 days of storage; "A small amount in 2 months" means a small amount of crystallization or precipitation after 2 months of storage.

[0078] It can be seen from the storage results in Table 2 above that no obvious crystallization or precipitation was observed in the suspended fertilizer samples A, B, and C with anti-crystallization materials added during the entire storage process under different temperature conditions; while the suspended fertilizer samples A1, B1, and C1 without anti-crystallization materials were obviously crystallized or precipitated during almost all temperature storage processes, indicating that the present invention effectively improves the stability of the prepared nano-suspended slow-release water-soluble fertilizer by adding anti-crystallization materials.

[0079] b. According to the preparation method of Example 3, suspension fertilizer treatments A (100 g of urea ammonium nitrate solution added in step (4)), B (150 g of urea ammonium nitrate solution added in step (4)), and C (200 g of urea ammonium nitrate solution added in step (4)) with different contents of urea ammonium nitrate solution were designed; and comparative treatments A1, B1, and C1 were set up in step (4) in which ordinary inhibitory material (nitrification inhibitor) was added instead of slow-release inhibitory material. The suspension fertilizer was packaged into 500 mL transparent bottles, and then a storage experiment was carried out. The suspension fertilizer was stored at 5, 25, and 50° C. for 2 months, and the bottom of the solution was observed to see whether there was crystallization or precipitation. The stability of the experimental samples was investigated. The storage results are shown in Table 3 below.

[0080] Table 3 Storage conditions of samples with different treatments

[0081]

[0082] Note: In the table: "None" means no obvious crystallization or precipitation after 2 months of storage; "Yes in 1 day" means obvious crystallization or precipitation after 1 day of storage; "Yes in 2 weeks" means obvious crystallization or precipitation after 14 days of storage; "A small amount in 2 months" means a small amount of crystallization or precipitation after 2 months of storage.

[0083] It can be seen from the storage results in Table 3 above that the suspended fertilizer samples A, B, and C prepared using the slow-release inhibitory material of the present invention showed no obvious crystallization or precipitation during the entire storage process; while the suspended fertilizer samples A1, B1, and C1 prepared using ordinary inhibitory materials showed obvious crystallization or precipitation during almost all temperature storage processes, indicating that the present invention effectively improves the stability of the prepared nano-suspended slow-release water-soluble fertilizer by adding a specific slow-release inhibitory material.

[0084] The changes in the content of the inhibitory materials in the suspended fertilizer samples of each treatment during storage were further tested according to national standards. The results are shown in Table 4.

[0085] After 2 months of storage, almost all the inhibitory materials were present in the suspended fertilizer samples A, B and C prepared with the slow-release inhibitory materials of the present invention, but less than 70% of the inhibitory materials were present in the suspended fertilizer samples A1, B1 and C1 treated with the common inhibitors.

[0086] Table 4 Changes in the content of inhibitory materials in suspended fertilizers

[0087]

[0088] (5) Sustained release test

[0089] a. Weigh 300g of air-dried soil and place them in 500ml reagent bottles. According to the ratio of 0.8gN / kg air-dried soil, add common urea, suspension fertilizer A (nano slow-release suspension fertilizer 1), B (nano slow-release suspension fertilizer 2), C (nano slow-release suspension fertilizer 3) prepared in stability test a, and common nitrogen, phosphorus and potassium liquid fertilizer (the same as the nitrogen, phosphorus and potassium of nano slow-release suspension fertilizer 1) into the reagent bottles. Add 1375g of water (equivalent to 60% of the field water holding capacity) to each reagent bottle, and then culture at 25°C for 60 days. Take samples at irregular intervals and use a continuous flow analyzer to determine the ammonium nitrogen content in the soil samples. During the test, weigh the test samples at irregular intervals and add water to keep the water content consistent with the treatment before the test. Each treatment was repeated three times, and the average value was finally taken. The results are as follows: Figure 4 As shown (where CK is soil without fertilizer, used as control).

[0090] from Figure 4It can be seen that after the application of ordinary urea, the ammonium nitrogen in the soil increases quickly and decreases quickly, and the slow release property is not reflected; although the ordinary water-soluble fertilizer increases and decreases more slowly than ordinary urea, compared with the nano slow-release suspended fertilizer of the present invention, it lacks the regulation of nitrogen release and conversion, and does not reflect the slow release property; and after the application of the nano slow-release suspended fertilizers with three different formulas, the ammonium nitrogen in the soil increases slowly, and a relatively high ammonium nitrogen content is maintained in the later stage, indicating that the regulation effect on nitrogen is better and the slow release property is stronger.

[0091] b. Weigh 300g of air-dried soil and place them in 500ml reagent bottles. Add 30% urea ammonium nitrate solution containing N (N1), common inhibitory material (nitrification inhibitor, the amount is the same as the slow-release inhibitory material in Example 3) + 30% urea ammonium nitrate solution containing N (N2), and the fertilizer prepared in Example 3 (N2) into the reagent bottles at a ratio of 0.8gN / kg air-dried soil. Add 1375g of water (equivalent to 60% of the field water holding capacity, and the water content in the urea ammonium nitrate solution is also taken into account) to each reagent bottle. Then, culture at 25°C for 60 days, take samples at irregular intervals, and use a continuous flow analyzer to determine the ammonium nitrogen content in the soil samples. During the test, weigh the test samples at irregular intervals and add water to keep the water content consistent with the treatment water content before the test. Each treatment was repeated three times, and the average value was finally taken. The results are as follows: Figure 5 As shown (where N0 is soil without fertilizer, used as control).

[0092] from Figure 5 It can be seen that after the application of UAN (N1) alone, the ammonium nitrogen in the soil increased quickly and decreased quickly, and did not reflect the slow release property; although the ordinary inhibitory material + urea ammonium nitrate solution (N2) increased and decreased more slowly than the single application, it lacked the regulation of nitrogen release and conversion compared with the fertilizer (N3) prepared in Example 3, and did not reflect the slow release property. After the fertilizer prepared in Example 3 was applied, the ammonium nitrogen in the soil increased slowly, and a relatively high ammonium nitrogen content was maintained in the later stage, indicating that the regulation effect of nitrogen was better and the slow release property was stronger.

[0093] (6) Field application test

[0094] Experimental purpose: To conduct a field fertilizer efficiency test on cabbage to test its field application effect;

[0095] Experimental location: Dahe Experimental Base of Hebei Academy of Agriculture and Forestry Sciences, Luquan Town, Shijiazhuang City, Hebei Province;

[0096] Experimental crop varieties: Cabbage, the variety is Dafendolak 1862;

[0097] Experiment 1: Nine experimental treatments were set up, each treatment was repeated three times, and the experimental plots were randomly arranged, with each repeated plot area of ​​40m 2,Protection rows were set up around the experimental area, and the treatment settings were as follows: different application rates of nitrogen fertilizer were set, and the application rates of phosphorus and potassium fertilizers were the same.

[0098] N0: no nitrogen fertilizer: control;

[0099] N1: customary nitrogen application rate, ordinary urea, 400N kg / hm 2 ;

[0100] N2: customary nitrogen application rate, ordinary NPK liquid fertilizer in slow-release test a of test example (5), 400N kg / hm 2 ;

[0101] N3: Optimized nitrogen application rate (100%), ordinary urea, 320N kg / hm 2 ;

[0102] N4: Optimized nitrogen application rate (100%), ordinary NPK liquid fertilizer in slow-release test a of test example (5), 320 Nkg / hm 2 ;

[0103] N5: Optimized nitrogen application rate (75%), nano slow-release suspended fertilizer 1,240 Nkg / hm2 in test example (5) slow-release test a 2 ;

[0104] N6: Optimized nitrogen application rate (75%), nano slow-release suspended fertilizer 2,240 Nkg / hm2 in slow-release test a of test example (5) 2 ;

[0105] N7: Optimized nitrogen application rate (50%), waste nano slow-release suspended fertilizer in test example (5) slow-release test a 1,160 Nkg / hm 2 ;

[0106] N8: Optimized nitrogen application rate (50%), nano slow-release suspended fertilizer in test example (5) slow-release test a 2,160 Nkg / hm 2 .

[0107] Except for the control group, all treatments were fertilized with nitrogen at the seedling stage, rosette stage, and heading stage. Ordinary nitrogen, phosphorus, and potassium liquid fertilizers and nano slow-release suspended fertilizers were applied by micro-sprinkler irrigation. The nano slow-release suspended fertilizer was diluted by the corresponding multiple according to the amount of nitrogen applied in the treatment. The cabbage was harvested and the yield was counted. Figure 6 shown.

[0108] from Figure 6(p<0.05%) The test results show that N6 (nano slow-release suspension fertilizer 2) still maintains the highest cabbage yield under the condition of 75% optimized nitrogen application. It is higher than the common nitrogen, phosphorus and potassium liquid fertilizers used to apply nitrogen, and more significantly higher than the common urea used to apply nitrogen. Although the N8 treatment has the same formula as the N6 treatment, the excessive reduction in nitrogen caused a certain degree of reduction in cabbage yield.

[0109] Experiment 2: Three experimental treatments were set up, each with three replicates. The experimental plots were randomly arranged, and the area of ​​each replicate plot was 40m 2 ,Protection rows were set up around the experimental area, and the treatment settings were as follows: different application rates of nitrogen fertilizer were set, and the application rates of phosphorus and potassium fertilizers were the same.

[0110] N0: no nitrogen fertilizer;

[0111] N1: customary nitrogen application rate, urea ammonium nitrate solution;

[0112] N2: Optimized nitrogen application rate (75%), common inhibitory material + urea ammonium nitrate solution in test example (5) slow-release test b;

[0113] N3: optimized nitrogen application rate (75%), fertilizer prepared in Example 3.

[0114] Except for the control group, nitrogen was applied to all treatments at the seedling stage, rosette stage, and heading stage by micro-sprinkler irrigation. Cabbages were harvested and their yields were counted. Figure 7 shown.

[0115] from Figure 7 (p<0.05%) The test results show that under the condition of optimized nitrogen application rate of 75%, the cabbage yield of N3 using the fertilizer prepared in Example 3 is still the highest, which is significantly higher than the urea ammonium nitrate solution with the usual nitrogen application rate of N1. The optimized nitrogen application rate of N2 common inhibitory material + urea ammonium nitrate solution is also 75%. Although the inhibitory material is combined, it may not be well coupled with nutrients, and the yield is not significantly increased compared with N1.

Claims

1. A nano-suspension slow-release water-soluble fertilizer, characterized in that: The preparation method of the water-soluble fertilizer comprises the following steps: (1) Pre-treating the discarded polymer biodegradable membrane material and causing a condensation reaction with an aldehyde substance under acidic conditions, adjusting the pH value of the liquid phase to neutral after the reaction, and adding a nitrogen-containing fertilizer; (2) adding a dispersant and then sodium carbonate under continuous stirring to obtain a solution A; (3) taking fatty alcohol polyoxyethylene ether and carboxymethyl cellulose to undergo cross-linking reaction under continuous stirring, and then adding liquid oil to obtain solution B; (4) adding solution A to solution B, adding water glass under continuous stirring, adjusting the pH of the solution to be close to neutral, adding an anti-crystallization material, stirring and then standing to obtain solution C; the anti-crystallization material is prepared as follows: paraffin wax and liquid oil are mixed, and then a paraffin wax emulsifier is added and stirred to prepare the solution; (5) After high shearing of solution C, an anti-skinning agent is added, and then a slow-release inhibitor material is added and mixed, and then high sheared again, added to the fertilizer and high sheared again to obtain the nano-suspended slow-release water-soluble fertilizer; the slow-release inhibitor material is obtained by combining a urease inhibitor and / or a nitrification inhibitor with montmorillonite after being complexed with polyamine.

2. The nano-suspension slow-release water-soluble fertilizer according to claim 1, characterized in that: The method for preparing the water-soluble fertilizer further comprises one or more of the following (1)-(8): (1) The polymer biodegradable film material is selected from one or more of poly (3-hydroxybutyrate-CO-3-hydroxyvalerate), polylactic acid, polyhydroxyalkanoic acid ester, adipic acid-terephthalic acid-butylene glycol ester copolymer, and polyvinyl alcohol; (2) The pretreatment includes: sorting, washing, drying and crushing the polymer biodegradable film material in sequence; (3) The nitrogen-containing fertilizer is selected from one or more of urea, monoammonium phosphate, and diammonium phosphate; (4) In step (2), the dispersant is selected from one or more of sodium dibutylnaphthalene sulfonate, sodium dodecylbenzene sulfonate, secondary alkyl ammonium sulfate, and pentadecylsulfonyl chloride; (5) The preparation method of the anti-crystallization material is as follows: after mixing 100-145g of paraffin wax with 75-200g of liquid oil, 140-300g of paraffin wax emulsifier is added and stirred evenly; (6) The preparation method of the sustained-release inhibitor material is as follows: 10-50 g of urease inhibitor and / or nitrification inhibitor is added to 40-200 g of polylactic acid and stirred at 20-50° C., and then 25-50 g of montmorillonite is added and high sheared until uniform; (7) the anti-skinning agent is selected from butanone oxime, silicon dioxide, aniline or azobenzene; (8) In step (5), solution C is subjected to high shearing at 10,000-30,000 rpm for 10-25 min, and then the anti-skinning agent and the slow-release inhibitor are added and stirred at 25-50° C. After the solution is clarified, the fertilizer is added at high shearing at 10,000-20,000 rpm for 10-25 min, and after mixing, the solution is subjected to high shearing at 10,000-20,000 rpm for 10-20 min.

3. The nano-suspension slow-release water-soluble fertilizer according to claim 2, characterized in that: Includes one or both of the following (1)-(2): (1) The drying temperature in the pretreatment is 40 to 80° C., and the particle size is crushed to less than 5.0 mm; (2) The liquid oil is selected from soybean oil or diesel.

4. The nano-suspension slow-release water-soluble fertilizer according to any one of claims 1 to 3, characterized in that: The preparation method of the water-soluble fertilizer comprises the following steps: (1) adding 75-120 g of pretreated polymer biodegradable film material to 500 ml-1000 ml of water at a temperature greater than 85° C. and heating the water under constant stirring until dissolved; adjusting the solution to a pH of 2-5 with sulfuric acid, adding 15-45 ml of formaldehyde after the water temperature drops to 40-60° C., controlling the solution temperature to 60-80° C., stirring for 30-60 min, then adding 10-60 ml of formaldehyde, and adjusting the solution pH to 6-8 with KOH; then adding 150-450 g of nitrogen-containing fertilizer dissolved in 20-60 g of water at 25-50° C. under constant stirring; (2) adding 2-8 g of dispersant and 30-50 ml of sodium carbonate in sequence under continuous stirring, stirring and standing to obtain solution A; (3) adding 5-15 g of carboxymethyl cellulose powder to 45-65 ml of water to obtain a carboxymethyl cellulose solution; weighing 15-45 g of fatty alcohol polyoxyethylene ether and adding it to 100-220 ml of water, stirring at 50° C., then adding the carboxymethyl cellulose solution and stirring evenly, then adding 30-55 g of liquid oil and stirring evenly, adding water to 500-700 ml, continuing to stir and standing to obtain a solution B; (4) adding solution A accounting for 5-20% of the weight of solution B to solution B, adding 50-120 ml of water glass with a mass percentage concentration of 10%-22% under continuous stirring, and adjusting the pH of the solution to 6.5-7.5 with dilute HCl; taking 500-650 g of the solution after standing, adding 55-220 g of anti-crystallization material, stirring and standing to obtain solution C; the preparation method of the anti-crystallization material is as follows: after mixing 30-105 g of paraffin and 55-200 g of liquid oil, adding 120-260 g of paraffin emulsifier and stirring evenly; (5) Place solution C in a high-speed shearing device and high-shear for 10 to 25 minutes at 10,000 to 30,000 rpm, add an anti-skinning agent accounting for 0.01% to 0.11% of the volume of solution C, and then add 7 to 20 g of a slow-release inhibitor and stir for 30 minutes, while maintaining the system temperature at 25 to 50° C.; after the solution is clarified, high-shear for 10 to 25 minutes at 10,000 to 20,000 rpm, then reduce the speed to 120 rpm and maintain continuous stirring at 25 to 50° C., while stirring, add 0.5% to 10% of the fertilizer weight. % is added to the fertilizer, mixed and stirred evenly, then cooled to 30-40°C, the rotation speed is increased to 10000-20000rpm again and high sheared for 15-20min, and after the solution is clarified, it is allowed to stand for 6-24 hours to prepare the nano-suspension slow-release water-soluble fertilizer; the preparation method of the slow-release inhibitor material is as follows: 100g of polylactic acid is heated to 20-50°C and stirred to dissolve evenly, 10-50g of urease inhibitor and / or nitrification inhibitor are added in portions, and after stirring, 25-50g of montmorillonite and 20g of water are added and high sheared until uniform.

5. The nano-suspension slow-release water-soluble fertilizer according to claim 4, characterized in that: The fertilizer in step (5) is a compound fertilizer consisting of 0.5-3.5 kg of water, 2.0-7.5 kg of urea, 1.1-5.5 kg of diammonium phosphate and 1.1-5.8 kg of potassium sulfate.

6. The nano-suspension slow-release water-soluble fertilizer according to claim 4, characterized in that: The fertilizer in step (5) is a urea ammonium nitrate solution containing 28-35% nitrogen.

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