Fertilizer additive, preparation method thereof and granular fertilizer

Abstract

The invention provides a fertilizer additive and a preparation method thereof, and a granular fertilizer, the fertilizer additive comprises the following components by weight: 92-95 parts of modified furfural residue; 5-8 parts of a filler; 3 to 6 parts of a synergistic agent; wherein the modified furfural residue is obtained by forming polydopamine on the surface of the furfural residue through dopamine in-situ polymerization under a weakly alkaline condition. The granular fertilizer prepared by adding the fertilizer additive disclosed by the invention has the advantages that the forming rate is obviously improved to 93% or above, the granular strength reaches 30N or above, the granular structure is firm, the surface is smooth, and the fertilizer additive is suitable for mechanical fertilization. According to the technology, resource utilization of the industrial waste furfural residue is achieved, nutrient leaching loss is effectively reduced through the specific adsorption and slow release functions of the furfural residue, and the fertilizer utilization rate is increased. The comprehensive effects of improving the soil structure and enhancing the water and fertilizer retention capability are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fertilizers, in particular to a fertilizer additive, a preparation method thereof and a granular fertilizer. BACKGROUND

[0002] The large-scale use of fertilizers has significantly improved crop yields and made important contributions to global agricultural development. However, long-term overuse of chemical fertilizers has also caused many problems, including a decrease in soil organic matter, an imbalance in nutrient ratios, soil acidification and compaction, and the destruction of microbial communities, which has led to weakened soil water and nutrient retention capacity and poor soil aeration, making it difficult to meet the normal growth needs of crops. At the same time, over-reliance on chemical fertilizers has resulted in excessive residues of harmful substances such as nitrite in agricultural products, and heavy metal elements carried by some fertilizers accumulate in the soil and enter the food chain through crops, threatening human health. In addition, a large amount of unabsorbed nutrients enter the environment with drainage, causing nitrate, phosphate and organic chloride pollution, and exacerbating the eutrophication of rivers and lakes.

[0003] Granular fertilizers are currently widely used due to their convenience of application and stable nutrient release. However, with the increasing popularity of mechanized fertilization, there are higher requirements for granulation of fertilizers, and new requirements for particle strength, use effect, and other aspects of fertilizers.

[0004] Furfural residue, as a cheap industrial waste, is rich in cellulose and lignin. During the granulation process of fertilizer raw materials, due to the extremely low viscosity of furfural residue and the density of furfural residue being much lower than that of conventional fertilizer raw materials, it is difficult to effectively combine after mixing with fertilizer raw materials, resulting in low molding rate, poor particle strength, and easy fragmentation during storage and transportation. To improve the molding property, a binder (such as attapulgite, bentonite) needs to be added, but the dosage control is difficult. If the amount of binder is too small, the cohesion cannot be improved and the molding rate cannot be improved; if the amount of binder is too large, the particle hardness will increase, leading to compaction, and the effective components of the fertilizer may be diluted, and even the soil aeration may be affected.

[0005] Therefore, under the premise of ensuring the steady improvement of agricultural productivity, it is an urgent need to develop new fertilizers with good molding property, high particle strength, excellent slow-release performance, and environmental friendliness, in order to promote the sustainable development of agriculture.

[0006] Therefore, the present application is proposed to solve the above technical problems. SUMMARY

[0007] The present application aims to provide a fertilizer additive, a preparation method thereof and a granular fertilizer. By adding the granular fertilizer additive of the present application to the granular fertilizer, the molding rate of the fertilizer particles, the strength of the fertilizer particles, and the soil structure and fertility can be improved.

[0008] The present application provides a kind of fertilizer additive, the additive includes the following weight parts components:

[0009] Modified furfural residue 92~95 parts

[0010] Filler: 5~8 parts

[0011] Synergist: 3~6 parts

[0012] Among them, the modified furfural residue is formed by dopamine in-situ polymerization on furfural residue under weak alkaline conditions to obtain polydopamine.

[0013] According to the additive of the present application, wherein the synergist includes one or several of bacterial cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, nanocellulose.

[0014] According to the additive of the present application, wherein the filler is one or several of kaolin, diatomite, talcum powder.

[0015] According to the additive of the present application, wherein the furfural residue is furfural residue after neutralization with alkaline solution.

[0016] The present application also provides a preparation method of the fertilizer additive, which comprises the step of mixing the components of the additive.

[0017] The present application also provides a granular fertilizer, which comprises the additive according to the present application, preferably, the amount of the fertilizer additive powder added is 5% based on the total weight of the granular fertilizer.

[0018] The granular fertilizer according to the present application comprises one or several of phosphorus fertilizer, nitrogen fertilizer, potassium fertilizer, compound fertilizer.

[0019] The present application has the following beneficial effects:

[0020] The fertilizer additive provided by the present application significantly improves the physical properties and agronomic benefits of fertilizer granules by using polydopamine modified furfural residue and compounding specific filler with cellulose-based synergist. The additive effectively solves the problem of low adhesion and difficult forming of furfural residue itself, and the forming rate of fertilizer granules is increased to more than 93%, the particle strength is more than 30N, the particle structure is solid and the surface is smooth, which greatly improves the mechanical processing property and storage stability of the fertilizer.

[0021] The additive has the dual advantages of environmental friendliness and high efficiency. It uses cheap industrial waste furfural residue as the main raw material, realizes waste resource utilization, reduces nutrient leaching through its unique adsorption and slow-release effect, and improves fertilizer utilization rate. Field tests have confirmed that the fertilizer with the additive can increase potato yield by about 30%, and the modified furfural residue in the additive itself is rich in organic matter (cellulose, lignin) and active substances (such as humic acid), which can improve the soil aggregate structure, and enhance the water and fertilizer retention capacity and air permeability of the soil. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] The present application provides a kind of fertilizer additive, comprising the following weight parts components: modified furfural residue 92~95 parts, filler: 5~8 parts, synergist: 3~6 parts

[0024] The polydopamine modified furfural residue is obtained by in-situ polymerization of dopamine on furfural residue under weak alkaline conditions. As an industrial by-product, furfural residue needs to be pretreated by alkali neutralization to eliminate its strong acidity before being applied in fertilizer. The present application does not have special requirements for alkali neutralization, and the neutralized furfural residue is preferably furfural residue neutralized by sodium hydroxide, potassium hydroxide or ammonia. The organic matter such as lignin and cellulose contained in the neutralized furfural residue can significantly improve the soil aggregate structure and enhance the water and fertilizer retention capacity. It can also be used as a carrier and nutrient release material to improve the fertilizer efficiency. What is particularly important is that the specific surface area is significantly increased after alkali neutralization, providing a large number of active sites for adsorption. In addition, the active substances such as humic acid contained in it are fully activated and retained. These substances can stimulate crop growth, integrate soil trace elements and inhibit soil-borne diseases.

[0025] The present application does not have special requirements for the preparation of the polydopamine modified furfural residue. Those skilled in the art know that the method of in-situ polymerization of dopamine on the surface of furfural residue under weak alkaline conditions can be used to form polydopamine. Specifically, furfural residue (passed through a 100-mesh sieve) can be dispersed in Tris-HCl buffer (15 mmol / L) with a solid-liquid ratio of 1:10 at pH 8.8, and dopamine can be added to a concentration of 2 mg / mL. Shake the bed for 16 hours to achieve in-situ polymerization. Finally, the modified furfural residue is obtained by filtration, washing and drying.

[0026] The modified furfural residue can introduce or expose a large number of functional groups such as carboxyl (-COOH), hydroxyl (-OH), amino (-NH2) and the like on its surface, and the adhesion and reactivity are enhanced, so that the modified furfural residue can better wrap the fertilizer particles or be combined with other raw materials. These functional groups can be strongly chemically combined with heavy metal ions (such as Pb2+, Cd2+) through ionic exchange, complexation, hydrogen bonding and the like, so as to reduce the absorption of crops to heavy metals. In an acidic or neutral condition, the -NH3 + group is easily protonated, while the nitrate (NO3 - ) is a negatively charged anion, and the two can be combined through electrostatic attraction, so as to reduce the leaching loss, improve the fertilizer utilization rate, and reduce the environmental pollution caused by the leaching loss.

[0027] According to the additive of the present application, the filler is one or more of kaolin, diatomite and talcum powder. The filler can be filled in the voids of the fiber structure of the modified furfural residue, so that the particle gradation of the mixture is more reasonable, the friction is reduced, the flowability of the additive is improved, and the uniformity of the mixture with the fertilizer raw material is improved. The mineral particles themselves have a certain hardness and strength, and are dispersed in the viscous network formed by the modified furfural residue to enhance the skeleton, thereby improving the mechanical strength and the crushing resistance of the final fertilizer particles.

[0028] According to the additive of the present application, the synergistic agent comprises one or more of bacterial cellulose, carboxymethyl cellulose, hydroxymethyl cellulose and nanocellulose. The bacterial cellulose, carboxymethyl cellulose, hydroxymethyl cellulose and nanocellulose can be tightly combined with the modified furfural residue through intermolecular forces such as hydrogen bonding, and form a fiber reinforced network on the basis of the bonding network, and interweave and penetrate each other, thereby greatly improving the mechanical strength and toughness of the overall structure. The network structure of the cellulose can better wrap and fix the filler particles, prevent the filler particles from falling off or unevenly distributing, and make the skeleton more stable. The addition of the cellulose can further fill the small gaps between the modified furfural residue and the filler, further improve the mechanical strength of the particles, and also help to slow down the invasion of water and the release speed of nutrients, and enhance the slow-release effect.

[0029] The present application also provides a preparation method of the fertilizer additive according to the present application, which comprises the step of mixing the components of the additive. Specifically, the components can be mixed in the form of an aqueous solution or in the form of a solid. When the components are mixed in the form of an aqueous solution, the fertilizer additive is convenient to transport and can be conveniently and uniformly added to a granulation system.

[0030] The present application also provides a granular fertilizer comprising the additive according to the present application, wherein the additive is added in an amount of 3-10%, preferably 5%, so as to significantly improve the strength and the forming rate of the fertilizer particles, and enhance the slow-release and fertilizer retention functions.

[0031] The granular fertilizer according to the present application comprises one or several of phosphorus fertilizer, nitrogen fertilizer, potassium fertilizer, compound fertilizer.

[0032] Specifically, the fertilizer additive can be added in the granulation process of the granular fertilizer, for example, the fertilizer additive can be added when granulation is performed in a disc granulator, a rotary drum granulator, or a melt tank of a tower granulator.

[0033] Example 1

[0034] The fertilizer additive comprises the following components in weight ratio: modified furfural residue 95 parts, kaolin 5 parts, bacterial cellulose 3 parts.

[0035] Example 2

[0036] The fertilizer additive comprises the following components in weight ratio: modified furfural residue 92 parts, diatomite 8 parts, bacterial cellulose 6 parts.

[0037] Example 3

[0038] The fertilizer additive comprises the following components in weight ratio: modified furfural residue 92 parts, talc 8 parts, carboxymethyl cellulose 5 parts.

[0039] Example 4

[0040] The fertilizer additive comprises the following components in weight ratio: modified furfural residue 92 parts, diatomite 4 parts, kaolin 4 parts, hydroxymethyl cellulose 5 parts.

[0041] Comparative Example 1

[0042] The fertilizer additive comprises the following components in weight ratio: furfural residue 92 parts, diatomite 8 parts, bacterial cellulose 6 parts.

[0043] Comparative Example 2

[0044] The fertilizer additive comprises the following components in weight ratio: modified furfural residue 92 parts, diatomite 8 parts.

[0045] Comparative Example 3

[0046] The fertilizer additive comprises the following components in weight ratio: modified furfural residue 92 parts, bacterial cellulose 6 parts.

[0047] Example 5

[0048] The fertilizer additive 2.5 kg prepared in Examples 1-4 and Comparative Examples 1-3 was mixed with urea 22 kg, ammonium dihydrogen phosphate 12 kg, and potassium chloride 13.5 kg, respectively, to granulate, and the obtained mixture was sieved and dried at a temperature of 105°C to obtain a granular fertilizer. The granular fertilizers manufactured in the above examples and comparative examples were analyzed and compared in terms of main performance indicators, and the granular appearance, yield of raw materials, and compression strength were observed, and the determination of each indicator of the granular fertilizer is shown in Table 1 below,

[0049] Table 1

[0050] Granular fertilizer Granular appearance Yield (%) Granular strength (N) Example 1 Granules were full and smooth 95.1 32 Example 2 Granules were full and smooth 94.2 31 Example 3 Granules were full and smooth 93.9 30 Example 4 Granules were full and smooth 93.6 31 Comparative Example 1 Granules were irregular and rough 65.5 12 Comparative Example 2 Granules were irregular and rough 71.4 15 Comparative Example 3 Granules were irregular and rough 72.6 18

[0051] As can be seen from Table 1, the granular fertilizer prepared by adding the fertilizer additive of Examples 1-4 of the present application compared with Comparative Examples 1-3 has a full appearance and a smooth surface, and the yield is significantly improved to more than 93%, and the granular strength reaches more than 30N. Therefore, the addition of the fertilizer additive of the present application in the granular fertilizer can effectively improve the forming rate and strength of the granules, and improve the machinability and storage stability of the fertilizer.

[0052] Example 6

[0053] The granular nitrogen-phosphorus-potassium compound fertilizer containing the fertilizer additive obtained in Example 5 was applied in a potato field, and the yield of potatoes was counted, and the results are shown in Table 2.

[0054] The test used a randomized block design with three repetitions, and the plot length was 10 m and the width was 10 m. Ten rows were planted with a row spacing of 85 cm and a plant spacing of 25 cm. The application amount of the compound fertilizer granules was 0.25 kg / m 2 , and the control group applied nitrogen-phosphorus-potassium compound fertilizer with an application amount of 0.25 kg / m 2 . The sowing date was December 10, 2024, and the harvest date was May 10, 2025.

[0055] Table 2

[0056] Granular fertilizer Average stem diameter (cm) Average plant height (cm) Average tuber weight per plant (kg) Yield (kg) Example 1 1.41 52.6 0.65 400 Example 2 1.42 53.2 0.64 398 Example 3 1.38 52.9 0.62 402 Example 4 1.39 52.8 0.64 397 Comparative Example 1 1.14 40.7 0.40 342 Comparative Example 2 1.23 41.2 0.39 328 Comparative Example 3 1.26 43.9 0.50 362 Control group 0.97 37.1 0.28 300

[0057] As can be seen from Table 2, the granular fertilizer prepared by adding the fertilizer additive of Examples 1-4 of the present application compared with Comparative Examples 1-3 and the control group has a full appearance and a smooth surface, and the yield is significantly improved to more than 93%, and the granular strength reaches more than 30N. Therefore, the addition of the fertilizer additive of the present application in the granular fertilizer can effectively improve the forming rate and strength of the granules, and improve the machinability and storage stability of the fertilizer.

[0058] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A fertilizer additive, characterized in that, The additive comprises the following components by weight: Modified furfural residue 92~95 parts Filler: 5~8 parts Synergist: 3~6 parts The modified furfural residue is obtained by in-situ polymerization of dopamine on furfural residue under weak alkaline conditions to form polydopamine.

2. The additive of claim 1, wherein The synergist comprises one or several of bacterial cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, and nanocellulose.

3. The additive of claim 1, wherein The filler is one or several of kaolin, diatomite, and talcum powder.

4. The additive of claim 1, wherein The furfural residue is furfural residue neutralized with an alkaline solution.

5. A method of producing the additive according to any one of claims 1 to 4, characterized in that, The method comprises the step of mixing the components of the additive.

6. A granular fertilizer, characterized in that, The additive according to any one of claims 1-4.

7. The granular fertilizer of claim 6, wherein, The additive is added in an amount of 5% based on the total weight of the granular fertilizer.

8. The granular fertilizer of claim 6, wherein, The granular fertilizer comprises one or several of phosphorus fertilizer, nitrogen fertilizer, potassium fertilizer, and compound fertilizer.