Fertilizer composition and preparation method thereof

Abstract

The invention provides a preparation method of a fertilizer composition and the fertilizer composition prepared by the preparation method. The preparation method of the fertilizer composition comprises the following steps: carrying out cross-linking reaction on cellulose and a cross-linking agent to obtain a polymer; the polymer is added into a plant fertilizer aqueous solution, and after mixing and drying, the fertilizer composition is obtained. The fertilizer composition provided by the invention has high water absorption capacity and contains nutrient substances of cotton plants. When the fertilizer disclosed by the invention is mixed with soil, under a drought condition, water-soluble nutrient substances and water can be released at the same time to provide water and nutrients for plants such as cotton, so that the yield and the quality of the cotton are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of agricultural planting, and particularly relates to a fertilizer composition and a preparation method thereof. BACKGROUND

[0002] Cotton is one of the most demanded natural fibers in the textile industry, and cotton production has become a part of our daily life. However, the cultivation, processing and production waste of cotton have a negative impact on the environment. Cotton requires a large amount of water and nutrients to grow during cultivation. According to an article by "Cotton Incorporated", the water requirement of cotton varies during the season, with the highest water requirement of cotton being about 0.28 inches per day during the middle of the season. The total cotton used to grow a t-shirt requires 157 gallons of water.

[0003] Nutrients are an important source for plants to achieve maximum cotton yield, and a lack of nutrients can reduce cotton yield. The three main nutrients for cultivation are nitrogen (N), phosphorus (P) and potassium (K). They all constitute three fertilizers known as NPK, which are key fertilizers used in cotton production. Other essential nutrients include copper, boron, calcium, magnesium, iron, zinc, cobalt and molybdenum.

[0004] Developing a fertilizer that can simultaneously provide water and nutrients required for cotton growth is expected to improve the yield and quality of cotton. SUMMARY

[0005] The present application provides a preparation method of a fertilizer composition and a fertilizer prepared by the method.

[0006] In one aspect, the present application provides a preparation method of a fertilizer composition, comprising: cross-linking cellulose with a cross-linking agent to obtain a polymer; adding the polymer to an aqueous solution of plant fertilizer, and obtaining the fertilizer composition after mixing and drying.

[0007] In some embodiments of the present application, the cellulose is recovered from textile waste, and the recovery step comprises: dispersing cotton-containing textile waste in an aqueous solution system of an organic acid catalyst to obtain a mixed system, the mass content of the organic acid catalyst in the aqueous solution system being 0.1%-30%; heating the mixed system to 110-180℃, and reacting for 0.5-3h under an autogenous pressure of 0.1 to 10 MPa to obtain the cellulose.

[0008] In some embodiments of the present application, the organic acid catalyst is one or more of methanesulfonic acid, oxalic acid, tartaric acid, citric acid, malic acid, formic acid and acetic acid.

[0009] In some embodiments of the present application, the cross-linking reaction step of the cellulose with the cross-linking agent comprises: dissolving cellulose powder, alkali metal hydroxide, and urea in water, then adding the cross-linking agent to form a cross-linking aqueous solution, and reacting the cross-linking aqueous solution at 40-50°C for 2-3 hours; wherein the volume concentration of the cross-linking agent in the cross-linking aqueous solution is 3%-30%, and the mass concentration of cellulose in the cross-linking aqueous solution is 0.1%-5%.

[0010] In some embodiments of the present application, the cross-linking agent is epichlorohydrin, ethylene glycol diglycidyl ether, or a combination thereof.

[0011] In some embodiments of the present application, the mass concentrations of sodium hydroxide and urea in the cross-linking aqueous solution are 1-10% and 0.1-10%, respectively.

[0012] In some embodiments of the present application, the plant fertilizer accounts for 5%-25% of the mass percentage of the fertilizer composition.

[0013] In some embodiments of the present application, the plant fertilizer is a fertilizer that can be dissolved in water.

[0014] In some embodiments of the present application, the fertilizer comprises 20%-40% total nitrogen, 10%-20% water-soluble phosphorus, and 10%-20% water-soluble potassium; or the fertilizer is one or more of zinc sulfate, ferrous sulfate, and magnesium sulfate.

[0015] In some embodiments of the present application, the preparation method further comprises grinding the fertilizer composition into particles with a particle size of 100-700 μm.

[0016] Another aspect of the present application provides a fertilizer composition prepared by the above preparation method.

[0017] The fertilizer composition of the present application has high water absorption capacity and contains nutrients for cotton plants. When the fertilizer of the present application is mixed with soil, under drought conditions, water-soluble nutrients are released simultaneously with water to provide water and nutrients for plants such as cotton, thereby improving the yield and quality of cotton. Further, the cellulose of the fertilizer composition of the present application is derived from cellulose obtained by degradation of textile waste, is environmentally friendly, and is degradable in soil without polluting the environment. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other features and advantages of the present application will become more apparent by describing in detail its example embodiments with reference to the attached drawings.

[0019] Figure 1 is a flowchart of a process for preparing the fertilizer composition of the present application using recycled cellulose.

[0020] Figure 2 is a schematic diagram of the fertilizer composition of the present application.

[0021] Figure 3 is a photograph of the polymer (SAP) prepared in Example 1, the fertilizer composition containing commercial fertilizer (NPK-SAP), and the polymer after the fertilizer was released.

[0022] Figure 4 is a FTIR analysis chart of the polymer (SAP) prepared in Example 1, the fertilizer composition containing commercial fertilizer (NPK-SAP), and the polymer after the fertilizer was released.

[0023] Figure 5 is the content of nutrients in the fertilizer composition prepared in Example 2 analyzed by ICP-OES / ICP-MS. DETAILED DESCRIPTION

[0024] The technical solutions of the present application are further described below according to specific examples. The protection scope of the present application is not limited to the following examples, and these examples are listed only for illustrative purposes and do not limit the present application in any way.

[0025] The scope of the present application is not limited to any specific embodiment described herein. The following examples are only for illustration.

[0026] The preparation method of the fertilizer composition of the present application comprises: cross-linking reaction of cellulose and cross-linking agent to obtain a polymer; adding the polymer into an aqueous solution of plant fertilizer, and obtaining the fertilizer composition after mixing and drying.

[0027] In some embodiments, the cellulose can be recovered from textile waste. When the cellulose is recovered from textile waste, a schematic diagram of an embodiment of the preparation method of the fertilizer composition of the present application is shown in Figure 1 The step of recovering cellulose from textile waste can include: dispersing cotton-containing textile waste in an aqueous solution system of an organic acid catalyst to obtain a mixed system, the mass content of the organic acid catalyst in the aqueous solution system being 0.1%-30%; heating the mixed system to 110-180°C, and obtaining cellulose after reacting for 0.5-3h under an autogenous pressure of 0.1 to 10 MPa.

[0028] Cotton textile waste can be natural, semi-synthetic, and / or synthetic cellulose or natural cellulose materials. Semi-synthetic cellulose materials include viscose, cuprammonium, polysilicic acid, lyocell, and cellulose acetate, etc. Cotton textile waste is treated with organic acid-catalyzed hydrothermal processes to obtain cellulose powder. The temperature, pressure, and reaction time during the hydrothermal treatment process can be selected according to the type and content of each component in the waste. For example, but not limited to, temperatures of 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, etc.; correspondingly, the autogenous pressure may be 0.1MPa, 1MPa, 3MPa, 5MPa, 7MPa, 9MPa, 10MPa, etc.; and correspondingly, the reaction time may be 0.5h, 1h, 2h, 3h, etc.

[0029] The organic acid catalyst used in hydrothermal treatment can be any suitable organic acid catalyst. For example, but not limited to one or more of methanesulfonic acid, oxalic acid, tartaric acid, citric acid, malic acid, formic acid, and acetic acid.

[0030] In some embodiments, the crosslinking reaction of cellulose with the crosslinking agent includes: dissolving cellulose powder, alkali metal hydroxide, and urea in water, then adding the crosslinking agent to form a crosslinking aqueous solution, and reacting the crosslinking aqueous solution at 40 to 50°C for 2 to 3 hours; wherein the volume concentration of the crosslinking agent in the crosslinking aqueous solution is 3%-30%, and the mass concentration of cellulose in the crosslinking aqueous solution is 0.1%-5%.

[0031] The crosslinking agent can be epichlorohydrin, ethylene glycol diglycidyl ether, or a combination thereof. The crosslinking agent crosslinks with cellulose to form a polymer with a network structure. Because each D-glucose unit of cellulose contains three hydroxyl groups, the polymer can absorb a large amount of liquid relative to its own mass, but is insoluble in water. When water is added to the polymer, it enters the polymer network due to osmotic pressure. The crosslinking between molecular chains prevents the polymer from dissolving in water, but forms a swollen gel that retains moisture even under external pressure.

[0032] In some embodiments of the present invention, the mass concentrations of sodium hydroxide and urea in the crosslinked aqueous solution are 1-10% and 0.1-10%, respectively. Those skilled in the art can select the mass concentrations of sodium hydroxide and urea in the crosslinked aqueous solution according to actual needs. For example, but not limited to, the mass concentration of sodium hydroxide is 1%, 3%, 5%, 7%, 9%, 10%, etc.; the mass concentration of urea is 0.1%, 1%, 3%, 5%, 7%, 9%, 10%, etc.

[0033] In some embodiments of the present invention, after crosslinking to form a polymer, a water washing step may be included. Water washing removes byproducts generated during the crosslinking reaction. Specifically, the water washing process may involve cutting the solidified mixture into small cubic pieces for washing after the crosslinking reaction is complete. The cubic pieces are immersed in water, with the water changed every 2 to 3 hours, until the water conductivity remains at approximately 200 to 300 (μS / cm).

[0034] Before washing, the cross-linked polymer can be cut to facilitate subsequent washing and fertilizer adsorption. Of course, the invention can also achieve its objective without the cutting step.

[0035] Finally, the resulting polymer is mixed with an aqueous solution of plant fertilizer. The polymer has high water absorption, and this process adsorbs both the plant fertilizer and water into the polymer. After drying to remove the moisture, the plant fertilizer remains in the polymer, forming a fertilizer composition.

[0036] In some embodiments, the plant fertilizer can be a water-soluble fertilizer. The fertilizer can be a commercial fertilizer containing 20%-40% total nitrogen, 10%-20% water-soluble phosphorus, and 10%-20% water-soluble potassium. It can also be one or more of zinc sulfate, ferrous sulfate, and magnesium sulfate.

[0037] In some embodiments, the fertilizer composition is further ground into particles with a particle size of 100 μm to 700 μm.

[0038] Figure 2 The diagram illustrates the formation and use process of the fertilizer composition of the present invention. Figure 2 Taking epichlorohydrin as an example of a crosslinking agent, the crosslinking agent used to form the polymer can, of course, be any other suitable crosslinking agent. As shown in the figure, the fertilizer composition of this invention is first obtained by compounding plant fertilizer with the polymer as described above. In use, it first absorbs water to form a complex rich in water and fertilizer. After being applied to the soil, under drought conditions, water-soluble nutrients are released simultaneously with the water to provide water and nutrients to the plants.

[0039] Example 1: Synthesizing a fertilizer composition using commercial fertilizers

[0040] Add 1750g sodium hydroxide, 750g urea, 1250g regenerated cellulose powder, and 1650ml deionized water to a 40L reactor. Stir the mixture for 1 hour and freeze to -15°C. Allow all the cellulose to dissolve in the aqueous solution at -15°C. When the aqueous solution reaches room temperature, add the crosslinking agent epichlorohydrin and stir for 30 minutes. Pour the mixture into a stainless steel tray and place it in a 40°C oven for the crosslinking reaction.

[0041] Once the reaction is complete, the mixture solidifies, is cut into small cubes, and washed with water until the conductivity of the water remains below 300 μS / cm. The washed polymer is then dried at 90°C for 4 hours.

[0042] 1g of commercial fertilizer was added to a 1000mL water bath and thoroughly mixed to prepare a target nutrient water bath. The commercial fertilizer contained 30.0% total nitrogen, 10.1% water-soluble phosphorus, and 10.1% potassium. The dried polymer was then placed in the target nutrient water bath (the mass ratio of polymer to target nutrient water bath was approximately 1:100) for 1 hour. During this process, the nutrients were absorbed by the polymer. The polymer containing the nutrients was then dried at 90°C until completely dry and ground to a particle size of 100μm to 700μm using a centrifugal mill.

[0043] Figure 3 The images show photographs of the polymer (SAP) before formation of the fertilizer composition prepared in this embodiment, the formed fertilizer composition (NPK-SAP), and the polymer after fertilizer release. The photographs show changes in both volume and color of the formed fertilizer composition (NPK-SAP) compared to the polymer (SAP) before fertilizer absorption, demonstrating that the method of this invention can load fertilizer into the polymer formed by cellulose crosslinking. Figure 3 As can be seen, the fertilizer composition (NPK-SAP) becomes smaller and lighter in color after releasing fertilizer, indicating that the fertilizer composition obtained by the method of the present invention can release fertilizer from the composition to provide nutrients for plants.

[0044] The FSC and CRC of the nutrient-containing SAP were measured using ISO (17190-5:2001) and EDANA (ERT 441.2-02) test methods. The FSC and CRC measurement results indicate that the water absorption capacity of the SAP did not decrease significantly after the addition of nutrients.

[0045] Nutrient concentrations were measured using ICP-OES / ICP-MS according to the EN16711-1-2015 test method. The ICP-OES / ICP-MS test results indicate that the nutrient concentrations in the SAP are considerable.

[0046] Example 2: Synthetic fertilizer composition using magnesium sulfate, zinc sulfate and ferrous sulfate as fertilizers

[0047] 1750g sodium hydroxide, 750g urea, 1250g regenerated cellulose powder, and 1650ml deionized water were added to a 40L reactor. The mixture was stirred for 1 hour and then frozen to -15°C. This allowed all the cellulose to dissolve in the aqueous solution at -15°C. When the aqueous solution reached room temperature, the cross-linking agent epichlorohydrin was added, and the mixture was stirred for 30 minutes. The mixture was then poured into a stainless steel tray and placed in a 40°C oven for further reaction.

[0048] Once the reaction is complete, the mixture solidifies, is cut into small cubes, and washed with water until the conductivity of the water remains below 300 μS / cm. The washed polymer is then dried at 90°C for 4 hours.

[0049] A target nutrient water bath was prepared by adding 21.38 g of zinc sulfate, 14.64 g of ferrous(II) sulfate, and 20 g of magnesium sulfate to 2 L of deionized water. 400 g of the dried polymer was placed in the target nutrient water bath, allowing the nutrient-containing water to be absorbed into the polymer. The nutrient-containing polymer was dried at 90°C until completely dry, and then ground to a particle size of 100 μm to 700 μm using a centrifugal mill.

[0050] The FSC and CRC of the nutrient-containing SAP were measured using ISO (17190-5:2001) and EDANA (ERT 441.2-02) test methods. The FSC and CRC measurement results indicate that the water absorption capacity of the SAP did not decrease significantly after the addition of nutrients.

[0051] Nutrient concentrations were measured using ICP-OES / ICP-MS according to the test method EN16711-1-2015. Figure 5 The measurement results are shown. The ICO-OES / ICP-MS test results indicate that the nutrient concentration in SAP is considerable.

[0052] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a fertilizer composition, comprising: A polymer is obtained by cross-linking cellulose with a cross-linking agent; The polymer was added to an aqueous solution of plant fertilizer, and after mixing and drying, the fertilizer composition was obtained.

2. The preparation method according to claim 1, wherein the cellulose is recovered from textile waste, and the recovery step includes: A mixed system is obtained by dispersing cotton textile waste in an aqueous solution of an organic acid catalyst, wherein the mass content of the organic acid catalyst in the aqueous solution is 0.1%-30%. The mixture is heated to 110-180°C and reacted for 0.5-3 hours under an autogenous pressure of 0.1 to 10 MPa to obtain the cellulose.

3. The method according to claim 2, wherein the organic acid catalyst is one or more selected from methanesulfonic acid, oxalic acid, tartaric acid, citric acid, malic acid, formic acid, and acetic acid.

4. The preparation method according to claim 1, wherein the step of the cellulose undergoing a crosslinking reaction with the crosslinking agent includes: Cellulose powder, alkali metal hydroxide, and urea are dissolved in water, and then the crosslinking agent is added to form a crosslinking aqueous solution. The crosslinking aqueous solution is reacted at 40 to 50°C for 2 to 3 hours. The crosslinking agent has a volume concentration of 3%-30% in the crosslinking aqueous solution, and the cellulose has a mass concentration of 0.1%-5% in the crosslinking aqueous solution.

5. The preparation method according to claim 4, wherein the crosslinking agent is epichlorohydrin, ethylene glycol diglycidyl ether, or a combination thereof.

6. The preparation method according to claim 4, wherein the mass concentrations of sodium hydroxide and urea in the crosslinked aqueous solution are 1-10% and 0.1-10%, respectively.

7. The preparation method according to claim 1, wherein the plant fertilizer accounts for 5%-25% of the fertilizer composition by mass.

8. The preparation method according to claim 7, wherein the plant fertilizer is a water-soluble fertilizer.

9. The preparation method according to claim 8, wherein the fertilizer comprises 20%-40% total nitrogen, 10%-20% water-soluble phosphorus and 10%-20% water-soluble potassium; or the fertilizer is one or more of zinc sulfate, ferrous sulfate and magnesium sulfate.

10. The preparation method according to claim 1, wherein the preparation method further comprises grinding the fertilizer composition into particles with a particle size of 100 μm to 700 μm.

11. A fertilizer composition prepared by any one of claims 1-10.

Images