Fertilizer composition and preparation method therefor

Abstract

Provided in the present disclosure are a preparation method for a fertilizer composition and a fertilizer composition prepared by the preparation method. Said preparation method comprises: cellulose and a crosslinker undergoing a cross-linking reaction to obtain a polymer; adding the polymer to a plant fertilizer aqueous solution; and performing mixing and drying to obtain the fertilizer composition. The fertilizer composition of the present disclosure has a high water absorption capacity and contains nutrients for cotton plants. When the fertilizer of the present disclosure is mixed with soil, the water-soluble nutrients and water will be simultaneously released under a drought condition, so as to provide water and nutrients for plants, such as cotton, thereby improving the yield and quality of cotton.

Description

Fertilizer composition and method of making same TECHNICAL FIELD

[0001] The present disclosure belongs to the field of agricultural planting, and particularly relates to a fertilizer composition and a method of making the same. 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 the cultivation process. 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 amount of water used for growing a t-shirt is 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.

[0005] SUMMARY

[0006] The present disclosure provides a method of making a fertilizer composition and a fertilizer made by the method.

[0007] In one aspect, the present disclosure provides a method of making 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.

[0008] In some embodiments of the present disclosure, 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°C, and reacting for 0.5-3h under an autogenous pressure of 0.1 to 10 MPa to obtain the cellulose.

[0009] In some embodiments of the present disclosure, the organic acid catalyst is one or more of methanesulfonic acid, oxalic acid, tartaric acid, citric acid, malic acid, formic acid, and acetic acid.

[0010] In some embodiments of the present disclosure, 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%.

[0011] In some embodiments of the present disclosure, the cross-linking agent is epichlorohydrin, ethylene glycol diglycidyl ether, or a combination thereof.

[0012] In some embodiments of the present disclosure, the mass concentrations of sodium hydroxide and urea in the cross-linking aqueous solution are 1-10% and 0.1-10%, respectively.

[0013] In some embodiments of the present disclosure, the plant fertilizer accounts for 5%-25% of the mass percentage of the fertilizer composition.

[0014] In some embodiments of the present disclosure, the plant fertilizer is a fertilizer that can be dissolved in water.

[0015] In some embodiments of the present disclosure, 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.

[0016] In some embodiments of the present disclosure, the preparation method further comprises grinding the fertilizer composition into particles with a particle size of 100-700 μm.

[0017] Another aspect of the present disclosure provides a fertilizer composition prepared by the above preparation method.

[0018] The fertilizer composition of the present disclosure has high water absorption capacity and contains nutrients for cotton plants. When the fertilizer of the present disclosure 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 disclosure comes from cellulose obtained by degradation of textile waste, is environmentally friendly, and is degradable in soil without polluting the environment. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and other features and advantages of the present disclosure will become more apparent by describing in detail its example embodiments with reference to the attached drawings.

[0020] FIG. 1 is a flowchart illustrating the preparation of the fertilizer composition of the present disclosure using recycled cellulose according to an embodiment of the present disclosure.

[0021] Figure 2 is a graphical illustration of the fertilizer composition of the present disclosure.

[0022] Figure 3 is a photograph of the polymer (SAP), the fertilizer composition containing commercial fertilizer (NPK-SAP), and the polymer after release of the fertilizer prepared in Example 1.

[0023] Figure 4 is a FTIR analysis of the polymer (SAP), the fertilizer composition containing commercial fertilizer (NPK-SAP), and the polymer after release of the fertilizer prepared in Example 1.

[0024] Figure 5 is the nutrient content of the fertilizer composition prepared in Example 2 analyzed by ICP-OES / ICP-MS. DETAILED DESCRIPTION

[0025] The technical solutions of the present application are further described below according to specific examples. The scope of the present application is not limited to the following examples, which are listed for illustrative purposes only and do not limit the present application in any way.

[0026] The scope of the present disclosure is not limited to any particular embodiment described herein. The following examples are for illustration purposes only.

[0027] The method for preparing the fertilizer composition of the present disclosure comprises: 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.

[0028] In some embodiments, the cellulose can be recovered from textile waste. When the cellulose is recovered from textile waste, a schematic diagram of one embodiment of the method for preparing the fertilizer composition of the present disclosure is shown in Figure 1. The steps for recovering cellulose from textile waste can include: dispersing cotton-containing textile waste in an aqueous solution system containing 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 reacting for 0.5-3h under an autogenous pressure of 0.1 to 10 MPa to obtain cellulose.

[0029] The cotton-containing textile waste can be natural, semi-synthetic and / or synthetic cellulosic or natural cellulosic material. Semi-synthetic cellulosic material includes viscose, cuprammonium, polysilicic, lyocell and cellulose acetate, etc. The cotton-containing textile waste is subjected to hydrothermal treatment catalyzed by organic acid to obtain cellulose powder. The temperature, pressure and reaction time in the hydrothermal treatment process can be selected according to the types and contents of each component in the waste. For example, but not limited to, the temperature is 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc. Correspondingly, the autogenous pressure can be 0.1 MPa, 1 MPa, 3 MPa, 5 MPa, 7 MPa, 9 MPa, 10 MPa, etc. Correspondingly, the reaction time can be 0.5 h, 1 h, 2 h, 3 h, etc.

[0030] The organic acid catalyst used in the 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, acetic acid.

[0031] In some embodiments, the cross-linking reaction step of cellulose with a cross-linking agent includes: dissolving the cellulose powder, alkali metal hydroxide and urea in water, then adding the cross-linking agent to form a cross-linking aqueous solution, and the cross-linking aqueous solution is reacted 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 the cellulose in the cross-linking aqueous solution is 0.1%-5%.

[0032] The cross-linking agent can be epichlorohydrin, ethylene glycol diglycidyl ether or a combination thereof. The cross-linking agent cross-links with the cellulose to form a polymer with a network structure. Since 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 not dissolved in water. When the polymer is added to water, water enters the polymer network due to osmotic pressure. The cross-linking between molecular chains prevents the polymer from dissolving in water, but forms a swollen gel that can retain water even under external pressure.

[0033] In some embodiments of the present disclosure, the mass concentrations of sodium hydroxide and urea in the cross-linking 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 cross-linking 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.

[0034] In some embodiments of the present disclosure, after the cross-linking reaction to form the polymer, a water washing step can be further included. The by-products from the cross-linking reaction can be removed by water washing. The specific water washing process can be that after the cross-linking reaction is completed, the mixture can be solidified, and the solidified mixture can be cut into small cubic pieces for water washing. The cubic pieces can be soaked in water, and the water can be changed every 2 to 3 hours until the conductivity of the water remains at about 200 to 300 (μS / cm).

[0035] Before water washing, the cross-linked polymer can also be cut to facilitate the subsequent water washing and the smooth absorption of the fertilizer. Of course, the cutting step can also be omitted to achieve the purpose of the present disclosure.

[0036] Finally, the obtained polymer is mixed with an aqueous solution of a plant fertilizer. The polymer has a high water absorption, and the process can absorb the plant fertilizer and water into the polymer. After drying, the plant fertilizer remains in the polymer to form a fertilizer composition.

[0037] In some embodiments, the plant fertilizer can be a fertilizer that can be dissolved in water. 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.

[0038] In some embodiments, the fertilizer composition is further ground to a particle size of 100 μm to 700 μm.

[0039] Figure 2 shows a schematic diagram of the formation and use process of the fertilizer composition of the present disclosure. In Figure 2, the cross-linking agent is taken as an example of epichlorohydrin, and of course the cross-linking agent for forming the polymer can also be any other suitable cross-linking agent. As can be seen from the figure, the plant fertilizer is first compounded with the polymer by the method as described above to obtain the fertilizer composition of the present disclosure. In use, water is first absorbed to form a complex rich in water and fertilizer. After being applied to the soil, the water-soluble nutrients are released at the same time as water to provide water and nutrients for plants in the case of drought.

[0040] Example 1: Synthesis of a fertilizer composition using a commercial fertilizer

[0041] 1750 g of sodium hydroxide, 750 g of urea, 1250 g of regenerated cellulose powder, and 1650 ml of deionized water were added to a 40 L reactor. The mixture was stirred for 1 hour and frozen to -15°C. All the cellulose was dissolved in the aqueous solution at -15°C. When the aqueous solution reached room temperature, the cross-linking agent epichlorohydrin was added, and then stirred for 30 minutes. The mixture was poured into a stainless steel tray and placed in a 40°C oven for a cross-linking reaction.

[0042] When the reaction is complete, the mixture is solidified, cut into small cubes and washed with water until the conductivity of the water remains below 300 (pS / cm). The washed polymer is dried at 90°C for 4 hours.

[0043] 1 g of commercial fertilizer is added to 1000 ml of water bath and mixed well to configure a target nutrient water bath. The commercial fertilizer contains 30.0% total nitrogen, 10.1% water-soluble phosphorus, and 10.1% potassium. The dried polymer is put into the target nutrient water bath (the mass ratio of the polymer to the target nutrient water bath is about 1:100) for 1 hour. In this process, the nutrients are absorbed by the polymer. The polymer containing nutrients is dried at 90°C until it is completely dried and ground to a particle size of 100-700 pm by a centrifugal grinder.

[0044] Figure 3 shows the photos of the polymer (SAP) before the formation of the fertilizer composition, the formed fertilizer composition (NPK-SAP), and the polymer after the release of the fertilizer. It can be seen from the photos that the formed fertilizer composition (NPK-SAP) has changed in volume and color compared to the polymer (SAP) before absorbing the fertilizer, indicating that the fertilizer can be loaded into the cross-linked polymer formed by cellulose by the method of the present disclosure. It can be seen from Figure 3 that the fertilizer composition (NPK-SAP) becomes smaller in volume and lighter in color after the release of the fertilizer, indicating that the fertilizer composition obtained by the method of the present disclosure can release the fertilizer from the composition to provide nutrients for plants.

[0045] The FSC and CRC of the SAP containing nutrients are measured by ISO (17190-5:2001) and EDANA (ERT 441.2-02) test methods. The FSC and CRC measurement results show that the water absorption capacity of the SAP does not decrease significantly after adding nutrients.

[0046] The nutrient concentration is measured by EN16711-1-2015 test method using ICP-OES / ICP-MS. The ICP-OES / ICP-MS test results show that the nutrient concentration in the SAP is observable.

[0047] Example 2: Synthesis of fertilizer composition with magnesium sulfate, zinc sulfate and ferrous sulfate as fertilizer

[0048] 1750 g of sodium hydroxide, 750 g of urea, 1250 g of regenerated cellulose powder, and 1650 ml of deionized water are added to a 40 L reactor. The mixture is stirred for 1 hour and frozen to -15°C. All the cellulose is dissolved in the aqueous solution at -15°C. When the aqueous solution reaches room temperature, the cross-linking agent epichlorohydrin is added, and then stirred for 30 minutes. The mixture is poured into a stainless steel tray and placed in a 40°C oven for further reaction.

[0049] When the reaction is complete, the mixture is solidified, cut into small cubes and washed with water until the conductivity of the water remains below 300 (μS / cm). The washed polymer is dried at 90°C for 4 hours.

[0050] In 2 L of deionized water, 21.38 g of zinc sulfate, 14.64 g of ferrous (II) sulfate and 20 g of magnesium sulfate are added to configure a target nutrient water bath. 400 g of the dried polymer is placed in the target nutrient water bath, and the nutrient-containing water is absorbed into the polymer species. The nutrient-containing polymer is dried at 90°C until it is completely dry, and ground to a particle size of 100 μm to 700 μm by a centrifugal mill.

[0051] The FSC and CRC of the nutrient-containing SAP are measured by ISO (17190-5:2001) and EDANA (ERT 441.2-02) test methods. The FSC and CRC measurements show that the water absorption capacity of the SAP does not decrease significantly after the addition of nutrients.

[0052] The nutrient concentration is measured by EN 16711-1-2015 test method using ICP-OES / ICP-MS, and the measurement results are shown in FIG. 5. The ICP-OES / ICP-MS test results show that the nutrient concentration in the SAP is observable.

[0053] The above description of the embodiments is to facilitate the understanding and application of the present application for those of ordinary skill in the art. Those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the embodiments described herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of the present application.

Claims

1.A method for preparing a fertilizer composition, comprising: cross-linking cellulose with a cross-linking agent to obtain a polymer; adding the polymer to an aqueous solution of a plant fertilizer, and obtaining the fertilizer composition after mixing and drying. 2.The method according to claim 1, wherein 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, wherein the mass content of the organic acid catalyst in the aqueous solution system is 0.1%-30%; heating the mixed system to 110-180℃, and reacting for 0.5-3h under an autogenous pressure of 0.1 to 10MPa to obtain the cellulose. 3.The method according to claim 2, wherein the organic acid catalyst is one or more of methanesulfonic acid, oxalic acid, tartaric acid, citric acid, malic acid, formic acid, and acetic acid. 4.The method according to any one of claims 1-3, wherein the step of cross-linking cellulose with a cross-linking agent comprises: dissolving cellulose powder, alkali hydroxide, and urea in water, and then adding the cross-linking agent to form a cross-linking aqueous solution, and reacting the cross-linking aqueous solution at 40 to 50℃ for 2 to 3h; 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%. 5.The method according to claim 4, wherein the cross-linking agent is epichlorohydrin, ethylene glycol diglycidyl ether, or a combination thereof. 6.The method according to claim 4, wherein the mass concentrations of sodium hydroxide and urea in the cross-linking aqueous solution are 1-10% and 0.1-10%, respectively. 7.The method according to any one of claims 1-6, wherein the mass percentage of the plant fertilizer in the fertilizer composition is 5%-25%. 8.The method according to any one of claims 1-7, wherein the plant fertilizer is a fertilizer that can be dissolved in water. 9.The method according to claim 8, wherein the fertilizer comprises 20%-40% of total nitrogen, 10%-20% of water-soluble phosphorus, and 10%-20% of water-soluble potassium; or the fertilizer is one or more of zinc sulfate, ferrous sulfate, and magnesium sulfate. 10.The method according to any one of claims 1-9, wherein the method further comprises grinding the fertilizer composition into particles with a particle size of 100μm to 700μm. 11.A fertilizer composition prepared by the method according to any one of claims 1-10.

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