Method for producing liquid fertilizer

Abstract

The invention provides a method for efficiently obtaining a liquid fertilizer containing polysaccharide hydrolysate and nutrients such as potassium, phosphoric acid and nitrogen. A method for producing a liquid fertilizer, characterized by comprising: a hydrolysis step for obtaining a mixture containing a polysaccharide hydrolysate by hydrolyzing a polysaccharide comprising at least one substance selected from the group consisting of cellulose and chitin using phosphoric acid as an acid catalyst; and a neutralization step in which potassium hydroxide is added as a basic compound after the hydrolysis step.

Description

[0001] This application is a divisional application of the patent application with application number 202180022112.5, invention name “Fertilizer Manufacturing Method” and application date March 31, 2021. Technical Field

[0002] The present invention relates to a method for producing a liquid fertilizer containing polysaccharide hydrolysate. Background Art

[0003] In recent years, in the agricultural field, as shown in the following patent document 1, it has been reported that xylo-oligosaccharides, cello-oligosaccharides or other oligosaccharides can be used for the growth promotion of plants. In addition, it has been reported in patent document 2 that the phytoalexin inducing activity (exciting activity) possessed by chitosan oligosaccharides and the antibacterial activity of at least one plant selected from chitosan, chitosan oligosaccharides and their salts against pathogens synergistically can bring excellent disease resistance imparting effect and growth promotion effect, and it is a very useful method to use polysaccharide hydrolysates such as these oligosaccharides for plant growth promoters.

[0004] As a method for synthesizing these polysaccharide hydrolyzates, Patent Document 3 shows the hydrolysis of chitosan using a hydrochloric acid catalyst, but in order to separate the hydrochloric acid, it is necessary to neutralize with an alkali and perform a desalting step of the byproduct salt by ion exchange membrane electrodialysis. Patent Document 4 shows a method for hydrolyzing cellulose using concentrated hydrochloric acid or concentrated sulfuric acid, but this is a treatment as a pre-stage of enzymatic decomposition, and there is no record of separation of the acid and the hydrolyzate.

[0005] Patent Documents 5 and 6 disclose the hydrolysis of chitosan using a ball mill in the presence of an acid catalyst such as sulfuric acid, nitric acid, hydrochloric acid, perchloric acid, phosphoric acid, nitrous acid, or an organic acid. This is an excellent method for hydrolysis, but does not disclose a method for separating the acid from the polysaccharide hydrolyzate.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 63-215606

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 9-143013

[0010] Patent Document 3: Japanese Patent Application Publication No. 2005-281648

[0011] Patent Document 4: Japanese Patent Publication No. 57-53801

[0012] Patent Document 5: Japanese Patent Application Publication No. 2017-197468

[0013] Patent Document 6: International Publication No. 2017 / 187672 Summary of the invention

[0014] Problems to be solved by the invention

[0015] Although there are methods for hydrolyzing sugars using enzymes or the like, these methods are costly and do not always yield good polysaccharide hydrolysates.

[0016] Although polysaccharide hydrolyzate can be manufactured by the hydrolysis that protonic acid is used for catalyst, if sulfuric acid, hydrochloric acid, phosphoric acid etc. do not have strong acid strength to a certain extent, then hydrolysis rate is slow. Under the state that such strong acid is present in the polysaccharide hydrolyzate, worry about having adverse effect on plant. In addition, under the state that makes strong acid be present in the polysaccharide hydrolyzate, unexpected side reaction can occur when mixing with other fertilizers or pesticides, and sometimes pH can produce precipitation when becoming neutral from acidity. Therefore, need to separate acid, but need the special method such as ion exchange membrane electrodialysis with acid separation, be difficult to industrially cheap manufacture.

[0017] The invention provides a method for efficiently obtaining a fertilizer containing polysaccharide hydrolysate and nutrients such as potassium, phosphoric acid, nitrogen and the like.

[0018] Solution

[0019] The present invention was completed in view of the above situation. The inventors of the present invention completely changed their thinking from the past and studied the use of alkaline compounds containing potassium, phosphoric acid, nitrogen, etc. that can become nutrients required by plants as neutralizers for acid catalysts, and the obtained polysaccharide hydrolyzates and neutralized salts can be used directly as fertilizers.

[0020] As a result, the present inventors have found a method of hydrolyzing a polysaccharide using an acid catalyst and then neutralizing it by adding at least one basic compound selected from potassium salts, phosphates, ammonium salts and ammonia.

[0021] That is, the present invention includes the following [1] to

[14] .

[0022] [1] A method for producing a fertilizer, characterized by comprising the following steps:

[0023] a hydrolysis step of hydrolyzing the polysaccharide with an acid catalyst to obtain a mixture containing a polysaccharide hydrolyzate, and

[0024] After the hydrolysis step, a neutralization step of adding at least one basic compound selected from potassium salt, phosphate, ammonium salt and ammonia is performed.

[0025] [2] The method for producing a fertilizer as described in [1], further comprising a pH adjustment step of adjusting the pH value to between 4 and 10 after the neutralization step.

[0026] [3] The method for producing a fertilizer according to [1] or [2], further comprising a filtration step of separating solid components by filtration after the neutralization step.

[0027] [4] The method for producing a fertilizer according to any one of [1] to [3], wherein the alkaline compound is at least one selected from potassium hydroxide, potassium carbonate and potassium bicarbonate.

[0028] [5] The method for producing a fertilizer according to any one of [1] to [3], wherein the alkaline compound is at least one selected from dipotassium monohydrogen phosphate, tripotassium phosphate and diammonium hydrogen phosphate.

[0029] [6] The method for producing a fertilizer according to any one of [1] to [5], wherein the acid catalyst is at least one acid selected from sulfuric acid, sulfurous acid, hydrochloric acid, perchloric acid, nitric acid, nitrous acid and phosphoric acid, or a partially neutralized salt thereof.

[0030] [7]. The method for producing a fertilizer as described in [6], wherein the acid catalyst is phosphoric acid or a partially neutralized salt thereof.

[0031] [8]. The method for producing a fertilizer as described in [7], wherein the acid catalyst is phosphoric acid.

[0032] [9] The method for producing a fertilizer according to [7] or [8], further comprising, after the hydrolysis step, an extraction step of adding water to the mixture to extract water-soluble components.

[0033]

[10] . The method for producing a fertilizer according to any one of [1] to [9], wherein the hydrolysis step is performed by a mechanochemical method.

[0034]

[11] . The method for producing fertilizer according to

[10] , wherein the mechanochemical method comprises pulverizing the fertilizer using a planetary ball mill or a vibration mill.

[0035]

[12] The method for producing a fertilizer according to

[10] or

[11] , wherein the amount of water in the hydrolysis step is 0.1 to 10 parts by mass relative to 100 parts by mass of the polysaccharide.

[0036]

[13] . The method for producing a fertilizer according to any one of [1] to

[12] , wherein the polysaccharide contains at least one selected from chitin and cellulose.

[0037]

[14] . The method for producing a fertilizer according to

[13] , wherein the polysaccharide contains both chitin and cellulose.

[0038] The fertilizer manufacturing method of the present invention comprises: a hydrolysis step, in which a mixture containing polysaccharide hydrolysate is obtained by hydrolyzing polysaccharides with an acid catalyst; and a neutralization step, in which at least one alkaline compound selected from potassium salt, phosphate, ammonium salt and ammonia is added after the hydrolysis step. The manufacturing method can effectively manufacture fertilizers containing polysaccharide hydrolysate and nutrients such as potassium, phosphoric acid and nitrogen. DETAILED DESCRIPTION

[0039] Hereinafter, embodiments of the present invention will be described. In addition, the embodiments described below are representative examples of the present invention, but the present invention is not limited thereto.

[0040] A method for producing a fertilizer according to one embodiment of the present invention is characterized by comprising the following steps:

[0041] a hydrolysis step of hydrolyzing the polysaccharide with an acid catalyst to obtain a mixture containing a polysaccharide hydrolyzate, and

[0042] After the hydrolysis step, a neutralization step of adding at least one basic compound selected from potassium salt, phosphate, ammonium salt and ammonia is performed.

[0043] <Hydrolysis process>

[0044] The hydrolysis step is a step of hydrolyzing the polysaccharide with an acid catalyst to obtain a mixture containing a polysaccharide hydrolyzate.

[0045] [Polysaccharides]

[0046] As long as the polysaccharide can be hydrolyzed by acid, there is no particular limitation on the polysaccharide, and for example, cellulose, xylan, xyloglucan, glucomannan, chitin, etc. can be used. The polysaccharide preferably comprises at least one selected from chitin, xylan and cellulose, and more preferably comprises at least one selected from chitin and cellulose. Only one polysaccharide can be used, or two or more polysaccharides can be used in combination. When combining two or more polysaccharides, the polysaccharide preferably comprises both chitin and cellulose.

[0047] Cellulose and chitin are called biomass, which are organic resources of plant origin, rather than fossil resources.

[0048] As cellulose-based biomass, for example, cotton, wood-based pulp, kenaf, hemp, small-diameter wood, sparse forest wood, sawdust, wood chips, defatted wood powder, waste paper, newspaper, wrapping paper, paper towels, toilet paper, cartons and other wood-based; bagasse, switchgrass, elephant grass, corn cobs, rice straw, wheat straw and other herbaceous biomass can be listed. They can be used alone or in combination of two or more. For example, chemical pulp (holocellulose) obtained by bleaching defatted wood powder by chlorine treatment can be used, and then alkali treatment can be performed to remove hemicellulose and insoluble cellulose. Cellulosic biomass can also contain chitin in addition to cellulose.

[0049] Generally, cellulose exhibits crystallinity by combining two or more cellulose molecules through hydrogen bonds. In one embodiment, cellulose having such crystallinity may also be used as a raw material. In this embodiment, in order to improve the hydrolysis rate, it is preferably subjected to a treatment such as pre-crushing to reduce the crystallinity before use. Cellulose with reduced crystallinity may partially reduce the crystallinity or completely or almost completely eliminate the crystallinity. There is no particular limitation on the method of the crystallinity reduction treatment, and it is preferred to cut the above-mentioned hydrogen bonds to at least partially generate single-chain cellulose molecules. By using cellulose that at least partially contains single-chain cellulose molecules as a raw material, the efficiency of hydrolysis can be greatly improved.

[0050] As the treatment for reducing the crystallinity of the raw material cellulose, there can be listed: a method of obtaining single-chain cellulose molecules by physically cutting the hydrogen bonds between cellulose molecules by ball milling or the like as a pre-crushing method (see (Zhao et al, Energy & Fuels, 20, 807 (2006)) and a method of chemically cutting the hydrogen bonds between cellulose molecules by phosphoric acid treatment without applying compressive shear stress to obtain single-chain cellulose (see Zhang et al, Biomacromolecules, 7, 644 (2006)). The treatment for reducing the crystallinity of cellulose does not necessarily require the treatment to completely eliminate the crystallinity of cellulose, but may be a treatment to partially reduce the crystallinity of cellulose before the treatment. By using cellulose subjected to these treatments as a raw material, the efficiency of hydrolysis can be greatly improved.

[0051] Examples of the treatment for reducing the crystallinity of the raw material cellulose include pressurized hot water treatment (see Hayashi et al, J. Jpn. Inst. Energy, 83, 805 (2004), Sasaki et al, Ind. Eng. Chem. Res., 39, 2883 (2000) etc.).

[0052] Xylan is a polysaccharide in which D-xylose residues are bonded in β-1,4 or β-1,3. Sugars constituting xylose may include arabinose, glucuronic acid, 4-O-methylglucuronic acid, glucose, galactose, and the like in addition to xylose.

[0053] The raw material containing xylan is preferably subjected to compressive shear stress for pre-crushing before the hydrolysis step. In order to apply compressive shear stress to the raw material containing xylan for crushing, a compression shearing type pulverizer can be used. A compression shearing type pulverizer is a machine that can apply both compressive stress and shear stress, and examples thereof include a vibrating rod mill, a vibrating ball mill, and the like. Among them, from the viewpoint of production efficiency, a vibrating rod mill is preferred. There is no particular restriction on the rod, and a rod with an outer diameter of 0.1 to 100 mm is preferred, and a rod with an outer diameter of 0.5 to 50 mm is more preferred. The filling rate of the rod (relative to the volume of the stirring portion of the vibration mill, the apparent volume of the rod) varies depending on the machine model, and is preferably 10 to 97%, and more preferably 15 to 95%.

[0054] The pulverization conditions such as the pulverization time and the rotation speed of the pulverizer can be appropriately set so as to obtain a desired pulverized product. From the viewpoint of obtaining a high hydrolysis rate, the crystallinity of the xylan-containing pulverized product is preferably low.

[0055] The raw material containing xylan can be coarsely pulverized in advance before applying compressive shear stress to pulverize. There is no particular restriction on the method for coarse pulverization, for example, as a pulverizer, a cutter-type pulverizer such as a roller cutter, an impact pulverizer such as a hammer mill, a grinding type pulverizer such as a colloid mill, etc. can be used.

[0056] Chitin is a substance contained in biomass such as the shells or skins of crustaceans such as shrimps and crabs, arthropods, insects, squids, shellfish, krill, etc., and the cell walls of fungi such as mushrooms.

[0057] Chitosan may be a purified product or an unpurified product, but is preferably a purified product. Purified chitosan, for example, in the case of crab shells, can be obtained by neutralization, solid-liquid separation, washing, etc. after dissolving protein by alkali, dissolving calcium by acid, etc. Purified chitosan can be easily obtained from industrially prepared chitosan. In the case of unpurified products, any chitosan obtained from nature can be used as long as the substances that hinder the hydrolysis of chitosan are removed.

[0058] Chitosan can be either dry or wet, and can be either crystalline or non-crystalline. Preferably, chitosan is pre-crushed before the hydrolysis step. By pre-crushing, the contact with the acid catalyst increases, promoting decomposition. Therefore, the shape and size of the chitosan used for pre-crushing are preferably suitable for pulverization. As such a shape and size, for example, a powder with a particle size of 20 to 1000 μm can be cited.

[0059] When chitosan is pre-crushed, pre-crushing machines such as shredder, jaw crusher, gyratory crusher, cone crusher, hammer crusher, roll crusher and roll mill can be used in the pre-crushing process, or pulverizers such as stamp mill, edge runner, cutting / shear mill, rod mill, autogenous pulverizer and roll mill. The time of pre-crushing is not particularly limited, as long as the chitosan after the process is micronized uniformly. In addition, in order to obtain high hydrolysis rate, the crystallinity of preferred chitosan is low.

[0060] [Acid catalyst]

[0061] As the acid catalyst for hydrolyzing the polysaccharide, for example, the conventionally known acids described in Patent Documents 3 to 6 can be used. Specifically, at least one acid selected from sulfuric acid, sulfurous acid, hydrochloric acid, perchloric acid, nitric acid, nitrous acid and phosphoric acid or a partially neutralized salt thereof can be used. As the partially neutralized salt of the above acid, for example, monopotassium dihydrogen phosphate, monoammonium dihydrogen phosphate, potassium hydrogen sulfate and the like can be cited. The acid catalyst is preferably phosphoric acid or a partially neutralized salt thereof, more preferably phosphoric acid.

[0062] [Hydrolysis reaction]

[0063] In the hydrolysis process, the amount of acid catalyst used varies depending on the hydrolysis method. For example, when hydrolyzing with hydrochloric acid at a concentration of 30% or more at room temperature, it is preferred to use a large excess of acid of 10 times or more molar equivalent relative to the polysaccharide. When hydrolyzing by mechanochemical method at a temperature below 110°C, the mass ratio of polysaccharide to acid catalyst is preferably: polysaccharide / acid catalyst = 2 to 100, more preferably polysaccharide / acid catalyst = 4 to 20, and further preferably polysaccharide / acid catalyst = 3 to 10. If the mass ratio of polysaccharide to acid catalyst is less than 100, hydrolysis is carried out at a speed that is not a problem in practical use. If the mass ratio of polysaccharide to acid catalyst is more than 2, side reactions such as dehydration reaction and breaking of carbon-carbon bonds can be suppressed during hydrolysis.

[0064] In addition, the mass of the polysaccharide mentioned here is the net weight (dry mass) of the polysaccharide after removing the water contained in the raw material. Usually, polysaccharides contain physically adsorbed water, so the amount of attached moisture is analyzed, and the mass ratio of the polysaccharide to the acid catalyst is calculated based on the mass of the polysaccharide after removing the water. As an analysis method for the amount of attached moisture, a method of placing the raw polysaccharide in a constant temperature dryer at 100°C to 150°C and drying until the mass no longer decreases for quantitative analysis can be cited. In order to prevent the influence of side reactions such as dehydration reactions during drying, it is more preferable to use a vacuum dryer to dry and quantify at a lower temperature. In addition, the mass of the acid catalyst is also the net weight (dry mass) of the acid catalyst.

[0065] As described above, the polysaccharide before hydrolysis already contains about 1 to 3% by mass of physically adsorbed water. In addition, acid catalysts such as hydrochloric acid and phosphoric acid often contain water in their commercially available forms. Therefore, the polysaccharide can be hydrolyzed using the water physically adsorbed on the polysaccharide and the water contained in the acid catalyst. Usually, even without adding water, the water content is sufficient in many cases, but for polysaccharides with high dryness, water can also be added for hydrolysis.

[0066] Whether water is added or not, the polysaccharide contains about 1 to 3% by mass of physically adsorbed moisture. Therefore, the amount of water in the hydrolysis process is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, relative to the net weight (dry mass) of 100 parts by mass of polysaccharides, and the amount of water includes the water physically adsorbed on the polysaccharide and the water contained in the acid catalyst, and also includes the amount of water further added when water is further added. If it is less than 10 parts by mass, not only a sufficient hydrolysis rate can be obtained, but also inoperability due to fixed bonding to the device can be prevented. In addition, if it is more than 0.1 parts by mass, side reactions such as dehydration reaction or branching reaction of the polysaccharide can be suppressed.

[0067] The hydrolysis method is not particularly limited, and examples include a method of hydrolyzing at a reaction temperature of 5°C to 30°C using hydrochloric acid at a concentration of 30% or more, a method of hydrolyzing using a catalytic amount of sulfuric acid and 10 times the mass of water relative to the polysaccharide to make it a subcritical state (150-350°C, 0.5-25MPa), and a mechanochemical method. Among them, the mechanochemical method is preferably used. The mechanochemical method is a method of hydrolyzing polysaccharides by applying mechanical external force through a pulverization process. When chitin is used as a polysaccharide, for example, the methods described in patent documents 5 and 6 can be used. When cellulose is used as a polysaccharide, for example, the method described in Kuga et al, Cellulose, 26, 215 (2019) can be used.

[0068] Examples of the pulverizing apparatus used for the pulverizing treatment include rolling ball mills such as pot mills, tube mills, and cone mills; wet type jet mills such as swirling flow jet mills, collision type jet mills, fluidized bed type jet mills, and wet type jet mills; shear mills such as tampers and Angmills; colloidal mills such as mortars and stone mills; impact pulverizers such as hammer mills, cage mills, pin mills, disintegrators, screen mills, turbo mills, and centrifugal classifying mills; vibration mills that pulverize by vibrating the drum to move the media inside; and planetary ball mills, which are types of pulverizers that use rotation and revolution.

[0069] The pulverizing device is preferably a ball mill or a vibration mill that applies strong compression force to the polysaccharide and tensile stress in two directions of the main chain. The pulverizing device is more preferably a planetary ball mill, a rolling ball mill or a vibration mill, and further preferably a planetary ball mill or a vibration mill.

[0070] At the laboratory level, a planetary ball mill is preferably used. Industrially, a vibration mill is preferably used. The vibration mill does not rotate the drum (crushing cylinder) into which the crushing media is inserted, but moves the media inside by vibrating the cylinder, thereby crushing in about 1 / 10 to 1 / 20 of the time compared to a drum rotary ball mill.

[0071] The pulverization process can be carried out continuously or intermittently. In order to suppress the temperature rise of the object to be processed accompanying the pulverization process, it is preferred to carry out the pulverization process intermittently. In the case of intermittent pulverization, the optimal value varies greatly depending on the pulverization device. For example, in the case of a planetary ball mill, it can be carried out by repeating the pulverization process for 5 to 15 minutes with a 5 to 15 minute break. In the case of continuous pulverization, it is preferred to cool the pulverization device by providing a shell jacket, etc., so as to carry out the pulverization process while maintaining the appropriate temperature.

[0072] When a pulverizing device such as a ball mill is used to hydrolyze the polysaccharide, the hydrolysis may be performed while the crystallinity of the polysaccharide is reduced by the pulverizing treatment, or the polysaccharide may be first subjected to the treatment of reducing the crystallinity as described above, and then the acid catalyst is added to perform the hydrolysis. In addition, when the polysaccharide is pre-crushed by a Henschel mixer and then pulverized by a ball mill, the acid catalyst may be mixed from the pre-crushing stage.

[0073] The temperature of the hydrolysis is preferably room temperature to 110°C, more preferably 50°C to 100°C. If it is above room temperature, the decomposition will not be slowed down, and the time required for decomposition will not become too long. In order to further accelerate the decomposition rate, the hydrolysis can also be carried out at a high temperature. If the temperature of the hydrolysis is below 110°C, side reactions such as dehydration reactions can be suppressed. When the temperature of the hydrolysis exceeds 110°C, dehydration reactions are likely to occur, and sometimes the volatilization of water is also promoted. In the case of hydrolysis using a mechanochemical method, due to the presence of shear heat, it is preferred to perform repeated cycles with intervals as described above, or to control the hydrolysis temperature by flowing cooling water in the shell of the pulverizing device.

[0074] The hydrolysis time is preferably 10 hours to 100 hours, more preferably 15 hours to 70 hours, further preferably 20 hours to 60 hours, and particularly preferably 30 hours to 50 hours. When the hydrolysis time is 10 hours or more, the decomposition of the polysaccharide is promoted. When the hydrolysis time is 100 hours or less, a polysaccharide hydrolyzate can be obtained more effectively. In addition, when the hydrolysis is performed by the above-mentioned mechanochemical method and the pulverization process is performed intermittently, the hydrolysis time refers to the net pulverization process time after removing the interval time.

[0075] The progress of hydrolysis of polysaccharides can be confirmed by collecting a small amount of the treatment object over time and measuring the amount of water-soluble components contained in the collected object.

[0076] After the hydrolysis step, a mixture containing polysaccharide hydrolysate is obtained. In addition to the polysaccharide hydrolysate, the mixture may also contain undecomposed polysaccharides and acid catalysts. In addition to oligosaccharides, the polysaccharide hydrolysate may also contain monosaccharides, dehydrated bodies in which the sugar ends have undergone dehydration reactions, branched bodies in which the 6-hydroxyl group reacts with the β-1,4-glycosidic bond to generate α-1,6-glycosidic bonds, or other by-products.

[0077] The mixture containing the polysaccharide hydrolysate obtained in the hydrolysis step can be used directly in the neutralization step, or can be used in the neutralization step after the extraction step described later. In the mixture obtained by the hydrolysis step, as the polysaccharide hydrolysate, by-products other than oligosaccharides are also contained, but these by-products also have plant growth effects or stimulating activities to some extent. Therefore, it is efficient to use it in the neutralization step while keeping these by-products.

[0078] <Neutralization process>

[0079] The neutralization step is a step of adding at least one basic compound selected from potassium salt, phosphate, ammonium salt and ammonia to neutralize after the hydrolysis step. In addition, in a system where concentrated hydrochloric acid is used excessively as an acid catalyst in the hydrolysis step, since the neutralization heat is significantly generated in the neutralization step, ice may be added instead of water to cool and stir, and the neutralization step and the extraction step described later may be performed simultaneously.

[0080] In the mixture containing the polysaccharide hydrolyzate obtained by the above-mentioned hydrolysis step, the acid catalyst used for hydrolysis remains. Therefore, by adding at least one alkaline compound selected from potassium salt, phosphate, ammonium salt and ammonia, the acid catalyst can be neutralized, and a fertilizer containing polysaccharide hydrolyzate and nutrients such as potassium, phosphoric acid and nitrogen can be efficiently produced.

[0081] [Basic compounds]

[0082] When potassium salt is used as the alkaline compound, for example, potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium formate, potassium acetate, potassium ethoxide, monopotassium dihydrogen phosphate, dipotassium monohydrogen phosphate, tripotassium phosphate, potassium amide, etc. can be used. Among them, potassium hydroxide, potassium carbonate, potassium bicarbonate, dipotassium monohydrogen phosphate and tripotassium phosphate are preferred, and at least one selected from potassium hydroxide, potassium carbonate and potassium bicarbonate is more preferred. The potassium salt may be used alone or in combination of two or more.

[0083] When phosphate is used as the alkaline compound, monopotassium dihydrogen phosphate, dipotassium monohydrogen phosphate, tripotassium phosphate, diammonium hydrogen phosphate, triammonium phosphate, etc. can be used. Among them, at least one selected from dipotassium monohydrogen phosphate, tripotassium phosphate and diammonium hydrogen phosphate is preferred. Therefore, the phosphate can be a potassium salt or an ammonium salt at the same time. Only one phosphate can be used, or two or more phosphates can be used in combination.

[0084] When an ammonium salt is used as the alkaline compound, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ammonium carbonate, diammonium hydrogen phosphate, triammonium phosphate, ammonium nitrate, ammonium sulfate, etc. can be used. Among them, diammonium hydrogen phosphate and ammonium sulfate are preferred. The ammonium salt can be used alone or in combination of two or more.

[0085] When ammonia is used as the basic compound, aqueous ammonia is preferably used.

[0086] By using only potassium salts as the basic compound, potash fertilizers can be made. By using only phosphates as the basic compound, phosphate fertilizers can be made. By using only ammonium salts or ammonia as the basic compound, nitrogen fertilizers can be made.

[0087] Furthermore, a compound fertilizer can be produced by using potassium salt, phosphate, ammonium salt or ammonia in combination.

[0088] The amount of the basic compound added is not necessarily an equimolar amount relative to the acid, and can be appropriately set in consideration of the use as a fertilizer. 2 O 5 )-Potassium (K 2 The amount of the component in (O) is a minimum guaranteed value, and therefore it is preferable to add an amount greater than this amount that can ensure the minimum guaranteed amount.

[0089] In the display of fertilizer components, the total amount of nitrogen, total amount of phosphate, and total amount of potassium are expressed in %. Therefore, specifically, the amount of alkaline compound added is adjusted so that the total amount of nitrogen, total amount of phosphate, or total amount of potassium is 2 to 5% greater than the amount of the component to be displayed. In addition, the definitions of the total amount of nitrogen, total amount of phosphate, and total amount of potassium in the display of fertilizer components are as follows (Ministry of Agriculture, Forestry, and Fisheries Notice No. 1163 on August 31, 2001).

[0090] 1 Total nitrogen

[0091] The amount of nitrogen in the test sample was quantified by the Kjeldahl method, and the percentage (%) relative to the weight of the test sample was taken as the total amount of nitrogen. However, in the case of containing nitrate nitrogen, the nitrate nitrogen was reduced to ammonia nitrogen as a pretreatment.

[0092] 2 Total phosphoric acid

[0093] The sample was incinerated and then dissolved in hydrochloric acid, and the phosphoric acid (P 2 O 5 ) and its percentage (%) relative to the weight of the test sample was taken as the total amount of phosphoric acid.

[0094] 3 Potassium Full

[0095] The sample was carbonized and dissolved in hydrochloric acid, and the potassium (K 2 The amount of potassium (O) was calculated and its percentage (%) relative to the weight of the test sample was taken as the total amount of potassium.

[0096] Fertilizer components are managed based on the element contents of nitrogen (N), phosphorus (P), and potassium (K). However, in the case of fertilizers, P and K are displayed as the total amount of phosphate and potassium, respectively, so it is necessary to consider these and determine the management value.

[0097] [Neutralization reaction]

[0098] The temperature of the neutralization reaction is preferably in the range of 0°C to 50°C, more preferably in the range of 5°C to 40°C, and further preferably in the range of 20°C to 30°C to prevent the polysaccharide hydrolyzate from overreacting. Although the neutralization reaction itself is very fast, in the presence of insoluble matter from the raw material polysaccharide, it is necessary to fully diffuse the acid, so the time of the neutralization reaction is preferably 0.1 hour to 10 hours, more preferably 0.5 hour to 5 hours, and further preferably 1 hour to 3 hours. As an apparatus for the neutralization reaction, no special apparatus is required, and a conventional stirring tank can be used. When hydrochloric acid or sulfuric acid is used as the acid, a stirring tank with a corrosion-resistant lining such as glass is preferably implemented.

[0099] When the prepared fertilizer is used as a soil-spreading fertilizer, the mixture obtained by the hydrolysis step can be directly used in the neutralization step in the state of containing solid components. When the neutralization step is directly performed in the state of containing solid components, the device (e.g., a pulverizing device) used in the hydrolysis step can be directly used in the neutralization step to mix the mixture containing the polysaccharide hydrolyzate and the alkaline compound. Alternatively, after taking out the mixture from the device used in the hydrolysis step, the neutralization step can be performed separately using a Henschel mixer or the like to mix the mixture containing the polysaccharide hydrolyzate and the alkaline compound.

[0100] When two or more polysaccharides are used as polysaccharides, each polysaccharide may be subjected to a hydrolysis step, and then the obtained hydrolyzates may be mixed and subjected to a neutralization step. Alternatively, the hydrolysis step may be carried out in a state where two or more polysaccharides are mixed from the beginning to obtain a mixture of multiple polysaccharide hydrolyzates, and then subjected to a neutralization step.

[0101] <Other Process>

[0102] In addition to the above-mentioned hydrolysis step and neutralization step, the following steps may be arbitrarily performed as necessary.

[0103] [Extraction process]

[0104] According to one embodiment of the method for preparing a fertilizer, after the hydrolysis step, water is added to a mixture containing a polysaccharide hydrolyzate obtained by the hydrolysis step (hereinafter sometimes referred to as a "mixture") to extract water-soluble components. In particular, when the hydrolysis is performed by a mechanochemical method, the mixture becomes a solid containing the polysaccharide hydrolyzate because the amount of water used is small, and it is preferable to perform the extraction step.

[0105] The extraction step may be performed after the hydrolysis step and before the neutralization step, or may be performed simultaneously with the neutralization step. When concentrated hydrochloric acid is used as an acid catalyst in the hydrolysis step, it is preferred to cool the mixture in ice while stirring in order to suppress heat generation in the neutralization step, thereby allowing the neutralization step and the extraction step to be performed simultaneously.

[0106] When the manufactured fertilizer is used as a liquid fertilizer, it is difficult to use if it contains undissolved components. In this case, it is preferred to add water to the mixture obtained in the hydrolysis step, extract the water-soluble components, perform filtering etc. as needed, and perform a neutralization step after removing the solid components.

[0107] The mass ratio of the amount of water added to the mixture is preferably: (amount of water added) / (mixture) = 0.5 to 100, more preferably 1 to 20, and further preferably 2 to 10. When the mass ratio of the amount of water added to the mixture is 0.5 or more, the water-soluble components (e.g., oligosaccharides) in the polysaccharide hydrolyzate can be effectively dissolved, and when it is 100 or less, the container for dissolution will not become too large, which is good in terms of efficiency.

[0108] The water added to the mixture is not particularly limited, and ion exchange water or distilled water is generally used. In addition to ion exchange water or distilled water, a solution or buffer containing a salt may also be used. An organic solvent miscible with water may also be added within a range that does not affect the dissolution of the water-soluble components in the polysaccharide hydrolyzate.

[0109] The separation of the water-soluble component and the solid component can be carried out by a commonly used method for removing the solid component from the suspension. For example, filtration can be carried out using filter paper, filter cloth, membrane filter, filter press, cross-flow filter, etc., or natural sedimentation or centrifugal sedimentation can be carried out.

[0110] In order to obtain oligosaccharides with relatively high purity as polysaccharide hydrolysates, after removing the solid components from the mixture, ethanol or the like is added to an aqueous solution containing a water-soluble component to reprecipitate the oligosaccharides, the obtained precipitate is dissolved again in water, and purification operations such as ethanol reprecipitation are repeated.

[0111] 〔pH adjustment process〕

[0112] The method for preparing a fertilizer according to one embodiment may include, after the neutralization step, a pH adjustment step of adjusting the pH value to between 4 and 10. When manufacturing an acidic fertilizer, the fertilizer is adjusted to be acidic after being dissolved in water, and when manufacturing an alkaline fertilizer, the fertilizer is adjusted to be alkaline after being dissolved in water.

[0113] As the pH adjuster, a pH adjuster used as a fertilizer is preferred. Examples of such substances include potassium dihydrogen phosphate and ammonium sulfate as acidic pH adjusters, and tripotassium phosphate, triammonium phosphate, lime, and calcium hydroxide as alkaline pH adjusters.

[0114] When used as a liquid fertilizer, the pH is preferably adjusted to 4 to 10, more preferably 5 to 9, in consideration of storage stability or stability when mixed with other agricultural materials. When the pH is 4 or higher, adverse conditions such as precipitation are less likely to occur when mixed with other agricultural materials, and when the pH is 10 or lower, storage stability is good.

[0115] [Filtration process]

[0116] According to the method for manufacturing fertilizer of one embodiment, a filtering step for separating solids by filtering may be included after the neutralization step. In the neutralization step, precipitation may occur due to bringing the pH to the neutral side. The precipitation is particularly significant when the polysaccharide is chitin. When the manufactured fertilizer is used as a liquid fertilizer, the presence of the precipitation is undesirable, so it is preferred to separate the solid components by filtering.

[0117] The solids can be separated by any commonly used method for removing solids from a suspension, for example, by filtering using filter paper, filter cloth, membrane filter, filter press, cross-flow filter, etc., or by natural sedimentation or centrifugal sedimentation.

[0118] In addition, when the filtration step is performed, the operation of separating (filtering) the water-soluble component and the solid component after extracting the water-soluble component in the above-mentioned extraction step can be omitted.

[0119] [Process of adding other ingredients]

[0120] The method for preparing fertilizer according to one embodiment may further include a step of adding other ingredients effective as fertilizers. Other ingredients include essential elements such as calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), boron (B), zinc (Zn), nickel (Ni), molybdenum (Mo), copper (Cu), chlorine (Cl), and elements that help plant growth: sodium (Na), silicon (Si), selenium (Se), cobalt (Co), aluminum (Al), vanadium (V), and other useful elements.

[0121] Example

[0122] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[0123] [Analysis method of filtrate]

[0124] Polysaccharide hydrolysate content:

[0125] The phosphate content obtained from the P content and the KOH content obtained from the K content were subtracted from the evaporation residue ratio of the filtrate analyzed at 105°C using a Kate moisture meter (Earthand Dei Co., Ltd., heating and drying moisture meter ML-50), and the resulting value was taken as the content of the polysaccharide hydrolyzate.

[0126] Polysaccharide hydrolysate content:

[0127] The content of the polysaccharide hydrolyzate was calculated from the evaporation residue ratio of the filtrate analyzed at 105°C using a Kate moisture meter (Earthand Dee Co., Ltd., heating and drying moisture meter ML-50), and the solid content was calculated from this value. The P content calculated from the phosphoric acid content and the potassium (K) content were subtracted from the solid content. 2 The K content was determined by the content of O) and the obtained value was taken as the content of the polysaccharide hydrolyzate.

[0128] P content:

[0129] Phosphoric acid (P) was calculated by dividing the concentration of water-soluble phosphoric acid (converted to phosphorus pentoxide) measured by the ammonium vanadium molybdate absorptiometry method by a coefficient of 2.291 in accordance with 4.2.4.a of the Fertilizer Testing Method (2019) prescribed by the Independent Administrative Institution Agricultural, Forestry and Fisheries Consumer Safety Technology Center. 2 O 5 ) content, and the P content is calculated based on this value.

[0130] K content:

[0131] Potassium (K) was calculated by dividing the water-soluble potassium (converted to potassium oxide) concentration measured by ICP emission spectrometry by a coefficient of 1.2046 in accordance with 4.3.3.d of the Fertilizer Testing Method (2019) prescribed by the Independent Administrative Institution Agricultural, Forestry and Fisheries Consumer Safety Technology Center. 2 O) content, and the K content is calculated based on this value.

[0132] N content:

[0133] The N content was calculated based on the ammonia nitrogen (N) content calculated by the formaldehyde method in accordance with 4.1.2.b of the Fertilizer Testing Methods (2019) prescribed by the Independent Administrative Institution Agricultural, Forestry and Fisheries Consumer Safety Technology Center.

[0134] [Example 1] Method for producing fertilizer containing cellulose hydrolysate

[0135] 3.91 kg of Avicel (crystalline fine cellulose powder manufactured by Merck) (water content 3.1%, dry weight 3.79 kg) and 0.53 kg of 85 wt % phosphoric acid (special grade reagent manufactured by Fujifilm Wako Junyao Co., Ltd.) were mixed using a Henschel mixer (device name: FM20C / I, manufactured by Japan Cox Industries, Ltd.). The mixing conditions were a rotation speed of 1400 rpm and a ventilation of 0.4 m 3 / Hr. According to the moisture content of the raw material (cellulose) and phosphoric acid, 5.3 parts by mass of water was contained with respect to 100 parts by mass of dry cellulose.

[0136] 350 g of the mixture was transferred to a vibration mill (device name: MB-1, manufactured by Chuo Kako Kikai Co., Ltd.) and ground to perform a mechanochemical hydrolysis step. The grinding conditions were a total amplitude of 8 mm, a vibration frequency of 16.2 Hz, and a φ3 / 4 inch carbon steel ball. The cooling water temperature flowing into the jacket was set at 80°C, and the hydrolysis was performed for 24 hours.

[0137] The pulverized product and the balls were separated from the vibration mill, and 186 g of the pulverized product was transferred to a dissolving device (2 L beaker). 721 g of ion exchange water was added, and the mixture was stirred at 25° C. for 1 hour using a motor (registered trademark: SLI-WAN MOTOR). Thus, the water-soluble components were dissolved to obtain an extract of cellulose hydrolyzate.

[0138] 154.4 g of a 15% by mass potassium hydroxide aqueous solution was added to the extract, and the mixture was stirred for 1 hour at 25° C. using a motor (registered trademark: Slywon Motor). 42 g of pearlite Parallel #31 (manufactured by Showa Chemical Industry Co., Ltd.) was added as a filter aid, and the mixture was filtered using a pressure filter (KST-293-20, manufactured by Adbandek Toyo Co., Ltd.) to obtain 674 g of a filtrate.

[0139] As a result of analyzing the filtrate, the pH was 6.8, the cellulose hydrolyzate was 47.8 g, 1.8 g of P was contained, and 6.8 g of K was contained. The composition containing the cellulose hydrolyzate thus obtained can be used favorably as a fertilizer.

[0140] [Example 2] Method for producing fertilizer containing chitin hydrolysate

[0141] Purified chitin (manufactured by Fujifilm Wako Junyaku Co., Ltd.) was used as a raw material.

[0142] 3.96 kg of the above raw materials (water content 3.3%, dry weight 3.83 kg) and 0.54 kg of 85% by mass phosphoric acid (special grade reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed using a Henschel mixer (device name: FM20C / I, manufactured by Japan Cox Industries, Ltd.). The mixing conditions were a rotation speed of 1400 rpm and a ventilation of 0.4 m 3 / Hr. From the water content of the raw material (chitin) and phosphoric acid, it was found that 5.5 parts by mass of water was contained per 100 parts by mass of dry chitin.

[0143] The mixture was transferred to a vibration mill (device name: MB-1, manufactured by Chuo Kako Kikai Co., Ltd.) and pulverized to perform a mechanochemical hydrolysis step. The pulverization conditions were a total amplitude of 8 mm, a vibration frequency of 16.2 Hz, and a φ3 / 4 inch carbon steel ball. The cooling water temperature flowing through the jacket was set at 80°C, and the hydrolysis was performed for 24 hours.

[0144] The pulverized product was separated from the balls in the vibration mill, and 101.6 g of the pulverized product was transferred to a dissolving device (2 L beaker). 431 g of ion exchange water was added, and the mixture was stirred at 25° C. for 1 hour using a motor (registered trademark: SLI-WAN MOTOR). Thus, the water-soluble components were dissolved to obtain an extract of chitin hydrolyzate.

[0145] 71.7 g of a 15% by mass potassium hydroxide aqueous solution was added to the extract, and the mixture was stirred for 1 hour at 25° C. using a motor (registered trademark: Slywon Motor). 24.3 g of pearlite Parallel #31 (manufactured by Showa Chemical Industry Co., Ltd.) was added as a filter aid, and the mixture was filtered using a pressure filter (KST-293-20, manufactured by Adbandec Toyo Co., Ltd.) to obtain 257 g of a filtrate.

[0146] The filtrate was analyzed and found to have a pH of 6.8, 19.7 g of chitin hydrolyzate, 0.61 g of P, 2.2 g of K, and 1.3 g of N. The chitin hydrolyzate-containing composition thus obtained can be used favorably as a fertilizer.

[0147] [Example 3] Method for producing fertilizer containing chitin hydrolysate

[0148] 11.7 g of 28% by mass ammonia water (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the extract of chitin hydrolyzate obtained by the same treatment as in Example 2, and stirred for 1 hour at 25° C. using a motor (registered trademark: Slywan Motor). 24.3 g of pearlite Parallel #31 (manufactured by Showa Chemical Industry Co., Ltd.) was added as a filter aid, and filtered using a pressure filter (KST-293-20, manufactured by Adbandek Toyo Co., Ltd.) to obtain 242 g of a filtrate.

[0149] The filtrate was analyzed to find that the pH was 6.8, the chitin hydrolyzate was 19.7 g, 1.4 g of P, and 4.0 g of N. The chitin hydrolyzate-containing composition thus obtained can be used favorably as a fertilizer.

[0150] [Example 4] Method for producing fertilizer containing chitin hydrolysate

[0151] As a raw material, 5 g of chitin (manufactured by Kyoto Chemical Co., Ltd.) (water content 1.9%, dry mass 4.91 g) was used. The chitin had a deacetylation degree of 5% or less, a viscosity of several tens of cps, and was pulverized to a size of 5 mm or less.

[0152] 5 g of the above raw materials were placed in a 200 mL Erlenmeyer flask, dispersed and dissolved in 50 mL of 35% concentrated hydrochloric acid, and a hydrolysis step was performed for 24 hours while maintaining the reaction temperature at 25° C. using a water bath.

[0153] After the hydrolysis step, about 300 g of ice was added to each reaction solution to quench the reaction solution, and a neutralization step was performed using 48 mass % KOH to a pH of 5 to 6. After the neutralization step, the solution was decolorized with activated carbon for one day and night, and filtered with diatomaceous earth to obtain 311 g of a filtrate.

[0154] As a result of analyzing the filtrate, the amount of chitin hydrolyzate was 2.2 g, and 25 g was contained as K. The chitin hydrolyzate-containing composition obtained in this way can be used favorably as a fertilizer.

[0155] [Example 5] Method for producing fertilizer containing cellulose hydrolyzate and chitin hydrolyzate

[0156] 349 g of the extract of the cellulose hydrolyzate obtained by the same treatment as in Example 1 and 103 g of the extract of the chitin hydrolyzate obtained by the same treatment as in Example 2 were mixed, 226.1 g of a 15 mass % potassium hydroxide aqueous solution was added, and the mixture was stirred for 1 hour at 25° C. using a motor (registered trademark: Slywon Motor). 70 g of pearlite Parallel #31 (manufactured by Showa Chemical Industry Co., Ltd.) was added as a filter aid, and the mixture was filtered using a pressure filter (KST-293-20, manufactured by Adbandek Toyo Co., Ltd.) to obtain 935 g of a filtrate.

[0157] The filtrate was analyzed to find that the pH was 6.8, the cellulose hydrolyzate was 48.5 g, the chitin hydrolyzate was 20.1 g, 2.5 g of P, 9.3 g of K, and 1.4 g of N. The composition containing the cellulose hydrolyzate and the chitin hydrolyzate thus obtained can be used favorably as a fertilizer.

[0158] As shown in Examples 1 to 5, after the polysaccharide is hydrolyzed with an acid catalyst, at least one alkaline compound selected from potassium salts, phosphates, ammonium salts and ammonia is added to carry out a neutralization step, thereby easily obtaining a fertilizer containing polysaccharide hydrolyzate and nutrients such as potassium, phosphoric acid and nitrogen.

[0159] [Reference Example 1]

[0160] After 10 g of purified chitin (manufactured by Fuji Film & Co., Ltd.) was dispersed in 30 mL of water containing 1.2 g of 85% by mass phosphoric acid (special grade reagent manufactured by Fuji Film & Co., Ltd.), the powder dried under reduced pressure and 100 g of alumina balls with a diameter of 5 mm were placed in an alumina pot with a capacity of 250 mL, and the mixture was placed in a planetary ball mill (manufactured by Flickr, PULVERISETTE6) and continuously treated at 500 rpm for 6 hours to obtain a chitin hydrolyzate. In addition, the temperature was set to room temperature, and the temperature rise caused by shear heat was left to its own devices.

[0161] Next, the chitin hydrolyzate was suspended in water and neutralized with calcium hydroxide, the resulting slurry was filtered through a Nutsche filter using 5B filter paper, and the recovered filtrate was freeze-dried to obtain chitin oligosaccharide powder.

[0162] 1.0 g of the obtained chitin hydrolyzate, 0.011 g of potassium dihydrogen phosphate (first grade manufactured by Fuji Feilumu Wako Junkaku Co., Ltd.), and 0.193 g of tripotassium phosphate (first grade manufactured by Fuji Feilumu Wako Junkaku Co., Ltd.) (total P: 0.031 g, K: 0.11 g) were dissolved in 11.5 g of water to obtain a fertilizer solution containing chitin hydrolyzate having substantially the same composition as in Example 2.

[0163] [Tomato cultivation experiment]

[0164] The fertilizer solutions prepared in Example 2 and Reference Example 1 were sterilized with a 0.45 μm filter to prepare a stock solution, which was diluted 1000 times with water and used in the following cultivation test.

[0165] Soak the tomato seeds in distilled water for 6 hours, remove the cuticle, and then dry them in a ventilated place for 30 minutes. Next, place 10 seeds on each of the culture dishes covered with absorbent paper, and then fill each culture dish with each fertilizer solution or water diluted 1000 times and immerse for 6 hours. Then, select 3 seeds of the same size from each culture dish for potting, and add each fertilizer solution or water diluted 1000 times 5 times every 2 days after the start, and cultivate for 11 days. The plant dry weight of the germinated seeds is measured and compared. The plant dry weight is measured after the root part is cut off and the remaining upper part is directly dried in a constant temperature dryer at 50°C for 12 hours. The results are shown in Table 1.

[0166] [Table 1]

[0167] Cultivation conditions Plant dry weight Fertilizer solution of Example 2 63g Fertilizer solution of Reference Example 1 61g Water only 38g

[0168] From the results in Table 1, it can be seen that the dry weight of the plant was about the same when the fertilizer solution of Example 2 was administered and when the fertilizer solution of Reference Example 1 was administered, and the dry weight of the plant increased compared to the case where only water was administered. Thus, the composition containing chitin hydrolyzate obtained by the method of Example 2 is effective as a fertilizer and can be produced more efficiently than the method of Reference Example 1.

[0169] Industrial Applicability

[0170] The method for producing a fertilizer of the present invention can efficiently produce a fertilizer containing a polysaccharide hydrolyzate and nutrients such as potassium, phosphoric acid, and nitrogen.

Claims

1. A method for producing a liquid fertilizer, characterized in that: It has the following processes: a hydrolysis step of hydrolyzing a polysaccharide composed of at least one selected from cellulose and chitin using phosphoric acid as an acid catalyst to obtain a mixture containing a polysaccharide hydrolyzate, and After the hydrolysis step, potassium hydroxide is added as a neutralization step of the alkaline compound.

2. The method for producing a liquid fertilizer according to claim 1, wherein the polysaccharide is purified chitin.

3. The method for producing a liquid fertilizer according to claim 1 or 2, further comprising a filtration step of separating a solid component by filtration after the neutralization step.

4. The method for producing liquid fertilizer according to claim 3, wherein the hydrolysis step is performed by a mechanochemical method. After the hydrolysis step, there is an extraction step of adding water to the mixture to extract water-soluble components.

5. The method for producing liquid fertilizer according to claim 4, wherein the mechanochemical method comprises pulverizing using a planetary ball mill or a vibration mill.