PH buffering synergistic carrier capable of reducing urea ammonia volatilization as well as preparation method and application of pH buffering synergistic carrier

Abstract

The invention belongs to the technical field of efficient utilization of fertilizers, and particularly relates to a pH buffer synergistic carrier capable of reducing urea ammonia volatilization as well as a preparation method and application of the pH buffer synergistic carrier. Hydroxyl-containing organic acid and alkali are adopted as raw materials to obtain a pH buffering agent, meanwhile, a pH buffering performance protective agent prepared by taking a metal ion chelating and precipitating agent as a main raw material is matched with the pH buffering agent to prepare a pH buffering synergistic carrier, and a chelating precipitating agent reacts with metal ions such as calcium, iron and aluminum in a soil solution to precipitate and chelate, so that the soil solution is obtained. Two-way protection on the buffering performance of the pH buffering agent is realized, and failure caused by reaction of the pH buffering agent and metal ions in soil is avoided; the pH buffer carrier is combined with urea, R-COOH of the pH buffer carrier and amino of the urea form an R-CO-NH-CO-NH2 structure, the stability of microdomain pH of urea fertilizer can be effectively enhanced, and ammonia volatilization loss is reduced while nitrogen fertilizer supply is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of efficient utilization of fertilizers, and in particular relates to a pH buffering synergistic carrier capable of reducing the volatilization of urea and ammonia, and a preparation method and application thereof. Background Art

[0002] Urea is an important type of nitrogen fertilizer in the world, accounting for 50% of the world's nitrogen fertilizer. Ammonia volatilization is an important loss pathway for urea nitrogen fertilizer, and ammonia volatilization caused by nitrogen fertilizer application in farmland accounts for about 40% of agricultural emissions. Therefore, the development of new high-efficiency urea products that can reduce urea ammonia volatilization is of great significance to improving nitrogen fertilizer utilization, protecting the environment and responding to global climate change.

[0003] At present, people mainly reduce urea ammonia volatilization losses by developing products such as coated urea and stabilized urea. The principle of coated urea to reduce ammonia volatilization is to coat the surface of urea with semi-permeable or impermeable membrane materials such as resin and polyurethane to slowly release nutrients. After urea is converted into ammonium carbonate, the ammonium ion concentration in the fertilizer microdomain is small and the ammonia partial pressure is low, thereby reducing ammonia volatilization losses. The principle of stabilized urea to reduce ammonia volatilization is to add urease inhibitors such as NBPT to urea granules or during urea application to slow down the conversion of urea to ammonium carbonate, thereby reducing ammonia volatilization losses.

[0004] The above-mentioned coated urea and stable urea, the main way to reduce the loss of urea ammonia volatilization, is to control urea release, regulate urea conversion, etc., and reduce the ammonium concentration in the urea fertilizer micro-domain. However, coated urea and stable urea often have the problem of nutrient release, conversion and crop demand mismatch in farmland application, that is to say, when crops need nutrients in large quantities during the critical growth period, fertilizers are often not released or converted in sufficient quantity, resulting in insufficient nutrient supply, and even causing crop yield reduction. Therefore, in the urea fertilizer micro-domain, while maintaining a higher ammonium concentration and ensuring nutrient supply, reducing ammonia volatilization loss is an important way to coordinate crop high yield and environmental protection. Summary of the invention

[0005] The purpose of the present invention is to provide a pH buffering synergistic carrier capable of reducing the volatilization of urea and ammonia, and a preparation method and application thereof. The pH buffering synergistic carrier provided by the present invention can reduce the loss of urea and ammonia volatilization, while maintaining a high ammonium concentration in the urea fertilizer microdomain.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a buffering synergistic carrier, comprising a pH buffer and a buffering performance protective agent:

[0008] The pH buffer comprises a hydroxyl-containing organic acid, a first alkaline compound and water; the types of the hydroxyl-containing organic acid are not less than 3; the pH value of the pH buffer is 5 to 7;

[0009] The buffering performance protecting agent comprises a chelating precipitant, a second alkaline compound and water; the pH value of the buffering performance protecting agent is 5-7.

[0010] Preferably, the hydroxyl-containing organic acid includes three or more of citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, salicylic acid, glycolic acid, lactobionic acid and glycolic acid.

[0011] Preferably, the hydroxyl-containing organic acid comprises the following components in parts by weight:

[0012] 200-400 parts of citric acid;

[0013] Lactic acid 100-200 parts;

[0014] Malic acid 50-100 parts;

[0015] 100-200 parts of gluconic acid;

[0016] 30-80 parts of tartaric acid;

[0017] 20-50 parts of salicylic acid.

[0018] Preferably, the first alkaline compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

[0019] Preferably, the chloride ion content of water in the pH buffer is ≤200 mg / L; the chloride ion content of water in the buffering performance protecting agent is ≤200 mg / L.

[0020] Preferably, the chelating precipitant comprises a chelating agent and a precipitating agent.

[0021] Preferably, the chelating agent is an aminopolycarboxylic acid chelating agent.

[0022] Preferably, the aminopolycarboxylic acid chelating agent includes one or both of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

[0023] Preferably, the precipitant comprises one or more of oxalic acid, succinic acid, glutaric acid and adipic acid.

[0024] Preferably, the second alkaline compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

[0025] Preferably, the chelating precipitant comprises the following components in parts by weight:

[0026] 130-260 parts of chelating agent;

[0027] 400-650 parts of precipitant.

[0028] Preferably, the precipitant comprises the following components in parts by weight:

[0029] 200-300 parts of oxalic acid;

[0030] 100-150 parts of succinic acid;

[0031] 50-100 parts of glutaric acid;

[0032] Adipic acid 50-100 parts;

[0033] The chelating agent comprises the following components in parts by weight:

[0034] 100-200 parts of ethylenediaminetetraacetic acid;

[0035] 30-60 parts of diethylenetriaminepentaacetic acid.

[0036] Preferably, the volume ratio of the pH buffer to the buffering performance protecting agent is 1:0.5-2.

[0037] The present invention also provides a method for preparing the buffering and synergistic carrier described in the above scheme, comprising the following steps:

[0038] (1) premixing a hydroxyl-containing organic acid and mixing it with a first alkaline compound and water to obtain a pH buffer;

[0039] (2) premixing the chelating agent and the precipitating agent and mixing them with the second alkaline compound and water to obtain a buffering property protecting agent;

[0040] (3) mixing the pH buffer and the buffering performance protecting agent to obtain a buffering synergistic carrier;

[0041] There is no requirement for the chronological order of step (1) and step (2).

[0042] Preferably, the mass ratio of the hydroxyl-containing organic acid to water in step (1) is 200-600:1000.

[0043] Preferably, the mass ratio of the total mass of the chelating agent and the precipitating agent to water in step (2) is 100 to 300:1.

[0044] The present invention also provides the use of the buffering and synergistic carrier described in the above scheme or the buffering and synergistic carrier obtained by the preparation method described in the above scheme in fertilization or buffering and synergistic urea granules.

[0045] Preferably, the application of the buffering synergistic carrier in fertilization comprises the following steps:

[0046] The buffering synergistic carrier is mixed with urea to obtain a mixed fertilizer, and then the obtained mixed fertilizer is applied.

[0047] Preferably, the volume mass ratio of the buffering and synergistic carrier to urea is (2-20) L:1000 kg.

[0048] Preferably, the use of the buffering and synergistic carrier in the buffering and synergistic urea granules includes method one or method two;

[0049] The method 1 is a method in which the volume mass ratio of the buffering synergistic carrier to urea is (2-6) L:1000 kg, comprising the following steps:

[0050] Based on the method of producing granular urea by fluidized bed granulation process, a buffering and synergistic carrier is added to the urea melt after the second evaporation stage, and then the obtained urea modified liquid is granulated to obtain buffering and synergistic urea granules;

[0051] The second method is a method in which the volume mass ratio of the buffering synergistic carrier to urea is (7-20) L:1000 kg, comprising the following steps:

[0052] Based on the method of producing granular urea by high tower granulation process, a buffering and synergistic carrier is added to the urea melt between the first evaporation section and the second evaporation section, and then the obtained urea modified liquid is granulated to obtain buffering and synergistic urea granules.

[0053] The present invention provides a buffering synergistic carrier. The present invention uses organic acid and alkali as raw materials, hydroxyl-containing organic acid is used for pH buffer, chelating precipitant is used for buffering performance protective agent, and the chelating precipitant is reacted with calcium, iron, aluminum and other metal ions in soil solution to precipitate and chelate, so as to achieve "two-way protection" of pH buffer buffering performance, avoid pH buffer and metal ions in soil reaction and failure, so as to better play the buffering performance and reduce urea ammonia volatilization loss. The buffering synergistic carrier provided by the present invention reduces urea ammonia volatilization loss by enhancing the stability of urea fertilizer micro-domain pH, and at the same time, the buffering synergistic carrier is combined with urea, and R-COOH in the buffer reacts with -NH2 of urea to form R-CO-NH-CO-NH2 structure, which can slow down the conversion of urea to ammonium, coordinate the contradiction between urea nitrogen fertilizer supply and ammonia volatilization loss, and provide a new technical approach for the development of high-efficiency urea products.

[0054] The present invention also provides a method for preparing the buffering synergistic carrier described in the above scheme. The preparation method provided by the present invention has simple steps, convenient operation, low cost and wide source of raw materials.

[0055] The present invention also provides the use of the buffering and synergistic carrier described in the above scheme or the buffering and synergistic carrier obtained by the preparation method described in the above scheme in fertilization or buffering and synergistic urea granules. The buffering and synergistic carrier provided by the present invention is used for fertilization, especially in the process of urea fertilization, and can form a pH buffer area in the urea fertilizer microdomain, effectively reducing ammonia volatilization loss when the ammonium ion concentration of the soil solution is high.

[0056] The buffering and synergistic carrier provided by the present invention can also be used for buffering and synergistic urea granules, and is added to the urea melt during the urea production process to produce a high-efficiency urea product with buffering and loss-reducing functions, without the need for secondary processing and without affecting the production capacity of the urea production device. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 A schematic diagram of a process for preparing buffering and synergistic urea granules using a buffering and synergistic carrier provided by the present invention; wherein the upper figure is a schematic diagram of a process for preparing a buffering and synergistic carrier when the volume mass ratio of the buffering and synergistic carrier to urea is (2-6) L:1000 kg, and the lower figure is a schematic diagram of a process for preparing a buffering and synergistic carrier when the volume mass ratio of the urea is (7-20) L:1000 kg;

[0059] Figure 2 This is a diagram showing the mechanism of action of the buffering and synergistic carrier provided by the present invention;

[0060] Figure 3 This is a schematic diagram of an experiment on the effect of the buffering and synergistic carrier provided by the present invention on ammonia volatilization;

[0061] Figure 4 This is a schematic diagram of the experiment of soil ammonia volatilization;

[0062] Figure 5 The structural characteristics of the products obtained by the reaction of the buffering and enhancing carrier (taking citric acid as an example of a hydroxyl-containing organic acid) with urea in Application Examples 1 to 6; wherein (a) is the mass spectrum of ordinary urea, (b) is the mass spectrum of the product of the citric acid-urea reaction, U is ordinary urea, and CAU10 is the product of the citric acid-urea reaction. DETAILED DESCRIPTION

[0063] The present invention provides a buffering synergistic carrier, comprising a pH buffer and a buffering performance protective agent:

[0064] The pH buffer comprises a hydroxyl-containing organic acid, a first alkaline compound and water; the types of the hydroxyl-containing organic acid are not less than 3; the pH value of the pH buffer is 5 to 7;

[0065] The buffering performance protecting agent comprises a chelating precipitant, a second alkaline compound and water; the pH value of the buffering performance protecting agent is 5-7; and the chelating precipitant comprises a chelating agent and a precipitant.

[0066] In the present invention, the mass ratio of the hydroxyl-containing organic acid to the first alkaline compound is preferably based on the pH value of the pH buffer of 5 to 7. The pH value of the pH buffer in the present invention is 5.0 to 7.0, and within this pH value range, ammonia volatilization loss can be better controlled.

[0067] In the present invention, the hydroxyl-containing organic acid preferably includes three or more of citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, salicylic acid, glycolic acid, lactobionic acid and glycolic acid, more preferably three or more of citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid, and further preferably citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid. The above-mentioned hydroxyl-containing organic acid used in the present invention is safe and environmentally friendly, and has no side effects on the environment.

[0068] In the present invention, when the hydroxyl-containing organic acid is citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid, the hydroxyl-containing organic acid preferably includes 200 to 400 parts of citric acid, more preferably 250 to 350 parts, and further preferably 280 to 320 parts; the hydroxyl-containing organic acid preferably includes 100 to 200 parts of lactic acid, more preferably 120 to 180 parts, and further preferably 140 to 160 parts; the hydroxyl-containing organic acid preferably includes 50 to 100 parts of malic acid. , more preferably 60-90 parts, further preferably 70-80 parts; the hydroxyl-containing organic acid preferably includes 100-200 parts of gluconic acid, more preferably 120-190 parts, further preferably 150-170 parts; the hydroxyl-containing organic acid preferably includes 30-80 parts of tartaric acid, more preferably 40-70 parts, further preferably 50-60 parts; the hydroxyl-containing organic acid preferably includes 20-50 parts of salicylic acid, more preferably 30-40 parts, further preferably 35 parts.

[0069] In the present invention, the first alkaline compound preferably includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

[0070] In the present invention, the water in the pH buffer is preferably deionized water; the chloride ion content of the water is preferably ≤200 mg / L, more preferably ≤150 mg / L. The present invention uses water with a low chloride ion content to ensure that the chloride ion concentration of the buffering synergistic carrier is low, and when the carrier is added during the urea production process, it will not corrode equipment such as the urine evaporator.

[0071] In the present invention, the mass ratio of the chelating precipitant to the second alkaline compound is preferably based on the pH value of the buffering performance protecting agent being 5 to 7. The pH value of the buffering synergistic carrier is adjusted to 5.0 to 7.0 in the present invention. Firstly, the ammonia volatilization loss can be better controlled within this pH value range. Secondly, the buffering synergistic carrier will not corrode the urea production equipment, such as the metering pump and the urine evaporator, etc., during the urea production process when the pH value is controlled within the above pH value range.

[0072] In the present invention, the chelating precipitant preferably includes a chelating agent and a precipitating agent; the chelating agent is preferably an aminopolycarboxylic acid chelating agent; the aminopolycarboxylic acid chelating agent preferably includes one or two of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), more preferably ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA); the precipitating agent preferably includes one or more of oxalic acid, succinic acid, glutaric acid and adipic acid, more preferably oxalic acid, succinic acid, glutaric acid and adipic acid.

[0073] In the present invention, the chelating precipitant preferably includes 130 to 260 parts of chelating agent, more preferably 150 to 240 parts, and further preferably 180 to 210 parts; the chelating precipitant preferably includes 400 to 650 parts of precipitant, more preferably 440 to 600 parts, and further preferably 480 to 550 parts.

[0074] In the present invention, the precipitant preferably includes 200-300 parts of oxalic acid, more preferably 220-280 parts, and further preferably 240-260 parts; the precipitant preferably includes 100-150 parts of succinic acid, more preferably 110-140 parts, and further preferably 120-130 parts; the precipitant preferably includes 50-100 parts of glutaric acid, more preferably 60-90 parts, and further preferably 70-80 parts; the precipitant preferably includes 50-100 parts of adipic acid, more preferably 60-90 parts, and further preferably 75-85 parts.

[0075] In the present invention, the chelating agent preferably includes 100-200 parts of ethylenediaminetetraacetic acid, more preferably 130-180 parts, and further preferably 150-170 parts; the chelating agent preferably includes 30-60 parts of diethylenetriaminepentaacetic acid, more preferably 40-50 parts, and further preferably 45 parts.

[0076] In the present invention, the second alkaline compound preferably includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

[0077] In the present invention, the water in the buffering performance protective agent is preferably deionized water; the chloride ion content of the water is preferably ≤200 mg / L, more preferably ≤150 mg / L. The present invention uses water with a low chloride ion content to ensure that the chloride ion concentration of the buffering synergistic carrier is low, and when the carrier is added during the urea production process, it will not corrode equipment such as the urine evaporator.

[0078] The present invention adopts a buffering protective agent, a precipitant and metal ions to produce precipitation, and a chelating agent and metal ions to form a stable chelate, through the "precipitation-chelation" double protection, to avoid the hydroxyl organic acid and Ca in the soil 2+ Mg 2+ , Fe 3+ and Al 3+ The metal ions undergo precipitation reactions, thereby avoiding reducing the buffering effect of the pH buffer and reducing the effect of ammonia volatilization.

[0079] In the present invention, the volume ratio of the pH buffer to the buffering performance protecting agent is preferably 1:0.5-2, more preferably 1:1-1.5, and further preferably 1:1.2.

[0080] The present invention also provides a method for preparing the buffering and synergistic carrier described in the above scheme, comprising the following steps:

[0081] (1) premixing a hydroxyl-containing organic acid and mixing it with a first alkaline compound and water to obtain a pH buffer;

[0082] (2) premixing the chelating agent and the precipitating agent and mixing them with the second alkaline compound and water to obtain a buffering property protecting agent;

[0083] (3) Mixing the pH buffer and the buffering performance protecting agent to obtain a buffering synergistic carrier.

[0084] In the present invention, the hydroxyl-containing organic acid is premixed and then mixed with the first alkaline compound and water to obtain a pH buffer. In the present invention, the water in step (1) is preferably deionized water.

[0085] In the present invention, the mass ratio of the hydroxyl-containing organic acid to water in step (1) is preferably 200-600:1000, more preferably 300-500:1000, and further preferably 350-400:1000.

[0086] The present invention premixes the chelating agent and the precipitating agent and then mixes them with the second alkaline compound and water to obtain a buffering performance protecting agent. In the present invention, the mass ratio of the total mass of the chelating agent and the precipitating agent to water is preferably 100 to 300:1, more preferably 150 to 250:1, and further preferably 180 to 220:1.

[0087] After obtaining the pH buffer and the buffer performance protecting agent, the present invention mixes the pH buffer with the buffer performance protecting agent to obtain a buffering synergistic carrier. In the present invention, the mixing is preferably stirring.

[0088] The present invention also provides the use of the buffering and synergistic carrier described in the above scheme or the buffering and synergistic carrier obtained by the preparation method described in the above scheme in fertilization or buffering and synergistic urea granules.

[0089] In the present invention, the use of the buffering and synergistic carrier in fertilization preferably includes the following steps: mixing the buffering and synergistic carrier with urea to obtain a mixed fertilizer, and then applying the obtained mixed fertilizer.

[0090] In the present invention, the volume-to-weight ratio of the buffering and synergistic carrier to urea is preferably determined according to the soil pH value of the urea application area; the concentration and pH value of the buffering and synergistic carrier are preferably determined according to the soil pH value of the urea application area.

[0091] In the present invention, the volume-to-weight ratio of the buffering and synergistic carrier to urea is preferably (2-20) L:1000 kg, more preferably (5-15) L:1000 kg, and further preferably (8-12) L:1000 kg.

[0092] In the present invention, the use of the buffering and synergistic carrier in the buffering and synergistic urea granules preferably includes method one or method two;

[0093] The method 1 is a method in which the volume mass ratio of the buffering synergistic carrier to urea is (2-6) L:1000 kg, preferably comprising the following steps:

[0094] Based on the method of producing granular urea by fluidized bed granulation process, a buffering and synergistic carrier is added to the urea melt after the second evaporation stage (excluding the second evaporation stage), and then the obtained urea modified liquid is granulated to obtain buffering and synergistic urea granules;

[0095] The second method is a method in which the volume mass ratio of the buffering and synergistic carrier to urea is (7-20) L:1000 kg, preferably comprising the following steps:

[0096] Based on the method of producing granular urea by high tower granulation process, a buffering and synergistic carrier is added to the urea melt between the first evaporation section and the second evaporation section, and then the obtained urea modified liquid is granulated to obtain buffering and synergistic urea granules.

[0097] In the present invention, in method 1, the particle size of the granulation is preferably 2 to 4 mm, more preferably 2 to 3.5 mm, and further preferably 2 to 3 mm.

[0098] In the present invention, in method 2, the particle size of the granulation is preferably 0.9 to 2.5 mm, more preferably 1 to 2 mm, and further preferably 1.5 to 2 mm.

[0099] Figure 1 The buffering synergistic carrier provided by the present invention is used to prepare a flow diagram of buffering synergistic urea granules: when the volume weight ratio of the buffering synergistic carrier to urea is (2-6) L: 1000 kg, the present invention adds the buffering synergistic carrier to the urea melt after the second evaporation section in urea production; when the volume weight ratio of the buffering synergistic carrier to urea is (7-20) L: 1000 kg, the present invention adds the buffering synergistic carrier to the urea melt between the first evaporation section and the second evaporation section in urea production. The present invention takes into account both the application effect (in the fertilization process) and the feasibility of urea production (in fertilizer), without increasing the load of the urea evaporation process and controlling the moisture content of urea.

[0100] Figure 2 Diagram of the action mechanism of the buffering and synergistic carrier provided by the present invention: The present invention mixes the buffering and synergistic carrier with urea, or directly prepares the buffering and synergistic urea, and then applies it to the soil. Under the action of urease, the urea is ammonized into ammonium ions, and the buffering performance protective agent precipitates or chelates with the metal ions in the soil to improve the stability of the buffering performance of the buffer solution, thereby reducing the volatilization loss of urea ammonia, and maintaining a high ammonium concentration in the urea fertilizer microdomain.

[0101] In order to further illustrate the present invention, the scheme of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be understood as limiting the protection scope of the present invention.

[0102] Example 1

[0103] (1) Preparation of pH buffer

[0104] (A) mixing citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid in a mass ratio of 300:150:80:150:50:40 to obtain a hydroxy acid mixed acid;

[0105] (B) mixing the hydroxy acid mixed acid and deionized water in a mass ratio of 400:1000, and then slowly adding potassium carbonate to the obtained acid solution to adjust the pH value of the acid solution to 6.0 to obtain a pH buffer;

[0106] (2) Preparation of buffer performance protective agent

[0107] (A) mixing oxalic acid, succinic acid, glutaric acid, adipic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in a mass ratio of 250:120:80:60:150:50 to obtain a mixed acid;

[0108] (B) mixing the mixed acid and deionized water in a mass ratio of 200:1, and then slowly adding potassium bicarbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0, thereby obtaining a buffering performance protective agent;

[0109] (3) Preparation of buffering and enhancing carrier

[0110] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:1 to obtain a buffering synergistic carrier.

[0111] Example 2

[0112] (1) Preparation of pH buffer

[0113] (A) mixing citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid in a mass ratio of 200:100:50:100:30:20 to obtain a hydroxy acid mixed acid;

[0114] (B) mixing the hydroxy acid mixed acid and deionized water at a mass ratio of 200:1000, and then slowly adding potassium hydroxide to the resulting acid solution to adjust the pH value of the acid solution to 5.0 to obtain a pH buffer;

[0115] (2) Preparation of buffer performance protective agent

[0116] (A) mixing oxalic acid, succinic acid, glutaric acid, adipic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in a mass ratio of 200:100:50:50:100:30 to obtain a mixed acid;

[0117] (B) mixing the mixed acid and deionized water in a mass ratio of 100:1, and then slowly adding sodium hydroxide to the resulting acid solution to adjust the pH value of the acid solution to 5.0, thereby obtaining a buffering performance protective agent;

[0118] (3) Preparation of buffering and enhancing carrier

[0119] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:0.5 to obtain a buffering synergistic carrier.

[0120] Example 3

[0121] (1) Preparation of pH buffer

[0122] (A) mixing citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid in a mass ratio of 400:200:100:200:80:50 to obtain a hydroxy acid mixed acid;

[0123] (B) mixing the hydroxy acid mixed acid and deionized water at a mass ratio of 600:1000, and then slowly adding sodium carbonate to the resulting acid solution to adjust the pH value of the acid solution to 7.0 to obtain a pH buffer;

[0124] (2) Preparation of buffer performance protective agent

[0125] (A) mixing oxalic acid, succinic acid, glutaric acid, adipic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in a mass ratio of 300:150:100:100:200:60 to obtain a mixed acid;

[0126] (B) mixing the mixed acid and deionized water in a mass ratio of 300:1, and then slowly adding sodium bicarbonate to the resulting acid solution to adjust the pH value of the acid solution to 7.0, thereby obtaining a buffering performance protective agent;

[0127] (3) Preparation of buffering and enhancing carrier

[0128] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:2 to obtain a buffering synergistic carrier.

[0129] Example 4

[0130] (1) Preparation of pH buffer

[0131] (A) mixing citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid in a mass ratio of 350:180:90:190:70:40 to obtain a hydroxy acid mixed acid;

[0132] (B) mixing the hydroxy acid mixed acid and deionized water at a mass ratio of 500:1000, and then slowly adding sodium carbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0 to obtain a pH buffer;

[0133] (2) Preparation of buffer performance protective agent

[0134] (A) mixing oxalic acid, succinic acid, glutaric acid, adipic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in a mass ratio of 280:140:90:90:180:50 to obtain a mixed acid;

[0135] (B) mixing the mixed acid and deionized water in a mass ratio of 250:1, and then slowly adding sodium bicarbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0 to obtain a buffering performance protective agent;

[0136] (3) Preparation of buffering and enhancing carrier

[0137] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:1.5 to obtain a buffering synergistic carrier.

[0138] Example 5

[0139] (1) Preparation of pH buffer

[0140] (A) mixing citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid in a mass ratio of 320:160:80:170:60:35 to obtain a hydroxy acid mixed acid;

[0141] (B) mixing the hydroxy acid mixed acid and deionized water at a mass ratio of 400:1000, and then slowly adding sodium carbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0 to obtain a pH buffer;

[0142] (2) Preparation of buffer performance protective agent

[0143] (A) mixing oxalic acid, succinic acid, glutaric acid, adipic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in a mass ratio of 260:130:80:85:170:45 to obtain a mixed acid;

[0144] (B) mixing the mixed acid and deionized water in a mass ratio of 220:1, and then slowly adding sodium bicarbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0 to obtain a buffering performance protective agent;

[0145] (3) Preparation of buffering and enhancing carrier

[0146] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:1.2 to obtain a buffering synergistic carrier.

[0147] Example 6

[0148] (1) Preparation of pH buffer

[0149] (A) mixing citric acid, lactic acid, malic acid, gluconic acid, tartaric acid and salicylic acid in a mass ratio of 200:100:50:100:30:20 to obtain a hydroxy acid mixed acid;

[0150] (B) mixing the hydroxy acid mixed acid and deionized water at a mass ratio of 200:1000, and then slowly adding sodium carbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0 to obtain a pH buffer;

[0151] (2) Preparation of buffer performance protective agent

[0152] (A) mixing oxalic acid, succinic acid, glutaric acid, adipic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in a mass ratio of 200:100:50:50:100:30 to obtain a mixed acid;

[0153] (B) mixing the mixed acid and deionized water in a mass ratio of 100:1, and then slowly adding sodium bicarbonate to the resulting acid solution to adjust the pH value of the acid solution to 6.0, thereby obtaining a buffering performance protective agent;

[0154] (3) Preparation of buffering and enhancing carrier

[0155] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:0.5 to obtain a buffering synergistic carrier.

[0156] Application Example 1

[0157] During the urea application process, the buffering synergistic carrier and urea are mixed in a volume-to-mass ratio of 50:1000 and then applied.

[0158] Application Example 2

[0159] During the urea application process, the buffering synergistic carrier and urea are mixed at a volume-to-mass ratio of 2:1000 and then applied.

[0160] Application Example 3

[0161] In the conventional urea production process (see Figure 1 ), the amount of the buffering and synergistic carrier added to the urea is 2L / t, and after the second evaporation section, the buffering and synergistic carrier is added to the urea melt obtained in this section.

[0162] Application Example 4

[0163] In the conventional urea production process (see Figure 1 ), the amount of the buffering and synergistic carrier added to the urea is 6L / t. After the second evaporation section, the buffering and synergistic carrier is added to the urea melt obtained in this section.

[0164] Application Example 5

[0165] In the conventional urea production process (see Figure 1), the amount of the buffering and synergistic carrier added to the urea is 7L / t, and between the first evaporation section and the second evaporation section, the buffering and synergistic carrier is added to the urea melt obtained in the section.

[0166] Application Example 6

[0167] In the conventional urea production process (see Figure 1 ), the amount of the buffering and synergistic carrier added to the urea is 20L / t, and between the first evaporation section and the second evaporation section, the buffering and synergistic carrier is added to the urea melt obtained in the section.

[0168] Test Example 1

[0169] Study on the effect of buffered synergistic carrier on reducing ammonia volatilization of ammonium bicarbonate solution

[0170] (1) Ammonium bicarbonate is formed first after urea hydrolysis. This test uses ammonium bicarbonate to simulate the higher ammonia concentration in the urea fertilizer microdomain.

[0171] The buffering synergistic carriers with low concentration (21 g / L), medium concentration (38 g / L) and high concentration (55 g / L) prepared in Examples 4 to 6 and with a pH value of 6 were selected, and the three buffering synergistic carriers were mixed with distilled water at a volume ratio of 20:1000 to obtain test buffer liquids, which were respectively recorded as L, M and H;

[0172] Ammonium bicarbonate and the experimental buffer liquid were mixed evenly at a fertilizer-water ratio of 1:500 to obtain the corresponding ammonium bicarbonate solution; at the same time, an ammonium bicarbonate solution of the same concentration was prepared with distilled water as a control (the volume ratio of ammonium bicarbonate solution to distilled water was 1:500), recorded as CK.

[0173] Measure 100 mL of ammonium bicarbonate solution, place it in a 1 L culture bottle, culture it in a 25 °C climate chamber, and use the "ventilation method" to collect NH3 (see the instrument installation for details). Figure 3 ) to explore the effect of buffering and enhancing carriers on ammonia volatilization. Samples were taken after 1 day of cultivation. The ammonium nitrogen absorbed by the sponge was treated with 1 mol·L -1 The volatilization amount of NH3 was calculated after extraction with KCl solution and measurement by continuous flow injection analyzer (SEAL, AA3). Each treatment was repeated 3 times. The results are shown in Table 1.

[0174] Table 1 Effect of buffering synergistic carrier on reducing ammonia volatilization of ammonium bicarbonate solution

[0175] Group Ammonia emission (Nmg / L) Ammonia volatilization reduction rate compared with CK CK 1454.5 / L 947.6 34.8％ M 862.0 40.7％ H 759.4 47.8％

[0176] It can be seen from Table 1 that the buffering synergistic carrier provided by the present invention can significantly reduce the ammonia volatilization loss of ammonium bicarbonate solution, with an average reduction of 41.1%, wherein group H can reduce the ammonia volatilization loss by 47.8%.

[0177] Test Example 2

[0178] Effect of buffering and enhancing carrier on urea conversion

[0179] Preparation of fertilizer: The low concentration (21 g / L), medium concentration (38 g / L), high concentration (55 g / L) buffered synergistic carriers prepared in Examples 4 to 6, with a pH value of 6, were added to a urea melt (130° C.) at a volume mass ratio of 1:100, cooled and crushed, and passed through a 0.149 mm sieve to obtain urea LU, MU and HU, respectively, with ordinary urea (U) as a control.

[0180] The urea conversion rate was determined according to GB / T 35113-2017. 0.500 g of the test urea (U, NU, NEU, NCU) was weighed respectively, 100 mL of urease solution (activity ~1 U / mg, concentration of 0.15 g / L) was added, and the mixture was incubated in a (37±2)°C incubator for 1 h. The urea conversion rate was then determined using the p-dimethylaminobenzaldehyde colorimetric method. The urea conversion rate was calculated using the following formula. The results are shown in Table 2.

[0181] Urea conversion rate (%) = (initial urea nitrogen content - residual urea nitrogen content after conversion) / initial urea nitrogen content × 100

[0182] Table 2 Effect of buffering and enhancing carrier on urea conversion

[0183] Group Urea conversion rate (%) U 22.71 LU 16.93 MU 16.77 HU 14.08

[0184] According to Table 2, compared with common urea U, LU, MU and HU can slow down urea conversion, and their urea conversion rates are significantly reduced by 5.78, 5.95 and 8.63 percentage points, respectively.

[0185] Test Example 3

[0186] Effect of Buffering and Synergistic Carrier on Urea Ammonia Volatilization

[0187] The experiment was designed according to the principle of equal nitrogen dosage, with nitrogen application rate of 0.3 g / kg dry soil, and four treatments were set: common urea U, low-concentration buffering and synergistic carrier LU, medium-concentration buffering and synergistic carrier MU and high-concentration buffering and synergistic carrier HU;

[0188] Weigh an air-dried soil sample equivalent to 100g of dry soil (passed through a 2mm sieve) and place it in a 1000mL culture bottle with a small hole drilled on the lid. Adjust the soil moisture content to 50% of the maximum field water holding capacity and pre-cultivate in a 25℃ constant temperature incubator in the dark for 3 days to activate soil microbial activity. After the pre-cultivation, add the weighed test fertilizer to the soil according to the experimental design, mix thoroughly and adjust the soil moisture content to 20%. Use the "ventilation method" to collect NH3 (see the instrument installation for details). Figure 4 ) and cultured in a 25°C climate chamber in the dark. Samples were taken on the 1st, 2nd and 3rd day after culture, and the ammonium nitrogen absorbed by the sponge was measured by 1 mol·L -1 The soil NH3 volatilization was calculated after extraction with KCl solution and measured by flow analyzer. Each treatment was repeated 3 times. At the same time, the soil pH value was measured.

[0189] SPSS23 software and Duncan's new multiple range method were used to perform variance analysis and correlation analysis on the data. The results are shown in Table 3.

[0190] Table 3 Effect of buffering synergistic carrier on reducing urea ammonia volatilization

[0191]

[0192] It can be seen from Table 3 that compared with common urea U, LU, MU and HU of the present invention can all slow down the volatilization of urea ammonia, and the reduction ratio can reach up to 33%.

[0193] Test Example 4

[0194] The products obtained by reacting the buffering synergistic carriers of Application Examples 1 to 6 of the present invention with urea were characterized in terms of structure. Figure 5 As shown. Figure 5 It can be seen that the buffering and synergistic carrier of the present invention is combined with urea, and the R-COOH in the pH buffer reacts with the -NH2 of urea to form a R-CO-NH-CO-NH2 structure.

[0195] It can be seen from the above examples that the buffering synergistic carrier provided by the present invention can reduce the loss of urea and ammonia volatilization, while slowing down the conversion of urea to ammonium, and coordinating the contradiction between urea nitrogen fertilizer supply and ammonia volatilization loss.

[0196] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A buffering and synergistic carrier, comprising a pH buffer and a buffering performance protective agent: The pH buffer comprises a hydroxyl-containing organic acid, a first alkaline compound and water; the types of the hydroxyl-containing organic acid are not less than 3; the pH value of the pH buffer is 5 to 7; The buffering performance protecting agent comprises a chelating precipitant, a second alkaline compound and water; the pH value of the buffering performance protecting agent is 5-7.

2. The buffering and synergistic carrier according to claim 1, characterized in that: The hydroxyl-containing organic acid includes three or more of citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, salicylic acid, glycolic acid, lactobionic acid and glycolic acid.

3. The buffering and synergistic carrier according to claim 1 or 2, characterized in that: The hydroxyl-containing organic acid comprises the following components in parts by weight: 200-400 parts of citric acid; Lactic acid 100-200 parts; Malic acid 50-100 parts; 100-200 parts of gluconic acid; 30-80 parts of tartaric acid; 20-50 parts of salicylic acid.

4. The buffering and synergistic carrier according to claim 1, characterized in that: The first alkaline compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

5. The buffering and synergistic carrier according to claim 1, characterized in that: The chloride ion content of water in the pH buffer is ≤200 mg / L; the chloride ion content of water in the buffer performance protecting agent is ≤200 mg / L.

6. The buffering and synergistic carrier according to claim 1, characterized in that: The chelating precipitant comprises a chelating agent and a precipitating agent.

7. The buffering and synergistic carrier according to claim 6, characterized in that: The chelating agent is an aminopolycarboxylic acid chelating agent.

8. The buffering and synergistic carrier according to claim 7, characterized in that: The aminopolycarboxylic acid chelating agent includes one or both of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

9. The buffering and synergistic carrier according to claim 6, characterized in that: The precipitant includes one or more of oxalic acid, succinic acid, glutaric acid and adipic acid.

10. The buffering and synergistic carrier according to claim 1, characterized in that: The second alkaline compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

11. The buffering and synergistic carrier according to any one of claims 6 to 9, characterized in that: The chelating precipitant comprises the following components in parts by weight: 130-260 parts of chelating agent; 400-650 parts of precipitant.

12. The buffering and synergistic carrier according to any one of claims 6 to 9, characterized in that: The precipitant comprises the following components in parts by weight: 200-300 parts of oxalic acid; 100-150 parts of succinic acid; 50-100 parts of glutaric acid; Adipic acid 50-100 parts; The chelating agent comprises the following components in parts by weight: 100-200 parts of ethylenediaminetetraacetic acid; 30-60 parts of diethylenetriaminepentaacetic acid.

13. The buffering and synergistic carrier according to any one of claims 1 to 12, characterized in that: The volume ratio of the pH buffer to the buffer performance protecting agent is 1:0.5-2.

14. The method for preparing the buffering and synergistic carrier according to any one of claims 1 to 13, comprising the following steps: (1) premixing a hydroxyl-containing organic acid and mixing it with a first alkaline compound and water to obtain a pH buffer; (2) premixing the chelating agent and the precipitating agent and mixing them with the second alkaline compound and water to obtain a buffering property protecting agent; (3) mixing the pH buffer and the buffering performance protecting agent to obtain a buffering synergistic carrier; There is no requirement for the chronological order of step (1) and step (2).

15. The preparation method according to claim 14, characterized in that: The mass ratio of the hydroxyl-containing organic acid to water in step (1) is 200-600:1000.

16. The preparation method according to claim 14, characterized in that: The mass ratio of the total mass of the chelating agent and the precipitating agent to water in step (2) is 100 to 300:

1.

17. Use of the buffering and synergistic carrier according to any one of claims 1 to 13 or the buffering and synergistic carrier obtained by the preparation method according to any one of claims 14 to 16 in fertilization or buffering and synergistic urea granules.

18. The use according to claim 17, characterized in that The application of the buffering synergistic carrier in fertilization comprises the following steps: The buffering synergistic carrier is mixed with urea to obtain a mixed fertilizer, and then the obtained mixed fertilizer is applied.

19. The use according to claim 18, characterized in that The volume mass ratio of the buffering synergistic carrier to urea is (2-20) L:1000 kg.

20. The use according to claim 17, characterized in that The use of the buffering and synergistic carrier in the buffering and synergistic urea granules includes method one or method two; The method 1 is a method in which the volume mass ratio of the buffering synergistic carrier to urea is (2-6) L:1000 kg, comprising the following steps: Based on the method of producing granular urea by fluidized bed granulation process, a buffering and synergistic carrier is added to the urea melt after the second evaporation stage, and then the obtained urea modified liquid is granulated to obtain buffering and synergistic urea granules; The second method is a method in which the volume mass ratio of the buffering synergistic carrier to urea is (7-20) L:1000 kg, comprising the following steps: Based on the method of producing granular urea by high tower granulation process, a buffering and synergistic carrier is added to the urea melt between the first evaporation section and the second evaporation section, and then the obtained urea modified liquid is granulated to obtain buffering and synergistic urea granules.

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