Ph-buffering and efficiency-enhancing carrier capable of reducing urea ammonia volatilization, and preparation method therefor and use thereof

Abstract

A pH-buffering and efficiency-enhancing carrier capable of reducing urea ammonia volatilization, and a preparation method therefor and a use thereof. A hydroxyl-containing organic acid and an alkali are used as raw materials to obtain a pH-buffering agent; furthermore, a pH-buffering performance protective agent prepared by taking a metal ion "chelating and precipitating" agent as a main raw material is combined with the pH-buffering agent to prepare the pH-buffering and efficiency-enhancing carrier. By reacting the chelating and precipitating agent with metal ions in a soil solution, e.g., calcium, iron, and aluminum, for precipitation and chelation, "bidirectional protection" of the buffering performance of the pH-buffering agent is achieved, and the pH-buffering agent is prevented from becoming ineffective due to reaction with the metal ions in soil. After the pH-buffering carrier is combined with urea, R-COOH thereof forms a structure of R-CO-NH-CO-NH2 with amino in urea, so that the stability of the pH in fertisphere of urea can be effectively enhanced, and the ammonia volatilization loss is reduced while nitrogen supply is ensured.

Description

A pH buffering synergistic carrier capable of reducing urea-ammonia volatilization, and its preparation method and application Technical Field

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

[0002] Urea is a major nitrogen fertilizer globally, accounting for 50% of global nitrogen fertilizer use. Ammonia volatilization is a significant source of nitrogen fertilizer loss, accounting for approximately 40% of agricultural emissions from farmland nitrogen fertilizer application. Therefore, developing new, high-efficiency urea products that can reduce ammonia volatilization is crucial for improving nitrogen fertilizer utilization, protecting the environment, and addressing global climate change.

[0003] Currently, efforts to reduce urea ammonia volatilization losses are primarily focused on developing products such as coated urea and stabilized urea. Coated urea reduces ammonia volatilization by coating the urea surface with a semipermeable or impermeable membrane material, such as resin or polyurethane. This allows for a slow release of nutrients. After urea is converted to ammonium carbonate, the ammonium ion concentration in the fertilizer microdomain is low, leading to a lower ammonia partial pressure and thus reducing ammonia volatilization losses. Stabilized urea reduces ammonia volatilization by adding urease inhibitors, such as NBPT, to the urea granules or during the urea application process. This slows 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 urea ammonia volatilization loss, 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 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.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a pH buffering synergistic carrier capable of reducing urea-ammonia volatilization, and a preparation method and application thereof. The pH buffering synergistic carrier provided by the present invention can reduce urea-ammonia volatilization loss while maintaining a high ammonium concentration in the urea fertilizer microdomain.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a buffering synergistic carrier, comprising a pH buffer and a buffering performance protecting agent:

[0009] 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;

[0010] 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.

[0011] 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.

[0012] Preferably, the hydroxyl-containing organic acid comprises the following components in parts by weight: 200-400 parts of citric acid; 100-200 parts of lactic acid; 50-100 parts of malic acid; 100-200 parts of gluconic acid; 30-80 parts of tartaric acid; and 20-50 parts of salicylic acid.

[0013] Preferably, the first alkaline compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

[0014] 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.

[0015] Preferably, the chelating precipitant comprises a chelating agent and a precipitating agent.

[0016] Preferably, the chelating agent is an aminopolycarboxylic acid chelating agent.

[0017] Preferably, the aminopolycarboxylic acid chelating agent includes one or both of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

[0018] Preferably, the precipitant comprises one or more of oxalic acid, succinic acid, glutaric acid and adipic acid.

[0019] Preferably, the second alkaline compound includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

[0020] Preferably, the chelating precipitant comprises the following components in parts by weight: 130 to 260 parts of chelating agent; and 400 to 650 parts of precipitating agent.

[0021] Preferably, 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; 50-100 parts of adipic acid;

[0022] The chelating agent comprises the following components in parts by weight: 100 to 200 parts of ethylenediaminetetraacetic acid; and 30 to 60 parts of diethylenetriaminepentaacetic acid.

[0023] Preferably, the volume ratio of the pH buffer to the buffering performance protecting agent is 1:0.5-2.

[0024] The present invention also provides a method for preparing the buffering and synergistic carrier described in the above scheme, comprising the following steps:

[0025] (1) premixing a hydroxyl-containing organic acid, mixing it with a first alkaline compound and water to obtain a pH buffer;

[0026] (2) premixing the chelating agent and the precipitating agent, and then mixing the premixed mixture with the second alkaline compound and water to obtain a buffering property protecting agent;

[0027] (3) mixing the pH buffering agent with the buffering performance protecting agent to obtain a buffering synergistic carrier;

[0028] There is no requirement for the time sequence of step (1) and step (2).

[0029] Preferably, the mass ratio of the hydroxyl-containing organic acid to water in step (1) is 200-600:1000.

[0030] Preferably, the mass ratio of the total mass of the chelating agent and the precipitant to water in step (2) is 100 to 300:1.

[0031] 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.

[0032] Preferably, the application of the buffering synergistic carrier in fertilization comprises the following steps:

[0033] The buffering synergistic carrier is mixed with urea to obtain a mixed fertilizer, and then the obtained mixed fertilizer is applied.

[0034] Preferably, the volume-to-mass ratio of the buffering and synergistic carrier to urea is (2-20) L:1000 kg.

[0035] Preferably, the application of the buffering and synergistic carrier in the buffering and synergistic urea granules includes method one or method two;

[0036] The first method is a method in which the volume-to-mass ratio of the buffering and synergistic carrier to urea is (2-6) L:1000 kg, comprising the following steps:

[0037] 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 the obtained urea modified liquid is then granulated to obtain buffering and synergistic urea granules;

[0038] The second method is a method in which the volume-to-mass ratio of the buffering and synergistic carrier to urea is (7-20) L:1000 kg, comprising the following steps:

[0039] 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.

[0040] 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 metal ions such as calcium, iron, and aluminum in the soil solution to precipitate and chelate, thereby achieving "two-way protection" of the buffering performance of the pH buffer, avoiding the pH buffer and the metal ions in the soil from reacting and failing, thereby better exerting the buffering performance and reducing the urea ammonia volatilization loss. The buffering synergistic carrier provided by the present invention reduces the urea ammonia volatilization loss by enhancing the pH stability of the urea fertilizer microdomain. At the same time, the buffering synergistic carrier is combined with urea, and the R-COOH in the buffer reacts with the -NH2 of urea to form an 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.

[0041] 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 a wide range of raw material sources.

[0042] The present invention also provides the use of the buffering and synergistic carrier described in the above embodiment or the buffering and synergistic carrier obtained by the preparation method described in the above embodiment in fertilization or buffering and synergistic urea granules. The buffering and synergistic carrier provided by the present invention is used in fertilization, especially in urea fertilization, to form a pH buffer zone in the urea-fertilizer microdomain, effectively reducing ammonia volatilization losses when the ammonium ion concentration of the soil solution is high.

[0043] The buffering and synergistic carrier provided by the present invention can also be used for buffering and synergistic urea granules, which can be added to the urea melt during the urea production process to produce high-efficiency urea products 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

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0045] FIG1 is a schematic flow diagram of a buffering and synergistic carrier provided by the present invention for preparing buffering and synergistic urea granules; wherein the upper figure is a schematic flow diagram of a preparation method when the volume mass ratio of the buffering and synergistic carrier to urea is (2 to 6) L:1000 kg, and the lower figure is a schematic flow diagram of a preparation method when the volume mass ratio of the buffering and synergistic carrier to urea is (7 to 20) L:1000 kg;

[0046] FIG2 is a diagram showing the mechanism of action of the buffering and synergistic carrier provided by the present invention;

[0047] FIG3 is a schematic diagram of an experiment showing the effect of the buffering and synergistic carrier provided by the present invention on ammonia volatilization;

[0048] FIG4 is a schematic diagram of a test of soil ammonia volatilization;

[0049] Figure 5 shows the structural characteristics of the products obtained by the reaction of the buffering and synergistic carrier (using 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 citric acid-urea reaction product, U is ordinary urea, and CAU10 is the citric acid-urea reaction product. DETAILED DESCRIPTION

[0050] The present invention provides a buffering synergistic carrier, comprising a pH buffer and a buffering performance protecting agent:

[0051] 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;

[0052] 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.

[0053] 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 ammonia volatilization loss can be better controlled within this pH range.

[0054] 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 even more preferably citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid. The hydroxyl-containing organic acids used in the present invention are safe and environmentally friendly, and have no side effects on the environment.

[0055] 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.

[0056] 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.

[0057] 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 use of water with a low chloride ion content in the present invention ensures a low chloride ion concentration in the buffering and synergistic carrier, and when the carrier is added during the urea production process, it does not corrode equipment such as the urine evaporator.

[0058] 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, within this pH range, ammonia volatilization loss can be better controlled. Secondly, within this pH range, the buffering synergistic carrier will not corrode urea production equipment, such as metering pumps and urine evaporators, during the urea production process.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] In the present invention, the water in the buffering performance protecting agent is preferably deionized water; the chloride ion content of the water is preferably ≤200 mg / L, more preferably ≤150 mg / L. The use of water with a low chloride ion content in the present invention ensures a low chloride ion concentration in the buffering and synergistic carrier, and when the carrier is added during the urea production process, it does not corrode equipment such as urine evaporators.

[0065] The present invention adopts a buffering performance 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+ Mg2+ 、Fe 3+ and Al 3+ The metal ions undergo precipitation reaction, thereby avoiding reducing the buffering effect of the pH buffer and reducing the effect of ammonia volatilization.

[0066] In the present invention, the volume ratio of the pH buffering agent to the buffering performance protecting agent is preferably 1:0.5-2, more preferably 1:1-1.5, and even more preferably 1:1.2.

[0067] The present invention also provides a method for preparing the buffering and synergistic carrier described in the above scheme, comprising the following steps:

[0068] (1) premixing a hydroxyl-containing organic acid, mixing it with a first alkaline compound and water to obtain a pH buffer;

[0069] (2) premixing the chelating agent and the precipitating agent, and then mixing the premixed mixture with the second alkaline compound and water to obtain a buffering property protecting agent;

[0070] (3) Mixing the pH buffering agent with the buffering performance protecting agent to obtain a buffering synergistic carrier.

[0071] The present invention premixes the hydroxyl-containing organic acid 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.

[0072] 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.

[0073] In the present invention, a chelating agent and a precipitating agent are premixed and then mixed with a 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 even more preferably 180 to 220:1.

[0074] After obtaining the pH buffer and the buffering performance protecting agent, the present invention mixes the pH buffer with the buffering performance protecting agent to obtain a buffering synergistic carrier. In the present invention, the mixing is preferably stirring.

[0075] 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.

[0076] In the present invention, the application of the buffering synergistic carrier in fertilization preferably includes the following steps: mixing the buffering synergistic carrier with urea to obtain a mixed fertilizer, and then applying the obtained mixed fertilizer.

[0077] 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.

[0078] 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.

[0079] In the present invention, the application of the buffering and synergistic carrier in the buffering and synergistic urea granules preferably includes method one or method two;

[0080] The method 1 is a method in which the volume-to-mass ratio of the buffering and synergistic carrier to urea is (2-6) L:1000 kg, preferably comprising the following steps:

[0081] 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 the obtained urea modified liquid is then granulated to obtain buffering and synergistic urea granules;

[0082] The second method is a method in which the volume-to-mass ratio of the buffering and synergistic carrier to urea is (7-20) L:1000 kg, preferably comprising the following steps:

[0083] 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.

[0084] 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 even more preferably 2 to 3 mm.

[0085] In the present invention, in the second method, the particle size of the granulation is preferably 0.9 to 2.5 mm, more preferably 1 to 2 mm, and even more preferably 1.5 to 2 mm.

[0086] FIG1 is a schematic flow diagram of a buffering and synergistic carrier provided by the present invention for preparing buffering and synergistic urea granules: when the volume-to-weight ratio of the buffering and synergistic carrier to urea is (2-6) L:1000 kg, the present invention adds the buffering and synergistic carrier to the urea melt after the second evaporation stage in urea production; when the volume-to-weight ratio of the buffering and synergistic carrier to urea is (7-20) L:1000 kg, the present invention adds the buffering and synergistic carrier to the urea melt between the first and second evaporation stages in urea production. The present invention takes into account both the application effect (during fertilization) and the feasibility of urea production (in fertilizer), without increasing the load of the urea evaporation process and controlling the moisture content of urea.

[0087] Figure 2 is a 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, thereby reducing the volatilization loss of urea and ammonia, while maintaining a high ammonium concentration in the urea fertilizer microdomain.

[0088] In order to further illustrate the present invention, the scheme of the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0089] Example 1

[0090] (1) Preparation of pH buffer

[0091] (A) citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid are mixed in a mass ratio of 300:150:80:150:50:40 to obtain a hydroxy acid mixture;

[0092] (B) uniformly mixing the hydroxy acid mixture and deionized water at a mass ratio of 400:1000, and then slowly adding potassium carbonate to the resulting acid solution to adjust the pH of the acid solution to 6.0 to obtain a pH buffer;

[0093] (2) Preparation of buffer performance protective agent

[0094] (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;

[0095] (B) uniformly mixing the mixed acid and deionized water at a mass ratio of 200:1, and then slowly adding potassium bicarbonate to the resulting acid solution to adjust the pH of the acid solution to 6.0 to obtain a buffering performance protecting agent;

[0096] (3) Preparation of buffering and synergistic carrier

[0097] The pH buffer and the buffer performance protective agent are mixed evenly in a volume ratio of 1:1 to obtain a buffer synergistic carrier.

[0098] Example 2

[0099] (1) Preparation of pH buffer

[0100] (A) citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid are uniformly mixed in a mass ratio of 200:100:50:100:30:20 to obtain a hydroxy acid mixture;

[0101] (B) uniformly mixing the hydroxy acid mixture 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;

[0102] (2) Preparation of buffer performance protective agent

[0103] (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;

[0104] (B) uniformly 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 to obtain a buffering performance protecting agent;

[0105] (3) Preparation of buffering and synergistic carrier

[0106] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:0.5 to obtain a buffer synergistic carrier.

[0107] Example 3

[0108] (1) Preparation of pH buffer

[0109] (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 mixture;

[0110] (B) uniformly mixing the hydroxy acid mixture 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;

[0111] (2) Preparation of buffer performance protective agent

[0112] (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;

[0113] (B) uniformly mixing the mixed acid and deionized water at 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 to obtain a buffering performance protective agent;

[0114] (3) Preparation of buffering and synergistic carrier

[0115] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:2 to obtain a buffer synergistic carrier.

[0116] Example 4

[0117] (1) Preparation of pH buffer

[0118] (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 mixture;

[0119] (B) uniformly mixing the hydroxy acid mixture 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;

[0120] (2) Preparation of buffer performance protective agent

[0121] (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;

[0122] (B) uniformly mixing the mixed acid and deionized water at 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;

[0123] (3) Preparation of buffering and synergistic carrier

[0124] The pH buffer and the buffer performance protective agent are mixed evenly in a volume ratio of 1:1.5 to obtain a buffer synergistic carrier.

[0125] Example 5

[0126] (1) Preparation of pH buffer

[0127] (A) citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid are uniformly mixed in a mass ratio of 320:160:80:170:60:35 to obtain a hydroxy acid mixture;

[0128] (B) uniformly mixing the hydroxy acid mixture 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 of the acid solution to 6.0 to obtain a pH buffer;

[0129] (2) Preparation of buffer performance protective agent

[0130] (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;

[0131] (B) uniformly mixing the mixed acid and deionized water at a mass ratio of 220:1, and then slowly adding sodium bicarbonate to the resulting acid solution to adjust the pH of the acid solution to 6.0 to obtain a buffering performance protecting agent;

[0132] (3) Preparation of buffering and synergistic carrier

[0133] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:1.2 to obtain a buffer synergistic carrier.

[0134] Example 6

[0135] (1) Preparation of pH buffer

[0136] (A) citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid are uniformly mixed in a mass ratio of 200:100:50:100:30:20 to obtain a hydroxy acid mixture;

[0137] (B) uniformly mixing the hydroxy acid mixture 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;

[0138] (2) Preparation of buffer performance protective agent

[0139] (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;

[0140] (B) uniformly 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 to obtain a buffering performance protective agent;

[0141] (3) Preparation of buffering and synergistic carrier

[0142] The pH buffer and the buffer performance protective agent are evenly mixed in a volume ratio of 1:0.5 to obtain a buffer synergistic carrier.

[0143] Application Example 1

[0144] 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.

[0145] Application Example 2

[0146] During the urea application process, the buffering synergistic carrier and urea are mixed in a volume-to-mass ratio of 2:1000 and then applied.

[0147] Application Example 3

[0148] In the conventional urea production process (see Figure 1), the amount of buffering and synergistic carrier added to urea is 2L / t. After the second evaporation stage, the buffering and synergistic carrier is added to the urea melt obtained in this stage.

[0149] Application Example 4

[0150] In the conventional urea production process (see Figure 1), the amount of buffering and synergistic carrier added to urea is 6L / t. After the second evaporation stage, the buffering and synergistic carrier is added to the urea melt obtained in this stage.

[0151] Application Example 5

[0152] In the conventional urea production process (see Figure 1), the amount of buffering and synergistic carrier added to urea is 7L / t. Between the first and second evaporation sections, the buffering and synergistic carrier is added to the urea melt obtained in this section.

[0153] Application Example 6

[0154] In the conventional urea production process (see Figure 1), the amount of buffering and synergistic carrier added to urea is 20L / t. Between the first and second evaporation sections, the buffering and synergistic carrier is added to the urea melt obtained in this section.

[0155] Test Example 1

[0156] Study on the effect of buffering synergistic carrier on reducing ammonia volatilization of ammonium bicarbonate solution

[0157] (1) Ammonium bicarbonate is first formed after urea hydrolysis. This test uses ammonium bicarbonate to simulate the higher ammonia concentration in the urea fertilizer microdomain.

[0158] The buffering synergistic carriers prepared in Examples 4 to 6 with a low concentration (21 g / L), a medium concentration (38 g / L), and a high concentration (55 g / L) and 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 experimental buffer liquids, which were respectively recorded as L, M, and H;

[0159] 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), which was recorded as CK.

[0160] 100 mL of ammonium bicarbonate solution was measured and placed in a 1 L culture bottle. The culture was cultured in a 25 °C climate chamber. The "ventilation method" was used to collect NH3 (see Figure 3 for instrument installation) to explore the effect of the buffering and enhancing carrier on ammonia volatilization. Samples were taken after 1 day of culture. The ammonium nitrogen absorbed by the sponge was 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.

[0161] Table 1 Effect of buffering synergistic carrier on reducing ammonia volatilization of ammonium bicarbonate solution

[0162] As shown in Table 1, 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%, among which group H can reduce the ammonia volatilization loss by 47.8%.

[0163] Test Example 2

[0164] Effects of buffering and synergistic carriers on urea conversion

[0165] Preparation of fertilizer: The low concentration (21 g / L), medium concentration (38 g / L), and high concentration (55 g / L) buffer synergistic carriers prepared in Examples 4 to 6, each with a pH value of 6, were added to a urea melt (130 ° C) at a volume mass ratio of 1:100. After cooling, the mixture was crushed and passed through a 0.149 mm sieve to obtain urea LU, MU, and HU, respectively, with ordinary urea (U) as a control.

[0166] The urea conversion rate was determined according to GB / T35113-2017. 0.500 g of the test urea (U, NU, NEU, NCU) was weighed and added to 100 mL of urease solution (activity ~1 U / mg, concentration 0.15 g / L). The mixture was placed in a (37±2)°C incubator and incubated 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.

[0167] Urea conversion rate (%) = (initial urea nitrogen content - residual urea nitrogen content after conversion) / initial urea nitrogen content × 100

[0168] Table 2 Effect of buffering and synergistic carrier on urea conversion

[0169] 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.

[0170] Test Example 3

[0171] Effects of buffering and synergistic carriers on ammonia volatilization from urea

[0172] 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: ordinary urea U, low concentration buffering synergistic carrier LU, medium concentration buffering synergistic carrier MU and high concentration buffering synergistic carrier HU.

[0173] Weigh an air-dried soil sample equivalent to 100g of dry soil (pass 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-culture in a 25℃ constant temperature incubator in the dark for 3 days to activate soil microbial activity. After the pre-culture, 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 Figure 4 for instrument installation) and culture in a 25℃ climate chamber in the dark. Sampling was carried out on the 1st, 2nd and 3rd day after incubation. The ammonium nitrogen absorbed in the sponge was tested by 1mol·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.

[0174] 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.

[0175] Table 3 Effect of buffering synergistic carrier on reducing urea ammonia volatilization

[0176] As shown in Table 3, compared with common urea U, LU, MU and HU of the present invention can all slow down the volatilization of urea ammonia, with the reduction ratio reaching up to 33%.

[0177] Test Example 4

[0178] The products obtained by reacting the buffering and synergistic carriers of Application Examples 1 to 6 of the present invention with urea were structurally characterized, and the results are shown in Figure 5. As shown in Figure 5, the buffering and synergistic carriers of the present invention bind to urea, and the R-COOH in the pH buffer reacts with the -NH2 of urea to form an R-CO-NH-CO-NH2 structure.

[0179] 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.

[0180] Although the above embodiment provides a detailed description of the present invention, 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 scope of protection of the present invention.

Claims

1. A buffer-enhanced carrier, comprising a pH buffer and a buffer performance protector: The pH buffer comprises a hydroxy-containing organic acid, a first basic compound and water; the types of the hydroxy-containing organic acid are not less than 3; the pH value of the pH buffer is 5-7; The buffer performance protector comprises a chelating precipitant, a second basic compound and water; the pH value of the buffer performance protector is 5-7.

2. The buffer-enhancing carrier according to claim 1, wherein The hydroxy-containing organic acid comprises more than three of citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, salicylic acid, glycolic acid, lactobionic acid and glycolic acid.

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

4. The buffer-enhancing carrier according to claim 1, characterized in that The first basic compound comprises one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

5. The buffer-enhancing carrier according to claim 1, wherein The chloride ion content of water in the pH buffer is ≤200 mg / L; the chloride ion content of water in the buffer performance protector is ≤200 mg / L.

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

7. The buffer-enhanced carrier according to claim 6, wherein The chelating agent is an aminopolycarboxylic acid chelating agent.

8. The buffer-enhancing carrier according to claim 7, characterized in that, The aminopolycarboxylic acid chelating agent comprises one or two of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

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

10. The buffering and synergistic carrier according to claim 1, wherein The second basic compound comprises one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate and sodium bicarbonate.

11. The buffer-enhancing 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; 50-100 parts of adipic acid. 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 buffer-enhancing carrier according to any one of claims 1 to 12, characterized in that The volume ratio of the pH buffer to the buffer performance protector is 1:0.5-2.

14. The preparation method of the buffer-enhanced carrier according to any one of claims 1-13, comprising the following steps: (1) Premix the hydroxy-containing organic acid and then mix it with the first basic compound and water to obtain a pH buffer; (2) Premix the chelating agent and the precipitant and then mix them with the second basic compound and water to obtain a buffer performance protector; (3) Mix the pH buffer with the buffer performance protector to obtain a buffer-enhanced carrier; There is no requirement for the time sequence of step (1) and step (2).

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

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

1.

17. The application of the buffer-enhanced carrier according to any one of claims 1-13 or the buffer-enhanced carrier obtained by the preparation method according to any one of claims 14-16 in fertilization or buffer-enhanced urea granules.

18. The application according to claim 17, wherein The application of the buffer synergistic carrier in fertilization includes the following steps: Mix the buffer synergistic carrier with urea to obtain a mixed fertilizer, and then apply the obtained mixed fertilizer.

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

20. The application according to claim 17, characterized in that The application of the buffer synergistic carrier in buffer synergistic urea granules includes Method 1 or Method 2; Method 1 is the method when the volume-mass ratio of the buffer synergistic carrier to urea is (2-6) L: 1000 kg, and includes the following steps: Based on the method of producing granular urea by fluidized bed granulation process, add the buffer synergistic carrier to the molten urea after the second evaporation section, and then granulate the obtained modified urea liquid to obtain buffer synergistic urea granules; Method 2 is the method when the volume-mass ratio of the buffer synergistic carrier to urea is (7-20) L: 1000 kg, and includes the following steps: Based on the method of producing granular urea by high tower granulation process, add the buffer synergistic carrier to the molten urea between the first evaporation section and the second evaporation section, and then granulate the obtained modified urea liquid to obtain buffer synergistic urea granules.

Images