Patent Application
20250223241
The present disclosure belongs to the technical field of efficient utilization of fertilizers, and specifically relates to a pH-buffering synergistic carrier for reducing ammonia volatilization in urea, and a preparation method and use thereof.
Urea is an important type of nitrogen fertilizer in the world, accounting for 50% of the global nitrogen fertilizers. Ammonia volatilization is an important loss pathway for urea nitrogen fertilizer, and the ammonia volatilization caused by nitrogen fertilizer application on farmland accounts for about 40% of agricultural emission sources. Therefore, the development of novel high-efficiency urea products that can reduce the ammonia volatilization in urea is of great significance to improve nitrogen utilization efficiency, protect the environment, and cope with global climate change.
At present, people mainly reduce the ammonia volatilization loss in urea by developing products such as coated urea and stable urea. A principle of the coated urea to reduce ammonia volatilization includes: coating a surface of the urea with semi-permeable or impermeable membrane materials such as resin and polyurethane to slowly release nutrients; after the urea is converted into ammonium bicarbonate, there is a lower concentration of ammonium ions in a fertilizer micro-domain. At this time, an ammonia partial pressure is lower, thereby reducing the ammonia volatilization loss. A principle of the stable urea to reduce ammonia volatilization is to add urease inhibitors such as N-(n-butyl) thiophosphoric triamide (NBPT) into urea particles or during urea application to slow down the conversion of urea into ammonium bicarbonate, thereby reducing the ammonia volatilization loss.
A main way for the coated urea and stable urea to reduce the ammonia volatilization loss in urea is to control the release of urea and regulate the conversion of urea, thereby reducing the ammonium concentration in the urea fertilizer micro-domain. However, when being used in farmland, the coated urea and stable urea generally have the problem of mismatch between the release and transformation of nutrients and the crop demands. That is to say, when crops require a large amount of nutrients during the critical growth period, fertilizers are generally unable to be released or converted in insufficient amounts, resulting in insufficient nutrient supply or even reduced crop yields. Accordingly, it is an important way to coordinate high crop yields and environmental protection by maintaining a high ammonium concentration in the urea fertilization micro-domain and ensuring nutrient supply while reducing the ammonia volatilization losses.
An objective of the present disclosure is to provide a pH-buffering synergistic carrier for reducing ammonia volatilization in urea, and a preparation method and use thereof. In the present disclosure, the pH-buffering synergistic carrier can reduce the ammonia volatilization loss in urea while maintaining a high ammonium concentration in the urea fertilization micro-domain.
To achieve the above objective, the present disclosure provides the following technical solutions:
The present disclosure provides a buffering synergistic carrier, including a pH buffer and a buffer performance protectant; where
Preferably, the hydroxyl-containing organic acid is three or more selected from the group consisting of citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, salicylic acid, lactobionic acid, and glycolic acid.
Preferably, the hydroxyl-containing organic acid includes the following components in parts by weight:
Preferably, the first alkaline compound is one or more selected from the group consisting of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.
Preferably, the water in the pH buffer has a chloride ion content of less than or equal to 200 mg/L; and the water in the buffer performance protectant has a chloride ion content of less than or equal to 200 mg/L.
Preferably, the chelating precipitant includes a chelating agent and a precipitant.
Preferably, the chelating agent is an aminopolycarboxylic acid chelating agent.
Preferably, the aminopolycarboxylic acid chelating agent is one or two selected from the group consisting of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA).
Preferably, the precipitant is one or more selected from the group consisting of oxalic acid, succinic acid, glutaric acid, and adipic acid.
Preferably, the second alkaline compound is one or more selected from the group consisting of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.
Preferably, the chelating precipitant includes the following components in parts by weight:
Preferably, the precipitant includes the following components in parts by weight:
Preferably, the pH buffer and the buffer performance protectant are at a volume ratio of 1:(0.5-2).
The present disclosure further provides a preparation method of the buffering synergistic carrier, including the following steps:
Preferably, the hydroxyl-containing organic acid and the water in step (1) are at a mass ratio of (200-600):1000.
Preferably, a total mass of the chelating agent and the precipitant and a mass of the water in step (2) are at a ratio of (100-300):1000.
The present disclosure further provides use of the buffering synergistic carrier or a buffering synergistic carrier prepared by the preparation method in fertilization or buffering synergistic urea granules.
Preferably, the use of the buffering synergistic carrier in the fertilization includes the following steps:
Preferably, the buffering synergistic carrier and the urea are at a volume-to-mass ratio of (2-20) L:1000 kg.
Preferably, the use of the buffering synergistic carrier in the buffering synergistic urea granules specifically includes a first method and a second method;
the first method is adopted when the buffering synergistic carrier and the urea are at a volume-to-mass ratio of (2-6) L:1000 kg, and includes the following steps:
The present disclosure provides a buffering synergistic carrier. In the present disclosure, an organic acid and an alkali are used as raw materials. The hydroxyl-containing organic acid is used as a pH buffer, and the chelating precipitant is used as a buffer performance protectant. By reacting, precipitating, and chelating with calcium, iron, aluminum and other metal ions in the soil solution using the chelating precipitant, “two-way protection” of a buffer performance of the pH buffer is achieved. In this way, the pH buffer is prevented from reacting with metal ions in the soil and becomes ineffective, thereby better exerting the buffer performance and reducing the ammonia volatilization loss in urea. The buffering synergistic carrier reduces the ammonia volatilization loss in urea by enhancing a stability of the pH value in a urea fertilizer micro-domain. At the same time, the buffering synergistic carrier is combined with urea, and an R—CO—NH—CO—NH2 structure formed by the reaction between R—COOH in the buffering synergistic carrier and —NH2 of the urea can slow down the conversion of urea into ammonium. This process coordinates a contradiction between the supply of urea nitrogen fertilizer and the ammonia volatilization loss, providing a new technological approach for the development of high-efficiency urea products.
The present disclosure further provides a preparation method of the buffering synergistic carrier. In the present disclosure, the preparation method has simple steps, convenient operation, low cost, and wide source of raw materials.
The present disclosure further provides use of the buffering synergistic carrier or a buffering synergistic carrier prepared by the preparation method in fertilization or buffering synergistic urea granules. In the present disclosure, the buffering synergistic carrier can form a pH-buffering area in the urea fertilizer micro-domain during fertilization, especially urea fertilization, thereby effectively reducing the ammonia volatilization loss when there is a high ammonium ion concentration in the soil solution.
In the present disclosure, the buffering synergistic carrier can also be used to produce buffering synergistic urea granules. During the urea production, the buffering synergistic carrier is added into the urea melt to produce a high-efficiency urea product with buffering and loss-reducing functions. This production process requires no secondary processing and does not affect the capacity of a urea production unit.
To describe the technical solutions in embodiments of the present disclosure or in the prior art more clearly, the accompanying drawings required for the embodiments are briefly described below. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and those of ordinary skill in the art may still derive other accompanying drawings from these accompanying drawings without creative efforts.
The present disclosure provides a buffering synergistic carrier, including a pH buffer and a buffer performance protectant; where
In the present disclosure, the mass ratio of the hydroxyl-containing organic acid to the first alkaline compound is preferably based on the pH buffer having a pH value of 5 to 7. The pH buffer has a pH value of 5 to 7, and the ammonia volatilization loss can be better controlled within this pH value range.
Preferably, the hydroxyl-containing organic acid is preferably three or more selected from the group consisting 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 selected from the group consisting of the citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid, and even more preferably the citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid. The hydroxyl-containing organic acid used is safe and environmental-friendly, and has no side effects on the environment.
In the present disclosure, when the hydroxyl-containing organic acid is selected from the citric acid, lactic acid, malic acid, gluconic acid, tartaric acid, and salicylic acid, the hydroxyl-containing organic acid preferably includes 200 parts to 400 parts, more preferably 250 parts to 350 parts, and even more preferably 280 parts to 320 parts of the citric acid; or preferably 100 parts to 200 parts, more preferably 120 parts to 180 parts, and even more preferably 140 parts to 160 parts of the lactic acid; or preferably 50 parts to 100 parts, more preferably 60 parts to 90 parts, and even more preferably 70 parts to 80 parts of the malic acid; or preferably 100 parts to 200 parts, more preferably 120 parts to 190 parts, and even more preferably 150 parts to 170 parts of the gluconic acid; or preferably 30 parts to 80 parts, more preferably 40 parts to 70 parts, and even more preferably 50 parts to 60 parts of the tartaric acid; or preferably 20 parts to 50 parts, more preferably 30 parts to 40 parts, and even more preferably 35 parts of the salicylic acid.
In the present disclosure, the first alkaline compound is preferably one or more selected from the group consisting of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.
In the present disclosure, the water in the pH buffer is preferably deionized water; and the water has a chloride ion content of preferably less than or equal to 200 mg/L, more preferably less than or equal to 150 mg/L. The water with low chloride ion content can ensure that the buffering synergistic carrier has a low chloride ion concentration, such that equipment such as urine evaporators are not corroded when the carrier is added during the urea production.
In the present disclosure, the mass ratio of the chelating precipitant and the second alkaline compound is preferably based on the buffer performance protectant having a pH value of 5 to 7. The pH value of the buffering synergistic carrier is adjusted to 5 to 7. First, ammonia volatilization loss can be better controlled within this pH value range. The second is that when controlling the pH value within the above range, the buffering synergistic carrier does not corrode urea production equipment such as metering pumps and urine evaporators during the urea production.
In the present disclosure, the chelating precipitant preferably includes a chelating agent and a precipitant; the chelating agent is preferably an aminopolycarboxylic acid chelating agent; the aminopolycarboxylic acid chelating agent is preferably one or two selected from the group consisting of EDTA and DTPA, and more preferably includes the EDTA and DTPA; and the precipitant is preferably one or more selected from the group consisting of oxalic acid, succinic acid, glutaric acid, and adipic acid, and more preferably includes the oxalic acid, succinic acid, glutaric acid, and adipic acid.
In the present disclosure, the chelating precipitant includes preferably 130 parts to 260 parts, more preferably 150 parts to 240 parts, and even more preferably 180 parts to 210 parts of the chelating agent, as well as preferably 400 parts to 650 parts, more preferably 440 parts to 600 parts, and even more preferably 480 parts to 550 parts of the precipitant.
In the present disclosure, the precipitant includes preferably 200 parts to 300 parts, more preferably 220 parts to 280 parts, and even more preferably 240 parts to 260 parts of the oxalic acid, preferably 100 parts to 150 parts, more preferably 110 parts to 140 parts, and even more preferably 120 parts to 130 parts of the succinic acid, preferably 50 parts to 100 parts, more preferably 60 parts to 90 parts, and even more preferably 70 parts to 80 parts of the glutaric acid, as well as preferably 50 parts to 100 parts, more preferably 60 parts to 90 parts, and even more preferably 75 parts to 85 parts of the adipic acid.
In the present disclosure, the chelating agent includes preferably 100 parts to 200 parts, more preferably 130 parts to 180 parts, and even more preferably 150 parts to 170 parts of the EDTA, as well as preferably 30 parts to 60 parts, more preferably 40 parts to 50 parts, and even more preferably 45 parts of the DTPA.
In the present disclosure, the second alkaline compound is preferably one or more selected from the group consisting of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.
In the present disclosure, the water in the buffer performance protectant is preferably deionized water; and the water has a chloride ion content of preferably less than or equal to 200 mg/L, more preferably less than or equal to 150 mg/L. The water with low chloride ion content can ensure that the buffering synergistic carrier has a low chloride ion concentration, such that equipment such as urine evaporators are not corroded when the carrier is added during the urea production.
In the present disclosure, the buffer performance protectant is used. The precipitant precipitates with the metal ions, and the chelating agent forms a stable chelate with the metal ions. The dual protection of “precipitation-chelation” prevents the precipitation between hydroxyl-containing organic acid and metal ions such as Ca2+, Mg2+, Fe3+, and Al3+ in the soil, thereby avoiding reducing the buffering effect of the pH buffer and reducing the effect of ammonia volatilization.
In the present disclosure, the pH buffer and the buffer performance protectant are at a volume ratio of preferably 1:(0.5-2), more preferably 1:(1-1.5), and even more preferably 1:1.2.
The present disclosure further provides a preparation method of the buffering synergistic carrier, including the following steps:
In the present disclosure, the hydroxyl-containing organic acid is premixed and then mixed with the first alkaline compound and the water to obtain the pH buffer. The water in step (1) is preferably deionized water.
In the present disclosure, the hydroxyl-containing organic acid and the water in step (1) are at a mass ratio of preferably (200-600):1000, more preferably (300-500):1000, and even more preferably (350-400):1000.
In the present disclosure, the chelating agent and the precipitant are premixed and then mixed with the second alkaline compound and the water to obtain the buffer performance protectant. A total mass of the chelating agent and the precipitant and a mass of the water are at a ratio of preferably (100-300):1000, more preferably (150-250):1000, further preferably (180-220):1000.
In the present disclosure, the pH buffer is mixed with the buffer performance protectant to obtain the buffering synergistic carrier. The mixing manner is preferably conducted by stirring.
The present disclosure further provides use of the buffering synergistic carrier or a buffering synergistic carrier prepared by the preparation method in fertilization or buffering synergistic urea granules.
In the present disclosure, the use of the buffering synergistic carrier in the fertilization includes preferably the following steps: mixing the buffering synergistic carrier with urea to obtain a mixed fertilizer, and then applying the mixed fertilizer.
In the present disclosure, the volume-to-mass ratio of the buffering synergistic carrier and the urea is preferably determined based on the soil pH value of a urea application area; and the concentration and pH value of the buffering synergistic carrier are preferably determined based on the soil pH value of the urea application area.
In the present disclosure, the buffering synergistic carrier and the urea are at a volume-to-mass ratio of preferably (2-20) L:1000 kg, more preferably (5-15) L:1000 kg, further preferably (8-12) L:1000 kg.
In the present disclosure, the use of the buffering synergistic carrier in the buffering synergistic urea granules preferably includes a first method and a second method;
the first method is adopted when the buffering synergistic carrier and the urea are at a volume-to-mass ratio of (2-6) L:1000 kg, and includes preferably the following steps:
In the present disclosure, the granulating in the first method is conducted with a particle size of preferably 2 mm to 4 mm, more preferably 2 mm to 3.5 mm, and even more preferably 2 mm to 3 mm.
In the present disclosure, the granulating in the second method is conducted with a particle size of preferably 0.9 mm to 2.5 mm, more preferably 1 mm to 2 mm, and even more preferably 1.5 mm to 2 mm.
In order to further illustrate the present disclosure, the technical solutions provided by the present disclosure are described in detail below in connection with accompanying drawings and examples, but these examples should not be understood as limiting the claimed scope of the present disclosure.
During the application of urea, the buffering synergistic carrier and the urea were mixed at a volume-to-mass ratio of 50:1000 and then applied.
During the application of urea, the buffering synergistic carrier and the urea were mixed at a volume-to-mass ratio of 2:1000 and then applied.
During the conventional urea production (
During the conventional urea production (
During the conventional urea production (
During the conventional urea production (
(1) Ammonium bicarbonate was formed after urea was hydrolyzed. In this test, the ammonium bicarbonate was used to simulate a relatively high ammonia concentration in the urea fertilizer micro-domain.
The buffering synergistic carriers prepared in Examples 4 to 6 with low concentration (21 g/L), medium concentration (38 g/L), and high concentration (55 g/L) were selected, with a pH value of 6. The 3 buffer synergistic carriers were separately mixed with distilled water at a volume ratio of 20:1000 to obtain test buffers, which were recorded as L, M, and H, respectively.
The ammonium bicarbonate and the test buffers were separately evenly mixed according to a fertilizer-to-water ratio of 1:500 to obtain the corresponding ammonium bicarbonate solutions; meanwhile, an ammonium bicarbonate solution of the same concentration was prepared using distilled water as a control (the ammonium bicarbonate solution and distilled water were at a volume ratio of 1:500), recorded as CK.
100 mL of the ammonium bicarbonate solution was placed in a 1 L culture bottle and cultured in a 25° C. climate chamber, and an influence of the buffering synergistic carrier on ammonia volatilization was explored using an “aeration method” to collect NH3 (referring to
As shown in Table 1, the buffering synergistic carrier provided by the present disclosure could significantly reduce the ammonia volatilization loss in the ammonium bicarbonate solution, with an average reduction of 41.1%; where the group H could reduce the ammonia volatilization loss by 47.8%.
Preparation of fertilizers: the buffering synergistic carriers prepared in Examples 4 to 6 with low concentration (21 g/L), medium concentration (38 g/L), and high concentration (55 g/L) at a pH value of 6 were separately added into a urea melt (130° C.) according to a volume-to-mass ratio of 1:100. The obtained products were separately cooled, crushed, and passed through a 0.149 mm sieve to obtain urea samples LU, MU, and HU, respectively, while ordinary urea (U) was used as a control.
The determination of urea conversion rate was based on GB/T 35113-2017. 0.500 g of test urea samples (U, NU, NEU, and NCU) were separately added into 100 mL of a urease solution (activity: 1 U/mg, concentration: 0.15 g/L), and cultured in a (37±2° C.) incubator for 1 h. After measuring using p-dimethylaminobenzaldehyde colorimetric method, the conversion rate of urea was calculated using the following formula. The results were shown in Table 2.
Urea conversion rate (%)=(initial urea nitrogen content−remaining urea nitrogen content after conversion)/initial urea nitrogen content×100
As shown in Table 2, compared with the ordinary urea U, the LU, MU, and HU could all slow down the conversion of urea, with urea conversion rates significantly reduced by 5.78%, 5.95%, and 8.63%, respectively.
The experiment was designed according to the principle of equal nitrogen amount. A nitrogen application rate was 0.3 g/kg of dry soil. 4 treatments were set up: ordinary urea U, low concentration buffering synergistic carrier LU, medium concentration buffering synergistic carrier MU, and high concentration buffering synergistic carrier HU.
An air-dried soil sample equivalent to 100 g of dry soil (passed through a 2 mm sieve) was placed in a culture bottle with a volume of 1,000 mL with a small hole drilled on its lid. The soil moisture content was adjusted to 50% of the maximum water holding capacity in the field, and the soil was pre-cultured for 3 d in a constant-temperature incubator at 25° C. in the dark to activate the activity of soil microorganisms. After the pre-culture, the weighed test fertilizer was added into the soil according to the experimental design, mixed thoroughly and adjusted to a soil moisture content of 20%. NH3 was collected using the “aeration method” (referring to
The data were analyzed using SPSS23 software and Duncan's new multiple range method for variance analysis and correlation analysis, and the results were shown in Table 3.
According to Table 3, compared with the ordinary urea U, the LU, MU, and HU could all slow down the ammonia volatilization in urea, with a reduction ratio reaching up to 33%.
The structures of the products obtained by reacting the buffering synergistic carrier in Use Examples 1 to 6 with urea were characterized, and the results were shown in
It can be seen from the above examples that the buffering synergistic carrier provided by the present disclosure can reduce the ammonia volatilization loss in urea and slow down the conversion of urea into ammonium, thereby coordinating the contradiction between the supply of urea nitrogen fertilizer and the ammonia volatilization loss.
Although the present disclosure is described in detail in conjunction with the foregoing examples, they are only a part of, not all of, the examples of the present disclosure. Other examples can be obtained based on these examples without creative efforts, and all of these examples shall fall within the protection scope of the present disclosure.
This patent application is a national stage application of International Patent Application No. PCT/CN2024/071558, filed on Jan. 10, 2024.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2024/071558 | Jan 2024 | WO |
| Child | 19010139 | US |
