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CN-117303969-B - Controlled-release phosphate fertilizer and preparation and application thereof

CN117303969BCN 117303969 BCN117303969 BCN 117303969BCN-117303969-B

Abstract

The invention belongs to the field of phosphate fertilizers, and particularly relates to a controlled-release phosphate fertilizer which comprises a core, an intermediate layer for coating the core and a shell layer for coating the intermediate layer, wherein the core comprises phosphate fertilizer, the intermediate layer is made of biochar and a phosphorus source adsorbed by the biochar, and the shell layer is made of a heat-treated intermediate layer material. The invention also comprises the preparation and the application of the controlled-release phosphate fertilizer. According to the invention, the biochar of the mixed phosphate fertilizer is taken as a core, the biochar adsorbed with the phosphorus source is taken as an intermediate transition layer, the heat treatment material of the biochar adsorbed with the phosphorus source is taken as a shell layer material, and the cooperation of components and structures can be realized through the joint control of the layers of materials and the special hierarchical structure, so that the gradual transmission of phosphorus from inside to outside can be promoted, the slow release effect of phosphorus can be effectively improved, and in addition, the slow release behavior of phosphorus can be conveniently regulated and controlled based on the use requirements of different plants, so that the controllable slow release of the phosphate fertilizer is realized.

Inventors

  • WANG ZHONGQING
  • NAN HONGYAN

Assignees

  • 郑州大学

Dates

Publication Date
20260508
Application Date
20220620

Claims (13)

  1. 1. The controlled-release phosphate fertilizer is characterized by comprising a core, an intermediate layer for coating the core and a shell layer for coating the intermediate layer; the core comprises phosphate fertilizer and biochar, wherein the phosphate fertilizer is at least one of calcium superphosphate, triple superphosphate and calcium magnesium phosphate fertilizer, and the mass ratio of the biochar to the phosphate fertilizer in the core is 1 (0.5-1); the intermediate layer material is biochar and a phosphorus source adsorbed by the biochar, wherein the phosphorus source is a water-soluble phosphorus-containing compound, and the content of phosphorus element in each gram of biochar in the intermediate layer material is 4-80 mg/g; The shell layer material is a material obtained by heat treatment of an intermediate layer material, wherein the atmosphere in the heat treatment stage is a protective atmosphere, the heat treatment temperature is 300-600 o ℃, the heat treatment time is 50-500 min, phosphorus in the shell layer material is chemically combined in a carbon material in a C-O-P covalent bond mode, and the phosphorus content in each gram of biochar is 3.6-72 mg; The weight ratio of the core to the middle layer to the shell is (1.5-2): (1-2).
  2. 2. The controlled-release phosphate fertilizer of claim 1, wherein the biochar and phosphate fertilizer are homogeneously mixed in the core.
  3. 3. The controlled release phosphate fertilizer of claim 1, wherein the biochar is obtained by carbonization of biomass.
  4. 4. The controlled release phosphate fertilizer of claim 3, wherein the biomass is an organic waste material.
  5. 5. The controlled-release phosphate fertilizer of claim 4, wherein the biomass is at least one of wood chips, peanut shells, and livestock manure.
  6. 6. The controlled-release phosphate fertilizer according to claim 3, wherein the carbonization temperature is 300-600 o ℃; the carbonization time is 50-500 min.
  7. 7. The controlled release phosphate fertilizer of claim 1, wherein the phosphorus source is at least one of phosphate, hydrogen phosphate, and dihydrogen phosphate; and (3) placing the biochar in a phosphorus source-containing aqueous solution, adsorbing under the condition of ultrasonic oscillation, and then carrying out solid-liquid separation and drying treatment to obtain the intermediate layer material.
  8. 8. The controlled-release phosphate fertilizer of claim 7, wherein the aqueous solution of a phosphorus-containing source is a phosphorus-containing wastewater.
  9. 9. The controlled-release phosphate fertilizer according to claim 1, wherein the core has a D50 particle size of 0.074 to 0.1mm, the intermediate layer has a thickness of 0.1 to 0.3mm, and the shell layer has a thickness of 0.1 to 0.9mm.
  10. 10. The controlled-release phosphate fertilizer according to any one of claims 1 to 9, wherein the core, the intermediate layer and the shell layer are mutually compounded by a binder, and the binder is at least one of an aqueous polyvinyl alcohol solution, an aqueous povidone solution, an aqueous hypromellose solution and a starch slurry.
  11. 11. The controlled-release phosphate fertilizer according to claim 10, wherein the total content of the binder in the controlled-release phosphate fertilizer is 0.5 to 1wt%.
  12. 12. A method for preparing the controlled release phosphate fertilizer according to any one of claims 1 to 11, wherein the core surface is coated with an intermediate layer material, and then coated with a shell layer material.
  13. 13. The use of a controlled release phosphate fertilizer according to any one of claims 1 to 11 as a slow release fertilizer for phosphorus.

Description

Controlled-release phosphate fertilizer and preparation and application thereof Technical Field The invention belongs to the field of fertilizers, and particularly relates to a controlled-release phosphate fertilizer. Background Phosphorus is an essential element of all organisms and plays a unique and critical role in food-energy-water connection, and more importantly, the demand for foodstuffs by rapidly growing populations is severely dependent on agricultural phosphate, and the proportion of biofuel production in the agricultural sector is also increasing, which leads to an increased demand for phosphate. These man-made phosphate fertilizers are mainly derived from geological phosphorite exploitation, and the position and total reserves of geological phosphorite are limited worldwide. In fact, several recent studies predict that, according to the current exploitation rate, the geological phosphorite reserves which can be exploited at present will be exhausted within 50 to 100 years, and this unbalance of phosphorus demand and phosphorus resources has raised great attention to phosphorus resource exhaustion and grain safety. On the other hand, the utilization efficiency of phosphorus by human beings is quite low, a large amount of phosphorus is lost in fertilizer production and soil application, food production and processing and waste treatment processes, and phosphorus runoff in these processes is one of main factors of water eutrophication and forms a great threat to the ecological system and human health. Disclosure of Invention Aiming at the problems that the prior phosphate fertilizer is unsatisfactory in slow release effect, difficult to controllably slow release and the like, the first aim of the invention is to provide a controlled-release phosphate fertilizer which aims at improving the slow release effect and is beneficial to the controllable slow release. The second object of the invention is to provide the preparation and application of the phosphate fertilizer slow release. A controlled release phosphate fertilizer comprises a core, an intermediate layer for coating the core and a shell layer for coating the intermediate layer; The core contains phosphate fertilizer; The intermediate layer material is biochar and a phosphorus source adsorbed by the biochar; The shell layer material is a material of the intermediate layer material after heat treatment. According to the invention, the biochar of the mixed phosphate fertilizer is taken as a core, the biochar adsorbed with the phosphorus source is taken as an intermediate transition layer, the heat treatment material of the biochar adsorbed with the phosphorus source is taken as a shell layer material, and the cooperation of components and structures can be realized through the joint control of the layers of materials and the special hierarchical structure, so that the gradual transmission of phosphorus from inside to outside can be promoted, the slow release effect of phosphorus can be effectively improved, and in addition, the slow release behavior of phosphorus can be conveniently regulated and controlled based on the use requirements of different plants, so that the controllable slow release of the phosphate fertilizer is realized. In the invention, the control of the components of each layer and the hierarchical composite structure is the key for synergistically improving the sustained and controlled release effect of the phosphate fertilizer. In the invention, the phosphate fertilizer in the core is a conventional phosphate fertilizer known in the industry, such as at least one of calcium superphosphate, triple superphosphate and calcium magnesium phosphate fertilizer. Preferably, the core further comprises biochar, and preferably, the biochar and the phosphate fertilizer are uniformly mixed. The invention discovers that the biochar is added in the core, so that the synergism of the components and the hierarchical structure can be further improved, and the sustained release effect of phosphorus can be further improved. In the invention, in the core, the mass mixing ratio of the biochar to the phosphate fertilizer is 1 (0.5-1). In the present invention, the biochar (e.g., additional biochar in the core and biochar before adsorbing the phosphorus source in the intermediate layer) can be prepared based on existing means, e.g., by conventional biomass carbonization. In the invention, the biomass is a biomass raw material well known in the industry, and can be at least one of wood chips, peanut shells and livestock manure in consideration of waste utilization and recycling. Preferably, the carbonization temperature is 300-600 ℃, preferably 300-500 ℃; preferably, the carbonization time is 50-500 min. In the invention, the intermediate layer is biochar with phosphorus source adsorbed on the surface. In the biochar loaded with the phosphorus source formed in the adsorption mode, the adsorbed phosphorus is combined with the surface of the biochar