The Investigation of Nanoporous Structure Morphology and Elemental Composition of Organo-mineral Fertilizer Granules

Abstract

The structure of carbamide granules, which are encapsulated with an organic shell, is studied in this article. A schematic diagram of an experimental setup for producing organo-mineral fertilizers with a nanoporous shell is proposed. The use of a disk (pan) granulator to encapsulate mineral fertilizers with an organic nanoporous shell has been substantiated. The features of the structure of nanopores that allow to obtain an effective dissolution process of the shell and granule in the soil are presented. Nanoporous structure of the shell is uniform over the entire surface of the shell and occupies from 65 to 75% for different samples. The thickness of the shell in the different parts of the granule is uneven, which requires additional study and correction of the technological parameters of the process. The morphology of the shell's porous structure: rectilinear and curved nanopores, the depth of which ranges from 0.1 to 0.2 of the shell thickness. The pores in shell create a developed structure throughout the entire thickness of the shell, connecting with each other at different depths (thicknesses) of the shell. On the shell surface there is a certain amount of "mechanical" pores, which probably formed during the drying of the sample; the presence of such pores leads to the need to revise the thermodynamic characteristics of the drying process. The elemental composition of the granule core and shell has been studied in order to predict the process of penetration of shell elements into the core within the chosen encapsulation technology. The obtained results allow to improve the technology of obtaining encapsulated fertilizers in pan granulators. Based on the obtained data, it seems possible to improve the algorithm for constructive calculation of the pan granulator.

Encapsulated organic–mineral fertilizers with nanoporous structure

“…The abrasion resistance and high static strength are required to prevent formation of fine particles and caking problems (Crusciol et al 2020). Water sorption from the soil by the fertilizer granules is also important as the granule water content determines the rate of dissolution and chemical diffusion (Thapa et al 2017;Artyukhov et al 2020;Jafari 2017). Soluble fertilizers could be coated in different ways to adjust the nitrogen release: with impermeable membranes, with Sulphur, lignosulphonate, acrylonitrile, or polymer coatings (Patent US 2007/0095118A1 2007).…”

“…This choice is depending on the active component and the acceptable properties of the final product. These characteristics can be reconciled concerning the physicochemical structure of the material in the capsules, the encapsulated product's storage conditions, the scale and density of the materials to be coated in the process, and the economic cost of production (Artyukhov et al 2020;Jafari 2017;Kotenko et al 2019;Vakal et al 2020a, b). For the production of organo-mineral fertilizers with the shell composition, which is discussed in this article, the most effective is the method of pelletizing in a pan granulator (Artyukhov et al 2020).…”

“…These characteristics can be reconciled concerning the physicochemical structure of the material in the capsules, the encapsulated product's storage conditions, the scale and density of the materials to be coated in the process, and the economic cost of production (Artyukhov et al 2020;Jafari 2017;Kotenko et al 2019;Vakal et al 2020a, b). For the production of organo-mineral fertilizers with the shell composition, which is discussed in this article, the most effective is the method of pelletizing in a pan granulator (Artyukhov et al 2020). In this article, we propose multicomponent organo-mineral fertilizers based on carbamide granules with phosphate shell with potassium and calcium humate as a plasticizer, and biochar as the addition to the shell.…”