Enhanced efficiency fertilizers (EEFs) have been widely used since they meet the crop nutritional needs and reduce the main problem of leaching. The objective was to evaluate the core-shell structures of the microcapsules by fluorescence microscopy using Rhodamine B (RB) as the fluorescent materials and determine the influence of microsphere or microcapsules on micronutrient release. Starch and poly (vinyl alcohol) - PVA were chosen, respectively, as core and shell of the microcapsules and starch for microsphere. PVA biodegradation increases if combined with starch; an important characteristic of the materials applied to agriculture. Mini Spray Dryer Buchi B-290 with double (2FN) and triple (3FN) atomizer nozzle produced microspheres and microcapsules, correspondingly, with RB and with Fe, Mn and Cu micronutrients. We observed the RB added to the starch allowed the fluorescent identification and location of the encapsulated compound. We observe, from the overlap of fluorescence and bright-field images, the fluorescence in the whole for microspheres, Fig 1. A, and only in the core for microcapsules, Fig 1. B suggesting RB was starch-encapsulated. The micronutrient releases in water show Fe &lt; Cu = Mn for microcapsules and Fe &lt; Cu &lt; Mn for microspheres, Fig 2. The results of release and microscopy corroborate for a shell-core structure where the PVA acts as a diffusion barrier, prolonging the release of the nutrient in water and reducing the initial burst release.

Design materials for agriculture based on microcapsules of PVA/Starch/micronutrients

ACS Spring Meeting 2021

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