Biodegradable Nanocomposite Microcapsules for Controlled Release of Urea

Abstract

Urea is the most used fertilizer around the world as the main source of nitrogen to soil and plants. However, the administration of nitrogen dosage is critical, as its excess can be harmful to the environment. Therefore, the encapsulation of urea to achieve control on its release rates has been considered in several areas. In this work, encapsulation of urea by biodegradable polymer poly(3-hydroxybutyrate) (PHB) and its nanocomposites, namely PHB/MMT and PHB/OMMT, producing microcapsules by emulsion method is carried out. MMT and OMMT refer to Brazilian clays in a natural state and organophilized, respectively. In addition, the microcapsules are thus prepared to have their physicochemical characteristics investigated, then tested for biodegradation. Increment of microcapsules’ crystallinity due to the increased amount of poly(vinylacetate) (PVA), as emulsifier agent in the continuous phase, was confirmed by X-ray diffractometry (XRD) and atomic force microscopy (AFM). The presence of urea within microcapsules was verified by XRD, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The soil biodegradation assessments showed that PHB/OMMT microcapsules present higher degradation rates in sandy soils. The overall results suggest that the composites performed better than neat PHB and are very promising; moreover, PHB/OMMT microcapsules proved to be the best candidate for the controlled-release of urea in soils.

Poly(3-hydroxybutyrate) Nanocomposites with Cellulose Nanocrystals

“…[ 28 ] and agriculture (carriers for the slow release of pesticides, herbicides, fertilizers etc.) [ 29 ]. However, the high degree of crystallinity of PHB [ 30 ] that imparts brittleness [ 14 ], the thermal degradation at temperatures just above its melting temperature [ 31 ] that narrows its processing window [ 26 ], the low elongation at break [ 32 ] and the high production costs [ 14 ], are serious disadvantages which have restrained the use of PHB on a large scale [ 33 ].…”

Microencapsulation for Functional Textile Coatings with Emphasis on Biodegradability—A Systematic Review

“…In the available literature, there are only a limited number of studies [194][195][196] that focussed on and specifically investigated the biodegradation of microcapsules. Since there is no standardised test method to evaluate the biodegradability of microcapsules, the next step would be to develop guidelines for testing or to create a new standard.…”

Enhancing Pectin Particles with Polymer Additives: Mitigating Rumen Degradation and Minimizing Yellowish Milk Color in Grazed Cows

“…Given the processing parameters, microparticles can be synthesized by spray drying [ 2 ], in situ polymerization [ 3 ], biological techniques, precipitation, and slow carbonation [ 4 ]. In contrast to nanometric scale objects, these structures’ micrometric architecture facilitates their handling and controlled release of additives, antimicrobials, flavoring agents, pigments, and fertilizers [ 5 , 6 ]. The encapsulation efficiency, release, permeability, solubility, and desired performance of microcapsules can vary in accord with the components of shell materials and their properties [ 1 ].…”