Aplicação de amido termoplástico com nanopartículas de quitosana para liberação de nutrientes NPK

Abstract

For this study, thermoplastic starch (TPS) films containing NPK nutrients reinforced with chitosan nanoparticles were produced and characterized, aiming at the adsorption of nutrients to them. A device for slow release of NPK nutrientes as prepared. Starch was chosen as the substrate, because it is a biodegradable polysaccharide and extremely abundant in nature. Chitosan has carrier properties on a nanometric scale, due to the increase in its contact surface and the presence of electrostatic groups in its composition. Nanochitosan was obtained through its ionic gelation, in combination with the radical polymerization of methacrylic acid. Using the dynamic light scattering (DLS) technique, an average size of 130.41 ± 1.45 nm and a zeta potential of 24.7 ± 0.7 mV were observed. Then, NPK nutrients were incorporated into the nanochitosan. The particles obtained were analyzed by transmission electron microscopy (TEM), before and after the incorporation of NPK nutrients. These were added to the preparation of thermoplastic starch (TPS) films by wet casting. The thicknesses of the films with and without nanochitosan did not show significant differences. The films with nanochitosan are more resistant to solubilization compared to films containing only NPK. The films were characterized by infrared spectroscopy (FT-IR) and contact angle analysis. The bands that appear with greater absorption intensity in the films refer to the C-O bonds (1600 cm-1) and the C-O-C bonds (between 750 cm-1 and 1000 cm-1) present in the cyclic rings of the starch structure. The contact angle was greater in the film with nanochitosan, indicating that it is capable of making the film less hydrophilic. Its release was studied in the laboratory, through the analysis of percolated samples of simulated soil in the UV-vis spectrophotometer and in situ, through application in the rooting of vegetatively propagated seedlings of the Trema Micrantha species. The percolated samples with the lowest presence of ions were those obtained from the simulated soil containing the films with nanoparticles. Better rooting was observed among the seedlings with nanoparticles. Therefore, the TPS films containing nanochitosan presented better physical properties and beneficial effect on the rooting of vegetatively propagated seedlings.