Preparation and characterization of Slow Release Formulations of Trifluralin based on alginate Modified Chitosan

Abstract

The aim of this work was to encapsulate the herbicide trifluralin in chitosan-alginate beads and characterize the resulting slow release formulations (SRFs) using scanning electron microscopy (SEM), and Fourier Transform infrared spectroscopy (FTIR). Two sets of formulations were made by extrusion into 0.25 M calcium chloride solution: chitosan core/alginate beads (SCTRF) and alginate core/chitosan beads (SCTRFA). Results showed highly porous spherical beads: the chitosan core/alginate beads were bigger and more porous than the alginate core/chitosan beads with diameters of 2.18±0.01 and 1.78±0.01 mm; porosity of 74.16±0.2% and 16.63±0.2% and swelling of 73.19±0.2% and 14.14±0.2% respectively. Both sets of beads exhibited reduced crystallinity of trifluralin. FTIR revealed a shift to longer wavelength of the band at 1528 cm^-1 which is due to the asymmetric stretching vibration of -NO₂, suggesting that encapsulation of trifluralin in chitosan decreases photolability of the herbicide.