Estudo e desenvolvimento de métodos de revestimentos a partir da metilcelulose em fertilizante nitrogenado

Abstract

This work aimed to study and develop coating techniques for urea, using methylcellulose as a coating polymer. The development of coating techniques consisted of investigating processes by immersion and spraying, which would enable the proper coating of fertilizers using as main parameters: the contact time of the polymer solution with the fertilizer, the percentage of loss of fertilizer. Three procedures were developed for each type of coating, resulting in a total of six procedures. The pure fertilizer and the coated fertilizers were characterized through the techniques of Spectroscopy in the Infrared Region with Fourier Transform (FTIR), Thermogravimetric/Differential Thermal Analysis (TGA/DTG), and Elemental Analysis (CHN). The FTIR and CHN characterizations were not conclusive to the presence of the polymeric coating on the fertilizer, possibly due to the high amounts of fertilizer that mask the effect of the presence of the film. Notwithstanding, the thermogravimetric analyzes proved that MC not only improved the thermal behavior of the urea but also increased the stability of the fertilizer in the main events of thermal decompositions. The coating technique developed with the best results was subjected to optimization by Doehlert Matrix, to investigate the best coating condition. The concentration of MC 4.63 %m/m in Ethanol/water (50/50) %v/v and the application of two coats were found to be the best condition. In the next steps, the in vitro release studies of coated urea in the optimized coating conditions will be of primary interest to better understand the influence and interactions established between urea and its coating and to assess the potential of the coating used for the controlled release of nutrients.