Elaboração de biofilmes de fécula de mandioca e avaliação do seu uso na imobilização de caulinita intercalada com ureia

Abstract

The study for the use of biofilms in replacing conventional plastic destined to some specific applications has been gaining strength and getting considerable attention in the scenario of renewable resources. Among the numerous applications of biofilms it can be cited its use in the coating of slow release fertilizers. Normally, most of the nitrogen applied as fertilizer in the soil is lost due to processes in which it is subjected to leaching by rain water and volatilization by heat. These losses, in addition to causing injuries to farmers, also cause contamination of soil and water due to excess nutrients leached. With this, it is observed that the slow release fertilizers of nitrogen are a more economical alternative to agriculture and less aggressive to the environment because they can reduce such losses. In this sense, the present work aims to produce a slow release nitrogen material through the lining of kaolinite intercalated with urea using biofilms produced from cassava starch. Biofilms were produced by casting using different concentrations of starch and adding sorbitol. The intercalation of urea in kaolinite was by mechanochemical reaction for 7 hours. Its coating was made from the homogenization of the filmogenic solution of starch with kaolinite intercalated with urea and subsequent dehydration of the material. The heating and leaching tests were performed to determine the nitrogen content in the material. The results obtained from the characterization by Fourier Transformed Infrared Spectroscopy, X-ray Diffractometry, thermal analysis and determination of the nitrogen content by Kjeldahl were promising and showed that the initial nitrogen content is reduced with the increase of leaching time and heating temperature, and that even after submitting the material to a temperature of 200 ° C and leaching for 48 hours, a part of nitrogen remains immobilized in the polymer matrix, corresponding to 35% for the film heated to 200 ° C and 9% for film leached for 48 hours. The results demonstrate that the biofilm containing kaolinite intercalated with urea can present potential for application in the slow release of nitrogen.