Desenvolvimento e caracterização do ecomaterial quitosana/escama de peixe para sistemas de liberação de defensivos agrícolas

• Ano de defesa: 2013
• Autor(a) principal: Chagas, Renata Almeida
• Orientador(a): Vieira, Eunice Fragoso da Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Química
• Palavras-chave em Português: Peixe - Escamas; Síntese orgânica; Quitosana
• Palavras-chave em Inglês: Chitosan; Organic compounds
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://ri.ufs.br/handle/riufs/6080

By the reaction of the polysaccharide chitosan (Chit) with scales of the Piau fish (ESC) of the species Leporinus elongatus, spheres called ESC-Chit were obtained. These spheres when crosslinked with sodium tetraborate, originated spheres designated ESC-Chit-B. The materials ESC-Chit and ESC-Chit-B were characterized by SEM, FTIR, XRD and TG/DTG. The SEM micrographs showed evidence of the presence of hydroxyapatite in the ESC-Chit spheres and clusters of Borax crystals in the highly rugous surface of the material ESC-Chit-B. In the FTIR spectra significant changes suggesting interactions between the polysaccharide Chit and the scales were observed, thus confirming that new materials were obtained. The X-ray diffractograms suggested that the structure of the crosslinked material, ESC-Chit-B, remained organized. From the thermal analysis it was observed that, due to presence of the hydroxyapatite, the obtained materials are thermally more stable that the chitosan. The spheres ESC-Chit and ESC-Chit-B were used as carrier matrices of the herbicides ATRAZINE and DIURON. The release experiments of the herbicides impregnated in the materials indicated that the release rates of ATRAZINE were higher than the amounts released of DIURON for both materials ESC-Quit (73% and 58%, respectively) and ESC-Chit-B (63% and 46%, respectively). With the purpose to determine the values of the diffusion exponent (n) and the apparent release rate (k), it was applied the linearized form of the power Law. For ATRAZINE impregnated in the material ESC-Chit-B and DIURON impregnated on both materials, the diffusion coefficient values indicated that the releases follow the Anomalous Transport model. However, the value of n concerning to release of the herbicide ATRAZINE impregnated in the material ESC-Chit is not within the range indicative of release mechanisms for controlled release systems with materials of spherical geometries. The material ESC-Chit-B was shown to be very promising for application in systems for sustained release, once the release times were of 6 days for DIURON and of 9 days for the ATRAZINE.