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Previous issue date: 2017-10-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Glyphosate is the most widely used herbicide in the world, due to its broad spectrum of action. But there is a need for reduction measures in its application, due to the risks associated with contamination of water and the environment. The development of controlled release systems appears as an alternative to minimize the application of this herbicide. This work aimed at the preparation of glyphosate-containing Poly (?-caprolactone) (PCL) microspheres. These were characterized as to their morphology, structure, physicochemical properties, and a bioassay was carried out to evaluate their use in rice cultivation, in order to create a possible alternative for the use of these herbicides in plantations. The PCL / glyphosate microspheres produced by the multiple emulsion technique and solvent evaporation were in the form of solid beads with mean sizes of 3 ?m ? 0.6 ?m. It was possible to incorporate 9.3% glyphosate in relation to the polymer mass in the formed particles, revealing an efficiency of incorporation IE of 30.9%. From the techniques used to quantify the incorporated glyphosate (UVvis, TGA and CHN), it can be stated that with the
increase of glyphosate concentration in the formulation there is an increase in its IE.
On the other hand, this increase leads to a decrease in the average size of the
microspheres. The release of the herbicide from the microspheres was evidenced by
bioassays, and in the assessment of the glyphosate release profile of the
microspheres, it can be seen that approximately 17% of the herbicide was released
into the medium, 0.01 M CaCl2 solution at room temperature, after 360 minutes of testing. This study allowed to affirm that the theoretical model described by Korsmeyer-Peppas is adequate to characterize the phenomenon of transport of glyphosate release from the microspheres, revealing an anomalous transport not governed by Fick diffusion. / O glifosato ? o herbicida mais utilizado no mundo, devido ao seu amplo espectro de a??o. Por?m existe a necessidade de medidas de redu??o na sua aplica??o, devido aos riscos associados ? contamina??o da ?gua e do meio ambiente. O desenvolvimento de sistemas de libera??o controlada surge como uma alternativa
para minimizar a aplica??o deste herbicida. Este trabalho teve como objetivo a prepara??o de microesferas de Poli (?-caprolactona) (PCL) contendo glifosato. Estas foram caracterizadas quanto a sua morfologia, estrutura, propriedades f?sicoqu?micas, e ainda, realizou-se um bioensaio para a avalia??o do seu uso na cultura
do arroz, a fim de criar uma poss?vel alternativa para o uso destes herbicidas em planta??es. As microesferas de PCL/glifosato produzidas atrav?s da t?cnica de emuls?o m?ltipla e evapora??o do solvente apresentaram a forma de esferas s?lidas com tamanhos m?dios de 3 ?m ? 0,6 ?m. Foi poss?vel incorporar 9,3% de
glifosato em rela??o ? massa de pol?mero nas part?culas formadas, revelando uma efici?ncia de incorpora??o (EI) de 30,9%. A partir das t?cnicas utilizadas para quantifica??o do glifosato incorporado (UVvis, TGA e CHN), pode-se afirmar que com o aumento da concentra??o de glifosato na formula??o existe um aumento de
sua EI. Por outro lado este aumento acarreta na diminui??o no tamanho m?dio das microesferas. A libera??o do herbicida das microesferas foi evidenciada atrav?s de bioensaios, e na avalia??o do perfil de libera??o do glifosato das microesferas, pode-se constatar que aproximadamente 17% do herbicida foi liberado para o meio, solu??o de CaCl2 0,01 M em temperatura ambiente, ap?s transcorridos 360 minutos de ensaio. Este estudo permitiu afirmar que o modelo te?rico descrito por Korsmeyer-Peppas ? adequado para caracterizar o fen?meno de transporte de libera??o do glifosato das microesferas, revelando um transporte an?malo n?o
governado pela difus?o de Fick.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/8326 |
| Date | 30 October 2017 |
| Creators | Holz, Juliana Pelisoli |
| Contributors | Ligabue, Rosane Ang?lica, Einloft, Sandra Mara Oliveira |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Engenharia e Tecnologia de Materiais, PUCRS, Brasil, Escola Polit?cnica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Hewlett-Packard Brasil Ltda, -7432719344215120122, 500, 500, 600, 4518971056484826825, 2075167498588264571 |
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