Controlled release system for ametryn using polymer microspheres: Preparation, characterization and release kinetics in water
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Data
2011-02-28
Autores
Grillo, Renato [UNESP]
Santo Pereira, Anderson do Espirito
Silva de Melo, Nathalie Ferreira [UNESP]
Porto, Raquel Martins
Feitosa, Leandro Oliveira
Tonello, Paulo Sergio [UNESP]
Dias Filho, Newton L. [UNESP]
Rosa, Andre Henrique [UNESP]
Lima, Renata
Fraceto, Leonardo Fernandes [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Resumo
The purpose of this work was to develop a modified release system for the herbicide ametryn by encapsulating the active substance in biodegradable polymer microparticles produced using the polymers poly(hydroxybutyrate) (PHB) or poly(hydroxybutyrate-valerate) (PHBV), in order to both improve the herbicidal action and reduce environmental toxicity. PHB or PHBV microparticles containing ametryn were prepared and the efficiencies of herbicide association and loading were evaluated, presenting similar values of approximately 40%. The microparticles were characterized by scanning electron microscopy (SEM), which showed that the average sizes of the PHB and PHBV microparticles were 5.92 +/- 0.74 mu m and 5.63 +/- 0.68 mu m, respectively. The ametryn release profile was modified when it was encapsulated in the microparticles, with slower and more sustained release compared to the release profile of pure ametryn. When ametryn was associated with the PHB and PHBV microparticles, the amount of herbicide released in the same period of time was significantly reduced, declining to 75% and 87%, respectively. For both types of microparticle (PHB and PHBV) the release of ametryn was by diffusion processes due to anomalous transport (governed by diffusion and relaxation of the polymer chains), which did not follow Fick's laws of diffusion. The results presented in this paper are promising, in view of the successful encapsulation of ametryn in PHB or PHBV polymer microparticles, and indications that this system may help reduce the impacts caused by the herbicide, making it an environmentally safer alternative. (C) 2010 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
Ametryn, Controlled release, Polymer microparticles, Environmental chemistry
Como citar
Journal of Hazardous Materials. Amsterdam: Elsevier B.V., v. 186, n. 2-3, p. 1645-1651, 2011.